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RGP wettability: the first day could be the worst day!
Clinical Article
RGP Wettability: The First Day Could Be the Ur,rst Day! Sylvie Bourassa, OD, MS, and William J. Benjamin,
Rigid gas permeable (RGP) contact lenses tend to lose in-eye wettabiliry when their surfaces have been exposed to various waxy and oily substances. Several of these substances may come in contact with lens surfaces during the manufacturing process, during shipment of lenses to the practitioner, and during in-office handling of lenses before lenses are dispensed. In this report, we have documented that ww RGP lenses can be less wettable and the frequency of nonwetting episodes significantly higher on the first day of wear, using several wetting-related clinical and luboratory assessments: The in viva contact angle, lens-surface breakup time, levels of deposition and discomfort, and verified presence or absence of functional wetability. The clinical impression that surface wettubility can be a formidable probkm during the first day of new lens wear has been confirmed. A multifaceted solution to the “first-day nonwetting syndrome” has been suggested, involving cooperation between manufacturer, practitioner, office sraff, and patients. The practitioner must lead a diligent and fastidious effort with several individuals in order to ensure optimum in-eye wetting of rigid contact lenses when dispensed at the office. Keywords:
Rigid gas permeable
contact
lenses; wettability
Introduction Contact lens practitioners are too often confronted with a rigid gas permeable (RGP) contact lens that does not wet properly when first inserted on the patient’s eye. The lens
OD, PhD
may quickly accumulate a coating visible under the biomicroscope and the lens-surface breakup time (LBUT) might be short, less than 1 second in duration and often close to zero. These instances of poor functional wettability can occur when lenses are first dispensed to a new contact lens wearer or when new replacement lenses are dispensed to veteran wearers. The functionally nonwetting area of the front lens surface may be large, perhaps covering the entire lens surface. The practitioner is in the unenviable situation of figuring out what may or may not be causing decreased surface wettability and managing a patient with unacceptable comfort, acuity, and physiological compatibility with contact lenses that were just inserted. The practitioner’s credibility and reputation are on the line, at least with the individual patient who is in the chair! Recently, we completed reports’V2 on the wettability of four rigid contact lens materials, focusing on the (1) overall relationships between five different gauges of wetting, i.e., the in viva contact angle, LBUT, level of visible deposition, level of discomfort, and verified presence of extremely poor and excellent functional wettability; and (2) influence of several study parameters on wettability, i.e., patient, contact lens material, and care regimen. We now focus on the effects of wearing duration on wettability measured in our study, in the hope of shedding light on the perceived clinical problem of reduced initial functional wettability when new lenses are dispensed.
Methods Address reprint requests to Dr. William J. Benjamin at the School of Optometry, University of Alabama at Birmingham, University Station, Birmingham, AL 35294. Accepted
for publication
November
0 1992 Butterworth-Heinemann
5, 1991.
The techniques and methodology of our investigation have been documented in detail within our earlier reports. le2 However, a brief description is included here with respect to revealing effects of lens wear duration. Sixteen
ICE,
Vol. 19, January/February
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25
Clinical Article previously successful daily wearers of RGP contact lenses wore lenses manufactured from four different rigid materials over a 4-month period, using two care regimens that were identical except for the preservative in the overnight soaking solution. The lens materials were Silafocon A (Polycon II), Paraperm EW, Boston IV, and Boston Equalens. The experimental design was double-masked and counterbalanced, such that by the end of the study each patient had worn each lens material/care regimen combination on each eye for 1 month in a daily wear manner. Patients were required to be at our clinic on the day of dispense of new lenses (day 1) and days 2, 15, 29, and 30 of each month of lens wear (20 days in all). Lenses and care regimens were replaced monthly. Measurements of LBUT and determination of in viva contact angle were performed 15 minutes after lens insertion (“0” hour), then again at 4, 8, and 12 hours of lens wear on each day of measurement, with the exception of day 15 of each month in which the 12-hour visit was omitted. Because of missed appearances, occasional instrumentation failures, and sometimes noncompliance, a total of 2,128 LBUTs and in viva contact angles were accumulated during the course of the study, or 87.5% of a possible 2,432 measurements of each parameter had all visits been successfully attended. At the end of each day of testing, the levels of deposition on the surface of each patient’s lenses were observed with a biomicroscope and graded from 0 (minimum) to 4 (maximum) in increments of 1.0 according to the classification system shown in our previous report.’ In addition, each patient was asked to grade the level of discomfort for both lenses at the end of every day on a O-4 scale in increments of 1.0. This resulted in 631 gradings of deposition and of discomfort at the end of a day’s wear, or 98.6% of a possible 640 determinations for each grading system. Three different manufacturers produced lenses for the study. Unfortunately, considerable time has passed since this study was performed (accumulation of data ended in 1987), and the “first-day nonwetting” phenomenon was a recent incidental finding. Therefore, the exact manner in which each of the three lens manufacturers ensured surface quality of the lenses received at our clinic are unknown. The duration of daily wear was 30 days (1 month) before lenses were replaced. Each contact lens was dispensed new, having been previously cleaned and soaked overnight with the care regimen prior to dispense. Basically, we did what we thought occurred in the offices of many practitioners: We took what the manufacturer supplied us with, cleaned the lenses with a normal contact lens cleaner, and soaked the lenses overnight prior to dispense. Results The four wetting parameters analyzed (in viva contact angle, LBUT, deposition, and discomfort) have been shown to be significantly correlated with each other, although the correlations between individual pairs of these
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ICLC, Vol. 19, January/February
1992
measures were moderate or low. ’ Considering the four factors to give an overall impression of “wettability,” the multivariate approach to analysis of variance (ANOVA) was initially undertaken for data recorded at the end of each day of testing to ascertain which independent variables influenced the four measured parameters in the aggregate. These variables, or treatment effects, were patient (PAT), lens material (MAT), care regimen (REG), day of wear (DAY), and hour of wear (HR). A statistical approach was then taken to perform univariate ANOVAs on each of the dependent variables. All ANOVAs used a pooled error (residual) term resulting from nonsignificant treatments and interactions.’ Although the distributions of contact angle and LBUT were not normal and levels of deposition and discomfort were not on a continuous (ratio) scale, statistical evaluations were, nevertheless, handled parametrically. 3,4 Significant treatments and interactions involving DAY and HR are shown in Tabk 1 of the Appendix. Influence of Wearing Duration: Day of the Month The reader will note from Table 1 of the Appendix that the following treatment effects and interactions involving day of wear (DAY) were significant for all dependent variables with only one exception: DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY’ Tukey’s multiple comparison tests were applied between days of wear for each dependent variable. These results, shown in Table 2 of the Appendix, signified that RGP wettability was significantly worse on the first day of wear in terms of in oivo contact angle, deposition, and discomfort. Also, in terms of LBUT, wettability was not significantly different for the first day than on those days in which LBUT was lowest. Thus, the overall effect of DAY in the multivariate ANOVA was explained, with respect to decreased wettability of lenses on the first day of wear. Mean values for the dependent variables for each day of wear are shown in Figure 1. In Table I, the overall lens material X day of wear (MAT x DAY) interaction was statistically significant in terms of contact angle and LBUT. Therefore, all four lens materials did not behave in an identical fashion in terms of their daily wettabilities over the 1 month of wear, as shown overall in Figure 1. When sorted by lens material, Tukey multiple comparisons between days of wear (p < 0.05) revealed that mean in viva contact angles on the first day were highest or tied for highest for all the lens materials, thus supporting the overall trend. The effect of “day” was significant for two of the lens materials in terms of LBUT
* Not significant only for level of deposition (DEP).
RGP wet&&y: (Polycon II and Paraperm EW, p < 0.01). However, there were only two pairwise comparisons that were significant at the p < 0.05 level, and we could not detect a discernible pattern from them. Therefore, the overall trend in Figure 1 with respect to LBUT was supported. In our earlier reports, 1,2 80 instances were recorded in which functional wettability was verifiably poor (absent). These were instances in which all four of the dependent variables simultaneously indicated that functional wetting losses had occurred: The in viva contact angle was greater than or equal to 20”, the LBUT was less than or equal to 5 seconds, and the levels of deposition and discomfort were equal to or greater than grade 2. Verified presence of functional wettability totaled 278 instances when the contact angle was less than 20”, LBUT was greater than 5 seconds, and levels of deposition and discomfort were less than grade 2. Sorted by day of wear, frequencies of presence and lack of functional wettability are shown in Figure 2 (taken from Table 3 of the Appendix). Double asterisks mark the frequencies of those days of wear that were outside the 95% confidence limit surrounding the mean frequency calculated by excluding the frequency of the indicated day. The reader will note that the first day of lens wear was significantly associated with the highest number of functional wettability losses. Although not significantly lower in terms of frequency, the first day was associated with the lowest number of verified instances of excellent wettability.
I
’
I
10 -
I
I
I
. CONTACT ANGLE 0 LBUT
!!Li 9
2
. 1
I
I
I
0 DEPOSITION 0 DISCOMFORT
??WElTlNG
SW
0
2
:
:s
$9
40
DAY OF WEAR Figure 1. Mean in viva contact angles, lens-surface break-up times (LBUTs), and levels of deposition and discomfort, sorted by day of wear. Values have been taken from Table 2.
IF
LOSS
EXCELLENT WE’ITING
15
29
30
DAY OF WEAR
Figure 2. Frequencies of presence and absence of functional wettability, sorted by day of wear. Values have been taken from Tuble 3. To inspect interactions between patient and day Tukey multiple comparisons (PAT x DAY interactions), were analyzed between days for patients whose lens wettability was significantly influenced by day of wear and are reported in Table 5. These patients were selected based on ANOVAs performed on data sorted by patient and summarized in Table 4. In terms of at least one of the wetting related parameters noted in Tables 4 and 5, the main treat, ment effect of “DAY” influenced data of each patient with the exception of patients 2, 3, and 5. Tabk 6 reveals that, in terms of all dependent variables except LBUT, the first day of wear was the most associated with decreased wettability. These statistics further corroborate the overall comparisons shown in Tables 2 and 3. Multiple comparisons inspecting the two prevalent ter, tiary interactions involving DAY (PAT X REG X DAY and PAT X MAT X DAY interactions) are summarized in Table 7 of the Appendix. It appears that, although analysis of the overall effect of “DAY” and the patient interaction with DAY (PAT x DAY interaction) showed overwhelms ingly that the first day was the “worst” day for RGP wettability overall, there were a limited number of statistically supportable instances when patients encountered adequate or even excellent wettability on the first day of wear. These instances were highly dependent on patient, lens material, care regimen, and the particular wetting-related factor that was analyzed. influence of Daily Wearing Duration:
;
Bourassa and Benjamin
Hour of the Day
Effects of wearing duration during the day could only be analyzed in terms of in viva contact angle and LBUT, for only these determinations were made during the day at 0 (15 minutes postinsertion), 4, 8, and 12 hours of daily lens wear. Table 1 shows significant patient x hour (PAT x HR) interactions for contact angle and LBUT, and a significant overall main effect of hour (HR) in terms of contact angle (but not for LBUT). A significant tertiary interaction (PAT X DAY X HR) was present for LBUT. Tukey’s multiple comparisons between hours of wear are
ICLC, Vol. 19, January/February
1992
27
Clinical Article I
I
I
I
I
.
- 10
CONTACT ANGLE
1-_
-6
E
-5 I
I
I
I
0
4
a
12
HOURS OF WEAR Figure 3. Mean in viwo contact angles and lens-surface break-up times (LBUTs) sorted by hour of wear. Values have been taken from Table 8.
shown in Table 8 of the Appendix and show that in viva contact angles were significantly higher at the beginning of a day’s wear. Day x hour interactions were not statistically significant for contact angle or LBUT. Mean values for the dependent variables at each hour of wear are shown in Figure 3. Data for seven of the 16 contact lens wearers were influenced by duration of wear in hours, as shown in Tuble 9. These data have been inspected in Table 10, which summarizes the outcomes of multiple comparisons between hours of wear for each patient in which the main effect of “hour” was found to be significant. Particularly in terms of in vitro contact angle, wetting was worse at the beginning of the day (hour 0). This helps to confirm that wetting was found least acceptable in this study 15 minutes after RGP lens insertion. Three patients had regimen X hour interactions and according to Tabk 9. three had day x hour interactions These have been inspected and are summarized in T&e I I. Evidently, there were only a very small number of instances for which statistically supportable evidence indicated better wetting at the beginning of the wearing day.
lenses on the second day of wear. The pertinent graph from that stud+ has been republished in Figure 4, with data points representing mean values computed from a study total of 3 12 contact angles. Note that previously worn RGP lenses began the day with a lower contact angle (better wettability) than did new lenses and that the situation was reversed at the end of the day. As the previous study5 was not designed to specifically look at the wetting of new vs. old lenses, there were several aspects of the study that could have accounted in total or in part for a wettability difference between previously worn and new lenses. First, the previously worn lenses had been maintained over their lifetimes by several care regimens other than the single regimen utilized during the earlier study. Because new RGP lenses were treated with one care regimen during their one-day lifetimes, as were the previously worn lenses only on the first day of study, it was possible that wetting was differentially influenced between the two lens groups. Second, the lenses used on the first day and on the second day of the study were different lenses. Any alterations of surface characteristics due to changes in manufacturing technique or polymer chemistry for the new lenses (on day 2) that had just been manufactured, or the previously manufactured and well-worn lenses (on day l), could have contributed to the wettability differences then attributed to the “newness” of the lenses. Third, the study was limited to one RGP polymer material that happened to be a “stocked” device (Polycon II) produced at a single facility for worldwide distribution. It is possible that the surface quality and cleanliness of the final product at that time could have been maintained at a different standard than is customary for some local rigid contact lens manufacturers. Fourth, the “old” lenses could have had preexisting remnants of coatings that promoted biocompatibility when first inserted, but also promoted deposit buildup over the course of a day’s wear that became deleterious to excellent surface wettability. Because the present study found an increased rate of functional wettability loss on the first
15 -1
Discussion Instances of functionally poor RGP lens wettability seem to more frequently occur when new lenses are initially worn, both for new rigid contact lens wearers at their first dispensation of lenses, as well as for veteran wearers when lenses are replaced. These instances also seem to occur after the first day of wear, when lenses are improperly handled and prepared prior to insertion by office staff or patients. A wettability difference between new and used RGP lenses was previously noted5 in 1986, with reference to the in vioo contact angle. In that report, in uivo contact angles were monitored over 2 days of wear, for which 13 patients wore their current lenses (mean lens age 8.2 months, range 1-21 months) on the first day and were supplied with new RGP
28
ICLC, Vol. 19, January/February
1992
;1 ;
.
MEAN, N I 26, “OLD” LENSES
0
MEAN, N = 26, “NEW” LENSES
Ii
!il 1121:
HOURS OF WEAR Figure 4. Graph republished from ICLC, 5 comparing in viva contact angles throughout a day of wear for “new” and “old” rigid contact lenses.
RGP wettability: Bourassa and Benjamin day of wear (Figure 2), it is interesting to note that more “new” lenses (lenses that were worn for only 1 day) developed functional wettability loss during that earlier study5 than did “old” lenses (five new lenses vs. three old lenses). Our present study was also not designed to specifically investigate wetting differences between “new” and “old” lenses. Even so, upon inspection, we feel that the design eliminated some notable disadvantages of the earlier study5 (1) by using the same lenses for follow up as when first worn; (2) by treatment of lenses with the same care regimens over I month lifetimes of daily wear; (3) by completion of a larger, more comprehensive investigation involving several lens polymer materials, including the Polycon II and three other lenses obtained from local manufacturers; and (4) by use of several measurements related to RGP surface wettability. Lens material X hour of wear (MAT X HR) interactions for data accumulated only on the first day of wear were statistically insignificant (Table I). Thus, all four lens materials behaved in a statistically indistinguishable fashion in terms of their hourly wettabilities over the course of a day, as shown overall in Figure 3. Comparing Figure 3 with the “flat” curve from “new” lenses in Figure 4 (from the earlier study5), we note the curves are much different. One might have thought that the curves would be similar. The difference is unexplained, but perhaps may be due to (1) a difference in quality or cleaning of lens surfaces at the manufacturer between the dates of the two studies; (2) a difference between surface preparation prior to insertion between the two studies; or (3) a difference between lens materials not statistically discerned in the present study. Here, the clinical impressions that RGP lenses do not wet as well when first dispensed new, and that there is an increased frequency of functionally nonwetting lenses when first worn, have been confirmed with lenses treated in a manner that, we feel, occurs in many practitioners’ offices. RGP wettability was significantly reduced during the first day of wear and was generally reduced at the beginning of days of wear. The most likely explanations for the “firstday” episodes of nonwetting phenomena are that (A) lenses received from manufacturers often have surface residues that are incompatible with proper wetting. These residues may be the result of improper, incomplete, or lack of cleaning prior to shipment and/or surface residues acquired from plastic “flatpacks” (contact lens cases) into which lenses are placed for shipment. It is possible that a certain small degree of residual surface residue may be unavoidable; and (B) other factors, such as improper, incomplete, or lack of lens maintenance (cleaning and wet storage/hydration) at the practitioner’s office or by the patient before dispensing of lenses to patients and/or improper, incomplete, or lack of hand washing and lens treatment at the office or by the patient prior to insertion of lenses on the eye. Many of these factors have been covered in detail by Grohe and Caroline, 6 and have been implicated in nonwetting episodes other than those occurring with new lenses.
“First-Day Nonwetting Syndrome”: A Potential Solution Little, if any, data are available to confirm the efficacy of many clinical and laboratory approaches to solving the formidable “first-day nonwetting” syndrome. 6 Based on clinical experience and “sage advice” of a few rigid lens manufacturers7 and practitioners,’ it appears that a systematic solution involving several surface preparation issues can dramatically increase the initial wettability of rigid lenses and reduce the frequency of functional nonwetting during the first day of wear. First, practitioners should select rigid lens manufacturers who pay attention to surface preparation and cleanliness during the manufacturing process and during shipment of lenses to the office. As a first step in the cleaning process, solvents such as “Universal Solvent” (Universal Photonics, Inc., Hicksville, NY) can be used to remove blocking pitch and other waxy or tarlike substances from RGP lens surfaces. This practice dates back to the “PMMA” days (before the advent of soft or RGP lenses), when “lighter fluid” was used as a cleaner by manufacturers and practitioners alike. Several soaps, such as Johnson & Johnson Baby Shampoo, Lobob contact lens cleaner, or some dishwater liquids, can be used next to clean lenses during and after the manufacturing process to remove oils and solvents from the lenses. Special lab cleaners have been developed to remove pitch and other sticky (oily, waxy) materials from lens surfaces. These include Fluorosolve (Paragon Optical, Mesa, AZ) and Boston Lab Cleaner (Polymer Technology, Boston, MA). Even though all these steps are utilized to reduce the quantity of unwanted substances on lens surfaces, however, it is possible that residual residues may remain on these surfaces. In addition, the surfaces of storage compartments in flatpacks or other contact lens containers should be cleaned before these devices are used to store rigid lenses. Otherwise, residues from the manufacture of these plastic containers may be transferred to the surfaces of rigid lenses during storage and shipment to the practitioner’s office. The least residue left on a lens prior to receipt at the office will be best for practitioner and patient. Sherman Laboratories’ De-Stat 3 may act as an effective intermediate agent between lens manufacture and receipt of lenses at the office. This solution is a special combination cleaning and storage solution that is used by some manufacturers as a final cleaning agent for lenses and storage cases after use of a lab cleaner and for storage during shipment to the practitioner’s office. Thus, an additional cleaning step takes place before shipment with a solution FDA-approved for lens maintenance by patients. The FDA does not, however, approve of the wet shipment of rigid lenses and many manufacturers are reluctant to ship their lenses in such a manner. During shipment, the solution may continue to “soften” residue on the surfaces of lenses and storage case compartments and may decrease the tendency for storage case contaminants to produce the “nonwetting” syndrome. 6 L enses can arrive at the practitioner’s
ICLC, Vol. 19, January/February
1992
29
Clinical Article office with surfaces hydrated. Hydration of lens surfaces for 48 hours has been claimed6 to help permit removal of oils and waxes from lens surfaces by care regimens prior to insertion. Assuming that rigid lenses were properly cleaned, conditioned, and delivered by the manufacturer, it would be a shame if lens surfaces were then recontaminated during verification and inspection procedures or preparatory to being inserted on the eye at the practitioner’s office. Staff responsible for handling rigid lenses should be educated to remove oily or waxy substances from their hands before touching lenses. Soaps containing lanolin or other waxes and oils should not be used. Staff members should be careful not to contaminate lenses with eye cosmetics that get on the hands. If such substances prove difficult to remove from the hands, in some cases it can be beneficial after regular hand washing to additionally clean, with a contact lens cleaner such as Sherman Lab’s De-Stat 3 or a lab cleaner such as Paragon Optical’s Fluorosolve, areas on the hand that come in direct contact with lenses. Based on past clinical performance of RGP lenses, the practitioner could be satisfied that his/her chosen manufacturer has adequately cleaned, prepared, and shipped RGP lenses to the office. If not hydrated prior to receipt at the office, lenses should ideally be cleaned and soaked at least overnight (48 hours would be better) with the practitioner’s selected care regimen before dispensing to patients. When not certain that lens surfaces are received as pristine as possible, RGP lenses can be cleaned at the office with a lab-strength cleaner (Fluorosolve or Boston Lab Cleaner) before lenses are again cleaned and soaked with a contact lens care regimen. It is important to remove residual labstrength cleaner from lens surfaces before dispensation of lenses to the patient. This multifaceted approach to solving the “first-day nonwetting” syndrome can only work with the cooperation of the manufacturer, practitioner, staff, and contact lens wearer. As ultimate responsibility for patient care rests with the contact lens practitioner, he/she must coordinate a consistently fastidious effort in many areas and with several individuals in order to optimize wettability of rigid lenses dispensed from the office and to minimize the “first-day nonwetting” syndrome of rigid contact lenses. In addition to small variations in lens parameters, such as those involving edge contour and peripheral lens design, reduced wettability on the first day of wear may be responsible for lens awareness not encountered by patients with their previous (old) contact lenses. If awareness of the new lens is due to surface residue, in many cases, the awareness will subside after a day or so. Proper patient education and troubleshooting in matters of cleanliness, soaps, oils, waxes, hairsprays, deodorants, and cosmetics can help reduce the frequency of later instances of the “nonwetting syndrome.“6 Occasional instances of nonwetting will continue to occur, however, when incompatibilities arise between lens materials and
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ICLC, Vol. 19, January/February
1992
tear fluid (during lens wear) or the skin of the patient’s hand (during lens maintenance). In these few instances, substances deleterious to excellent surface wettability cannot be reasonably eliminated from contacting RGP lens surfaces, and practitioners may urge patients to consider other contact lens or corrective options.
Acknowledgments This study was funded by a grant from Allergan Optical, Inc., a division of Allergan, Inc., to W.J.B. with the understanding that results could be published regardless of outcome. The authors have no financial interest in the funding agency and its parent company or subsidiaries, including no consultational arrangements or travel grants. The authors do not derive indirect monetary benefit from Allergan Optical, Inc., for invitations to symposia made on the basis of recommendation by Allergan Optical, Inc., as a sponsor of those events. Approval for use of human subjects came
from a university-affiliated
institutional
review
board.
References 1. Bourassa S, Benjamin WJ: Clinical findings correlated with contact angles on rigid gas permeable contact lens surfaces in ho. J Am Opom Assoc 1989;60(8):584-590. 2. Benjamin WJ, Bourassa S: Comparison of two contact lens storage solution preservatives with respect to in-eye wetting of rigid oxygen-permeable lens surfaces and related factors. ICLC 1989;16(9,10):273-301. 3. Keppel G: Assumptions and other considerations, in Keppel G (Ed): Design and Analysis, A Researcher’s Handbook. Englewood Cliffs, NJ, Prentice-Hall, 1982, pp. 85-86. 4. Gaito J: Measurement scales and statistics: Resurgence of an old misconception. Psych Bull 1980;87:564-567. 5. Benjamin WJ, Yeager MD, Desai NN, Carmichael CA: In vivo analysis of contact angles. ICLC 1986;14(3):58-61. 6. Grohe RM, Caroline PJ: RGP non-wetting syndrome. Contact Lens Spectrum 1989;4(3):32-44. 7. Personal conversations with Mr. Quid0 Capelli, of Capelli Ophthalmics, Tuckahoe, NY, and Mr. Al Blackbum, of Metro Optics, Dallas TX, 1991. 8. Personal conversations with Dr. N. Rex Ghormley of St. Louis, MO, and Dr. Lamar Zigler of Columbus, OH, 1991.
Appendix Table 1. Overall Statistical
Analyses
Dependent Variable
Independent Variable
Viue
MULTI MULTI MULTI MULTI
DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY
O.OcOl 0.0001 0.0006 0.0001
CA CA CA
DAY HR PAT PAT MAT PAT PAT
0.0001 0.0001 0.0001 0.0002 0.0001 0.0001 0.0001
:: CA CA
x DAY x HR x DAY x MAT x DAY x REG x DAY
RGP wettubility: Bourassa and Benjamin Dependent Variable
Independent Variable
P
Value
LBUT LBUT LBUT LBUT LBUT LBUT LBUT
DAY PAT PAT MAT PAT PAT PAT
0.0001 0.0001 0.0001 0.0008 0.0001
DEP DEP DEP
DAY PAT x DAY PAT x REG x DAY
0.0001 0.0001 0.0001
DIS DIS DIS DIS
DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY
0.0001 0.0001 0.0048
x DAY x HR x DAY x MAT x DAY x REG x DAY x DAY x HR
Table 3. Verified Instances of Functional
Functional Wettability
1 30 29 2 15
8.8710.43 7.4710.33 7.3310.34 7.1610.33 6.9810.42
29 30 15 1 2
B A A A A Deposition
Day 1 2 15 30 29
c B AB A A
Mean/SEM A
6.8810.22 6.3110.17 6.2610.18 6.2210.19 5.7810.17
B CB CB c Discomfort
Mean&EM
Day
1.15/0.10 0.8610.08 0.6410.09 0.52lO.07 0.43IO.07
1 29 2 30 15
Mea&EM B A A A A
1.52/0.11 1.14/0.08 1.06/0.08 1.03lO.08 1.00/0.07
For each wetting parameter, days of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of days. Days covered by the same letter for a particular parameter were found not to be significantly different from each other. Days not covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of rev sponse, L.e., A = most desirable, B = less desirable, and C = least desirable.
Mean SD
16.0 13.7
55.6 7.6
Dependent Variable
Effects Involving
Day
VaZe
LBUT DEP DIS
DAY DAY DAY
0.0098 0.0037 0.0062
CA LBUT
REG x DAY DAY x HR
0.0068 0.0010
LBUT DIS
MAT x DAY MAT x DAY
0.0026 0.0032
CA LBUT DIS
DAY DAY DAY
0.0014 0.0001 0.0034
CA
DIS
REG x DAY REG x DAY
0.0053 0.0009
6 6 6 6 6
CA CA LBUT DEP DIS
DAY DAY x HR DAY REG x DAY REG x DAY
0.0006 0.0034 0.0042 0.0008 0.0028
7 7
LBUT DIS
REG x DAY DAY
0.0074 0.0002
8 8 8 8
CA CA CA LBUT
DAY MAT x DAY DAY x HR DAY x HR
0.0001 0.0001 0.0001 0.0040
9 9 9 9 9 9
LBUT DEP DEP DIS DIS DIS
REG DAY REG DAY MAT REG
x DAY x DAY
0.0075 0.0005 0.0009 0.0002 0.0003 0.0001
10 10 10
CA LBUT LBUT
MAT x DAY DAY MAT x DAY
0.0001 0.0055 0.0007
11 11 11
LBUT DEP DIS
REG x DAY DAY DAY
0.0056 0.0004 0.0060
LBUT Day
47 51 67” 58 55
Independent Variable
Patient
(p < 0.05) between Days of Wear
MeanfSEM
40” 6 10 14 10
Table 4. Significant Main and Interactive of Wear, Sorted by Patient (p < 0.01)
Table 2. Overall Tukey’s Multiple Comparison Tests
hY
2 15 29 30
Frequencies of presence and absence of functional wettability are listed according to criteria outlined in the text and have been sorted by day of wear. Double asterisks indicate frequencies outside 95% confidence intervals.
well as for the multivariate ANOVA. The ANOVAs concerning contact angle (CA) and lens-surface breakup time (LBUT) were derived from data accumulated throughout each day (N = 2128). Treatment effects are labeled PAT (patient), MAT (lens material), REG (care regimen), DAY (day of wear), and HR (hour of wear during the day, but only for dependent variables CA and LBUT).
Contact Angle
Present
1
0.0001
An analysis of variance (ANOVA) was performed for each of the dependent variables and in a multivariate mode (MULTI) using error terms pooled from nonsignificant effects within the models. Shown here are those significant effects and interactions involving duration of lens wear (DAY and HR, p < 0.01). The analyses are for data recorded at the end of the day (N = 63 1) concerning dependent variables deposition (DEP) and discomfort (DIS) as
Absent
Day of Wear
0.0001
0.0001
Wettability
x DAY x DAY
ICLC, Vol. 19, January/February
1992
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Clinical Article
Patient
Dependent Variable
Independent Variable
Va?ue
DIS DIS
DAY REG x DAY
0.0024 0.0051
13 13 13 13 13
CA LBUT LBUT DEP DEP
REG x DAY DAY REG x DAY DAY REG x DAY
0.0044 0.0037 0.0002 0.0002 0.0002
14 :: 14
CA CA LBUT LBUT
DAY MAT x DAY MAT x DAY REG x DAY
0.0056 0.0001 0.0001 0.0001
12
15 15 15 15 15
% LBUT DEP DIS
DAY REG x DAY REG x DAY DAY DAY
O.OCOl 0.0024 0.0043 0.0001 0.0001
13
16 16
CA DIS
REG x DAY DAY
0.0071 0.0028
Patient
Contact Angle
1
4
6
LBUT
Deposition
Discomfort
15 A 29 AB 1 AB 30 B 2 B
2B 1 BA 30 BA 15 A 29 A
1B 2 BA 29 BA 15 A 30 A
30 B 1B 29 B 2 BA 15 A
29 A 15 AB 30 AB 1 BC 2 c
1B 15 BA 30 A 2 A 29 A
29 A 1A 15 AB 2 AB 30 B
1B 2 BA 15 BA 30 BA 29 A
15 B 29 A 1 A 2 A 30 A
7
8
LBUT
Deposition
Discomfort
11
1B 15 2 30 29
A A A A
15 B 30 BA 29 BA 1 A 2 A 29 B 1B 2 BA 30 BA 15 A
29 A 30 AB 1 AB 15 AB 2B
14
1B 30 B 29 BA 2 A 15 A
15
1B 29 2 30 15
1c 2 CB 15 BA 30 A 29 A
1c 2 B 15 BA 30 BA 29 A
A A A A
16
IB 29 2 15 30
A A A A
1B 2 BA 15 A 29 A 30 A
For each patient and wetting parameter found to have a significant “DAY” effect in Table 4, days of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of days. Days covered by the same letter for a particularparameter were found not to be significantly different from each other. Days nor covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of response, i.e., A = most desirable, B = less desirable, and C = least desirable.
Table 6. Summary of Multiple Comparisons between Days of Wear, Sorted by Patient Patient X Day Interaction
15 B 1B 2 BA 29 A 30 A
Best
Same
Worse
CA LBUT
0
0 3
5 1
DEP DIS
:2
:
2
Total
3
4
16
Parameter
1B 2B 30 BA 15 A 29 A
9
10
Contact Angle
1 AB 2 AB 15 B
12 12
Table 5. Tukey’s Multiple Comparison Tests (p < 0.05) between Days of Wear, Sorted by Patient, for Each Significant Main-Day Effect
32
Patient
29 A 30 AB
ICLC, Vol. 19, January/February
1992
1B 29 BA 15 BA 2 BA 30 A
The results of Tukey’s multiple comparisons for each patient in T&k 5 showing at least one significant pairwise comparison are summarized. The frequencies with which the first day was (A) the best day or statistically indistinguishable from the day of
RGP wettability: Bourassa and Benjamin best wetting (BEST); (B) not significantly different than either best or worst day in terms of wettability (SAME); and (C) the worst day or statistically indistinguishable from the day of worst wetting (WORSE) are listed for each wetting-related parameter.
Table 7. Inspection of Wear
of Tertiary Interactions
Involving
Patient
Dependent Variable
Independent Variable
P
Value
8 8 8 8 8 8
CA CA CA CA LBUT LBUT
HR MAT REG DAY HR DAY
9 9
CA LBUT
HR HR
0.0002 0.0037
Worse
10
LBUT
REG x HR
0.0001
11
LBUT
REG x HR
0.0031
13
LBUT
HR
0.0002
14
CA
HR
0.0009
Day
0.0015 0.0029 0.0001 0.0001 0.0065 0.0040
x HR x HR x HR x HR
Tertiary Interactions PAT x REG x Parameter
Best
CA LBUT DEP DIS
1 1 0 1
Total
3
PAT x MAT x DAY
DAY
Same
Worse
Best
3 4 1 2
1 3 2 1
3 :
0 E,
2
0
3 0 0 2
10
7
9
1
5
Same
Tukey’s multiple comparisons (p < 0.05) were performed for every patient in Table 4 shown to have a significant regand the results imen X day or material X day interaction, of comparisons showing at least one significant day compari, son are summarized. The frequencies with which the first day was (A) the best day or statistically indistinguishable from the day of best wetting (BEST); (B) not significantly different than either best or worst day in terms of wettability (SAME); and (C) the worst day or statistically indistinguishable from the day of worst wetting (WORSE) are listed for each wetting-related parameter.
Table 8. Overall Tukey’ s Multiple Comparison (p < 0.05) between Hours of Wear Contact Hour 0
12 4 8
B A A A
Tests
LBUT
Angle MeanlSEM
Hour
9.1810.42 7.5210.45 7.0210.26 6.7510.24
0 8 4 12
Mean&EM A A A A
64210.17 6.2710.14 62610.15 6.0510.22
For each wetting parameter, hours of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of hours. Hours covered by the same letter for a particular parameter were found not to be significantly different from each other. Hours not covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of response, i.e., A = most desirable and B = least desirable.
Table 9. Significant Main and Interactive Effects Involving Hour of Wear, Sorted by Patient (p < 0.01)
Patient
Dependent Variable
Independent Variable
V&e
:
LBUT LBUT
HR DAY x HR
0.0058 0.0010
6 6
CA CA
!:Y
0.0003 0.0034
7
CA
HR
x HR
0.0010
Table 10. Summary of Multiple Comparisons Wear, Sorted by Patient Patient
between
Hours of
X Hour Interaction
Parameter
Best
Same
Worse
CA LBUT
0 2
0 0
5 2
Total
2
0
7
The results of Tukey’s multiple comparisons for each patient in Table 9 showing at least one significant pairwise comparison are summarized. The frequencies with which wettability after insertion at hour “0” was (A) the best hour or statistically indistinguishable from the hour of best wetting (BEST); (B) not significantly different from either best or worst hour in terms of wettability (SAME); and (C) the worst hour or statistically indistinguishable from the hour of worst wetting (WORSE) are listed for the two wetting-related parameters that were recorded hourly.
Table 11. Inspection of Wear
of Tertiary Interactions
Involving
Hour
Tertiary Interactions PAT x REG x HOUR
PAT x DAY x HOUR
Parameter
Best
Same
Worse
Best
Same
Worse
CA LBUT
0 1
0 0
1 2
2 2
0 0
2 1
Total
1
0
3
4
0
3
Tukey’s multiple comparisons (p < 0.05) were performed for every patient in Table 9 shown to have a significant regimen X hour or day X hour interaction, and the results of comparisons showing at least one significant hour comparison are summarized. The frequencies with which wettability after insertion at hour “0” was (A) the best hour or statistically indistinguishable from the hour of best wetting (BEST); (B) not significantly different than either best or worst hour in terms of wettability (SAME); and (C) the worst hour or statistically indistinguishable from the hour of worst wetting (WORSE) are listed for the two wetting-related parameters that were recorded hourly. ICLC, Vol. 19, January/February
1992
33
Clinical Artick Clinical
Implications
RGP nonwetting is the most common yet easiest to correct complication among rigid lens wearers. The authors have demonstrated through a carefully controlled study and statistical analysis that the first day of RGP wear will most likely be the poorest surface wetting day. By correlating dependent variables of deposition, discomfort, contact angle, and LBUT with independent variables relating to the patient, lens material, or care regimen, it is quite apparent that many complex interactions are occurring. There are multiple causes of RGP nonwetting, including the manufacturer, clinician, staff, and contact lens wearer. By using reputable and “authorized” laboratories, most cases of manufacturer nonwetting can be avoided. Clinicians and their staff need to remain militant in properly verifying, handling, and storing RGPs prior to dispensing. Contact lens wearers must be instructed, then periodically reminded, about the proper use of skin care products, especially in avoiding moisturized soaps. Clinicians now have a significant array of in-office lab cleaners to attack RGP nonwetting. Mild nonwetting due to moisturizer contamination can be treated with combination surfactant cleaners such as the Boston or Sherman lab cleaners. Moderate nonwetting due to waxy manufacturing residues respond well to the Fluorosolve solvent cleaner. Also, an unapproved but highly effective cleaner for severe RGP nonwetting is Miraflow, an alcohol-based cleaner. The ultimate treatment is still using special care in handling lenses and avoiding known contaminants. Robert M. Grohe, OD 18019 Dixie Hwy. Homewood, IL 60430
William “Joe” Benjamin received his OD and PhD degrees from The Ohio State University in Columbus, and is now an Associate Professor at the School of Optometry/The Medical Center, University of Alabama at Birmingham. He is a fellow of the American Academy of Optometry, an American Optometric Association representative to the American National Standards Institute and International Standards Organization, and a council member of the International Society for Contact Lens Research. His interests include the impact of contact lenses on the physiology of the eye and interactions of tear fluid with contact lenses and cornea. His work has included initial studies of rigid extended wear, in viva measurements of surface wettability, and physiology of the eye and tear fluid under conditions of lid closure and contact lens wear. Dr. Benjamin is a contributing editor for International Contact Lens Clinic.
34
ICLC, Vol. 19, January/February
1992
RGP Wettability: The First Day Could Be the Ur,rst Day! Sylvie Bourassa, OD, MS, and William J. Benjamin,
Rigid gas permeable (RGP) contact lenses tend to lose in-eye wettabiliry when their surfaces have been exposed to various waxy and oily substances. Several of these substances may come in contact with lens surfaces during the manufacturing process, during shipment of lenses to the practitioner, and during in-office handling of lenses before lenses are dispensed. In this report, we have documented that ww RGP lenses can be less wettable and the frequency of nonwetting episodes significantly higher on the first day of wear, using several wetting-related clinical and luboratory assessments: The in viva contact angle, lens-surface breakup time, levels of deposition and discomfort, and verified presence or absence of functional wetability. The clinical impression that surface wettubility can be a formidable probkm during the first day of new lens wear has been confirmed. A multifaceted solution to the “first-day nonwetting syndrome” has been suggested, involving cooperation between manufacturer, practitioner, office sraff, and patients. The practitioner must lead a diligent and fastidious effort with several individuals in order to ensure optimum in-eye wetting of rigid contact lenses when dispensed at the office. Keywords:
Rigid gas permeable
contact
lenses; wettability
Introduction Contact lens practitioners are too often confronted with a rigid gas permeable (RGP) contact lens that does not wet properly when first inserted on the patient’s eye. The lens
OD, PhD
may quickly accumulate a coating visible under the biomicroscope and the lens-surface breakup time (LBUT) might be short, less than 1 second in duration and often close to zero. These instances of poor functional wettability can occur when lenses are first dispensed to a new contact lens wearer or when new replacement lenses are dispensed to veteran wearers. The functionally nonwetting area of the front lens surface may be large, perhaps covering the entire lens surface. The practitioner is in the unenviable situation of figuring out what may or may not be causing decreased surface wettability and managing a patient with unacceptable comfort, acuity, and physiological compatibility with contact lenses that were just inserted. The practitioner’s credibility and reputation are on the line, at least with the individual patient who is in the chair! Recently, we completed reports’V2 on the wettability of four rigid contact lens materials, focusing on the (1) overall relationships between five different gauges of wetting, i.e., the in viva contact angle, LBUT, level of visible deposition, level of discomfort, and verified presence of extremely poor and excellent functional wettability; and (2) influence of several study parameters on wettability, i.e., patient, contact lens material, and care regimen. We now focus on the effects of wearing duration on wettability measured in our study, in the hope of shedding light on the perceived clinical problem of reduced initial functional wettability when new lenses are dispensed.
Methods Address reprint requests to Dr. William J. Benjamin at the School of Optometry, University of Alabama at Birmingham, University Station, Birmingham, AL 35294. Accepted
for publication
November
0 1992 Butterworth-Heinemann
5, 1991.
The techniques and methodology of our investigation have been documented in detail within our earlier reports. le2 However, a brief description is included here with respect to revealing effects of lens wear duration. Sixteen
ICE,
Vol. 19, January/February
1992
25
Clinical Article previously successful daily wearers of RGP contact lenses wore lenses manufactured from four different rigid materials over a 4-month period, using two care regimens that were identical except for the preservative in the overnight soaking solution. The lens materials were Silafocon A (Polycon II), Paraperm EW, Boston IV, and Boston Equalens. The experimental design was double-masked and counterbalanced, such that by the end of the study each patient had worn each lens material/care regimen combination on each eye for 1 month in a daily wear manner. Patients were required to be at our clinic on the day of dispense of new lenses (day 1) and days 2, 15, 29, and 30 of each month of lens wear (20 days in all). Lenses and care regimens were replaced monthly. Measurements of LBUT and determination of in viva contact angle were performed 15 minutes after lens insertion (“0” hour), then again at 4, 8, and 12 hours of lens wear on each day of measurement, with the exception of day 15 of each month in which the 12-hour visit was omitted. Because of missed appearances, occasional instrumentation failures, and sometimes noncompliance, a total of 2,128 LBUTs and in viva contact angles were accumulated during the course of the study, or 87.5% of a possible 2,432 measurements of each parameter had all visits been successfully attended. At the end of each day of testing, the levels of deposition on the surface of each patient’s lenses were observed with a biomicroscope and graded from 0 (minimum) to 4 (maximum) in increments of 1.0 according to the classification system shown in our previous report.’ In addition, each patient was asked to grade the level of discomfort for both lenses at the end of every day on a O-4 scale in increments of 1.0. This resulted in 631 gradings of deposition and of discomfort at the end of a day’s wear, or 98.6% of a possible 640 determinations for each grading system. Three different manufacturers produced lenses for the study. Unfortunately, considerable time has passed since this study was performed (accumulation of data ended in 1987), and the “first-day nonwetting” phenomenon was a recent incidental finding. Therefore, the exact manner in which each of the three lens manufacturers ensured surface quality of the lenses received at our clinic are unknown. The duration of daily wear was 30 days (1 month) before lenses were replaced. Each contact lens was dispensed new, having been previously cleaned and soaked overnight with the care regimen prior to dispense. Basically, we did what we thought occurred in the offices of many practitioners: We took what the manufacturer supplied us with, cleaned the lenses with a normal contact lens cleaner, and soaked the lenses overnight prior to dispense. Results The four wetting parameters analyzed (in viva contact angle, LBUT, deposition, and discomfort) have been shown to be significantly correlated with each other, although the correlations between individual pairs of these
26
ICLC, Vol. 19, January/February
1992
measures were moderate or low. ’ Considering the four factors to give an overall impression of “wettability,” the multivariate approach to analysis of variance (ANOVA) was initially undertaken for data recorded at the end of each day of testing to ascertain which independent variables influenced the four measured parameters in the aggregate. These variables, or treatment effects, were patient (PAT), lens material (MAT), care regimen (REG), day of wear (DAY), and hour of wear (HR). A statistical approach was then taken to perform univariate ANOVAs on each of the dependent variables. All ANOVAs used a pooled error (residual) term resulting from nonsignificant treatments and interactions.’ Although the distributions of contact angle and LBUT were not normal and levels of deposition and discomfort were not on a continuous (ratio) scale, statistical evaluations were, nevertheless, handled parametrically. 3,4 Significant treatments and interactions involving DAY and HR are shown in Tabk 1 of the Appendix. Influence of Wearing Duration: Day of the Month The reader will note from Table 1 of the Appendix that the following treatment effects and interactions involving day of wear (DAY) were significant for all dependent variables with only one exception: DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY’ Tukey’s multiple comparison tests were applied between days of wear for each dependent variable. These results, shown in Table 2 of the Appendix, signified that RGP wettability was significantly worse on the first day of wear in terms of in oivo contact angle, deposition, and discomfort. Also, in terms of LBUT, wettability was not significantly different for the first day than on those days in which LBUT was lowest. Thus, the overall effect of DAY in the multivariate ANOVA was explained, with respect to decreased wettability of lenses on the first day of wear. Mean values for the dependent variables for each day of wear are shown in Figure 1. In Table I, the overall lens material X day of wear (MAT x DAY) interaction was statistically significant in terms of contact angle and LBUT. Therefore, all four lens materials did not behave in an identical fashion in terms of their daily wettabilities over the 1 month of wear, as shown overall in Figure 1. When sorted by lens material, Tukey multiple comparisons between days of wear (p < 0.05) revealed that mean in viva contact angles on the first day were highest or tied for highest for all the lens materials, thus supporting the overall trend. The effect of “day” was significant for two of the lens materials in terms of LBUT
* Not significant only for level of deposition (DEP).
RGP wet&&y: (Polycon II and Paraperm EW, p < 0.01). However, there were only two pairwise comparisons that were significant at the p < 0.05 level, and we could not detect a discernible pattern from them. Therefore, the overall trend in Figure 1 with respect to LBUT was supported. In our earlier reports, 1,2 80 instances were recorded in which functional wettability was verifiably poor (absent). These were instances in which all four of the dependent variables simultaneously indicated that functional wetting losses had occurred: The in viva contact angle was greater than or equal to 20”, the LBUT was less than or equal to 5 seconds, and the levels of deposition and discomfort were equal to or greater than grade 2. Verified presence of functional wettability totaled 278 instances when the contact angle was less than 20”, LBUT was greater than 5 seconds, and levels of deposition and discomfort were less than grade 2. Sorted by day of wear, frequencies of presence and lack of functional wettability are shown in Figure 2 (taken from Table 3 of the Appendix). Double asterisks mark the frequencies of those days of wear that were outside the 95% confidence limit surrounding the mean frequency calculated by excluding the frequency of the indicated day. The reader will note that the first day of lens wear was significantly associated with the highest number of functional wettability losses. Although not significantly lower in terms of frequency, the first day was associated with the lowest number of verified instances of excellent wettability.
I
’
I
10 -
I
I
I
. CONTACT ANGLE 0 LBUT
!!Li 9
2
. 1
I
I
I
0 DEPOSITION 0 DISCOMFORT
??WElTlNG
SW
0
2
:
:s
$9
40
DAY OF WEAR Figure 1. Mean in viva contact angles, lens-surface break-up times (LBUTs), and levels of deposition and discomfort, sorted by day of wear. Values have been taken from Table 2.
IF
LOSS
EXCELLENT WE’ITING
15
29
30
DAY OF WEAR
Figure 2. Frequencies of presence and absence of functional wettability, sorted by day of wear. Values have been taken from Tuble 3. To inspect interactions between patient and day Tukey multiple comparisons (PAT x DAY interactions), were analyzed between days for patients whose lens wettability was significantly influenced by day of wear and are reported in Table 5. These patients were selected based on ANOVAs performed on data sorted by patient and summarized in Table 4. In terms of at least one of the wetting related parameters noted in Tables 4 and 5, the main treat, ment effect of “DAY” influenced data of each patient with the exception of patients 2, 3, and 5. Tabk 6 reveals that, in terms of all dependent variables except LBUT, the first day of wear was the most associated with decreased wettability. These statistics further corroborate the overall comparisons shown in Tables 2 and 3. Multiple comparisons inspecting the two prevalent ter, tiary interactions involving DAY (PAT X REG X DAY and PAT X MAT X DAY interactions) are summarized in Table 7 of the Appendix. It appears that, although analysis of the overall effect of “DAY” and the patient interaction with DAY (PAT x DAY interaction) showed overwhelms ingly that the first day was the “worst” day for RGP wettability overall, there were a limited number of statistically supportable instances when patients encountered adequate or even excellent wettability on the first day of wear. These instances were highly dependent on patient, lens material, care regimen, and the particular wetting-related factor that was analyzed. influence of Daily Wearing Duration:
;
Bourassa and Benjamin
Hour of the Day
Effects of wearing duration during the day could only be analyzed in terms of in viva contact angle and LBUT, for only these determinations were made during the day at 0 (15 minutes postinsertion), 4, 8, and 12 hours of daily lens wear. Table 1 shows significant patient x hour (PAT x HR) interactions for contact angle and LBUT, and a significant overall main effect of hour (HR) in terms of contact angle (but not for LBUT). A significant tertiary interaction (PAT X DAY X HR) was present for LBUT. Tukey’s multiple comparisons between hours of wear are
ICLC, Vol. 19, January/February
1992
27
Clinical Article I
I
I
I
I
.
- 10
CONTACT ANGLE
1-_
-6
E
-5 I
I
I
I
0
4
a
12
HOURS OF WEAR Figure 3. Mean in viwo contact angles and lens-surface break-up times (LBUTs) sorted by hour of wear. Values have been taken from Table 8.
shown in Table 8 of the Appendix and show that in viva contact angles were significantly higher at the beginning of a day’s wear. Day x hour interactions were not statistically significant for contact angle or LBUT. Mean values for the dependent variables at each hour of wear are shown in Figure 3. Data for seven of the 16 contact lens wearers were influenced by duration of wear in hours, as shown in Tuble 9. These data have been inspected in Table 10, which summarizes the outcomes of multiple comparisons between hours of wear for each patient in which the main effect of “hour” was found to be significant. Particularly in terms of in vitro contact angle, wetting was worse at the beginning of the day (hour 0). This helps to confirm that wetting was found least acceptable in this study 15 minutes after RGP lens insertion. Three patients had regimen X hour interactions and according to Tabk 9. three had day x hour interactions These have been inspected and are summarized in T&e I I. Evidently, there were only a very small number of instances for which statistically supportable evidence indicated better wetting at the beginning of the wearing day.
lenses on the second day of wear. The pertinent graph from that stud+ has been republished in Figure 4, with data points representing mean values computed from a study total of 3 12 contact angles. Note that previously worn RGP lenses began the day with a lower contact angle (better wettability) than did new lenses and that the situation was reversed at the end of the day. As the previous study5 was not designed to specifically look at the wetting of new vs. old lenses, there were several aspects of the study that could have accounted in total or in part for a wettability difference between previously worn and new lenses. First, the previously worn lenses had been maintained over their lifetimes by several care regimens other than the single regimen utilized during the earlier study. Because new RGP lenses were treated with one care regimen during their one-day lifetimes, as were the previously worn lenses only on the first day of study, it was possible that wetting was differentially influenced between the two lens groups. Second, the lenses used on the first day and on the second day of the study were different lenses. Any alterations of surface characteristics due to changes in manufacturing technique or polymer chemistry for the new lenses (on day 2) that had just been manufactured, or the previously manufactured and well-worn lenses (on day l), could have contributed to the wettability differences then attributed to the “newness” of the lenses. Third, the study was limited to one RGP polymer material that happened to be a “stocked” device (Polycon II) produced at a single facility for worldwide distribution. It is possible that the surface quality and cleanliness of the final product at that time could have been maintained at a different standard than is customary for some local rigid contact lens manufacturers. Fourth, the “old” lenses could have had preexisting remnants of coatings that promoted biocompatibility when first inserted, but also promoted deposit buildup over the course of a day’s wear that became deleterious to excellent surface wettability. Because the present study found an increased rate of functional wettability loss on the first
15 -1
Discussion Instances of functionally poor RGP lens wettability seem to more frequently occur when new lenses are initially worn, both for new rigid contact lens wearers at their first dispensation of lenses, as well as for veteran wearers when lenses are replaced. These instances also seem to occur after the first day of wear, when lenses are improperly handled and prepared prior to insertion by office staff or patients. A wettability difference between new and used RGP lenses was previously noted5 in 1986, with reference to the in vioo contact angle. In that report, in uivo contact angles were monitored over 2 days of wear, for which 13 patients wore their current lenses (mean lens age 8.2 months, range 1-21 months) on the first day and were supplied with new RGP
28
ICLC, Vol. 19, January/February
1992
;1 ;
.
MEAN, N I 26, “OLD” LENSES
0
MEAN, N = 26, “NEW” LENSES
Ii
!il 1121:
HOURS OF WEAR Figure 4. Graph republished from ICLC, 5 comparing in viva contact angles throughout a day of wear for “new” and “old” rigid contact lenses.
RGP wettability: Bourassa and Benjamin day of wear (Figure 2), it is interesting to note that more “new” lenses (lenses that were worn for only 1 day) developed functional wettability loss during that earlier study5 than did “old” lenses (five new lenses vs. three old lenses). Our present study was also not designed to specifically investigate wetting differences between “new” and “old” lenses. Even so, upon inspection, we feel that the design eliminated some notable disadvantages of the earlier study5 (1) by using the same lenses for follow up as when first worn; (2) by treatment of lenses with the same care regimens over I month lifetimes of daily wear; (3) by completion of a larger, more comprehensive investigation involving several lens polymer materials, including the Polycon II and three other lenses obtained from local manufacturers; and (4) by use of several measurements related to RGP surface wettability. Lens material X hour of wear (MAT X HR) interactions for data accumulated only on the first day of wear were statistically insignificant (Table I). Thus, all four lens materials behaved in a statistically indistinguishable fashion in terms of their hourly wettabilities over the course of a day, as shown overall in Figure 3. Comparing Figure 3 with the “flat” curve from “new” lenses in Figure 4 (from the earlier study5), we note the curves are much different. One might have thought that the curves would be similar. The difference is unexplained, but perhaps may be due to (1) a difference in quality or cleaning of lens surfaces at the manufacturer between the dates of the two studies; (2) a difference between surface preparation prior to insertion between the two studies; or (3) a difference between lens materials not statistically discerned in the present study. Here, the clinical impressions that RGP lenses do not wet as well when first dispensed new, and that there is an increased frequency of functionally nonwetting lenses when first worn, have been confirmed with lenses treated in a manner that, we feel, occurs in many practitioners’ offices. RGP wettability was significantly reduced during the first day of wear and was generally reduced at the beginning of days of wear. The most likely explanations for the “firstday” episodes of nonwetting phenomena are that (A) lenses received from manufacturers often have surface residues that are incompatible with proper wetting. These residues may be the result of improper, incomplete, or lack of cleaning prior to shipment and/or surface residues acquired from plastic “flatpacks” (contact lens cases) into which lenses are placed for shipment. It is possible that a certain small degree of residual surface residue may be unavoidable; and (B) other factors, such as improper, incomplete, or lack of lens maintenance (cleaning and wet storage/hydration) at the practitioner’s office or by the patient before dispensing of lenses to patients and/or improper, incomplete, or lack of hand washing and lens treatment at the office or by the patient prior to insertion of lenses on the eye. Many of these factors have been covered in detail by Grohe and Caroline, 6 and have been implicated in nonwetting episodes other than those occurring with new lenses.
“First-Day Nonwetting Syndrome”: A Potential Solution Little, if any, data are available to confirm the efficacy of many clinical and laboratory approaches to solving the formidable “first-day nonwetting” syndrome. 6 Based on clinical experience and “sage advice” of a few rigid lens manufacturers7 and practitioners,’ it appears that a systematic solution involving several surface preparation issues can dramatically increase the initial wettability of rigid lenses and reduce the frequency of functional nonwetting during the first day of wear. First, practitioners should select rigid lens manufacturers who pay attention to surface preparation and cleanliness during the manufacturing process and during shipment of lenses to the office. As a first step in the cleaning process, solvents such as “Universal Solvent” (Universal Photonics, Inc., Hicksville, NY) can be used to remove blocking pitch and other waxy or tarlike substances from RGP lens surfaces. This practice dates back to the “PMMA” days (before the advent of soft or RGP lenses), when “lighter fluid” was used as a cleaner by manufacturers and practitioners alike. Several soaps, such as Johnson & Johnson Baby Shampoo, Lobob contact lens cleaner, or some dishwater liquids, can be used next to clean lenses during and after the manufacturing process to remove oils and solvents from the lenses. Special lab cleaners have been developed to remove pitch and other sticky (oily, waxy) materials from lens surfaces. These include Fluorosolve (Paragon Optical, Mesa, AZ) and Boston Lab Cleaner (Polymer Technology, Boston, MA). Even though all these steps are utilized to reduce the quantity of unwanted substances on lens surfaces, however, it is possible that residual residues may remain on these surfaces. In addition, the surfaces of storage compartments in flatpacks or other contact lens containers should be cleaned before these devices are used to store rigid lenses. Otherwise, residues from the manufacture of these plastic containers may be transferred to the surfaces of rigid lenses during storage and shipment to the practitioner’s office. The least residue left on a lens prior to receipt at the office will be best for practitioner and patient. Sherman Laboratories’ De-Stat 3 may act as an effective intermediate agent between lens manufacture and receipt of lenses at the office. This solution is a special combination cleaning and storage solution that is used by some manufacturers as a final cleaning agent for lenses and storage cases after use of a lab cleaner and for storage during shipment to the practitioner’s office. Thus, an additional cleaning step takes place before shipment with a solution FDA-approved for lens maintenance by patients. The FDA does not, however, approve of the wet shipment of rigid lenses and many manufacturers are reluctant to ship their lenses in such a manner. During shipment, the solution may continue to “soften” residue on the surfaces of lenses and storage case compartments and may decrease the tendency for storage case contaminants to produce the “nonwetting” syndrome. 6 L enses can arrive at the practitioner’s
ICLC, Vol. 19, January/February
1992
29
Clinical Article office with surfaces hydrated. Hydration of lens surfaces for 48 hours has been claimed6 to help permit removal of oils and waxes from lens surfaces by care regimens prior to insertion. Assuming that rigid lenses were properly cleaned, conditioned, and delivered by the manufacturer, it would be a shame if lens surfaces were then recontaminated during verification and inspection procedures or preparatory to being inserted on the eye at the practitioner’s office. Staff responsible for handling rigid lenses should be educated to remove oily or waxy substances from their hands before touching lenses. Soaps containing lanolin or other waxes and oils should not be used. Staff members should be careful not to contaminate lenses with eye cosmetics that get on the hands. If such substances prove difficult to remove from the hands, in some cases it can be beneficial after regular hand washing to additionally clean, with a contact lens cleaner such as Sherman Lab’s De-Stat 3 or a lab cleaner such as Paragon Optical’s Fluorosolve, areas on the hand that come in direct contact with lenses. Based on past clinical performance of RGP lenses, the practitioner could be satisfied that his/her chosen manufacturer has adequately cleaned, prepared, and shipped RGP lenses to the office. If not hydrated prior to receipt at the office, lenses should ideally be cleaned and soaked at least overnight (48 hours would be better) with the practitioner’s selected care regimen before dispensing to patients. When not certain that lens surfaces are received as pristine as possible, RGP lenses can be cleaned at the office with a lab-strength cleaner (Fluorosolve or Boston Lab Cleaner) before lenses are again cleaned and soaked with a contact lens care regimen. It is important to remove residual labstrength cleaner from lens surfaces before dispensation of lenses to the patient. This multifaceted approach to solving the “first-day nonwetting” syndrome can only work with the cooperation of the manufacturer, practitioner, staff, and contact lens wearer. As ultimate responsibility for patient care rests with the contact lens practitioner, he/she must coordinate a consistently fastidious effort in many areas and with several individuals in order to optimize wettability of rigid lenses dispensed from the office and to minimize the “first-day nonwetting” syndrome of rigid contact lenses. In addition to small variations in lens parameters, such as those involving edge contour and peripheral lens design, reduced wettability on the first day of wear may be responsible for lens awareness not encountered by patients with their previous (old) contact lenses. If awareness of the new lens is due to surface residue, in many cases, the awareness will subside after a day or so. Proper patient education and troubleshooting in matters of cleanliness, soaps, oils, waxes, hairsprays, deodorants, and cosmetics can help reduce the frequency of later instances of the “nonwetting syndrome.“6 Occasional instances of nonwetting will continue to occur, however, when incompatibilities arise between lens materials and
30
ICLC, Vol. 19, January/February
1992
tear fluid (during lens wear) or the skin of the patient’s hand (during lens maintenance). In these few instances, substances deleterious to excellent surface wettability cannot be reasonably eliminated from contacting RGP lens surfaces, and practitioners may urge patients to consider other contact lens or corrective options.
Acknowledgments This study was funded by a grant from Allergan Optical, Inc., a division of Allergan, Inc., to W.J.B. with the understanding that results could be published regardless of outcome. The authors have no financial interest in the funding agency and its parent company or subsidiaries, including no consultational arrangements or travel grants. The authors do not derive indirect monetary benefit from Allergan Optical, Inc., for invitations to symposia made on the basis of recommendation by Allergan Optical, Inc., as a sponsor of those events. Approval for use of human subjects came
from a university-affiliated
institutional
review
board.
References 1. Bourassa S, Benjamin WJ: Clinical findings correlated with contact angles on rigid gas permeable contact lens surfaces in ho. J Am Opom Assoc 1989;60(8):584-590. 2. Benjamin WJ, Bourassa S: Comparison of two contact lens storage solution preservatives with respect to in-eye wetting of rigid oxygen-permeable lens surfaces and related factors. ICLC 1989;16(9,10):273-301. 3. Keppel G: Assumptions and other considerations, in Keppel G (Ed): Design and Analysis, A Researcher’s Handbook. Englewood Cliffs, NJ, Prentice-Hall, 1982, pp. 85-86. 4. Gaito J: Measurement scales and statistics: Resurgence of an old misconception. Psych Bull 1980;87:564-567. 5. Benjamin WJ, Yeager MD, Desai NN, Carmichael CA: In vivo analysis of contact angles. ICLC 1986;14(3):58-61. 6. Grohe RM, Caroline PJ: RGP non-wetting syndrome. Contact Lens Spectrum 1989;4(3):32-44. 7. Personal conversations with Mr. Quid0 Capelli, of Capelli Ophthalmics, Tuckahoe, NY, and Mr. Al Blackbum, of Metro Optics, Dallas TX, 1991. 8. Personal conversations with Dr. N. Rex Ghormley of St. Louis, MO, and Dr. Lamar Zigler of Columbus, OH, 1991.
Appendix Table 1. Overall Statistical
Analyses
Dependent Variable
Independent Variable
Viue
MULTI MULTI MULTI MULTI
DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY
O.OcOl 0.0001 0.0006 0.0001
CA CA CA
DAY HR PAT PAT MAT PAT PAT
0.0001 0.0001 0.0001 0.0002 0.0001 0.0001 0.0001
:: CA CA
x DAY x HR x DAY x MAT x DAY x REG x DAY
RGP wettubility: Bourassa and Benjamin Dependent Variable
Independent Variable
P
Value
LBUT LBUT LBUT LBUT LBUT LBUT LBUT
DAY PAT PAT MAT PAT PAT PAT
0.0001 0.0001 0.0001 0.0008 0.0001
DEP DEP DEP
DAY PAT x DAY PAT x REG x DAY
0.0001 0.0001 0.0001
DIS DIS DIS DIS
DAY PAT x DAY PAT x MAT x DAY PAT x REG x DAY
0.0001 0.0001 0.0048
x DAY x HR x DAY x MAT x DAY x REG x DAY x DAY x HR
Table 3. Verified Instances of Functional
Functional Wettability
1 30 29 2 15
8.8710.43 7.4710.33 7.3310.34 7.1610.33 6.9810.42
29 30 15 1 2
B A A A A Deposition
Day 1 2 15 30 29
c B AB A A
Mean/SEM A
6.8810.22 6.3110.17 6.2610.18 6.2210.19 5.7810.17
B CB CB c Discomfort
Mean&EM
Day
1.15/0.10 0.8610.08 0.6410.09 0.52lO.07 0.43IO.07
1 29 2 30 15
Mea&EM B A A A A
1.52/0.11 1.14/0.08 1.06/0.08 1.03lO.08 1.00/0.07
For each wetting parameter, days of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of days. Days covered by the same letter for a particular parameter were found not to be significantly different from each other. Days not covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of rev sponse, L.e., A = most desirable, B = less desirable, and C = least desirable.
Mean SD
16.0 13.7
55.6 7.6
Dependent Variable
Effects Involving
Day
VaZe
LBUT DEP DIS
DAY DAY DAY
0.0098 0.0037 0.0062
CA LBUT
REG x DAY DAY x HR
0.0068 0.0010
LBUT DIS
MAT x DAY MAT x DAY
0.0026 0.0032
CA LBUT DIS
DAY DAY DAY
0.0014 0.0001 0.0034
CA
DIS
REG x DAY REG x DAY
0.0053 0.0009
6 6 6 6 6
CA CA LBUT DEP DIS
DAY DAY x HR DAY REG x DAY REG x DAY
0.0006 0.0034 0.0042 0.0008 0.0028
7 7
LBUT DIS
REG x DAY DAY
0.0074 0.0002
8 8 8 8
CA CA CA LBUT
DAY MAT x DAY DAY x HR DAY x HR
0.0001 0.0001 0.0001 0.0040
9 9 9 9 9 9
LBUT DEP DEP DIS DIS DIS
REG DAY REG DAY MAT REG
x DAY x DAY
0.0075 0.0005 0.0009 0.0002 0.0003 0.0001
10 10 10
CA LBUT LBUT
MAT x DAY DAY MAT x DAY
0.0001 0.0055 0.0007
11 11 11
LBUT DEP DIS
REG x DAY DAY DAY
0.0056 0.0004 0.0060
LBUT Day
47 51 67” 58 55
Independent Variable
Patient
(p < 0.05) between Days of Wear
MeanfSEM
40” 6 10 14 10
Table 4. Significant Main and Interactive of Wear, Sorted by Patient (p < 0.01)
Table 2. Overall Tukey’s Multiple Comparison Tests
hY
2 15 29 30
Frequencies of presence and absence of functional wettability are listed according to criteria outlined in the text and have been sorted by day of wear. Double asterisks indicate frequencies outside 95% confidence intervals.
well as for the multivariate ANOVA. The ANOVAs concerning contact angle (CA) and lens-surface breakup time (LBUT) were derived from data accumulated throughout each day (N = 2128). Treatment effects are labeled PAT (patient), MAT (lens material), REG (care regimen), DAY (day of wear), and HR (hour of wear during the day, but only for dependent variables CA and LBUT).
Contact Angle
Present
1
0.0001
An analysis of variance (ANOVA) was performed for each of the dependent variables and in a multivariate mode (MULTI) using error terms pooled from nonsignificant effects within the models. Shown here are those significant effects and interactions involving duration of lens wear (DAY and HR, p < 0.01). The analyses are for data recorded at the end of the day (N = 63 1) concerning dependent variables deposition (DEP) and discomfort (DIS) as
Absent
Day of Wear
0.0001
0.0001
Wettability
x DAY x DAY
ICLC, Vol. 19, January/February
1992
31
Clinical Article
Patient
Dependent Variable
Independent Variable
Va?ue
DIS DIS
DAY REG x DAY
0.0024 0.0051
13 13 13 13 13
CA LBUT LBUT DEP DEP
REG x DAY DAY REG x DAY DAY REG x DAY
0.0044 0.0037 0.0002 0.0002 0.0002
14 :: 14
CA CA LBUT LBUT
DAY MAT x DAY MAT x DAY REG x DAY
0.0056 0.0001 0.0001 0.0001
12
15 15 15 15 15
% LBUT DEP DIS
DAY REG x DAY REG x DAY DAY DAY
O.OCOl 0.0024 0.0043 0.0001 0.0001
13
16 16
CA DIS
REG x DAY DAY
0.0071 0.0028
Patient
Contact Angle
1
4
6
LBUT
Deposition
Discomfort
15 A 29 AB 1 AB 30 B 2 B
2B 1 BA 30 BA 15 A 29 A
1B 2 BA 29 BA 15 A 30 A
30 B 1B 29 B 2 BA 15 A
29 A 15 AB 30 AB 1 BC 2 c
1B 15 BA 30 A 2 A 29 A
29 A 1A 15 AB 2 AB 30 B
1B 2 BA 15 BA 30 BA 29 A
15 B 29 A 1 A 2 A 30 A
7
8
LBUT
Deposition
Discomfort
11
1B 15 2 30 29
A A A A
15 B 30 BA 29 BA 1 A 2 A 29 B 1B 2 BA 30 BA 15 A
29 A 30 AB 1 AB 15 AB 2B
14
1B 30 B 29 BA 2 A 15 A
15
1B 29 2 30 15
1c 2 CB 15 BA 30 A 29 A
1c 2 B 15 BA 30 BA 29 A
A A A A
16
IB 29 2 15 30
A A A A
1B 2 BA 15 A 29 A 30 A
For each patient and wetting parameter found to have a significant “DAY” effect in Table 4, days of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of days. Days covered by the same letter for a particularparameter were found not to be significantly different from each other. Days nor covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of response, i.e., A = most desirable, B = less desirable, and C = least desirable.
Table 6. Summary of Multiple Comparisons between Days of Wear, Sorted by Patient Patient X Day Interaction
15 B 1B 2 BA 29 A 30 A
Best
Same
Worse
CA LBUT
0
0 3
5 1
DEP DIS
:2
:
2
Total
3
4
16
Parameter
1B 2B 30 BA 15 A 29 A
9
10
Contact Angle
1 AB 2 AB 15 B
12 12
Table 5. Tukey’s Multiple Comparison Tests (p < 0.05) between Days of Wear, Sorted by Patient, for Each Significant Main-Day Effect
32
Patient
29 A 30 AB
ICLC, Vol. 19, January/February
1992
1B 29 BA 15 BA 2 BA 30 A
The results of Tukey’s multiple comparisons for each patient in T&k 5 showing at least one significant pairwise comparison are summarized. The frequencies with which the first day was (A) the best day or statistically indistinguishable from the day of
RGP wettability: Bourassa and Benjamin best wetting (BEST); (B) not significantly different than either best or worst day in terms of wettability (SAME); and (C) the worst day or statistically indistinguishable from the day of worst wetting (WORSE) are listed for each wetting-related parameter.
Table 7. Inspection of Wear
of Tertiary Interactions
Involving
Patient
Dependent Variable
Independent Variable
P
Value
8 8 8 8 8 8
CA CA CA CA LBUT LBUT
HR MAT REG DAY HR DAY
9 9
CA LBUT
HR HR
0.0002 0.0037
Worse
10
LBUT
REG x HR
0.0001
11
LBUT
REG x HR
0.0031
13
LBUT
HR
0.0002
14
CA
HR
0.0009
Day
0.0015 0.0029 0.0001 0.0001 0.0065 0.0040
x HR x HR x HR x HR
Tertiary Interactions PAT x REG x Parameter
Best
CA LBUT DEP DIS
1 1 0 1
Total
3
PAT x MAT x DAY
DAY
Same
Worse
Best
3 4 1 2
1 3 2 1
3 :
0 E,
2
0
3 0 0 2
10
7
9
1
5
Same
Tukey’s multiple comparisons (p < 0.05) were performed for every patient in Table 4 shown to have a significant regand the results imen X day or material X day interaction, of comparisons showing at least one significant day compari, son are summarized. The frequencies with which the first day was (A) the best day or statistically indistinguishable from the day of best wetting (BEST); (B) not significantly different than either best or worst day in terms of wettability (SAME); and (C) the worst day or statistically indistinguishable from the day of worst wetting (WORSE) are listed for each wetting-related parameter.
Table 8. Overall Tukey’ s Multiple Comparison (p < 0.05) between Hours of Wear Contact Hour 0
12 4 8
B A A A
Tests
LBUT
Angle MeanlSEM
Hour
9.1810.42 7.5210.45 7.0210.26 6.7510.24
0 8 4 12
Mean&EM A A A A
64210.17 6.2710.14 62610.15 6.0510.22
For each wetting parameter, hours of wear are listed vertically in ascending order of magnitude. Also oriented vertically are letters used to indicate statistically significant differences between pairs of hours. Hours covered by the same letter for a particular parameter were found not to be significantly different from each other. Hours not covered by the same letter were found to be significantly different. Letters are also indicative of clinical desirability of response, i.e., A = most desirable and B = least desirable.
Table 9. Significant Main and Interactive Effects Involving Hour of Wear, Sorted by Patient (p < 0.01)
Patient
Dependent Variable
Independent Variable
V&e
:
LBUT LBUT
HR DAY x HR
0.0058 0.0010
6 6
CA CA
!:Y
0.0003 0.0034
7
CA
HR
x HR
0.0010
Table 10. Summary of Multiple Comparisons Wear, Sorted by Patient Patient
between
Hours of
X Hour Interaction
Parameter
Best
Same
Worse
CA LBUT
0 2
0 0
5 2
Total
2
0
7
The results of Tukey’s multiple comparisons for each patient in Table 9 showing at least one significant pairwise comparison are summarized. The frequencies with which wettability after insertion at hour “0” was (A) the best hour or statistically indistinguishable from the hour of best wetting (BEST); (B) not significantly different from either best or worst hour in terms of wettability (SAME); and (C) the worst hour or statistically indistinguishable from the hour of worst wetting (WORSE) are listed for the two wetting-related parameters that were recorded hourly.
Table 11. Inspection of Wear
of Tertiary Interactions
Involving
Hour
Tertiary Interactions PAT x REG x HOUR
PAT x DAY x HOUR
Parameter
Best
Same
Worse
Best
Same
Worse
CA LBUT
0 1
0 0
1 2
2 2
0 0
2 1
Total
1
0
3
4
0
3
Tukey’s multiple comparisons (p < 0.05) were performed for every patient in Table 9 shown to have a significant regimen X hour or day X hour interaction, and the results of comparisons showing at least one significant hour comparison are summarized. The frequencies with which wettability after insertion at hour “0” was (A) the best hour or statistically indistinguishable from the hour of best wetting (BEST); (B) not significantly different than either best or worst hour in terms of wettability (SAME); and (C) the worst hour or statistically indistinguishable from the hour of worst wetting (WORSE) are listed for the two wetting-related parameters that were recorded hourly. ICLC, Vol. 19, January/February
1992
33
Clinical Artick Clinical
Implications
RGP nonwetting is the most common yet easiest to correct complication among rigid lens wearers. The authors have demonstrated through a carefully controlled study and statistical analysis that the first day of RGP wear will most likely be the poorest surface wetting day. By correlating dependent variables of deposition, discomfort, contact angle, and LBUT with independent variables relating to the patient, lens material, or care regimen, it is quite apparent that many complex interactions are occurring. There are multiple causes of RGP nonwetting, including the manufacturer, clinician, staff, and contact lens wearer. By using reputable and “authorized” laboratories, most cases of manufacturer nonwetting can be avoided. Clinicians and their staff need to remain militant in properly verifying, handling, and storing RGPs prior to dispensing. Contact lens wearers must be instructed, then periodically reminded, about the proper use of skin care products, especially in avoiding moisturized soaps. Clinicians now have a significant array of in-office lab cleaners to attack RGP nonwetting. Mild nonwetting due to moisturizer contamination can be treated with combination surfactant cleaners such as the Boston or Sherman lab cleaners. Moderate nonwetting due to waxy manufacturing residues respond well to the Fluorosolve solvent cleaner. Also, an unapproved but highly effective cleaner for severe RGP nonwetting is Miraflow, an alcohol-based cleaner. The ultimate treatment is still using special care in handling lenses and avoiding known contaminants. Robert M. Grohe, OD 18019 Dixie Hwy. Homewood, IL 60430
William “Joe” Benjamin received his OD and PhD degrees from The Ohio State University in Columbus, and is now an Associate Professor at the School of Optometry/The Medical Center, University of Alabama at Birmingham. He is a fellow of the American Academy of Optometry, an American Optometric Association representative to the American National Standards Institute and International Standards Organization, and a council member of the International Society for Contact Lens Research. His interests include the impact of contact lenses on the physiology of the eye and interactions of tear fluid with contact lenses and cornea. His work has included initial studies of rigid extended wear, in viva measurements of surface wettability, and physiology of the eye and tear fluid under conditions of lid closure and contact lens wear. Dr. Benjamin is a contributing editor for International Contact Lens Clinic.
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ICLC, Vol. 19, January/February
1992