Corneal Ulcers Associated with Daily-Wear andExtended-Wear Contact Lenses

Bartly J. Mondino, M.D., Barry A. Weissman, o.n., M. Daniel Farb, M.D.,and Thomas H. Pettit, M.D.

Over a 21-month period, we treated cornealulcers in 11 patients using daily-wear contactlenses and 29 patients using extended-wearcontact lenses. Since more patients use daily­wear than extended-wear lenses, this suggeststhat patients using extended-wear lenses are atgreater risk for the development of cornealulcers. Positive bacterial cultures were ob­tained from the corneal scrapings of nine of 11patients using daily-wear lenses and 20 of 29patients using extended-wear lenses. In thedaily-wear group, all 11 patients failed to exer­cise satisfactory care in using and disinfectingtheir contact lenses: three did not wash theirhands before manipulating the contact lenses,eight wore them overnight, two did not useany disinfecting system, and four had contam­inated contact lens cases, solutions, or drops.In the extended-wear group, 17 patients failedto exercise satisfactory care in using and disin­fecting their contact lenses: 12 had contaminat­ed contact lens care systems, two did not useany disinfection system, five reported notwashing their hands before contact lens ma­nipulation, and two disinfected their contactlenses at intervals of more than a month. Wewere unable to identify any defect in the way12 patients took care of their extended-wearlenses, suggesting that there may be a problemwith these contact lenses even when care issatisfactory.

EXTENDED-WEAR contact lenses have beenused for nearly a decade. Although early stud­ies suggested few serious complications.v- re-

Accepted for publication April 21, 1986.From the Department of Ophthalmology and Jules

Stein Eye Institute, UCLA School of Medicine, LosAngeles, California. This study was supported in partby grant EY04606 from the National Eye Institute and bythe Wasserman Fund.

Reprint requests to Bartly J. Mondino, M.D., JulesStein Eye Institute, UCLA School of Medicine, LosAngeles, CA 90024.

cent reports have shown that extended-wearcontact lenses may be associated with bacterialcorneal ulcers'" and that the incidence of thiscomplication may be higher with extended­wear than with daily-wear lenses. S Cornealepithelial breakdown related either to recentcontact lens manipulation7 or to long-termovernight anoxic stress'" and contamination ofcontact lens solutions or cases":" may be im­portant factors in the pathogenesis of theseulcers.

We compared contact lens care proceduresused by patients who developed corneal ulcerswhile using daily-wear contact lenses withthose of patients who used extended-wear con­tact lenses. We sought to identify factors thatmay be important in the development of corne­al ulcers in these patients and to account for theincreased incidence of corneal ulcers associatedwith extended-wear contact lenses.

Subjects and Methods

We studied 40 patients treated at the JulesStein Eye Institute over a 21-month period(from February 1984 to November 1985) withthe clinical diagnosis of bacterial corneal ulcerassociated with the use of daily-wear orextended-wear contact lenses for refractive,nontherapeutic purposes. All our patientshad ocular pain, conjunctival hyperemia andedema, and corneal ulcers associated withdense, white, stromal infiltration. Our studypopulation included 29 patients using extend­ed-wear contact lenses and 11 patients usingdaily-wear contact lenses.

Cultures were obtained in a uniform mannerfrom all patients. After topical application ofproparacaine hydrochloride 0.5%, a platinumspatula was used to obtain material from theleading edge and base of all corneal ulcers. Thecorneal scrapings were streaked on blood andchocolate agar plates and Sabourauds medium

58 ©AMERICAN JOURNAL OF OPHTHALMOLOGY 102:58-65, JULY, 1986

Vol. 102, No. 1 Corneal Ulcers Associated With Contact Lenses 59

and immersed in thioglycolate. Diagnosticscrapings of material from the corneal ulcerswere examined after staining with Gram andGiemsa stains. We also cultured all contact lenscases and care solutions as well as any oculardrops used by the patient.

All patients were treated with fortified genta­micin sulfate (15 mg/ml) and cefazolin (50mg/ml) applied topically at least once eachhour. Additionally, some patients were treatedinitially with subconjunctival injections of gen­tamicin sulfate (20 mg) and cefazolin (100 mg).In ulcers threatening perforation, intravenousgentamicin sulfate (80 mg every eight hours)and cefazolin (1,500 mg every six hours) werealso used. Antibiotic administration was modi­fied later on the basis of specific sensitivities ofisolated organisms by the microdilution test.When the overlying epithelium was intact, cor­neal ulcers were considered to be healed, andthe patients were discharged.

Patients were questioned in detail regardingtheir contact lens care practices, including dis­infection technique, washing hands before con­tact lens manipulation, frequency of contactlens removal and disinfection, and the lastmanipulation of the contact lens before theonset of symptoms and last visit to dispensingprofessional. Information on the type and theage of the contact lens worn was obtained andverified whenever possible by a telephone callto the dispenser. Patients were also questionedabout the duration of symptoms before theysought treatment as well as the nature of anytreatment instituted elsewhere. Inappropriatetreatment was defined as the use of topicalcorticosteroids, pressure patching, or reassur­ance that nothing was wrong.

Care was considered satisfactory if the pa­tient met the following criteria: (1) washedhands before contact lens manipulation; (2)used any contact lens care system approved bythe Food and Drug Administration according tothe manufacturer's recommendations; (3) re­moved and disinfected daily-wear contact lens­es nightly and extended-wear contact lenses atleast once a month; and (4) did not have bacter­ial contamination of contact lens cases or caresolutions.

Results

Daily-wear contact lenses-Eleven patientsin our study developed corneal ulcers while

using daily-wear contact lenses (Table 1). Thepatients in this group ranged in age from 20 to73 years (mean, 42 years). There were sevenmen and four women. Two patients withaphakia wore polymethylmethacrylate contactlenses; the remaining nine patients includedeight with myopia and one with hyperopia whowore hydrogel contact lenses. Four patientsused chemical disinfection, three used heat,one used peroxide, two used no disinfectionsystem, and one developed a corneal ulcerbefore she had an opportunity to disinfect hercontact lenses. Six patients generally disinfect­ed their contact lenses every day, one every tendays, and one every 15 days. Three patientsremoved their contact lenses daily, and eightreported overnight wear although their contactlenses were not approved by the Food andDrug Administration for extended-wear use.The contact lenses ranged from two weeks tosix years old (mean, 19 months).

Positive bacterial cultures were obtainedfrom the corneal scrapings of nine of the 11patients. In this group, two of 11 contact lenssolutions, none of eight eyedrop bottles, andthree of seven contact lens cases were foundcontaminated with bacteria. A total of fourpatients in this group had bacterial contamina­tion of their contact lens care systems (cases,care solutions, or ocular drops). The same or­ganism, Pseudomonas aeruginosa, was recoveredfrom both the corneas and care systems of twopatients.

All 11 patients failed to exercise satisfactorycare in using and disinfecting their contactlenses: three did not wash their hands beforemanipulating the contact lenses, eight worethem overnight, two did not use any disinfect­ing system, and four had contaminated contactlens cases, solutions, or drops. Patient 6, whoused no disinfection system and stored hiscontact lenses in 0.5% proparacaine, was themost flagrant example of improper care.

The intervals from last professional evalua­tion to onset of corneal ulceration ranged fromnine days to 48 months (mean, 19 months).Seven patients delayed seeking treatment formore than 24 hours after the development ofocular symptoms. Only one patient in thisgroup received inappropriate initial treatment(pressure patching).

In this group, six patients had central ulcersinvolving the middle third of the cornea andfive had peripheral ulcers involving the superi­or third of the cornea. Only two patients hadhypopyons (Fig. 1).

60 AMERICAN JOURNAL OF OPHTHALMOLOGY July, 1986

TABLE1CLINICAL DATA FOR PATIENTS WITH DAILY-WEAR CONTACT LENSES

CONTACT LENS

PATIENT NO., REFRACTION WATER CONTENT AGE CARE SYSTEM DISINFECTION OVERNIGHT HANDWASHING COMPLIANCE

SEX, (%j (MOS) FREQUENCY (DAVS) WEAR BEFORE MANIPULATION

AGE (VRS)

1, M, 20 Myopia Unknown* 1.5 None Yes Yes No

2, M, 45 Myopia 38 30.0 Cold 10 Yes Yes No

3, M, 23 Myopia 38 48.0 Heat 1 No No No

4, M, 33 Myopia 38 12.0 Cold 1 Yes Yes No

5, M, 71 Aphakia ot 72.0 Cold 1 Yes Yes No

6, M, 73 Aphakia ot 7.0 None No Yes No

7, F,58 Hyperopia 46 12.0 Cold 15 Yes Yes No

8, M, 23 Myopia 38 11,0 Heat 1 No No No

9, F,22 Myopia Unknown* 16.0 Heat 1 Yes No No

10, F,51 Myopia 55 4.0 Peroxide Yes Yes No

11, F,45 Myopia 45 0.5 No chance to use Yes Yes No

*Hydrogel contact lenses of unknown water content.

'Polyrnethylrnethacrylate contact lenses.

Fig. 1 (Mondino and associates). Locations of cor­neal ulcers. The cornea is divided into superior andinferior thirds and into a peripheral 3-mm area and acentral 6-mm area. Diagonally lined area representsextended-wear group and open area representsdaily-wear group. The number of ulcers at eachlocation is indicated.

Extended-wear contact lenses-Twenty-ninepatients in our study developed corneal ulcerswhile using extended-wear contact lenses(Table 2). The patients in this group ranged inage from 18 to 83 years (mean, 36 years). Therewere ten men and 19 women. Twenty-eightpatients wore hydrogel contact lenses, and one(Patient 31) wore a flexible silicone lens. Therewere 21 myopic patients, four hyperopic pa­tients, and four aphakic patients in this group.Sixteen patients used chemical disinfection,five used heat, four used peroxide, two used nodisinfection system, and two developed corne­al ulcers before they had the opportunity todisinfect their contact lenses. The contact lens­es in this group were three days to 30 monthsold (mean, 7.5 months). Seven patients disin­fected their contact lenses every three to sevendays, 13 every two weeks, three every threeweeks, two everyone or two months, two hadno chance to disinfect their contact lenses be­fore the development of corneal ulcers, and twoused no disinfection system (Fig. 2).

Bacteria were cultured from the corneas of 20of 29 patients. Pseudomonas aeruginosa was themost common (nine of 20 patients). In thisgroup, two of 59 solutions, two of 18 eyedropbottles, and 12 of 20 cases were contaminatedwith bacteria. A total of 12 patients in this

Vol. 102, No. 1 Corneal Ulcers Associated With Contact Lenses

TABLE 1 (Continued)

RESULTS OF BACTERiAl CULTURES

61

CORNEA

Staphylococcus epidermidisS. epidermidisPropionibacterium acnesNo growth

Proteus mirabilisS. epidermidisPseudomonas aeruginosaS. epidermidisStaphylococcus aureus,

P. aeruginosaP. aeruginosaNo growth

SOLUTIONS

No growth

No growth

No growth

No growth

Pseudomonas fJuorescens putidaNot tested

No growth

No growth

Serratia marcescens, P.aeruginosa, Klebsiella oxytoca

Not tested

Not tested

CASE

Enterobacter cloacaeNot tested

No growth

Not tested

Not tested

No growth

No growth

No growth

P. aeruginosa

P. aeruginosaNot tested

ULCERLOCATION

Central; middle third

Peripheral; superior third

Central; middle third

Peripheral; superior third

Peripheral; superior third

Central; middle third

Central; middle third

Peripheral; superior third

Central; middle third

Central; middle third

Peripheral; superior third

group had bacterial contamination of the con­tact lens care systems (cases, solutions, or ocu­lar drops). In eight patients, the organism cul­tured from the cornea also contaminated someaspect of the care system.

Seventeen patients failed to exercise satisfac­tory care in using and disinfecting their contactlenses. Five patients reported not washingtheir hands before contact lens manipulation,12 had contaminated care systems, two used nodisinfection system, and two disinfected theircontact lenses less often than once a month.

In this group, 11 patients had last manipulat­ed their contact lenses one or two days beforethe onset of symptoms; for seven patients, theinterval was three to five days, and for ten itwas more than seven days. In one case, the lastmanipulation could not be determined. Ninepatients delayed seeking treatment for morethan 24 hours after the development of ocularsymptoms. Ten patients described inappropri­ate initial treatment. The time from the lastprofessional examination to the developmentof corneal ulceration was one month or less fornine patients, four to five months for six pa­tients, six to nine months for eight patients,nine to 12 months for two patients, and longerthan one year for the remaining four patients.

In this group, 17 patients had central cornealulcers and 12 had peripheral corneal ulcers.Eleven ulcers involved the superior third of thecornea, 14 involved the middle third, and four

involved the inferior third of the cornea (Fig.1). Three patients had hypopyons.

Discussion

In a previous study, we reported that the useof soft contact lenses on an extended-wearbasis may be complicated by the developmentof bacterial corneal ulcers." We suspected thatthe incidence of corneal ulcers was higher withextended-wear than daily-wear lenses becausewe treated corneal ulcers in 18 patients wearingextended-wear contact lenses compared to 11patients wearing daily-wear contact lenses dur­ing a two-year period. The results of the pres­ent study supported our previous findings.Over a 21-month period, we treated cornealulcers in 29 patients using extended-wear con­tact lenses and only 11 patients using daily­wear contact lenses. Because more patientswear contact lenses on a daily basis (approxi­mately 5:1, according to C. A. Schwartz, un­published data), we suggest that patients usingextended-wear contact lenses are at greater riskfor the development of bacterial corneal ulcers.

In the present report, we studied factors thatmight be important in the development of bac­terial corneal ulcers in patients using eitherdaily- or extended-wear contact lenses (Table3). The ages of patients in both groups were

62 AMERICAN JOURNAL OF OPHTHALMOLOGY July, 1986

TABLE 2CLINICAL DATA FOR PATIENTS WITH EXTENDED-WEAR CONTACT LENSES

CONTACT LENSu,

DISINFECTIONPATIENT NO., REFRACTION WATER CONTENT AGE CARESYSTEM FREQUENCY OVERNIGHT HANDWASHING BEFORE

SEX, (%) (MOS) (DAYS) WEAR MANIPULATIONAGE (YRS)

12, F,20 Myopia 45 1.0 Cold 14 ' Yes No

13, M, 26 Myopia Unknown" 10.0 Heat 7 Yes Yes

14, F,26 Myopia 55 6.0 Cold 18 Yes Yes

15, F,29 Myopia 74 0.25 Cold 14 Yes Yes

16, F, 26 Myopia 45 7.0 Heat 14 Yes Yes

17, F,28 Myopia 55 3.5 Cold 5 Yes Yes

18, M, 39 Myopia 55 6.0 Cold 10 Yes Yes

19, F,30 Aphakia 55 2.0 None Yes No

20, M, 31 Myopia 74 5.0 Cold 5 Yes Yes

21,F,83 Aphakia 79 1.0 Heat 30 Yes Yes

22, M, 28 Myopia 55 12.0 Heat 7 Yes Yes

23, F,25 Myopia 55 5.0 Cold 14 Yes No

24, F,51 Hyperopia 55 0.5 No chance to use Yes Yes

25, F,29 Myopia 55 9.0 Peroxide 14 Yes Yes

26, F,46 Myopia 38 11.0 Heat 3 or 4 Yes No

27, F,51 Hyperopia 55 13.0 Cold 14 Yes Yes

28, M, 26 Myopia 71 12.0 Cold 14 Yes Yes

29, M, 68 Aphakia 55 12.0 None Yes Yes

30, F,23 Myopia 38 4.0 Cold 14 .Yes Yes

31, M, 48 Aphakia ot 0.1 No chance to use Yes

32, F,22 Myopia 55 4.0 Cold 21 Yes No

33, M, 40 Myopia 55 6.0 Cold 14 to 21 Yes Yes

34, F, 18 Myopia 71 0.25 Peroxide 14 Yes Yes

35, F,45 Hyperopia 55 24.0 Cold 42 to 56 Yes Yes

36, M, 28 Myopia 55 30.0 Cold 14 Yes Yes

37, M, 53 Hyperopia 55 1.5 Cold 14 Yes Yes

38, F,32 Myopia 71 10.0 Cold 14 'Yes Yes

39, F,35 Myopia 70 12.0 Peroxide 7 Yes Yes

40, F,27 Myopia 55 9.0 Peroxide 49 Yes Yes

'Hydrogel contact lenses of unknown water content.

tSilicone contact lenses.

Vol. 102, No. 1 Corneal Ulcers Associated With Contact Lenses

TABLE 2 (Continued)

RESULTS OF BACTERIAL CULTURES

63

COMPLIANCE CORNEA SOLUTIONS CASE ULCER LOCATION

No Propionibacterium acnes No growth Corynebacterium sp. Peripheral; superior third

Yes Pseudomonas aeruginosa, Not tested Not tested Central; inferior third;

Staphylococcus epidermidis hypopyon

Yes S. epidermidis No growth No growth Central; middle thirdNo P. acnes No growth P. acnes Peripheral; superior third

Yes No growth No growth No growth Central; middle third;

hypopyonNo Staphylococcus aureus; No growth S. epidermidis Peripheral; inferior third

S. epidermidis

No P. aeruginosa Not tested P. aeruginosa Central; middle thirdNo P. aeruginosa No growth P. aeruginosa Central; middle third;

hypopyonYes No growth No growth No growth Central; middle third;Yes S. epidermidis, Coryne- Not tested Not tested Central; inferior third

bacterium sp.

No P. aeruginosa P. aeruginosa S. epidermidis Central; middle thirdNo No growth No growth Not tested Peripheral; inferior thirdNo Hemophilus influenzae No growth P. aeruginosa Peripheral; superior thirdNo S. epidermidis Serratia marcescens; S. S. marcescens, P. multiphilia, Peripheral; superior third

epidermidis, Pseudomonas Flavobacteria

multiphilia, Klebsiella,

Pseudomonas f1uorescens

putidaNo P. aeruginosa Not tested P. aeruginosa Central; middle thirdYes S. epidermidis No growth No growth Central; middle thirdNo No growth No growth S. epidermidis Peripheral; superior thirdNo P. aeruginosa Not tested Not tested Central; middle thirdYes No growth No growth No growth Peripheral; superior thirdYes Morganella morgagni None None Central; middle thirdNo No growth No growth Not tested Peripheral; superior thirdYes P. aeruginosa No growth No growth Central; middle thirdYes No growth Not tested Not tested Central; superior thirdNo S. epidermidis, Coryne- No growth Not tested Central; middle third

bacterium sp.

Yes S. aureus No growth Not tested Peripheral; superior thirdNo P. aeruginosa No growth P. aeruginosa, S. epidermidis, Central; middle third

Corynebacterium sp.Yes P. aeruginosa No growth No growth Central; middle thirdNo No growth No growth S. epidermidis Peripheral; superior thirdNo No growth No growth No growth Peripheral; superior third

64 AMERICAN JOURNAL OF OPHTHALMOLOGY July, 1986

4

TABLE 3

SUMMARY OF CLINICAL DATA

20

40

60

100

o 38 45 55 Unknown

WATER CONTENT (%)

Fig. 4 (Mondino and associates). Percentages ofpatients in extended-wear group (diagonally linedbars) and daily-wear group (open bars) using contactlenses of various water contents. Numbers of pa­tients are shown at the top of each bar.

80

PATIENTS

DAILY·WEAR EXTENDED-WEARCLINICAL DATA GROUP GROUP

No. 11 29Age (yrs)

Mean 42 36Range 20 to 73 18 to 83

Sex

Male 7 10Female 4 19

Refractive error

Myopia 8 21Hy~ropia 1 4Aphakia 2 4

Positive corneal cultures 9 20Bacterial contamination

of lens care system 4 12Unsatisfactory care in using

and disinfecting 11 17No. of contact lenses

more than 6 mos old 8 13

nea (Fig. 1). We do not know why the inferiorcornea was less frequently involved.

Most available water-content contact lenseswere represented in both groups (Fig. 4). Thehigh percentage of 55% and 70% water-contentcontact lenses in the extended-wear group maybe more representative of dispensing trendsthan a risk factor. Old as well as new con­tact lenses were represented in both groups.Daily-wear patients generally had older contact

(f) 100f-Zw 80f-«o,

I..L.. 60 160

w<D 40«f-zw 20ua::wn,

None Cold Heot Peroxide Noneyet

Fig. 3 (Mondino and associates). Percentages ofpatients in extended-wear group (diagonally linedbars) and daily-wear group (open bars) using eachtype of disinfection procedure. The number of pa­tients is shown at top of each bar. Three patientsdeveloped corneal ulcers before they had the oppor­tunity to disinfect their contact lenses and four pa­tients used no disinfection procedures.

s I 1-2 3 1-2 Not Not---Weeks ----t Months yet Disinfection

RemovedDISINFECTION FREQUENCY

Fig. 2 (Mondino and associates). Numbers ofextended-wear patients routinely removing and dis­infecting their contact lenses at various periods. Twopatients developed symptoms before they had anopportunity to disinfect their contact lenses and twopatients used no disinfection procedures.

20en~w 16I-0;:[a,u, 120

a::w 8CD~:::>z 4

approximately the same. There were more menthan women in the daily-wear group but morewomen than men in the extended-wear group.The most common refractive error in bothgroups was myopia. The most commonly useddisinfection system in both groups was chemi­cal, but patients using heat or peroxide alsodeveloped ulcers (Fig. 3). In both groups, therewere more central than peripheral corneal ul­cers, and the superior and middle cornea wasmore commonly involved than the inferior cor-

Vol. 102, No. 1 Corneal Ulcers Associated With Contact Lenses 65

References

Extended-wear hydrogel contact lenses haveproduced changes in all layers of the cornea."Epithelial changes include staining, micro­cysts, thinning, and decreases. in mitosis andoxygen utilization. Stromal edema and endo­thelial polymegethism have also been de­scribed. Repeated overnight anoxic stress asso­ciated with extended-wear contact lenses maydisturb epithelial metabolism and lead to epi­thelial breakdown. Bacteria normally present inthe eye or contaminating some aspect of thecare system may gain access to the cornealstroma and cause both corneal infiltrates andulcers.

>12

4

9-12

440

20

60

80

oI 4-5 6-9

INTERVAL (MONTHS)Fig. 5 (Mondino and associates). Intervals (in

months) between professional evaluation and onsetof corneal ulcer symptoms for both extended-wear(diagonally lined bars) and daily-wear (open bars)groups. The number of patients is shown at the topof each bar.

If) 100I-Zwi=«0..u,oW(!)

i=!zwua:w0..

lenses and longer intervals between the lastprofessional evaluation and onset of cornealulceration (Fig. 5).

Recent manipulation of extended-wear con­tact lenses has been implicated as a factor in thedevelopment of corneal ulcers." In our study,however, ten patients in the extended-weargroup had last manipulated their contact lensesmore than seven days before the developmentof symptoms. Overwear may also be a riskfactor, but 20 patients in the extended-weargroup removed and disinfected their contactlenses at intervals of two weeks or less and twopatients did not even have an opportunityto remove and disinfect their contact lenses(Fig. 2).

It could be argued that patients usingextended-wear contact lenses seek convenienceand therefore are less likely to exercise strin­gent care compared to patients who are willingto clean their contact lenses on a daily basis.Conversely, daily care of contact lenses mayafford more opportunity for a break in the caresystem and resultant contamination. There­fore, we investigated care procedures in bothgroups. Of the 11 patients using daily-wearcontact lenses, all failed to exercise satisfactorycare. Of the 29 patients using extended-wearcontact lenses, 17 failed to exercise satisfactorycare. In 12 cases, we were unable to identifyany defect in the patients' handling and disin­fecting procedures, suggesting that extended­wear contact lenses may produce problemseven when care is satisfactory.

1. Stark, W. J., Kracher, G. P., Cowan, C. L., Tay­lor, H. R., Hirst, L. W., Oyakawa, R. T., andMaumenee, A. E.: Extended-wear contact lenses andintraocular lenses for aphakic correction. Am. J.Ophthalmol. 88:535, 1979.

2. Lernbach, R. G., and Keates, R. H.: Permalensextertded wear contact lenses. In Hartstein, J. (ed.):Extended Wear Contact Lenses. St. Louis, C. V.Mosby, 1982, pp. 76 and 77.

3. Stark, W. J., and Martin, N. F.: Extended wearcontact lenses for myopic correction. Arch. Ophthal­mol. 99:1963, 1981.

4. Martin, N. F., Kracher, G. P., Stark, W. J., andMaumenee, A. E.: Extended-wear soft contact lensesfor aphakic correction. Arch. Ophthalmol. 101:39,1983.

5. Eichenbaum, J. W., Feldstein, M., and Podos,S. M.: Extended-wear aphakic soft contact lensesand corneal ulcers. Br, J. Ophthalmol. 66:663, 1982.

6. Hassman, G., and Sugar, J.: Pseudomonas corne­al ulcer associated with extended soft contact lensesfor myopia. Arch. Ophthalmol. 101:1549, 1983.

7. Adams, C. P., Jr., Cohen, E. J., Laibson, P. R.,Galentine, P., and Arentsen, J. J.: Corneal ulcers inpatients with cosmetic extended-wear contact lenses.Am. J. Ophthalmol. 96:705, 1983.

8. Weissman, B. A., Mondino, B. J., Pettit, T. H.,and Hofbauer, J. D.: Corneal ulcers associated withextended-wear soft contact lenses. Am. J. Ophthal­mol. 97:476, 1984.

9. Holden, B. A., Sweeney, D. F., Vannas, A.,Nilsson, K. T., and Efron, N.: Effects of long-termextended contact lens wear on the human cornea.Invest. Ophthalmol. Vis. Sci. 26:1489, 1985.

10. Krachmer, J. H., and Purcell, J. J.: Bacterialcorneal ulcers in cosmetic soft contact lens wearers.Arch. Ophthalmol. 96:57, 1978.

11. Pitts, R. E., and Krachmer, J. H.: Evaluation ofsoft contact lens disinfection in the home environ­ment. Arch. Ophthalmol. 97:470, 1979.