Living with peroxide

Living with Peroxide M. R. Killpartrick BSc, FBCO Abstract -- A new preservative-free disinfection system for soft lenses was introduced to the U.K. market one year

ago. It has been predicted that lenses disinfected using such systems should show a low incidence of adversephysiological response due to better cleaning and disinfecting properties and the elimination of chemicals associated with sensitivity reactions. A study was initiated to assess: (i) physiological response to lenses subjected to the system (ii) lens~system inter-reaction. In the study a mixture of new and existing soft lens wearers were selected and supplied with the system. They were instructed to follow the manufacturers'recommendations, but additionally were required to daily surfactant clean prior to disinfection. Physiological response was primarily assessed using the limbal vessel grading method suggested by Larke and the lens~system inter-reaction was monitored using a new graded dark field illumination assessment method. Patients were also asked to assess the system for ease of use, cost and case design.

Introduction In order to minimise the numbers of organisms introduced into the eye with the contact lens by the lens vehicular effect, it has always been considered preferable to carry out some form of cleaning and disinfection of the lens during the non-wearing period. Due to the more porous, water loving nature of soft lens materials, the risks of inducing ocular irritation or infection is generally considered to be higher than with hard, non porous material lenses. (Brown 1972, Gasset 1972, Tregakis 1973, Phillips 1980, Penley 1980, Grant 1984, Hopkins 1986) Soft lenses have been disinfected using chemical (e.g. chlorhexidine, thimerosal, alkyl diethyl ammonium chloride), heat, halide (iodine, chlorine) and oxidizing (peroxide) methods. Chemical disinfection methods have been the most popular for many years due to their simplicity and ease of use (Young 1984), However, chemical sensitivity responses are quite common, with incidences of between 10% - 50% reported (Wilson 1981, Eriksen 1978, Callender 1978, Ruben 1980, Killpartrick 1983). Thermal disinfection, with lenses stored in unpreserved saline, overcomes these sensitivity problems, but generally the life expectancy of lenses is probably reduced due to the denaturing effects of heat on proteins and other tear component residues (Phillips 1980, Schwegler 1980). The necessity for a suitable heat source is also inconvenient, and heat is inappropriate to some high water content lenses. The efficacy of halide products is questionable, (PenIcy 1980, 1981) and they have also generally suffered from confusing presentation, marketing and packaging, and to date have failed to gain popularity in the U.K. market. Oxidising methods have also suffered from similar problems, although there are apparently significant advantages: (i) more rapid and effective than conventional chemical disinfectants (Schwegler 1981, Levine et al 1981. Penley et a11981, Grant 1984, Houlsby et al 1984) (ii) minimal possibility of adverse physiological

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response when neutralized with unpreserved saline. (It should be appreciated that peroxide systems are not totally "chemical" free; the peroxide contains a stabilizing agent and the neutralizer may contain catalysts or enzyme additives). (iii) some cleaning activity also possessed by peroxide (Schwegler 1981, Sunderdeik 1984, Billig et al 1984) There are two peroxide systems currently available in the U.K., SEPTICON TM by American Optical and 1010 TM by Contactasol. The Contactasol "10/10" oxidising system was introduced twelve months ago to the U.K. market. The perceived advantages of the system over the Septicon system are: (i) simplified "one-pot" procedure. This reduces the possibility of contamination by the second pot neutralizer stage. (Kerr 1982, Rogan 1985) (ii) The peroxide neutralizing agent, pyruvate, is contained in the neutralizing fluid. The patient does not need to remember to change the platinum disc catalyst of the AO system, and pyruvate also acts more quickly (Krezanoski 1985) (iii) qhe 10/10 system uses a non-preserved unit-dose pyruvate based neutralizer whereas Septicon uses a preserved fluid which could produce sensivity responses. Pyruvate is claimed to have good biocompatibility (Houlsby 1984)

Method We decided to test the system on a small number of patients initially, with a view to switching more patients to the system if no major problems were encountered. All patients in the study were either existing wearers of, or were fitted with, thin 38% p H E M A CIBASOVF, WEICON 38E, SOFLENS, OR HYDRON Z6 lenses. Patients in the study were supplied with the 10/10 system and instructed to follow the manufacturers recommendations, but with the following additional prrocedures:-(i) Cleaning of lenses Tests with trial lenses, which were examined using a

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dark field illumination system, (see description in "lens system inter-reaction") support the suggestions of Sibley 1985, Josephson 1985, Callender 1985, of the need for careful surface massaging of the lens surface prior to the peroxide disinfecting procedure. Our tests showed that little coating seems to occur on the posterior lens surfaces presumably due to tears drying on the front of the lens (Lowther 1984) and we therefore emphasise to patients cleaning should be concentrated on the anterior lens surface. Lenses with early protein films showed little improvement if merely subjected to the manufacturer's recommendations. Various massage cleaning methods were tried using saline, Mirasol (Cooper) and LC 65 (Allergan). We eventually decided on LC65, as saline seemed less effective and Mirasol was found to be so sticky that it was difficult to achieve a smooth massaging of the very thin lenses in the palm of the hand. Our tests also suggest that additional use of the Titmus cleaning sponge in conjunction with LC65 could remove particularly stubborn surface deposits (Parker 1985). We therefore asked patients to initially daily palm massage clean their lenses with LC65 upon removal. Sponges were given to patients at the first after-care appointment, with a fortnightly usage instructed in addition to the daily palm massage. Our experience has shown that in order for sponge cleaning to be effective, it is necessary to use a dry finger and a nearly dry lens. All surplus fluid must be shaken from the lens and a 20 - 30 second subsequent air-dry is required. The lens can now be securely !'mounted" on the finger tip, and the LC65 cleaner is then squirted onto the lens, thereby insuring all the movement is between the front of the lens and the sponge, not between the finger-tip and the back of the sponge. A 30 - 60 second massage of the lens may, on occasions, be necessary, and a dark field analyser will reveal how effective the cleaning attempts have been. (ii) Rinsing Patients were also instructed to rinse the lenses with unpreserved aerosol saline (Solar by Contactasol), after massage cleaning and prior to 10/10 disinfecting, and again prior to insertion. The final rinse was advised to "blast away" small particulate matter from the lens surfaces. The patient's "starter kit" therefore comprised storage case, LC65 cleaner, Solar aerosol spray, one bottle 10/10 disinfecting solution, unit dose sachets of 10/10 neutralizing saline, 10/10 instruction card, soft lens handling book, emergency medical card, and a big bag to carry the lot in! We wished to test the perceived advantages of the system i.e. low adverse physiologicial response incidence and improved fife expectancy of lenses compared to heat disinfection, which typically seems around 12-18 months. We designed the protocolto include and assess: 1 previous history 2 significant acuity loss

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3 the incidence of adverse physiological response 4 the lens/system inter-reaction 5 patient attitude and assessment -- (i.e. user -friendliness) of system These criteria were assessed and recorded at the routine re-check appointments which were scheduled at (i) 1 - 2 weeks, (ii) 3 months, (iii) 6 months, (iv) 12 months. Additional appointments, where necessary, were not included in the protocol. 1 Previous history-- Patients in the studywere a mixture of totally new patients (NP), existing soft lens wearers using chemical methods with suspected solution sensitivity problems (EPC) or existing wearers using heat and non-preserved saline (EPH). We were particularly interested in the two latter groups to discover whether the peroxide method solved suspected sensitivity responses, and how patients using heat disinfection (usually due to previous suspected chemical sensitivity) fared, especially with respect to lens deterioration rates. 2 Significant acuity loss -- Assuming a well-fitted lens and the absence of significant astigmatism, these could only occur as a result of adverse physiological response or deterioration in lens condition or a combination. The loss of one Standard Snellen line or more was therefore recorded where fitting characteristics and astigmatism were known not to be involved. 3 The incidence of adverse physiological response -- MCMonnies 1982, 1985 and Guillon etal1985 have described in detail the limbal changes associated with adverse physiological responses to soft lens wear, and this can be graded using the limbal vessel count method originally suggested by Larke 1981, and subsequently adopted and described by the author. The method involves assessing the number of blood filled limbal vessels and counts at 3 and 12 o'clock limbal areas are carried out, and the worse count determines the grade. Limbal vessel count I (LVI) less than 1 in 10 limbal vessel filled Limbal vessel count II (LVII) more than 1 in 10 but less than 5 in 10 limbal vessels filled Limbal vessel count III (LVIII) more than 5 in 10 limbal vessels filled Limbal vessel count IV (LVIV) all vessels filled and engorged no neo-vascularization Limbal vessel count V (LVV) neo-vascularization. Discontinue lens wear advisable. Shifts from gradings were recorded as +1, - 1 , - 3 etc. + indicating an improvement and - a deterioration in the count category. 4 Lens/system inter-reaction -- The claimed clean-

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ing activity of peroxide, and the avoidance of heating, with the associated denatured tear component problems, would seem to offer the hope of lengthening the life expectance of lenses subjected to the 10/10 system. In order to assess the overall condition and relative cleanliness of the lenses, a dark field analyser was used. This method enables protein films to be easily disclosed, and by tilting the lenses to produce total internal reflection even slight discolouration can be detected by examining the bright crescent of transmitted light emitted on the lens edge remote to the light source. The following grading method was used: (i) Lens condition I (LCI) Lens as new. No surface contamination or discolouration (ii) Lens condition II (LCII) Slight contamination. Either faint surface contamination or discolouration or combination. Surface contamination totally removable by surfactant cleaning. Continued lens wear acceptable. (iii) Lens condition III (LCIII) Medium contamination. Advanced depositions and discolouration, surface contamination not totally removable. Continued lens wear questionable. (iv) Lens condition IV (LCIV) Heavy contamination/ discolouration. Discontinuation of lens wear and replacement strongly advisable. No change in lens condition was recorded as 0, and a deterioration was recorded as --1, --2, --3, etc. depending on category change. Patient attitudes and assessment of system-- The 10/10 system seemed to be rather more complex and laborious than conventional chemical or heat disinfection methods, and we also felt the case design could be improved. The cost of disinfection systems is also significant as poor patient compliance may result if the patient attempts to economise and we therefore asked patients the following questions: (I) How would you rate the system for ease-of-use (i) easy ( + + + ) (ii) moderate (++) (iii) difficult (+) (II) Do you consider the case design to be (i) good ( + + + ) (ii) average ( + + ) (iii) poor (+) (III)Do you consider the cost to be (i) low (-'H-'l-) (ii) reasonable ( + + ) (iii) excessive (+) Finally, additional comments on the above or other aspects of the system were invited (e.g. stinging upon insertion, irritation of hands etc.)

existing patients heat (EPH) Total

4 12% 34 100%

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(2) Significant acuity loss (67 eyes 1 monocular fitting) Fig 2 no loss 1 Snellen 2 Snellen 3 or Total line lines more check-up 1 (1-2 weeks) 54 13 0 0 check-up 2 (3 months) 43 24 0 0 check-up 3 (6 months) 40 25 0 0 2 discontinue at 6 months 2.. l~c_o~T"I L~S3

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Results (1) Patient populationFig 1 new patients (NP) existing patients chemical (EPC)

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Loss

(3) Adverse physiological response at 6 months -limbal vessel count method Fig 3 improvement no change deterioration +2 +1 0 --1 -2 --3 --4 1 4 13 14 1 0 0 3% 13% 38% 43% 3% 2 discontinued wear 81% No change or loss of one grade only 16% Improved (previous chemical users) 3. P~"l$~t,u~61~u gf.3¢ol,tSE

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16 47% 14 41%

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(4) Lens system inter-reaction at 6 months (32 patients) Fig 4 Lens condition LCI, II etc (at 6 months) No change --1 -2 -3 26 (81%) 6 ( 1 9 % ) 0 0 81% of patients' lenses showed no visible deteriotation

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(5) Patient attitudes (I) Ease of use Figs 5(i) (ii) (iii) (i) easy 16 (47%) (ii) moderate 13 (38%) (iii) difficult 5 (15%) (II) Case design (i)- good 3 (8%) (ii) average 14 (42%) (iii) poor 17 (50%) (III) Cost (i) low 0 (0%) (ii) reasonable 18(53%) (iii) excessive 16 (47%) Additional comments Stinging 5 (15%) Forgot to neutralize 3 (8%) Switched from chemical problems to 10/10 successfully 18 (100%)

Discussion Patient population, significant acuity loss and adverse physiological response The results to date appear extremely encouraging, with a very low incidence of signs to suggest poor biocompatibility. Limbal vessel changes especially seemed minimal, and patients with a known sensitivity to chemicals (18 ) showed no adverse response using peroxide. Only 5 (15 %) complained of stinging upon inserting their lenses. 3 (8%) patients inserted lenses directly into their eyes without neutralizing; unfortunately none of the patients concerned reported back to enable the corneal condition to be assessed but no permanent damage has been seen. All patients reported that they would not wish to repeat the experience!

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Lens/system inter-reaction:The dark field analyser may be considered as a "disclosing device". In the same way as dentists use disclosers to reveal dental deposits, this method enables the practitioner and patient to readily identify and demonstrate lens contamination problems. The results to date suggest that by combining good surfactant cleaning methods, enhancing these effects with cleaning sponges, and peroxide disinfection, lens spoilage rates can be low. In-practice experience with good cleaning prior to heat and chemical disinfection has still shown discolouration to be present within a few months, whereas these results using peroxide show a definite improvement. It is still too early in the study to be sure, but it seems reasonable to speculate that the relative cleanliness and low degradation results so far seen would suggest that 38% pHEMA lens longevity could be significantly better using these care procedures.

Patient attitudes Ease of use: Despite the more laborious "two-step" (i.e. disinfecting and neutralizing) stages, generally patients surprisingly rated the system "easy-to-use" 16 (47%).

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However, 2 older hyperopic patients in the study, who already were experiencing some disillusionment with soft lenses due to handling difficulties, found the system too complex and have been switched to alternative, simpler methods. Case design: Probably the worst aspect of the system, with 14 (42%) patients rating the case as "average" and 17 (50%) as "poor". Patients complained of case leakage (usually due to poor seating of the silicone sealing ring), difficulty in removing the lenses from the case (due to the excessive radius of curvature of the supporting dome) and lens damage due to the clip-hds. Cost: We estimate that patients could spend as much as £10 per month purchasing the cleaner, aerosol and 10/10 system, which probably explains why 16 (47%) considered the system expensive. However, other methods are similar in cost, and the probable improved lens life expectancy favours the peroxide method. Additional comments The main objection was the general bulkiness of the system, especially for travelling patients.

Conclusions After one year's usage: (i) the incidence of adverse physiological response definitely attributable to the 10/10 system is very low. (ii) lens cleanliness, provided a prior surfactant cleaning technique is used is good. We predict a likely lens life expectancy of more than two years for 38% pHEMA lenses (iii) The system is reasonably "user-friendly", although we think older patients are less likely to cope with the complications.

Comments and Recommendations (1) We found the biggest "in-practice" problems to be the increased amount of time needed during handling appointments to explain the care procedures. (2) This study only describes the system's use with 38 % pHEMA lenses. We additionally tried the system with some high water content lenses (Essel Lunelle) and found the lenses became diseoloured pink (3) The use of a dark field analyser in order to disclose contamination is recommended in order to determine lens condition and advise patients on replacement frequency (4) The case design is poor (5) The system is at present bulky and with an added cleaner incoherently presented. We would like the manufacturers to consider: (a) including a "surfactant cleaning" recommendation prior to disinfection and to incorporate a suitable cleaner, less "tacky" than Mirasol, with the starter kit (b) to re-design the case so that it does not leak, has a smaller radius of curvature supporting dome, and ideally avoids the use of "clip" lids

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(c) Develop an unpreserved aerosol saline containing the neutralizing catalyst pyruvate. This would make the system less bulky, and would combine as a rinsing fluid. (d) We believe the best method of maintaining lens cleanliness is: (i) daily surfactant dean, occasionally enhanced with a cleaning sponge, on the front lens surface. 'The correct cleaning technique must be carefully taught for maximum effect. (ii) Rinse with either unpreserved saline (or possibly fresh tap water?) (iii) Peroxide disinfect and neutralize (iv) Rinse again prior to insertion We did not find any need for enzyme cleaning in the study using this regime, confirming Josephson's opinion. However, enzyme products may be useful where inadequate cleaning has occurred in order to loosen protein based deposits, probably followed by a thorough Sl~0nge enhanced cleaning (as suggested by Callender).

Ackowledgements The author would like to thank clinical assistants Maria Naugton and Nichola Bray for their help in this study and the preparation of the manuscripts and to Malcolm Rogan of Cooper Vision for technical help and preparation of slides.

References Billig, H., Bailey, N., Fleisehman, W., Ghormley, N.R., Seger, R~G., Yamane, S.J., 1984, A new rapid hydrogen peroxide system for contact lens disinfection, CLAO Journal, 10, (4), 341-345 Brunn, S.I., Tragakis, M.P., 1972 Sterilisation of soft contact lenses, Soft Contact Lens, The C.V. Mosby Company, 240-243 Callender, M. (1978) A comparison of Softens (Polymacon) wearer sensitivity to thermal or cold disinfecting systems, The Contact Lens Journal 7.3. June 1978 Callender, M. 1985 Discussion extract "Hydrogen Peroxide, the hydrogel disinfection system of the future?" International Contact Lens Clinic Vol 12 No 3 135-138 Eriksen, S. (1978) A rational comparison of heat vs. cold disinfection of hydrophilic lenses. The Contact LensJournal 7 (4): 18-23 Gasser, A.R., Kaufman H.E. (1972) Fitting manual for Bausch & Lomb and Griffin lenses. Soft Contact Lens, C.V. Mosby Company 298-299 Grant, R. (1984) Microbial aspects of hydrogel lenses. Journal of B.C.L.A. Vol.7 No.3 146-151 Guillon,-M., Bilton, S., Bleshoy, H., Gui]ion, J.P., Lydon, D.P., (1985 ) Limbal changes associated with hydrogel contact lens wear. Journal of the B.C.L.A. Vol.8, N o d 15-19

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Hopkins, G.A., (1986) The formulation of rigid lens care systems. The Optician March 21 18-22 Houlsby, R.D., (1984) Sterilising treatment with hydrogen peroxide and neutralisation of residual amounts thereof EP 0110 609 Houlsby, R.D., Ghajar, M.,Chavez, G., (1984) Microbiological evaluation of soft contact lens disinfecting solutions. Journal of the American Optometric Association Vol. 55, No.3 205-211 Josephson, J.E., (1985) Discussion extract "Hydrogen peroxide, the hydrogel disinfection system of the future?" International Contact Lens Clinic Vol. 12, No.3 135-138 Kerr, C., (1982) Solutions? the case for hydrogen peroxide, The Optician, 184 (14), 16 Killpartrick, M.R., (1982) Weicon 38e soft lenses, The Optician, December Killpartrick, M.R., (1983) Do contact lens disinfectants cause "red eye"? Contact Lens Forum 8 (10): 79-86 Krezanoski, J.Z., (1985) 'Discussion extract "Hydrogen peroxide, the hydrogel disinfection system of the future?" International Contact Lens Clinic Vol. 12 No.2 78-80 Larke, J.R., Humphreys, J.A.., and Holmes, R., (1981) Apparent corneal vascularization in soft lens wearers. Journal of the B.C.L.A. 4 105-106 Levine, W.L., Litsky, W., Lamm, R.A., (1981) Disinfection of hydrophilic contact lenses with commercial preparations of 3% and 6% hydrogen peroxide, Dev. Ind. Microbiol, 22, 813-819 Lowther, G. (1984) Coating, filming, degradation. Journal of the American Optometric Association Vol.55, No.3 193 MCMonnies, C.W., (1985) Contact lens induced corneal vascularization -- aetiology and risk factors. Journal of the B.C.L.A. Vol. 7 No°3 154-157 Parker, J., Contact Us! The Optician October 4 p.33 Penley, C.A., Schlitzer, R.L., Aheam, D.G., Wilson, L.A., (1980) I Laboratory evaluation of chemical

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disinfection of soft contact lenses. Contact lens Vol.7 No.2 101-110 and II Fungi as challenge organisms, Contact Lens Vol.7 No.3 196-204 1980 Penley, C.A., Ahearn, D.G., Wilson, L.A., (1983) Inhibition of fungi by soft contact lens solutions as determined by FDA recommended tests. Developments in industrial microbiology 24, 369-375 Penley, C.A., Llabres, C., Wilson, L.A., Ahearn, D.G., (1985) Efficacy of hydrogen peroxide disinfection systems for soft contact lenses contaminated with fungi. The C.L.A.O. Journal, 11 (1), 65-68 Phillips, A.J., (1980) The cleaning of hydrogel contact lenses. The Opthalmic Optician May 24th 387-388 Rogan, M., (1985 ) Systems for hydrogen peroxide disinfection of soft contact lenses. Transactions of the B.C.L.A. Annual Clinical Conference, Blackpool 40-42 Roth, H.W., (1978) The aetology of ocular irritation of soft lens wearers. Contact and Intraocular Lens Medical Journal 4:38-46 Ruben, M., (1980) Chlorhexidine and the pHEMA soft lens. The Contact Lens Journal 9:3-14 Schwegler, Y., (1981) Simple, efficient and original method of cleaning and aseptization for hydrophilic lenses. Contacto May 32-35 Sibley, M.J., (1985) Discussion extract "Hydrogen peroxide, the hydrogel disinfection system of the future?" International Contact Lens Clinic Vol.12 No.2 78-80 sunderdiek; R., (1984) Investigation of the microbiological and cleaning efficiency of contact lens solutions on the basis of oxidation. DOZ, 10, 78-80 Tragakis, M.P., Brown, S.I., Pearce, D.B., (1973) Bacteriologic studies for contamination associated with soft contact lenses. American Journal of Ophthal mology Bol.75 No.3 496-499 Wilson, L.A., et al(1981) Delayed hypersensitivity to thimerosol in soft contact lens wearers. Arch. Ophthalmol.88:808-809

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