Contact lens trends in the United Kingdom in 1991

Journal of the British Contact Lens Association, Vol. 15, No. 1, pp 17-23, 1992

©1992 British Contact Lens Association

Printed in Great Britain

CONTACT LENS T R E N D S IN THE U N I T E D KINGDOM IN 1991 Richard

M.

Pearson*

(Received 12th May 1991; in revised form 1st July 1991)

Abstract - A questionnaire was sent to 750 randomly selected members of the British Contact Lens Association in order to provide a survey of selected aspects of contact lens practice in the UK. The response rate was 40.5%. A n average of 247 pairs of contact lenses were prescribed by each member per annum and 61% of the patients had not previously worn contact lenses. A higher proportion of soft lenses (60.6%) than of rigid lenses (39.1%) were fitted. Nearly half the respondents either did not undertake fitting of lenses for extended wear or would only do so as a matter of clinical necessity.

KEY WORDS:Contact lens prescribing, contact lens care, extended wear, survey, questionnaire.

Introduction N 1989 the population of the UK was 57.2 million and it is projected to reach just over 61 million by 2025. The age group of 16-39 years, which corresponds to that of most new contact lens patients, is projected to decline from 20.4 million in 1989 to 18.1 million by 2011.1 According to the annual report for 1990 of the General Optical Council (GOC), the total numbers of the optical professions registered in the UK at 31st December were:

I

• Optometrists • Dispensing opticians

6644 3558

Information as to the number of ophthalmologists serving the UK population is seldom published. It has been stated that these comprise2: • Consultant ophthalmologists • Ophthalmic registrars • Ophthalmic medical practitioners

350 350 150

The Opticians Act 1989, section 25, restricts the practice of fitting contact lenses to registered medical practitioners, registered opticians, and medical and optical students where it is undertaken as part of their training. The Contact Lens (Qualifications, etc.) Rules 1988 of the GOC define the qualifications t h a t must be held by a registered optician in order to undertake contact lens fitting. In essence, any optometrist who registered with the GOC after the 31st December 1960 is deemed qualified to fit contact lenses. Dispensing opticians are required to hold a contact lens diploma. Some members of both professions are permitted to fit contact lenses on the grounds of proven practical experience and competence. * MPhil, FBOA(HD), FBCO, DCLP, DOrth.

No information is available concerning the actual numbers of medical and optical practitioners who engage in contact lens fitting. Similarly, there is no knowledge of the degree of involvement in contact lens practice of those practitioners of any profession who do undertake this work. A report published in 1985~ indicated that the number of contact lens wearers in the UK was 1,297,000 or 2.3% of the total population. In order to achieve some understanding of British contact lens prescribing habits, both full-time and part-time practitioners were surveyed by Atkinson 4 in 1976. Analysis of the results of a questionnaire showed that the former group fitted equal numbers of hard and soft lenses, but the latter group fitted more hard lenses than soft. It was inferred that a trend towards the greater use of soft lenses was evident at that time. In a subsequent smaller review 4 years later, both those engaged in full-time and part-time contact lens work were shown to fit hard and soft lenses in equal percentages3 This finding was interpreted as an indication that preference was moving towards rigid lenses. Extensive national surveys have been conducted periodically in Australia by the Cornea and Contact Lens Research Unit of the University of New South Wales. Results of two of these surveys have been published. ¢7 A similar nationwide survey has been undertaken in Canada 8, but no study of comparable scope has been undertaken in the UK. The aim of the present investigation was to address this omission. The results of such a survey provide an overview of current contact lens prescribing trends and can be compared either with data from individual practitioners or with findings from similar studies. Methods A questionnaire (Figure 1), largely based on that of Holden et alJ, was sent to 750 randomly selected

17

R I C H A R D M. P E A R S O N

CONTACT

LENS

QUESTIONNA/RE

CONFIDENTIAL

All questions relate to the period 1st April 1990 - 31st March 1991. 9. What percentage of your SOFT l e n s p a t i e n t s were f i t t e d TORIO lenses?

If accurate statistics are not available, do not hesitate to give estimates.

with

What percentage of your RIGID l e n s p a t i e n t s were f i t t e d TORIC lenses?

Would you please answer as many questions as possible and then return the form even if you are unable to complete every question.

with

10. What percentage of your RIGID l e n s p a t i e n t s do you recommend the use of?: I. A r e

you: an O p t o m e t r i s t ? a Dispensing Optician?

Daily surfactant Enzyme c l e a n e r

2. Do you have a s p e c i a l i s t q u a l i f i c a t i o n l e n s work? [ d e l e t e as a p p r o p r i a t e ]

in contact Yes/No

11. What methods of SOFT l e n s d i s i n f e c t i o n do you advise your p a t i e n t s t o use? Heat Hydrogen p e r o x i d e Chemical (preserved solutions) Chlorine based (e,g. Softab) Other (please specify) .....................

3. How many p a i r s of c o n t a c t lenses d i d you f i t i n t h e past year? [excluding supply of replacement pairs on grounds of loss, damage, etc]

4. What percentage of t h e above c o n t a c t l e n s f i t t i n g s NO p r e v i o u s c o n t a c t l e n s wear? HAD p r e v i o u s c o n t a c t l e n s wear?

had:

TOTAL 5. What per centage o f p a t i e n t s d i d you f i t types of lenses?:

cleaner

TOTAL

100~

w i t h the f o l l o w i n g

SOFT LENSES

12. What method of d i s i n f e c t i o n do you use f o r TRIAL s e t s of SOFT lenses? Heat Hydrogen peroxide Chemical (preserved solutions) Chlorine based (e.g. Softab] Other (please specify) ..................... ....... .......... ...,

Low w a t e r c o n t e n t ( u n d e r 40%) w i t h : c e n t r e t h i c k n e s s Tess t h a n 0.06 mm ( " h y p e r - t h i n " ) c e n t r e t h i c k n e s s 0.06 t o 0.10 mm ("ultra-thin") centre thickness o v e r 0 . 1 0 mm ("standard") Hid High

water water

content

(41

content

to

60%)

(over

60%)

1OO% i

TOTAL

100~

13. What method of d i s i n f e c t i o n do you use f o r TRIAL s e t s of RIGID lenses? Hydrogen p e r o x i d e Chemical ( p r e s e r v e d s o l u t i o n s ) Other ( p l e a s e s p e c i f y ) . . . . . . . . . . . . . . . . . . . . . .

RIGID CORNEAL LENSES TOTAL Nominal oxygen p e r m e a b i l i t y (Dk) Zero (PMMA) I to 9 e . g . CAB 10 t o 39 e . g . Boston I I & IV, 40 t o 69 e . g . Paraperm EW, C o n f l e x A i r , 70 or m o r e e . g . Quantum, Argon

I n t h e case of RIGID l e n s e s , what p e rc e n ta g e of lenses w h i c h you o r d e r a r e : P r o p r i e t a r y design e . g . Quantum, C o n f l e x , GP20/50, e t c S p e c i f i e d design e , g . own d e s i g n , e CAEL d e s i g n , e t c

15.

I n t h e c a s e o f SOFT l e n s e s , what percentage of lenses which you order are: Proprietary design e.g. Hydron Z6, Cibasoft, U3, e t c S p e c i f i e d design e . g . own d e s i g n or e p u b l i s h e d design

RXD

TOTAL OTHER LENS TYPES [Please specify

type]

....................

TOTAL of S o f t + R i g i d Corneal + Ot he r

TOTAL

100%

100%

DO NOT f i t a n y EW W i l l f i t SOFT lenses ONLY i f EW i s DEMANDED by p a t i e n t _ _ W i l l f i t RIGID lenses ONLY i f EW i s DEMANDED by p a t i e n t W i l l f i t SOFT lenses w i l l i n g l y W i l l f i t RIGID lenses w i l l i n g l y Oth e r [ p l e a s e d e s c r i b e ] ...........................

100%

+ a t what i n t e r v a l d i d you advise d i s p o s a l ? * a t what i n t e r v a l d i d you advise replacement? [Please i n d i c a t e w h e t h e r t h e i n t e r v a l s p e c i f i e d i s WEEKS or MONTHS]

¢7.

IF you fit you advise

extended wear lenses, how m a n y n i g h t s p e r w e e k do patients t h a t t h e y may s l e e p w e a r i n g them?

SOFT l e n s e s

7. What percentage of your CONTACT LENS p a t i e n t s were presbyopes? 18. 8. What percentage of ALL your presbyopic p a t i e n t s are w e a r i n g :

Please indicate (with a tick) (i.e. use of instruments such focimeter, etc):

RIGID

lenses

your policy on verification as Radiuscope, Optimec, RIGID

Spectacles only Bifocal contact lenses

lenses

* SOFT l e n s e s

Never check Check when suspicious Check every lens

a) soft b) r i g i d Nonovision (one eye f o r D i s t a n c e , one eye f o r Near) DISTANCE c o n t a c t l e n s e s + r e a d i n g g l a s s e s NEAR c o n t a c t lenses + distance glasses Other (please specify] .................. TOTAL

100%

16. What i s your a t t i t u d e t o extended wear (EW)? [ E x c l u d i n g a l l cases of o c u l a r p a t h o l o g y ]

6. Of t h e p a t i e n t s f i t t e d w i t h s p h e r i c a l SOFT l e n s e s , what p r o p o r t i o n were f i t t e d w i t h ? : + Disposable l e n s e s Planned replacement lenses Replacement as needed due t o l o s s , damage, e t c TOTAL

100%

14.

EXCLUDING d i s p o s a b l e

SOFT l e n s e s

1OO%

Figure 1. The questionnaire used in the survey repo~ted herein. members (both optometrists and dispensing opticians) of the British Contact Lens Association. Information on selected aspects of contact lens fitting was requested for the period 1st April 1990 to 31st March 1991.

18

Results A total of 304 forms were returned, which represents a response rate of 40.5%. This rate compares favourably with that achieved in similar studies (Table 1). Eleven of these forms were not completed because

CONTACT LENS TRENDS

IN THE UNITED

K I N G D O M 1N 1991

Table 1. The response rate achieved in previous surveys of contact lens practice or extended wear. Principal Author

Year

Number Surveyed

Response Rate (%)

Atkinson4 Swarbrick et al. 6

1976 1985

106 572

Persen and Farris 9

1985

Pye 1° Weissman et al. tl Holden et al. 7 Fonn et al. s

1987 1987 1989 1990

Scope of Survey

Respondents

75 25

Contact lens practice Contact lens practice

314

46

262 2926 600 2500

42 26 19 10

Medical contact lens practice Extended wear Extended wear Contact lens practice Contact lens practice

Optometrists Optometrists and ophthalmologists Ophthalmologists

the recipient had undertaken no contact lens work for various reasons, such as maternity or retirement from practice. A total of 293 completed questionnaires was, therefore, available for analysis and the professional profile of the respondents is illustrated in Figure 2. Of these, 73% were optometrists and 27% were dispensing opticians. A specialist qualification in contact lens work was held by 31% of the former and by 79% of the latter.

100%

Optometrists Optometrists Optometrists Optometrists

N u m b e r of Contact Lens Patients The respondents fitted an average of 247 patients per annum [standard error (SE), _+16.4; n, 281; range, 1-1507]. Figure 3 illustrates the number of pairs of contact lenses fitted by practitioners, 41% of whom fitted up to 100 pairs in a year and 65% of whom fitted up to 200 pairs. N e w Cases and Re-fitting Of the patients fitted, an average of 61% (SE, _+1.2; n, 283; range, 10-100%) were 'new' patients with no previous history of contact lens wear.

90% -

Presbyopia and Its Correction An average of 14% of the respondents' contact lens patients were presbyopic (SE, ___0.6; n, 286; range, 0-50%). The use of various modes of correction of all presbyopic patients seen by respondents is shown in Table 2.

80% 70% • 60% (3 q)

50% 40%

30% 20% 10% 0%

Optometrists

Dispensing opticians

Figure 2. The profession of respondents. The proportion of those holding a specialist qualification in contact lens work is indicated by the shaded area. 1501-1600 1401-1500 1501-1400 1201-1500 1101 1200 "~:~. 1 0 0 1 - 1 1 0 0 901-1000 801-900 .~ 701-800 601-700 501-600 0 (,~ 40/-500

] ] 1

Table 2. Methods of correction of all presbyopic patients seen by responding practitioners (n, 219). The category of other methods embraces procedures such as modified monovision. Mode of Correction (n, 219)

]

301-400 201-300 101-200

1-100 0

Rigid Corneal Lenses The average extent of usage of rigid corneal lenses was 39.1% (SE, ___1.1; n, 247; range, 0-100%), the corresponding figure for soft lenses was 60.6% (SE, _+1.1; range, 0-100%), and that of other types was

I0

20

50

40

50

Practitioners (%)

Figure 3. Number of pairs of contact lenses fitted per year.

Spectacles only Soft bifocal lenses Rigid bifocal lenses Monovision Distance contact lenses with reading spectacles Near contact lenses with distance spectacles Other methods

Average Use (%)

SE

Range (%)

90.3 1.4 0.8 2.4 4.9

_+0.6 _+0.2 _+0.1 _+0.2 _+0.4

60-100 0-17 0-10 0-15 0-30

0.1

_+0.05

0-9

0.1

+_0.02

0-5

19

RICHARD M. PEARSON

Soft, 60.6%

Dk O, 3O/o

Dk >

Other 0.3%

Dk 40-69, 280/¢

10-39,44o/o Corneal, 39.1%

Figure 4. Comparison of the average numbers of soft and corneal lenses fitted. The 'other' group comprises lens types such as scleral and silicone elastomer.

Figure 5. Comparison of the use of different rigid materials according to their oxygen permeability (Dk). Never checked, 5%

Chemical, 83°,4 Suspec~

Hydrogen peroxide, 8%

checked, 50~ AIIchecked,

45O/o Other, 9%

Figure 6. Methods used for the disinfection of rigid trial lenses. The 'other' group represents the use of agents such as cetrimide.

Figure 7. Practitioners' policy on the verification of the specification of rigid lenses. 'Suspects checked' signifies that lenses were only checked if their fitting appeared to be incorrect.

6. Respondents indicated that the 'other' category 0.3% (SE,_+0.1; range, 0-20%) (Figure 4). Although commonly comprised the use of cetrimide, but some the category of 'other types' was dominated by scleral lenses, their use was mentioned by only nine (3.6%) stated under this heading that trial lenses were stored in a dry state. of all the respondents. Practitioners' policy on the verification of preThe use of rigid materials according to their nominal scribed rigid lenses is depicted in Figure 7. A little oxygen permeability (Dk) is shown in Figure 5. Manufacturers' proprietary designs accounted for less than half the respondents routinely verified the specification of rigid lenses and 50% checked the an average of 64% (SE, +_2.2; n, 291; range, 0-100%) of the rigid lenses, as compared with designs specified lenses when the in vivo assessment of the fitting gave by the practitioner. Toric rigid lenses werdprescribed :rise to suspicion that the lens had been incorrectly for an average of 4% (SE, _+0.3; n, 286; range, 0-60%) manufactured. Only a small number of practitioners (5%) never verified rigid lenses. of cases. In relation to the cleaning of rigid lenses by patients, a surfactant cleaner was recommended in Soft Lenses an average of 99% (SE, +_0.5; n, 291; range, 10-100%) The average use of soft lenses, as mentioned earlier, of cases. A surfactant was, in fact, advised in every was 60.6%. The utilisation of different hydrogel materials is illustrated in Figure 8, which shows that case by 96% of the responding practitioners. An an average of 55% of lenses used had a water content enzymatic cleaner was recommended in an average of under 40%. The designations of 'hyper-thin', 'ultraof 57% (SE, _+2.4; range, 0-100%) of cases. The use of an enzymatic cleaner was advocated for every thin' and 'standard' categories were assigned to lenses with centre thicknesses of <0.06, 0.06-0.10, and patient by 32% of the practitioners. The use of different methods employed for the >0.10mm, respectively. The 'medium' group repredisinfection of rigid trial lenses is illustrated in F i g u r e sented a water content of 41-60%. A water content

20

CONTACT L E N S T R E N D S IN T H E U N I T E D KINGDOM IN 1991

Hvper-thin, 7%

t~t~rti,,m

Planned replacement, 23%

water, 20%

osables 11%

Ultra-thin, 39%

High water, 25%

Standard, 9%

Unscheduled ,replacement, 66%

Figure 8. Comparison of the use of different hydrogel materials. 'Hyper-thin ', 'Ultra-thin', and 'Standard' represent lenses with a water content under 40% and with centre thicknesses of 0.10ram, respectively. 'Medium' and 'High' water correspond to water contents of 41-60% and over 60%, respectively.

Figure 9. Different bases for the replacement of old lenses with new ones. 'Unscheduled replacement' describes the supply of new lenses only when previous pairs are unsuitable .for further use. Chlnrine 26o/n

Chemical, 13%

-al, 8% ;%

Chlorine, 25'

Heatl 2°A

3ther, 1%

Other, 7%

Hydrogen peroxide, 63%

Hydrogen peroxide, 29%

Figure 10. Methods used for the disinfection of trial soft

Figure 11. Methods used for disinfection of sob lenses by

lenses. The 'other' group represents the use of an autoclave.

patients.

exceeding 60% was described as 'high'. Manufacturers' proprietary designs were used for an average of 93% (SE, _+1.1; n, 288; range, 0-100%) of the soft lenses, as compared with designs specified by the practitioner. Toric soft lenses were prescribed for an average of 9% (SE, _+0.4; n, 286; range, 0-50%) of cases. The different bases upon which spherical soft lenses were replaced are shown in Figure 9. Disposable lenses accounted for an average of 11% (SE, _+1.1; n, 277; range, 0-90%), and planned replacement for an average of 23% (SE, _+1.8; range, 0-100%). The majority of the lenses, an average of 66%, were replaced on an unscheduled basis as and when they became damaged or otherwise unsuitable for further use (SE, _+2.1; range, 0-100%). The average interval at which disposable lenses were discarded was 2 weeks, and the average interval for planned replacement was 6 months. It was noted from the remarks made on the completed forms that many practitioners recommended that lenses be discarded at different intervals, depending on whether they had been used

in daily or extended wear. Similarly, planned replacement was offered by many respondents in a range of intervals, which varied according to factors such as the type of lens, the rate of soilage, and the financial resources of the patient. Methods employed in the disinfection of soft trial lenses are represented in Figure 10. The average use of hydrogen peroxide for this purpose was 29% (SE, _+2.6; n, 281). The use of heat disinfection averaged 26% (SE, _+2.4), chemical disinfection 13% (SE, _+1.8), chlorine 25% (SE, _+2.3), and other methods 7% (SE, _+1.4). The range of use of each of these methods was 0-100%. Specific mention of the use of an autoclave to sterilise trial lenses was made by 6.4% of respondents. The most popular method provided to patients for disinfection of soft lenses was hydrogen peroxide, which averaged 63% (SE, _+1.9; n, 286; range, 0-100%). The average use of chlorine was 26% (SE, _+1.7), that of chemical disinfection 8% (SE, _+0.9), that of thermal 2% (SE, _+0.5), and other methods averaged 1% (SE, _+0.5). This distribution is illustrated in Figure 11.

21

R I C H A R D M. P E A R S O N

100%

r checked 2 1 % 75%

80% (3

All checked,

60%"

9% ~

57%

38%

40%

3#Z 28%

~

18%

2o%-

No EW

Suspects checked,

fitted

70%

SOFT on

demand

[~]

Figure 12. Practitioners' policy on the verification of soft lenses. Practitioners' policies on the verification of prescribed soft lenses are represented in Figure 12. Relatively few practitioners (9%) verified the specification of every non-disposable soft lens supplied. When in vivo inspection of the fit indicated that the lens was incorrect, 75% of practitioners checked the lenses. For the remaining 21% of practitioners, soft lenses were never checked in vitro. E x t e n d e d Wear Of the practitioners who responded, the attitudes to extended wear are shown in Figure 13. The respondents represented by the 'other' category indicated that they were only prepared to fit extended wear lenses when this was a matter of clinical necessity for the patient. The most frequent example cited of such need was that of the elderly aphakic. The nonfitting group (30%) and the 'other' group, which expressed very strong reservations on extended wear (19%), comprised nearly half the responses to this question. Of those practioners who were prepared to undertake the fitting of extended wear lenses, soft lenses were more readily used than rigid lenses. In Figure 14, the attitudes toward extended wear between those practitioners who did not fit disposable lenses and those who did are compared. Use of dispos-

50%

40%

~

30%

~

20%

RIGID on

demand

NO disposables used

~

RIGID

willingly

Other

Fit disposables

Figure 14. Comparison of attitudes towards extended wear (EW) of those practitioners who do not fit disposable soft lenses (open column) with those who do (shaded column). able lenses seems to be associated with a more favourable disposition towards extended wear lenses. Discussion Holden et al. 7 drew attention to some of the inherent limitations of surveys of this nature. They advanced several reasons why results reported may not represent the overall situation and should, therefore, be treated with caution: • Respondents may not be representative of the population of practitioners who fit contact lenses. • It is probable that most of the data provided were derived from estimates rather than being actual figures. • Questions may have been misinterpreted. Accordingly, the results of this survey should be treated with caution and regarded as providing only an indication of recent trends in British contact lens practice. A number of findings from the present study are compared in Table 3 with those of other surveys. Since the investigations were conducted at different times, comparisons should be made with reservation. It does, nevertheless, appear that significantly fewer soft lenses are fitted in the UK, in comparison with Australia and Canada. The reason for this particular difference in prescribing habits is a matter for speculation. It may reflect a different emphasis in training in relation to soft and rigid lenses, or it may be due

3 . Comparison of particular findings between Australian 7, Canadian s, and British surveys, respectively.

Table

10%

Average Values 0%

NO EW

fitted

SOFT on RIGID on

demand

SOFT

demand willingly

RIGID

Other

willingly

Figure 13. Attitudes towards extended wear (EW) of all respondents.

22

SOFT

willingly

Pairs of lenses fitted per year Proportion of new patients Use of soft lenses Use of corneal lenses Use of other lenses

Holden et al.7

Fonn et al.s

Present Study

95 62% 82% 18% -

160 50% 85% 14% 1%

247 61% 60.6% 39.1% 0.3%

CONTACT LENS TRENDS IN THE UNITED KINGDOM IN 1991

to other factors, such as the long tradition of hard lens fitting in the UK stemming from experience with scleral lenses. Although the average number of patients fitted was highest in the UK, attention has already been drawn to the wide range and to the fact that 41% of respondents fitted up to 100 pairs of contact lenses per year. In all three countries, hydrogen peroxide was the most popular method of disinfection used by soft lens patients. The predominant attitude of practitioners towards extended wear lenses appears to be one of reluctance and great caution. However, when this modality is adopted, soft lenses are more popular for the purpose. It seems that bifocal contact lenses, both rigid and soft, have gained very little acceptance in the correction of presbyopia. In reply to the question on the method of disinfection employed with rigid trial lenses, some respondents indicated that these were stored dry. This method of storage does not, however, achieve disinfection. It may, nevertheless, be reasonable to assume that the dry-stored lenses were treated with a surfactant cleaner before and/or after their use. It is pertinent to note that cleaning solutions, when used in accordance with the manufacturers' directions for either hard or soft lenses, have significant antiviral efficacy. 12

Acknowledgement The author is deeply indebted to those colleagues who took both the time and trouble to complete the questionnaire. Many included helpful remarks on their

forms which, unfortunately, are impossible to reflect adequately in a broad review of this nature.

Address for Correspondence Richard M. Pearson, Department of Optometry and Visual Science, The City University, 311-321 Goswell Rd., London EC1V 7DD, UK. REFERENCES 1 Griffin, T. Social Trends 21, Central Statistical Office, HMSO, London, p.23 (1991). 2 Ruben, M. La l~gislation des lentilles de contact en Grands Bretagne. Contactologia, 2, 138-141 (1980). 3 The European Market for Contact Lenses, ERC Statistics International Ltd, London (1985), cited in Optom. Today, 2, 297 (1985). 4 Atkinson, T.C.O. Farewell to hard times? Soft and hard lenses Compared - from a practitioner's viewpoint. Ophthal. Optician, 16, 919-937 (1976). 5 Atkinson, T.C.O. The return of hard times? J. Br. Contact Lens Assoc., 3, 2-12 (1980). 6 Swarbrick, H., Pye, D., and Holden, B.A. CmTent Australian contact lens practice, Aust. J. Optom., 68, 2-7 (1985). 7 Holden, B.A., Sweeney, D.F., Southgate, D.C., and Wong, R. Contact lens practice in Australia 1987-1988. Clin. Exp. Optom., 72, 113-122 (1989). s Fonn, D., Anderson, R., Sorbara, L., and Callender, M.G.E. A survey of optometric contact lens use in Canada. Can. J. Optom./Rev. Can. d'Optom., 52, 90-95 (1990). 9 Persen, R.D. and Farris, R.L. A CLAO Journal survey of trends in ophthalmology practice, CLAO J., 11, 251-254 (1985). 10 Pye, D.C. Current Australian attitudes to contact lens extended wear. Clin. Exp. Optom., 70, 85-90 (1987). 11 Weissman, B.A., Remba, M.J., and Fugedy, E. Results of the extended wear contact lens survey of the Contact Lens Section of the American Optometric Assocation. J. Am. Optom. Assoc., 58, 166-170 (1987). 12 Vogt, M.W., Ho, D.D., Bakar, S.R., Gilbard, J.P., Schooley, R.T., and Hirsch, M.S. Safe disinfection of contact lenses after contamination with HTLV-III. Ophthalmology, 93, 771-774 (1986).

23