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The effect of cleaning soft lenses on thecurvature of various commercially available soft lenses
The Effect of Cleaning Soft Lenses on the Curvature of Various Commercially available Soft Lenses N. F. Burnett Hodd DCLP and Mrs. G. Haig-Brown DCLP
Nigel Burnett Hodd is in private practice in London and is a B. C.L.A. Council member.
The purpose of this paper was to find out how various soft lens cleaners affected the radius of different soft lenses. To do this we had to develop and make a new soft lens radiuscope that reads the radius of soft lenses accurately in millimetres to two decimal places. Using this instrument we were able to test Monoclens, Amiclair Triple-Enzyme tablets, Liprofin and Ren-oGel with very interesting results. We used four makes of soft lens of a standard size. Two makes were high water content being Scanlens/Duragel 75 and Igel 67s. Two makes were H E M A being Bausch & Lomb ultrathins and Wohlk Hydroflex Mini. No attempt was made to find out the cleaning efficiency of any of the cleaners.
Developing the "Optison" Soft Lens Radiuscope This soft lens radiuscope has been developed by us over the past eighteen months to meet a need in the practice for a method of measuring soft contact lenses to a high degree of accuracy, as cheaply and as quickly and as simply as possible. The method chosen is based upon the sagitta principle and involves the use of ultra sound and a wet cell. The lens is mounted centrally, concave side downwards on a stainless steel tube (chuck) of 8.50mm. diameter in saline. (This chord length was adopted after trying various sizes, being a good compromise for the range of lens sizes commonly encountered in general practice.) The diameter of the chuck was turned and then ground to ___0.002mm, and to further compensate for
32
the effect of errors arising from the measurement of this diameter the machine was checked using standard hard blanks of 7.90, 8.00, 8.10 and 8.30mm. radius. Every effort was made in the manufacturing process to maintain a square shoulder on the outside edge of the chuck circumference consistent with avoiding the detrimental effects upon the lens. In order to take a reading the machine was initially zeroed using a piano PMMA blank. The lens to be measured was then loaded into a retaining basket designed to locate and centre the lens on the chuck. Once centred, and having checked that no air was caught under the lens, the ultra-sound signal was tried. The reading, which registers within 0.25 of a second, is in fact an average of 10,000 separate echos from the back surface of the lens counted by the machine within that time interval, and is given as radius in mm. The machine can be calibrated to read to 0.02mm. for manufacturers and 0.05mm. for practitioners. The saline bath is readily detachable from the device to facilitate cleaning at the end of a session and the periodic changing of the fluid in the wet cell. (This was found to be necessary despite the handling of lenses with tweezers, since appreciable amounts of debris in the solution became apparent.) All measurements were taken at the prevailing ambient temperature which was not infuenced by the use of the machine, there being no heat source of any significance. To combat the effects of changes in temperature of the solution in the wet cell the machine was periodically recalibrated by zeroing using the plano blank.
Journal of the British Contact Lens Association
Cleaning Methods Wherever possible the cleaning procedures were carried out to the manufacturer's instructions. The only exception to this being with Liprofin where a magnetic stirrer was not used and the temperature was set at 80°C for "boiling". We standardized the saline and distilled water by using the Abatron products:-AMIDOSE - - SALINE AMI-O - - Distilled Water All cleaning was carried out by one researcher in an organized controlled way so as not to vary the procedure accidentally. MONOCLENS (Made by C.L.M.) 1° Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings C) Lens simmered in Monoclens for two hours D) Lens boiled in saline for thirty minutes E) Lens rinsed in saline F) Lens boiled twice in saline G) Lens stored for six hours in saline H) Lens measured average 5 readings Repeat A to H 3 × to give 4 results. AMICLAIR TRIPLE ENZYME TABLETS (Made by Abatron) Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings c) Lens placed in vial with saline and tablet D) Vial shaken until tablet dissolved E) Lens left to stand for six hours F) Lens cleaned with Ami-Clean gel G) Lens rinsed with saline H) Lens boiled twice in saline i) Lens stored for six hours in saline J) Lens measured average 5 readings Repeat A to J 3 × to give 4 results.
2.
3. LIPROFIN (Made by Alcon) Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings c) Lens boiled in Liprofin for four hours at 80°C D) Lens rinsed in saline E) Lens cleaned with Preflex F) Lens rinsed in saline G) Lens boiled twice in saline H) Lens stored for six hours in saline I) Lens measured average 5 readings Repeat A to 1 3 x to give 4 results
Journal of the British Contact Lens Association
4. REN-O-GEL (Made byAlCon) Procedure A) Lens stored in saline (after purge) B) Lens measured on"Optison" average 5 readings C) Lens boiled in Ren-o-gel-1 for ten minutes D) Lens cleaned in Pliagel E) Lens rinsed with saline F) Lens boiled in Ren-o-gel-2 for ten minutes G) Lens rinsed in saline H) Lens boiled twice in saline I) Lens stored for six hours in saline J) Lens measured average5 readings Repeat A t'o J 3 x to give 4 results
The Test Lenses We chose four makes of lens and tested all four in the four different solutions. To stop the possibility of random errors we used four of each make in each solution. So we had sixteen test lenses in each make. We further decided to avoid variations in lens thickness by using sixteen lenses of the same power and dimension. We also decided to use the average fitting for each make, so as to ensure good manufacture. The only exception to all this was with Ren-ogel on Scanlens. The manufaturer specifically states that Ren-o-gel will break down Vinyl-Pryollidone based soft lens so we saw no point in risking the lenses unnecessarily. A total of 60 lenses were purchased from the manufacturers without their knowledge of the intended use. Upon receipt of the lenses they were all opened and boiled twice in distilled water and then three times in Saline. This purging procedure was necessary to ensure that no chemical storage solution supplied in the vials could upset our measurements. The lenses were then clean and ready for test. All the lenses were checked against their vial specification and a record made of their real radius and power. Any lens with a power more than + 0.25 incorrect would have been rejected and replaced but this did not occur. The following lenses were used: (1) Igel 67% from Igel Optics. Ordered Specification: 8.10 × 13.00 - 4.00 (2) Scanlens/Durage175 from Scanlens UK Ltd. Ordered Specification: 8.30 × 13.50 -4.00 (3) Bausch & Lomb Series U4 from Bausch and Lomb (UK Ltd.) Ordered Specification: U4 - 4.00 (4) W6hlk Hydroflex Mini from W6hlk Contact Lenses Ltd. Ordered Specification: 8.10 x 13.00 - 4.00 We felt that this selection of lenses gave a good cross section of types of lenses available. We were very sorry not to have increased the study to have
33
included
Permalens,
Durasoft,
Hydrocurve
55 a n d
S a u f l o n 85. Table(l)
CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-Gel
INITIAL RADIUS DII~'FERENCE
RADIUS
AlrrER
CLEANING
1st.
2rid.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIFFERENCE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Nil + 0.05 + 0.05 + 0.15 + 0.10 Nil - 0.15 - 0.05 + 0.15 + 0.15 + 0.05 Nil - 0.05 - 0.15 - 0.25 + 0,05
7.75 7.95 8.55 8.00 8.35 7.80 8.25 7.90 8.10 7.90 8.00 7.80 8.15 8.10 8.10 7.75
7.90 8.130 8.55 8.00 8.30 7.70 8.30 7.90 8.00 7.85 7.95 7.90 7.90 8.00 8.10 7.55
7.95 8.05 8.70 8.00 8.25 7.85 8.50 7.90 8.00 7.90 8.10 7.90 8.15 7.50 8.20 7.60
7.90 7.90 8.55 7.95 8.15 7.75 8.50 8.05 8.00 8.10 8.05 7.65 7.75 7.75 DISTORTED 7.60
4- 0.15 Nil + 0.05 + 0.10 - 0.10 - 0.05 + 0.10 - 0.10 + 0.05 + 0.35 + 0.10 - 0.15 - 0.45 - 0.50
7.75 7.90 8.50 %85 8.25 7.80 8.40 7;95 7.95 7.75 7.95 7.80 8.20 8.25 8.35 7.70
LENS I N I T I A L RADIUS
NO
Results for S c a n l e n s / D u r a g e 1 7 5
INITIAL RADIUS DIFI~'ERENCE
+ 0.25 1 8.30 + 0.20 2 8.70 + 0.20 3 8.35 - 0.10 4 8.80 - 0.10 AMICLAIR 5 8.40 - 0.05 6 8.70 - 0.15 7 8.45 - 0.20 8 8.30 + 0.05 LIPROFIN 9 8.60 + 0.20 10 8.50 + 0.25 11 8.25 + 0.45 12 8.35 R E N - O - G E L ot R e c o m m e n d e d by Manufacturer U n d o u b t e d l y would destroy lenses.
MONOCLENS
T a b l e (III)
CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-GEL
34
8 . 1 0 × 13.00 - 4 . 0 0
LENS I N I T I A L NO RADIUS
T a b l e (II)
CLEANER
Results f o r lge167%
LENS I N I T I A L NO RADIUS
1 2 3 5 6 7 8 9 10 11 12 13 14 15 16
8.30 8.30 8.30 8.35 8.30 8.30 8.40 8.30 8.30 8.20 8.30 8.30 8.30 8.30 8.25 8.20
8.30 × 13.50 - 4 . 0 0
RADIUS
AFTER
CLEANING
1st.
2nd.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIt't'ERENCE
8.55 8.90 8.55 8.70 8.30 8.65 8.30 8.10 8.65 8.70 8.50 8.80
8.30 8.80 8.35 8.75 8.35 8.65 8.40 8.30 8.65 8.60 8.25 8.70
8.25 8.75 8.40 8.70 8.30 8.70 8.35 8.15 8.60 8.70 8.70 8.90
8.30 8.50 8.45 8.75 8.30 8.50 8.40 8.20 8.75 8.85 8.55 8.90
Nil - 0.20 + 0.10 - 0.05 - 0.10 - 0.20 - 0.05 - 0.10 + 0.15 + 0.35 + 0.30 + 0.55
FINAL RADIUS
Results for B a u s c h & L o m b H E M A U 4 - 4 . 0 0
INITIAL RADIUS DIt'FERENCE
RADIUS
AFTER
CLEANING
PROCEDURE
1st.
2nd.
3rd.
4th.
+ 1.50
9.80 ? ? 9.65 8.65 8.30 8.50 8.50 8.65 8.70 8.65 8.65 8.40 8.50 8.50 8.40
+ 1.30 + 0.35 Nil + 0.10 + 0.20 + 0.35 + 0.50 + 0.35 + 0.35 + 0.10 + 0.20 + 0.25 + 0.20
- 0.10
D~'ERENCE
8.70 8.90 9.00 8.80 8.60 8.50 8.60 8.55 8.55 8.55 8.55 8.60 8.45 8.35 8.35 8.30
UNCHECKABLE UNCHECKABLE UNCHECKABLE UNCHECKABLE 8.35 8.30 8.30 8.35 8.35 8.30 8.40 8.45 8.50 8.30 8.50 8.45 8.55 8.50 8.55 8.45 8.30 8.05 8.25 8.25 7.60 8.10 UNCHECKABLE
+ + + + Nil + 0.05 - 0.10 + 0.15 Nil + 0.25 + 0.20 ÷ 0.15 - 0.25 - 0.05 - 0.15
Journal of the British Contact Lens Association
Table(IV) Results for W6hlk Hydroflex Mini. 8.10× 13.00--4.00 CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-GEL
LENS INITIAL NO RADIUS
INITIAL RADIUS DIFFERENCE
RADIUS 1st.
AFTER
CLEANING
2nd.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIFFERENCE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
+ 1.60 + 1.50 + 1.50 + 1.50 - 0.45 - 0.20 - 0.50 - 0.45 - 0.15 - 0.20 - 0.30 - 0.50 + 0.10 + 0.35 Nil + 0.10
9.70 9.80 9.60 9.70 7.65 8.20 7.55 7.85 7.70 8.00 7.90 7.70 8.30 8.30 8.00 8.30
8.15 8.30 8.00 8.25 7.90 8.25 7.85 7.90 7.90 7.90 7.85 7.65 7.90 7.70 7.60 7.80
8.65 8.80 8.25 8.50 7.85 8.20 7.75 8.00 8.00 8.05 8.00 7.90 7.75 7.45 7.30 7.80
9.30 9.15 8.80 9.45 7.90 8.20 7.80 8.00 7.80 7.90 7.70 7.50 7.80 7.70 7.55 7.95
+ + + + -
8.10 8.30 8.10 8.20 8.10 8.40 8.05 8.30 8.05 8.20 8.20 8.20 8.20 7.95 8.00 8.20
1.20 0.85 0.70 1.25 0.20 0.20 0.25 0.30 0.25 0.30 0.50 0.70 0.40 0.25 0.45 0.25
C o m m e n t s on Table (I) Ige167% (1) (2) (3) (4)
Monoclens slightly flattened lenses and gave acceptable result. Amiclair slightly steepened lenses and gave acceptable result. L i p r o f i n f l a t t e n e d t h e l e n s e s twice as m u c h as M o n o c l e n s , R e n - o - g e l t e n d e d to d e s t r o y t h e l e n s e s a f t e r t h r e e c l e a n s a n d t h e f o u r t h c l e a n f i n i s h e d t h e m off. T h e l e n s e s w e n t u p to 0 . 5 0 m m . s t e e p a n d v e r y d i s t o r t e d . A l s o t h e m a t e r i a l h a r d e n e d c o n s i d e r a b l y to t h e touch. OK for one clean only.
C o m m e n t s on Table (lI) Scanlens/Durage175 (1) (2) (3) (4)
M o n o c l e n s h a d a m i n i m a l e f f e c t o n lens r a d i u s - - first c l e a n f l a t t e n e d l e n s e s b y 0 . 2 0 m m . T h e n g r a d u a l l y steepened over four cleans. Amiclair steepened lenses by about 0.10mm. consistently over four cleans. L i p r o f i n f l a t t e n e d l e n s e s c o n s i d e r a b l y a n d e r r a t i c a l l y a n d is c o n t r a - i n d i c a t e d f o r u s e o n this m a t e r i a l . A l t h o u g h f o u r l e n s e s w e r e initially flat w e w e r e p l e a s e d to find t h a t s u c h h i g h w a t e r c o n t e n t l e n s e s l a t h e cut were made reasonably accurately.
C o m m e n t s on Table (III) B. & L. H e m a U 4 (1) (2) (3) (4) (5)
M o n o c l e n s is a d i s a s t e r o n U 4 s - - c o n t r a - i n d i c a t e d . A m i c l a i r is s a f e a n d f l a t t e n s 0 . 2 0 m m . a f t e r o n e c l e a n , b u t b e c o m e s c o n s i s t e n t w i t h r e g u l a r u s e g i v i n g a slight flattening. L i p r o f i n f l a t t e n s t h e l e n s e s a lot a f t e r o n e c l e a n a n d is still t o o fiat a f t e r f o u r c l e a n s - - u s e w i t h c a u t i o n . U s e d o n l y o n c e o r t w i c e R e n - o - g e l is t h e b e s t " i n p r a c t i c e " c l e a n e r o f t h e s e t h r e e . Bausch and Lomb U4 lenses have very accurate radius reproducability.
C o m m e n t s on Table (IV) W 6 h l k Hydroflex M i n i (1) (2) (3) (4) (5)
36
M o n o c l e n s d r a m a t i c a l l y f l a t t e n s H y d r o f l e x l e n s e s a n d t u r n s t h e m m i l k y a f t e r o n e clean. It is c o n t r a indicated, Regular use of Amiclair produces a consistent 0.25mm. steepening of the lens after several cleans. The initial c l e a n h a s t h e w o r s t effect. L i p r o f i n s t e e p e n s t h e l e n s e s b y u p to 0 . 5 0 m m . o n o n e c l e a n a n d p e r h a p s s h o u l d o n l y b e u s e d as a b r i e f cleaner. Four cleans does not help. R e n - o - g e l is t h e b e s t " i n p r a c t i c e " c l e a n e r h e r e as o n e c l e a n h a s little e f f e c t b u t s u b s e q u e n t c l e a n i n g s h a v e as b a d a n e f f e c t as L i p r o f i n . O r i g i n a l l e n s a c c u r a c y is n o t as g o o d as o n e m i g h t e x p e c t for H E M A s h o w i n g t h e p r o b l e m o f l a t h e c u t lenses.
Journalof the BritishContact LensAssociation
Points for Discussion (1)
Monoclens
known. Except for Ultrathins HEMA lenses a 0.10mm to 0.20mm steepening effect can be expected.
This cleaner seems quite safe on high water content materials. It slightly flattens these materials at the initial clean and after four cleans the effect is less. O n low water content H E M A lenses the cleaner is contraindicated as it causes a dramatic flattening effect after one clean and in the case of ultrathins the lenses distort and become uncheckable after three cleans.
(3) Liprof'm is not good at maintaining lens parameters. It was safe on Ultrathin HEMA and Igel 67 but its effect on Scanlens/Duragel 75 and W r h l k Hydroflex was not acceptable.
(2)
(4) Ren-o-gel had no worrying effects on the three lenses we tested on thefirst clean. On the second and subsequent cleans the radius readings became rapidly steeper and unacceptable.
Amiclair Triple Enzyme Tablets
This cleaner used initially on high water content materials produces a 0.10 steepening effect but after four cleans the steepening is the same. So it is quite safe as long as this effect is noted by the practitioner. This cleaner had different effects on different H E M A lenses. It steepened W6hlk hydroflex lenses by 0.35mm. initially but flattened Bausch & Lomb ultrathins by 0.20mm. After four cleans W6hlk lenses still showed an 0.20mm. steepening whereas ultrathins were almost back to initial specification.
(3)
The patient may use Amiclair Triple Enzyme tablets routinely to clean their lenses. But the practitioner should check the radius at all after care visits.
Liprof'm
This cleaner changed the radius of all the four lenses by different amounts. With each lens it had a consistent effect. Ige167 was consistently flattened by about 0.10mm. Scanlens/Duragel 75 was consistently flattened by about 0,35mm. W r h l k Hydroflex was consistently steepened by about 0.45mm. B & L U4s were consistently flattened by about 0.15mm.
(4)
As a result of this paper we would like to make the following six recommendations:-Recommendation (1) Use of Amiclair
Ren-o-gel
Recommendations (2) "In Practice" Cleaning. High water content lenses. Monoclens has the least effect on radius when used several times. H E M A lenses. We recommend Ren-o-gel for the first clean. Subsequent cleanings may be done with Liprofin if the lens is not replaced.
Recommendation (3) Do not trust any lens cleaner. Do not trust any lathe cut lens. Remember we cleaned new lenses and not dirty ones.
Ren-o-gel did not destory Igel 67 after one clean. Indeed it had only a 0.10mm. steepening effect, Even two cleans was acceptable but further cleaning was contraindicated. Ren-o-gel initially slightly flattened HEMA lenses but caused a larger steepening effect on the second and subsequent cleans. After four cleans Wrhlk lenses were 0.35mm. steep and U4s were 0.15ram. steep.
Recommendation (4)
Conclusions
Recommendation (5)
(1) Monoclens is the best high water content cleaner but is unsafe on HEMA. (2) Amiclair Triple Enzyme Tablets were quite safe on all materials but their effect should be
38
The soft lens radius should be checked on the following o c c a s i o n s : A) As the final check in the laboratory. B) As the initial check in the practice. C) At all subsequent after care checks. D) Before and after"in practice" cleaning.
If a patient presents with a red eye condition consistent with a tight fitting heavily proteinised lens consider very carefully whether cleaning the lens will make the situation worse. In our practice we usually renew the lens.
Journal of the British Contact Lens Association
Recommendation (6) As a final comment and encouragement to manufacturers we would say that cleaning lenses in the practice can have an unacceptable effect on lens radius and we look forward to the coming of the cheap, spuncast or moulded "throw away" lens.
Journal of the British Contact Lens Association
Address for future correspondence to: 7 Devonshire Street, London, W l N 1FT.
39
Nigel Burnett Hodd is in private practice in London and is a B. C.L.A. Council member.
The purpose of this paper was to find out how various soft lens cleaners affected the radius of different soft lenses. To do this we had to develop and make a new soft lens radiuscope that reads the radius of soft lenses accurately in millimetres to two decimal places. Using this instrument we were able to test Monoclens, Amiclair Triple-Enzyme tablets, Liprofin and Ren-oGel with very interesting results. We used four makes of soft lens of a standard size. Two makes were high water content being Scanlens/Duragel 75 and Igel 67s. Two makes were H E M A being Bausch & Lomb ultrathins and Wohlk Hydroflex Mini. No attempt was made to find out the cleaning efficiency of any of the cleaners.
Developing the "Optison" Soft Lens Radiuscope This soft lens radiuscope has been developed by us over the past eighteen months to meet a need in the practice for a method of measuring soft contact lenses to a high degree of accuracy, as cheaply and as quickly and as simply as possible. The method chosen is based upon the sagitta principle and involves the use of ultra sound and a wet cell. The lens is mounted centrally, concave side downwards on a stainless steel tube (chuck) of 8.50mm. diameter in saline. (This chord length was adopted after trying various sizes, being a good compromise for the range of lens sizes commonly encountered in general practice.) The diameter of the chuck was turned and then ground to ___0.002mm, and to further compensate for
32
the effect of errors arising from the measurement of this diameter the machine was checked using standard hard blanks of 7.90, 8.00, 8.10 and 8.30mm. radius. Every effort was made in the manufacturing process to maintain a square shoulder on the outside edge of the chuck circumference consistent with avoiding the detrimental effects upon the lens. In order to take a reading the machine was initially zeroed using a piano PMMA blank. The lens to be measured was then loaded into a retaining basket designed to locate and centre the lens on the chuck. Once centred, and having checked that no air was caught under the lens, the ultra-sound signal was tried. The reading, which registers within 0.25 of a second, is in fact an average of 10,000 separate echos from the back surface of the lens counted by the machine within that time interval, and is given as radius in mm. The machine can be calibrated to read to 0.02mm. for manufacturers and 0.05mm. for practitioners. The saline bath is readily detachable from the device to facilitate cleaning at the end of a session and the periodic changing of the fluid in the wet cell. (This was found to be necessary despite the handling of lenses with tweezers, since appreciable amounts of debris in the solution became apparent.) All measurements were taken at the prevailing ambient temperature which was not infuenced by the use of the machine, there being no heat source of any significance. To combat the effects of changes in temperature of the solution in the wet cell the machine was periodically recalibrated by zeroing using the plano blank.
Journal of the British Contact Lens Association
Cleaning Methods Wherever possible the cleaning procedures were carried out to the manufacturer's instructions. The only exception to this being with Liprofin where a magnetic stirrer was not used and the temperature was set at 80°C for "boiling". We standardized the saline and distilled water by using the Abatron products:-AMIDOSE - - SALINE AMI-O - - Distilled Water All cleaning was carried out by one researcher in an organized controlled way so as not to vary the procedure accidentally. MONOCLENS (Made by C.L.M.) 1° Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings C) Lens simmered in Monoclens for two hours D) Lens boiled in saline for thirty minutes E) Lens rinsed in saline F) Lens boiled twice in saline G) Lens stored for six hours in saline H) Lens measured average 5 readings Repeat A to H 3 × to give 4 results. AMICLAIR TRIPLE ENZYME TABLETS (Made by Abatron) Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings c) Lens placed in vial with saline and tablet D) Vial shaken until tablet dissolved E) Lens left to stand for six hours F) Lens cleaned with Ami-Clean gel G) Lens rinsed with saline H) Lens boiled twice in saline i) Lens stored for six hours in saline J) Lens measured average 5 readings Repeat A to J 3 × to give 4 results.
2.
3. LIPROFIN (Made by Alcon) Procedure A) Lens stored in saline (after purge) B) Lens measured on "Optison" average 5 readings c) Lens boiled in Liprofin for four hours at 80°C D) Lens rinsed in saline E) Lens cleaned with Preflex F) Lens rinsed in saline G) Lens boiled twice in saline H) Lens stored for six hours in saline I) Lens measured average 5 readings Repeat A to 1 3 x to give 4 results
Journal of the British Contact Lens Association
4. REN-O-GEL (Made byAlCon) Procedure A) Lens stored in saline (after purge) B) Lens measured on"Optison" average 5 readings C) Lens boiled in Ren-o-gel-1 for ten minutes D) Lens cleaned in Pliagel E) Lens rinsed with saline F) Lens boiled in Ren-o-gel-2 for ten minutes G) Lens rinsed in saline H) Lens boiled twice in saline I) Lens stored for six hours in saline J) Lens measured average5 readings Repeat A t'o J 3 x to give 4 results
The Test Lenses We chose four makes of lens and tested all four in the four different solutions. To stop the possibility of random errors we used four of each make in each solution. So we had sixteen test lenses in each make. We further decided to avoid variations in lens thickness by using sixteen lenses of the same power and dimension. We also decided to use the average fitting for each make, so as to ensure good manufacture. The only exception to all this was with Ren-ogel on Scanlens. The manufaturer specifically states that Ren-o-gel will break down Vinyl-Pryollidone based soft lens so we saw no point in risking the lenses unnecessarily. A total of 60 lenses were purchased from the manufacturers without their knowledge of the intended use. Upon receipt of the lenses they were all opened and boiled twice in distilled water and then three times in Saline. This purging procedure was necessary to ensure that no chemical storage solution supplied in the vials could upset our measurements. The lenses were then clean and ready for test. All the lenses were checked against their vial specification and a record made of their real radius and power. Any lens with a power more than + 0.25 incorrect would have been rejected and replaced but this did not occur. The following lenses were used: (1) Igel 67% from Igel Optics. Ordered Specification: 8.10 × 13.00 - 4.00 (2) Scanlens/Durage175 from Scanlens UK Ltd. Ordered Specification: 8.30 × 13.50 -4.00 (3) Bausch & Lomb Series U4 from Bausch and Lomb (UK Ltd.) Ordered Specification: U4 - 4.00 (4) W6hlk Hydroflex Mini from W6hlk Contact Lenses Ltd. Ordered Specification: 8.10 x 13.00 - 4.00 We felt that this selection of lenses gave a good cross section of types of lenses available. We were very sorry not to have increased the study to have
33
included
Permalens,
Durasoft,
Hydrocurve
55 a n d
S a u f l o n 85. Table(l)
CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-Gel
INITIAL RADIUS DII~'FERENCE
RADIUS
AlrrER
CLEANING
1st.
2rid.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIFFERENCE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Nil + 0.05 + 0.05 + 0.15 + 0.10 Nil - 0.15 - 0.05 + 0.15 + 0.15 + 0.05 Nil - 0.05 - 0.15 - 0.25 + 0,05
7.75 7.95 8.55 8.00 8.35 7.80 8.25 7.90 8.10 7.90 8.00 7.80 8.15 8.10 8.10 7.75
7.90 8.130 8.55 8.00 8.30 7.70 8.30 7.90 8.00 7.85 7.95 7.90 7.90 8.00 8.10 7.55
7.95 8.05 8.70 8.00 8.25 7.85 8.50 7.90 8.00 7.90 8.10 7.90 8.15 7.50 8.20 7.60
7.90 7.90 8.55 7.95 8.15 7.75 8.50 8.05 8.00 8.10 8.05 7.65 7.75 7.75 DISTORTED 7.60
4- 0.15 Nil + 0.05 + 0.10 - 0.10 - 0.05 + 0.10 - 0.10 + 0.05 + 0.35 + 0.10 - 0.15 - 0.45 - 0.50
7.75 7.90 8.50 %85 8.25 7.80 8.40 7;95 7.95 7.75 7.95 7.80 8.20 8.25 8.35 7.70
LENS I N I T I A L RADIUS
NO
Results for S c a n l e n s / D u r a g e 1 7 5
INITIAL RADIUS DIFI~'ERENCE
+ 0.25 1 8.30 + 0.20 2 8.70 + 0.20 3 8.35 - 0.10 4 8.80 - 0.10 AMICLAIR 5 8.40 - 0.05 6 8.70 - 0.15 7 8.45 - 0.20 8 8.30 + 0.05 LIPROFIN 9 8.60 + 0.20 10 8.50 + 0.25 11 8.25 + 0.45 12 8.35 R E N - O - G E L ot R e c o m m e n d e d by Manufacturer U n d o u b t e d l y would destroy lenses.
MONOCLENS
T a b l e (III)
CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-GEL
34
8 . 1 0 × 13.00 - 4 . 0 0
LENS I N I T I A L NO RADIUS
T a b l e (II)
CLEANER
Results f o r lge167%
LENS I N I T I A L NO RADIUS
1 2 3 5 6 7 8 9 10 11 12 13 14 15 16
8.30 8.30 8.30 8.35 8.30 8.30 8.40 8.30 8.30 8.20 8.30 8.30 8.30 8.30 8.25 8.20
8.30 × 13.50 - 4 . 0 0
RADIUS
AFTER
CLEANING
1st.
2nd.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIt't'ERENCE
8.55 8.90 8.55 8.70 8.30 8.65 8.30 8.10 8.65 8.70 8.50 8.80
8.30 8.80 8.35 8.75 8.35 8.65 8.40 8.30 8.65 8.60 8.25 8.70
8.25 8.75 8.40 8.70 8.30 8.70 8.35 8.15 8.60 8.70 8.70 8.90
8.30 8.50 8.45 8.75 8.30 8.50 8.40 8.20 8.75 8.85 8.55 8.90
Nil - 0.20 + 0.10 - 0.05 - 0.10 - 0.20 - 0.05 - 0.10 + 0.15 + 0.35 + 0.30 + 0.55
FINAL RADIUS
Results for B a u s c h & L o m b H E M A U 4 - 4 . 0 0
INITIAL RADIUS DIt'FERENCE
RADIUS
AFTER
CLEANING
PROCEDURE
1st.
2nd.
3rd.
4th.
+ 1.50
9.80 ? ? 9.65 8.65 8.30 8.50 8.50 8.65 8.70 8.65 8.65 8.40 8.50 8.50 8.40
+ 1.30 + 0.35 Nil + 0.10 + 0.20 + 0.35 + 0.50 + 0.35 + 0.35 + 0.10 + 0.20 + 0.25 + 0.20
- 0.10
D~'ERENCE
8.70 8.90 9.00 8.80 8.60 8.50 8.60 8.55 8.55 8.55 8.55 8.60 8.45 8.35 8.35 8.30
UNCHECKABLE UNCHECKABLE UNCHECKABLE UNCHECKABLE 8.35 8.30 8.30 8.35 8.35 8.30 8.40 8.45 8.50 8.30 8.50 8.45 8.55 8.50 8.55 8.45 8.30 8.05 8.25 8.25 7.60 8.10 UNCHECKABLE
+ + + + Nil + 0.05 - 0.10 + 0.15 Nil + 0.25 + 0.20 ÷ 0.15 - 0.25 - 0.05 - 0.15
Journal of the British Contact Lens Association
Table(IV) Results for W6hlk Hydroflex Mini. 8.10× 13.00--4.00 CLEANER
MONOCLENS
AMICLAIR
LIPROFIN
REN-O-GEL
LENS INITIAL NO RADIUS
INITIAL RADIUS DIFFERENCE
RADIUS 1st.
AFTER
CLEANING
2nd.
3rd.
PROCEDURE 4th.
FINAL RADIUS DIFFERENCE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
+ 1.60 + 1.50 + 1.50 + 1.50 - 0.45 - 0.20 - 0.50 - 0.45 - 0.15 - 0.20 - 0.30 - 0.50 + 0.10 + 0.35 Nil + 0.10
9.70 9.80 9.60 9.70 7.65 8.20 7.55 7.85 7.70 8.00 7.90 7.70 8.30 8.30 8.00 8.30
8.15 8.30 8.00 8.25 7.90 8.25 7.85 7.90 7.90 7.90 7.85 7.65 7.90 7.70 7.60 7.80
8.65 8.80 8.25 8.50 7.85 8.20 7.75 8.00 8.00 8.05 8.00 7.90 7.75 7.45 7.30 7.80
9.30 9.15 8.80 9.45 7.90 8.20 7.80 8.00 7.80 7.90 7.70 7.50 7.80 7.70 7.55 7.95
+ + + + -
8.10 8.30 8.10 8.20 8.10 8.40 8.05 8.30 8.05 8.20 8.20 8.20 8.20 7.95 8.00 8.20
1.20 0.85 0.70 1.25 0.20 0.20 0.25 0.30 0.25 0.30 0.50 0.70 0.40 0.25 0.45 0.25
C o m m e n t s on Table (I) Ige167% (1) (2) (3) (4)
Monoclens slightly flattened lenses and gave acceptable result. Amiclair slightly steepened lenses and gave acceptable result. L i p r o f i n f l a t t e n e d t h e l e n s e s twice as m u c h as M o n o c l e n s , R e n - o - g e l t e n d e d to d e s t r o y t h e l e n s e s a f t e r t h r e e c l e a n s a n d t h e f o u r t h c l e a n f i n i s h e d t h e m off. T h e l e n s e s w e n t u p to 0 . 5 0 m m . s t e e p a n d v e r y d i s t o r t e d . A l s o t h e m a t e r i a l h a r d e n e d c o n s i d e r a b l y to t h e touch. OK for one clean only.
C o m m e n t s on Table (lI) Scanlens/Durage175 (1) (2) (3) (4)
M o n o c l e n s h a d a m i n i m a l e f f e c t o n lens r a d i u s - - first c l e a n f l a t t e n e d l e n s e s b y 0 . 2 0 m m . T h e n g r a d u a l l y steepened over four cleans. Amiclair steepened lenses by about 0.10mm. consistently over four cleans. L i p r o f i n f l a t t e n e d l e n s e s c o n s i d e r a b l y a n d e r r a t i c a l l y a n d is c o n t r a - i n d i c a t e d f o r u s e o n this m a t e r i a l . A l t h o u g h f o u r l e n s e s w e r e initially flat w e w e r e p l e a s e d to find t h a t s u c h h i g h w a t e r c o n t e n t l e n s e s l a t h e cut were made reasonably accurately.
C o m m e n t s on Table (III) B. & L. H e m a U 4 (1) (2) (3) (4) (5)
M o n o c l e n s is a d i s a s t e r o n U 4 s - - c o n t r a - i n d i c a t e d . A m i c l a i r is s a f e a n d f l a t t e n s 0 . 2 0 m m . a f t e r o n e c l e a n , b u t b e c o m e s c o n s i s t e n t w i t h r e g u l a r u s e g i v i n g a slight flattening. L i p r o f i n f l a t t e n s t h e l e n s e s a lot a f t e r o n e c l e a n a n d is still t o o fiat a f t e r f o u r c l e a n s - - u s e w i t h c a u t i o n . U s e d o n l y o n c e o r t w i c e R e n - o - g e l is t h e b e s t " i n p r a c t i c e " c l e a n e r o f t h e s e t h r e e . Bausch and Lomb U4 lenses have very accurate radius reproducability.
C o m m e n t s on Table (IV) W 6 h l k Hydroflex M i n i (1) (2) (3) (4) (5)
36
M o n o c l e n s d r a m a t i c a l l y f l a t t e n s H y d r o f l e x l e n s e s a n d t u r n s t h e m m i l k y a f t e r o n e clean. It is c o n t r a indicated, Regular use of Amiclair produces a consistent 0.25mm. steepening of the lens after several cleans. The initial c l e a n h a s t h e w o r s t effect. L i p r o f i n s t e e p e n s t h e l e n s e s b y u p to 0 . 5 0 m m . o n o n e c l e a n a n d p e r h a p s s h o u l d o n l y b e u s e d as a b r i e f cleaner. Four cleans does not help. R e n - o - g e l is t h e b e s t " i n p r a c t i c e " c l e a n e r h e r e as o n e c l e a n h a s little e f f e c t b u t s u b s e q u e n t c l e a n i n g s h a v e as b a d a n e f f e c t as L i p r o f i n . O r i g i n a l l e n s a c c u r a c y is n o t as g o o d as o n e m i g h t e x p e c t for H E M A s h o w i n g t h e p r o b l e m o f l a t h e c u t lenses.
Journalof the BritishContact LensAssociation
Points for Discussion (1)
Monoclens
known. Except for Ultrathins HEMA lenses a 0.10mm to 0.20mm steepening effect can be expected.
This cleaner seems quite safe on high water content materials. It slightly flattens these materials at the initial clean and after four cleans the effect is less. O n low water content H E M A lenses the cleaner is contraindicated as it causes a dramatic flattening effect after one clean and in the case of ultrathins the lenses distort and become uncheckable after three cleans.
(3) Liprof'm is not good at maintaining lens parameters. It was safe on Ultrathin HEMA and Igel 67 but its effect on Scanlens/Duragel 75 and W r h l k Hydroflex was not acceptable.
(2)
(4) Ren-o-gel had no worrying effects on the three lenses we tested on thefirst clean. On the second and subsequent cleans the radius readings became rapidly steeper and unacceptable.
Amiclair Triple Enzyme Tablets
This cleaner used initially on high water content materials produces a 0.10 steepening effect but after four cleans the steepening is the same. So it is quite safe as long as this effect is noted by the practitioner. This cleaner had different effects on different H E M A lenses. It steepened W6hlk hydroflex lenses by 0.35mm. initially but flattened Bausch & Lomb ultrathins by 0.20mm. After four cleans W6hlk lenses still showed an 0.20mm. steepening whereas ultrathins were almost back to initial specification.
(3)
The patient may use Amiclair Triple Enzyme tablets routinely to clean their lenses. But the practitioner should check the radius at all after care visits.
Liprof'm
This cleaner changed the radius of all the four lenses by different amounts. With each lens it had a consistent effect. Ige167 was consistently flattened by about 0.10mm. Scanlens/Duragel 75 was consistently flattened by about 0,35mm. W r h l k Hydroflex was consistently steepened by about 0.45mm. B & L U4s were consistently flattened by about 0.15mm.
(4)
As a result of this paper we would like to make the following six recommendations:-Recommendation (1) Use of Amiclair
Ren-o-gel
Recommendations (2) "In Practice" Cleaning. High water content lenses. Monoclens has the least effect on radius when used several times. H E M A lenses. We recommend Ren-o-gel for the first clean. Subsequent cleanings may be done with Liprofin if the lens is not replaced.
Recommendation (3) Do not trust any lens cleaner. Do not trust any lathe cut lens. Remember we cleaned new lenses and not dirty ones.
Ren-o-gel did not destory Igel 67 after one clean. Indeed it had only a 0.10mm. steepening effect, Even two cleans was acceptable but further cleaning was contraindicated. Ren-o-gel initially slightly flattened HEMA lenses but caused a larger steepening effect on the second and subsequent cleans. After four cleans Wrhlk lenses were 0.35mm. steep and U4s were 0.15ram. steep.
Recommendation (4)
Conclusions
Recommendation (5)
(1) Monoclens is the best high water content cleaner but is unsafe on HEMA. (2) Amiclair Triple Enzyme Tablets were quite safe on all materials but their effect should be
38
The soft lens radius should be checked on the following o c c a s i o n s : A) As the final check in the laboratory. B) As the initial check in the practice. C) At all subsequent after care checks. D) Before and after"in practice" cleaning.
If a patient presents with a red eye condition consistent with a tight fitting heavily proteinised lens consider very carefully whether cleaning the lens will make the situation worse. In our practice we usually renew the lens.
Journal of the British Contact Lens Association
Recommendation (6) As a final comment and encouragement to manufacturers we would say that cleaning lenses in the practice can have an unacceptable effect on lens radius and we look forward to the coming of the cheap, spuncast or moulded "throw away" lens.
Journal of the British Contact Lens Association
Address for future correspondence to: 7 Devonshire Street, London, W l N 1FT.
39