Extended-Wear Contact Lenses and Intraocular Lenses for Aphakic Correction

AMERICAN JOURNAL OF OPHTHALMOLOGY VOLUME 88

NUMBER 3, PART II

SEPTEMBER, 1979

EXTENDED-WEAR CONTACT L E N S E S AND INTRAOCULAR L E N S E S FOR APHAKIC CORRECTION W A L T E R J. STARK, M.D., H U G H R. T A Y L O R , M.D.,

G R E G O R Y P. K R A C H E R , O.D., L A W R E N C E W. H I R S T , M.D., A. E D W A R D M A U M E N E E , Baltimore,

Daily-wear contact lenses and intraocu­ lar lenses have helped to overcome the visual problems associated with the re­ fractive correction of aphakia. However, some aphakic patients cannot manipulate a contact lens because of poor dexterity or reduced vision, and intraocular lens im­ plantation is contraindicated in some phakic patients. Availability of an effec­ tive extended-wear aphakic contact lens would offer significant benefit to these patients, in addition to providing added convenience to aphakic patients who are now using contact lenses on a daily-wear basis. For those reasons, we undertook a trial of extended-wear soft contact lenses for the correction of aphakia. We define ex­ tended wear of a contact lens as continu­ ous use on the eye for more than 60 hours at a time. Although there are a number of high-oxygen-transmission contact lenses now available for investigational use in the United States, the Cooper Permalens (Cooper Laboratories, Palo Alto, Califor­ nia) was chosen. We report herein our experience with the use of the Cooper From the Wilmer Institute, Johns Hopkins Hospi­ tal, Baltimore, Maryland. This study was supported in part by the National Institutes of Health, Grant EY-01302-04 (Dr. Stark). Reprint requests to Walter J. Stark, M.D., Wilmer Institute, Room 100, Johns Hopkins Hospital, 600 N. Wolfe St., Baltimore, MD 21205.

C L A U D E L. C O W A N ,

RAY T. OYAKAWA, M.D.,

M.D., AND

M.D.

Maryland

Permalens for extended wear in aphakia, and compare our results to the results obtained by intraocular lens implanta­ tion. M A T E R I A L AND M E T H O D S

The Cooper lens is manufactured by Global Vision (U.K.), a division of Cooper Laboratories. The proprietary name for use in the United States is Permalens hydrophilic contact lens. The Perfilcon A material from which the lens is made is a terpolymer of hydroxyethyl methacrylate, N-vinyl pyrrolidone, and methacrylic acid. The lens was specifically designed for extended wear and is lathe-manu­ factured for this purpose. The lens has a 7 1 % water content when fully hydrated. Powers range from +8.25 to +20.75 di­ opters and thickness varies from 0.36 mm to 0.43 mm in the aphakic state. The high water content, the polymer itself (Perfilcon A), and the relative thinness of the lens allow high oxygen transmission through the lens, permitting it to be used on an extended-wear basis. 1 - 3 The aphakic patients recruited for this study had either been previously unsuc­ cessful in wearing a contact lens, or were assessed as being unable to wear or ma­ nipulate a conventional contact lens. The lens was initially fitted with a back curve 0.3 to 0.6 mm steeper than the patient's

AMERICAN JOURNAL O F OPHTHALMOLOGY 88:535-542, 1979

535

536

AMERICAN JOURNAL OF OPHTHALMOLOGY

average corneal keratometer reading, and a lens diameter that equalled the size of the cornea. These lenses proved to be too steep for our patients, however, and based on our own experience we began fitting lenses with the same back curvature as the flattest keratometer reading (in milli­ meters), and with a diameter about 1 mm larger than the cornea. The lenses most frequently fitted were those with an 8.0-mm base curve and 13.5-mm diameter and those with an 8.3-mm base curve and 14.0-mm diameter. An acceptable fit was considered to be a lens with good centration, showing slight movement (less than 0.1 mm) with blinking, and stable vision with overcorrection. Patients who were chosen for the study were seen 24 hours after the initial lens fitting, then once a week for one month, and once a month for one year. The lenses were removed at monthly visits (in most cases) for cleaning and were reinserted in the eye after thermal disinfecting. No prophylactic antibiotics or corticosteroid drops were used, although other ocular medication with the exception of epinephrine was continued as needed. RESULTS

Of the 126 patients who were fitted, 16 had lenses fitted for both eyes, for a total of 142 eyes fitted. Within three months of the fitting, 13 patients (all of them suc­ cessful with the continuous-wear lens) were discontinued from the study. Four of these 13 died; eight patients were un­ able to make the follow-up visits as re­ quired by the Food and Drug Administra­ tion and were discontinued from the study; and one patient was taking epinephrine for glaucoma control and was discontinued from the study. This left a total of 113 patients (with 128 eyes fitted) in the study. Eleven patients had to be discontinued from the study for lensrelated problems. Currently, 102 aphakic patients are

SEPTEMRER, 1979

using the contact lenses on an extendedwear basis. Fourteen of these patients are wearing the lenses in both eyes, for a total of 116 eyes (Table 1). The median age of these patients is 64 years, with a range of seven months to 92 years. Seventy-one of the patients are over 60 years of age; 52 are males and 50 are females. The mean follow-up of our patients is ten months, with a range of four to 22 months. Of the 102 patients who are wearing the lens 55 had previously worn contact lens­ es. Eleven of these 55 had been success­ ful with daily-wear lenses but they pre­ ferred the extended-wear lens. Forty-four of the patients previously had been un­ successful with hard or soft contact lenses for the following reasons: difficulty with manipulation in 18 cases, insufficient vi­ sion to insert the lens in 13 cases, and lens intolerance in another 13 cases. The average number of trial lenses used to achieve a satisfactory fit for a patient decreased as we gained more experience with the lenses. During the first months of the study we found that an average of 5.8 lenses were used in fitting each eye. After we began fitting flatter and larger lenses, patients were fitted satisfactorily after an average trial of three lenses per eye (Table 2). The extended-wear schedule varies slightly according to individual tolerance and the need to clean the lens (Table 3). In all patients the lens is periodically removed regardless of whether the patient TABLE 1 N U M B E R O F APHAKIC P A T I E N T S E N R O L L E D IN E X T E N D E D - W E A R S O F T C O N T A C T L E N S STUDY

Patient Status No. fitted Discontinued Not lens-related Lens-related Total remaining in study

No. of Patients

No. of Eyes

126

142

13 11 102

14 12 116

VOL. 88, NO. 3, PART II

CORRECTION OF APHAKIA

537

TABLE 2

TABLE 3

A V E R A G E N U M B E R O F L E N S E S U S E D T O OBTAIN A G O O D F I T A T D I F F E R E N T T I M E S IN T H E STUDY

EXTENDED-WEAR S O F T CONTACT LENS WEARING SCHEDULE F O R 1 0 2 PATIENTS ( 1 1 6 EYES)

Month of Study

Average No. of Lenses to Fit*

1 2 3 4 18

5.8 5.2 3.5 3.2 2.9

Schedule Extended wear Monthly removal by investigator Removal every one to two weeks Removal every three days

No. of Eyes 12 91 12 1

*Per eye

is symptomatic. In 12 of the 116 eyes the lens is removed by the investigator once every three months for lens cleaning and inspection of the cornea; in 91 eyes the lens is removed monthly for cleaning and for corneal inspection; and in 12 eyes, lens removal by the patient is necessary at one- or two-week intervals for cleaning. These patients tend to be those with slightly dry eyes or mild blepharitis. One patient, who had previously been intoler­ ant of soft contact lenses, has to remove the Permalens for six hours (overnight) every three days to prevent irritation. No significant change in corneal thickness has been seen with the extended wear of this contact lens in 17 aphakic patients whom we examined at one week and at three months after fitting. We have had several complications, but none have resulted in permanent sequelae (Table 4). They include ten cases of the

TABLE 4 COMPLICATIONS RELATED TO T H E WEARING O F EXTENDED-WEAR SOFT CONTACT LENSES

Complication Tight-fit syndrome Conjunctivitis with sterile corneal infiltrate Vascularization of Cornea 0-1 mm 1-2 mm 2-5 mm

No. of Patients 10

30 3 0

tight-fit syndrome consisting of conjunctival and ciliary injection and a visibly tight-fitting lens with compression of the peripheral conjunctiva and occasionally associated with mild and transitory iritis. In seven of these patients the tight-fit syndrome developed within two weeks of initial fitting, and in three it occurred about four months after fitting. These ten patients have been refitted with a flatter lens without recurrence of this problem. Another eight patients have developed conjunctivitis with sterile peripheral cor­ neal infiltrates. These peripheral infil­ trates stained with fluorescein and are similar to those seen with Staphylococcus hypersensitivity. Smears and cultures were negative. Two of these patients, who had moderate blepharitis at the time of entering the study, developed recurrent episodes of sterile corneal infiltrates and were discontinued from the study. The other patients were refitted with larger and flatter lenses and are doing well. There has been no corneal neovascularization greater than 2 mm. In 30 patients we saw dilatation of the limbal blood vessels, and extension of vessels up to 1 mm past the corneoscleral limbus. In three eyes there was superior terminalloop corneal vascularization extending 1 to 2 mm in from the corneoscleral lim­ bus. We have seen no progression of these vessels during a further four months of observation with continued contact-lens wear, and we have not had to use cortico-

538

AMERICAN JOURNAL OF OPHTHALMOLOGY TABLE 5

T O T A L NUMBER O F EXTENDED-WEAR S O F T CONTACT LENSES REPLACED

Reason for Replacement Lenses lost Lens deposits Lenses torn Spontaneous Manipulation

No. of Patients 53 19 5 20

steroid drops or other preventive treat­ ment. Other minor lens-related problems have occurred (Table 5). Fifty-three lens­ es have been lost from 30 eyes. Two children have lost over ten lenses each. Lens deposits have necessitated lens re­ placement in 19 patients. In 25 patients the contact lens was torn; in five of these the lens tore spontaneously while on the patient's eye, and in the other 20 the lens was torn by the patient or the investigator during removal for lens cleaning or for corneal inspection. Eleven patients were discontinued from the study because of lens-related problems (Table 6). Five had unsatisfac­ tory fit or poor visual acuity with the lens. Four of these five patients were seen within the first three months of the study, before our fitting techniques were per-

fected. Two young children were unable to retain the lens. Two patients were discontinued because of recurrent infil­ trates in the corneal periphery. These patients had mild blepharitis, and the corneal infiltrates cleared with no residu­ al scarring. A further patient had transient corneal edema; and another patient, who was wearing lenses in both eyes, devel­ oped bilateral papillary hypertrophy of the tarsal conjunctiva and was discontin­ ued from the study. We have not had to discontinue any patients because of in­ fectious corneal ulcers or corneal vascularization, and none of the discontinued patients have permanent sequelae from wearing the lens. With contact-lens correction alone, 55 of the 116 eyes (47%) have a visual acuity between 6/4.5 (20/15) and 6/7.5 (20/25), and 100 eyes (86%) have visual acuity of 6/12 (20/40) or better (Tables 7 and 8). Soft contact lenses will not correct a sig­ nificant amount of astigmatism, and we expected that many patients would need to wear a spectacle overcorrection. With spectacle overcorrection, 107 eyes (92%) have achieved visual acuity of 6/12 (20/40) or better. Nine eyes have best cor­ rected visual acuity of less than 6/12 (20/40), but in all nine cases the reduc­ tion in visual acuity can be explained by

TABLE 7

TABLE 6 NUMBER O F PATIENTS DISCONTINUED FROM STUDY BECAUSE O F LENS-RELATED PROBLEMS

Lens-Related Problems Unsatisfactory fit or poor vision Unable to retain lens Corneal infiltrates Transient corneal edema Papillary hypertrophy of tarsus Total

SEPTEMBER, 1979

V I S U A L ACUITY A T T A I N E D W I T H AND W I T H O U T O V E R C O R R E C T I O N IN 1 0 2 P A T I E N T S WEARING EX­ T E N D E D - W E A R APHAKIC S O F T C O N T A C T L E N S E S

No. of Patients Visual Acuity 5 2 2 1 1 11

6/4.5(20/15)-6/7.5(20/25)

With With Contact Contact Lens Plus Overcorrection Lens

(%)

47

(%)

78 86

6/9(20/30)-6/12(20/40) 6/15(20/50)-6/18(20/60) 6/21(20/70)-6/30(20/100) 6/30(20/100)-6/60(20/200) Total

39 6 7 1 100

92 14 7 0 1 100

CORRECTION OF APHAKIA

VOL. 88, NO. 3, PART II TABLE 8

R E A S O N S F O R P O O R V I S I O N IN E I G H T P A T I E N T S W H O H A D A B E S T C O R R E C T E D VISUAL ACUITY O F LESS THAN 6 / 1 2 (20/40) WITH T H E EXTENDED-WEAR S O F T C O N T A C T L E N S AND O V E R C O R R E C T I O N

Complication

No. of Patients

Vitreous opacities Macular degeneration Optic atrophy Previous retinal detachment

1 5 1 2

pre-existing ocular pathology. This in­ cludes: vitreous opacities in one case, mac­ ular degeneration in five, optic atrophy in one; and, in two cases, previous retinal detachment with macular involvement. All the patients have been satisfied with the visual acuity they achieved with the lens, but ten patients state that vision was not as sharp as with their glasses or hard contact lenses. Ten patients achieved one line better vision on the Snellen chart than with their aphakic spectacle correc­ tion, and in 20 patients the contact lens visual acuity was one Snellen line less than visual acuity with aphakic spectacle correction. The 20 patients whose best corrected visual acuity was one line less with the Permalens correction are satis­ fied with their vision, mainly because of the convenience of having an extendedwear lens. DISCUSSION

There are several requirements for an extended-wear soft contact lens: good op­ tics, reproducible lens dimension, and high oxygen-transmission. 1 " 3 Lens dura­ bility is important, especially because the Food and Drug Administration will re­ quire periodic removal of the lens for cleaning. Important patient factors in­ clude motivation and absence of external ocular diseases such as significant bleph­ aritis or dry eyes. Potential problems with extended-wear aphakic contact lenses involve frequent

539

lens replacement and the possibility of corneal complications. Possible corneal complications, in particular, neovascularization or infection, must be watched for when the lenses become readily available. In our study, we have had no infectious corneal ulcers and no significant corneal neovascularization. However, our longest follow-up is only 22 months, and we believe that continued close observation is necessary to determine the long-term success rates and complication rates of extended-wear contact lenses in aphakia. Now that the feasibility of extendedwear soft contact lenses has been shown by this study and others, 4 " 6 and they will soon be approved for use, the important question to be answered is: should a patient receive an intraocular lens at the time of cataract surgery, or should he be fitted with a contact lens? To try to an­ swer this question, we reviewed the re­ sults obtained with intraocular lenses here and compared the relative advan­ tages of both intraocular lenses and extended-wear contact lenses. Four years ago we began a conservative approach to intraocular lens implantation, using strict criteria for patient selection. 7 Two years later, we began this study of the extended-wear soft contact lens in apha­ kic patients to evaluate contact lenses as a reasonable alternative to intraocular lenses. Between January 1975 and December 1977, two of us (W.J.S. and A.E.M.) im­ planted 200 four-loop Binkhorst intraocu­ lar lenses (Group 1). The lenses were obtained from Morcher through Medical Work Shop and were sterilized by the wet pack method (sodium hydroxide storage and neutralization with sodium bicarbon­ ate before use). After the beginning of Food and Drug Administration control of intraocular lenses in January 1978 and the requirement that lenses be sterilized by ethylene oxide, we have obtained the four-loop Binkhorst lens mainly from

540

AMERICAN JOURNAL O F OPHTHALMOLOGY

S E P T E M B E R , 1979

TABLE 9 B E S T C O R R E C T E D VISUAL ACUITY R E S U L T S O B T A I N E D A F T E R INTRAOCULAR L E N S I N S E R T I O N IN T H E T W O G R O U P S O F P A T I E N T S

Visual Acuity

Group If 200 Eyes (%)

Group 2 | 60 Eyes (%)

6/4.5(20/15)-6/7.5(20/25) 6/4.5(20/15)-6/12(20/40) 6/4.5(20/15)-6/12(20/40)*

138 (69) 182 (91) 188 (94)

41 (69) 52 (87) 56 (94)

* Excluding known macular degeneration or amblyopia. t IOL sterilized with sodium hydroxide. JIOL sterilized with ethylene oxide.

two American suppliers (Iolab Corp., San Dimas, California and Intermedics Intraocular, Inc., Freeport, Texas) and have performed 60 lens implantations (Group 2). The average age of the patients in the two groups who received the intraocular lenses is approximately the same (71 years for Group 1 and 72 years for Group 2). The average follow-up is longer in the first group than in the second group (20 months for Group 1 and five months for Group 2). The visual results obtained with the sodium-hydroxide-sterilized lenses as compared to the ethyleneoxide-sterilized lenses are similar, in that 94% of the patients in both groups have achieved visual acuity of 6/12 (20/40) or better, excluding those with known mac­ ular degeneration or amblyopia (Table 9). TABLE 10 MAJOR OPERATIVE COMPLICATIONS IN T H E T W O GROUPS O F P A T I E N T S IN W H O M INTRAOCULAR LENSES WERE INSERTED

Complication Vitreous loss Unplanned extracapsular extrac­ tion Related to IOL insertion: rupture of vitreous face

Group 1 200 Eyes (%) 0 (0) 5 (2.5)

2 (1)

Group 2 60 Eyes (%)

Our operative and postoperative compli­ cation rates, excluding intraocular in­ flammation, were similar in the two groups (Tables 10 and 11). However, we found that the incidence of excessive and prolonged postoperative intraocular in­ flammation has been much greater in the ethylene-oxide-sterilized lenses produced by the American companies (Table 12). Although we had one case of endophthalmitis in the first 200 cases using sodium hydroxide sterilization, this cannot be definitely traced to contamination of the intraocular lens. However, we have had a 7% incidence (four eyes) of sterile hypopyon in Group 2 as compared to 1.5% (three eyes) in Group 1. Vitritis and papillitis have been a problem in 3 % (two eyes) of cases in the last 60 intraocular lenses inserted. Only 7% (14 eyes) of the patients in Group 1 had recurrent or per­ sistent iritis eight weeks after surgery, but 27% (16 eyes) receiving lenses sterilized TABLE 11 NONINFLAMMATORY POSTOPERATIVE COMPLICA­ T I O N S IN THE TWO GROUPS OF PATIENTS IN WHOM INTRAOCULAR LENSES WERE INSERTED

1 (2) 1 (2)

1 (2)

Complication

Group 1 200 Eyes (%)

Group 2 60 Eyes (%)

Corneal edema Retinal detachment Hyphema Subluxation

1 (0.5) 5 (2.5) 0 (0) 12 (6)

0 (0) 1 (2) 0 (0) 2 (3)

VOL. 88, NO. 3, PART II

CORRECTION OF APHAKIA

TABLE 12 INFLAMMATORY POSTOPERATIVE COMPLICATIONS IN THE TWO GROUPS OF PATIENTS IN WHOM INTRA­ OCULAR LENSES WERE INSERTED

Complication Endophthalmitis Hypopyon (sterile) Vitritis and papillitis Persistent iritis Glaucoma

Group 1 200 Eyes (%) 1 (0.5) 3 (1.5) 0(0) 14(7) 0(0)

Group 2 60 Eyes (%) 0(0) 4(7) 2(3) 16 (27) 2(3)

with ethylene oxide have had persistent iritis more than two months after surgery and have required continued corticosteroid drops. The two patients who devel­ oped vitritis also had severe inflammatory glaucoma. Overall, about one third of our patients in Group 2 have had postopera­ tive inflammatory problems. When the cause of this problem is known and the incidence of postoperative inflammatory complications returns to a reasonable lev­ el, a fair comparison of continuous-wear contact and intraocular lenses as a means of aphakic correction can be made. Intraocular lenses and extended-wear contact lenses have several features in common: both give reasonably good uncorrected visual acuity with a full periph­ eral visual field and avoid the marked spectacle distortion found in aphakic spectacle correction, and both are rela­ tively safe with proper patient selection. However, it must be stressed that longterm follow-up data are lacking for both intraocular and extended-wear contact lenses. The advantages of an extended-wear contact lens over an intraocular lens are: (1) a contact lens is probably safer than an intraocular lens because it can be easily removed and refitted at a later date; (2) the extended-wear lens can usually be used when an intraocular lens is contraindicated and can be fitted by surgeons who do

541

not recommend intraocular lens implan­ tation; (3) extended-wear lenses can pre­ vent the need for secondary intraocular lens insertion or keratophakia; (4) the power of the contact lens can readily be changed to give the desired spherical equivalent; and (5) intraocular complica­ tions rarely develop with extended-wear contact lens use. There are some advantages to an intra­ ocular lens over an extended-wear lens if no operative or postoperative complica­ tions develop from lens implantation: (1) the intraocular lens will probably be less expensive than a contact lens and not need to be replaced; (2) the intraocular lens may provide more stable vision but no better stereoscopic acuity 8 ; (3) the in­ traocular lens is more convenient for the patient; and (4) an intraocular lens may be more successful in patients with external ocular problems such as blepharitis, eye­ lid abnormalities, and dry eyes. Neither the extended-wear soft contact lens nor the intraocular lens has been perfected, but extended-wear aphakic correction contact lenses offer a reasona­ ble alternative to intraocular lenses. We use the following guidelines when con­ sidering a patient for cataract surgery. For an elderly patient with no contraindica­ tions to lens implantation and no compli­ cations at the time of surgery, several options are available: an intraocular lens can be implanted; or the patient can be fitted in the postoperative period with spectacles, a daily-wear soft or hard con­ tact lens, or an extended-wear lens. Younger patients or those with contrain­ dications to intraocular lens implantation or complications at the time of intraocular lens surgery are generally ideal candi­ dates for extended-wear contact lenses. In most cases the availability of extendedwear aphakic soft contact lenses should obviate the need for bilateral or secondary insertion of intraocular lenses or for kera­ tophakia. With Food and Drug Adminis-

542

AMERICAN JOURNAL OF OPHTHALMOLOGY

tration approval of the Permalens and several other extended-wear lenses, fur­ ther improvements in fitting techniques and lens material will be made, so that the success rate for fitting and extended wear can be improved above the 90% success rate we found in our study. SUMMARY

We evaluated extended-wear soft con­ tact lens use in 128 aphakic eyes of 113 patients, 44 of whom had been unable to wear conventional contact lenses; 116 eyes (91%) have been successfully fitted and have worn the extended-wear lenses without significant complication. Eleven patients were unable to wear the lens or had to be discontinued for transient lensrelated problems. In 103 eyes successful­ ly fitted the lens is removed for cleaning less often than monthly. Ninety six of the 116 eyes fitted have visual acuity as good as, or better than, with aphakic correct­ ing spectacles. The results obtained with the extended-wear soft contact lens are similar to those obtained with intra­

SEPTEMBER, 1979

ocular lenses, except for the recent high incidence of inflammation seen after intraocular lens insertion when using ethylene-oxide-sterilized lenses. REFERENCES 1. Poise, K. A., and Mandell, R. B.: Critical oxy­ gen tension at the corneal surface. Arch. Oph­ thalmol. 84:505, 1970. 2. Fatt, I., Freeman, R. D., and Lin, D.: Oxygen tension distribution in the cornea. A re-examination. Exp. Eye Res. 18:357, 1974. 3. Hill, R. M.: Oxygen permeable contact lenses. How convinced is the cornea? Int. Contact Lens Clin. 4:34, 1977. 4. Gasset, A. R., Lobo, L., and Houde, W.: Perma­ nent wear of soft contact lenses in aphakic eyes. Am. J. Ophthalmol. 83:115, 1977. 5. Dahl, A. A., and Brocks, E. R.: The use of continuous wear silicone contact lenses in the opti­ cal correction of aphakia. Am. J. Ophthalmol. 85: 454, 1978. 6. Nesburn, A. B.: Prolonged-wear contact lenses in aphakia. Ophthalmology 85:73, 1978. 7. Stark, W. J., Hirst, L. W., Snip, R. C , and Maumenee, A. E.: A two-year trial of intraocular lenses at the Wilmer Institute. Am. J. Ophthalmol. 84:769, 1977. 8. Galin, M. A., and Baras, I.: Stereoscopic acuity measurement in aphakia. Am. J. Ophthalmol. 86: 825, 1978.