morning the cases were opened and the solution was cultured by the same method and with the same media as for the next
Evaluation of Soft Contact Lens
Disinfection in the Home Environment R. Edwin
Pitts, MD, Jay H. Krachmer,
MD
• Recent reports of bacterial corneal ulcers in cosmetic soft contact lens wear¬ ers prompted an evaluation of one possi¬ ble source of contamination, inadequate home disinfection of the lenses. Twentynine patients were asked to come for an early morning examination. They were told not to wear their lenses so their usual home disinfection procedure could be observed. On arrival, extensive bacterial and fungal cultures were taken of the solution in the previously unopened cases. Ten of the 29 patients (34.5%) had contaminated cases. Some patients did not follow the manufacturer's disinfection guidelines. The current disinfection pro¬ cedure has repeatedly proven adequate in the laboratory. However, the practical fact is that a substantial percentage (34.5% in this study) of soft lens wearers are inade¬ quately disinfecting their lenses. This serves as a possible source of contamina¬ tion leading to bacterial corneal ulcers.
(Arch Ophthalmol 97:470-472, 1979)
contact lenses have become a ÇJoftpopular modality for the correction
of refractive
errors.
The ease of
tation, comfort, and prolonged
adap¬
wear¬
ing time make them very appealing to patient. Approximately 1,300,000 patients are presently wearing soft contact lenses (C. Titus, MD, oral the
communication, March 1977). Few reports have appeared in the
literature concerning the possibility that cosmetic soft contact lenses are a potential source for corneal and con¬ junctival infection. Because of recent articles1-'4 concerning bacterial corneal ulcers in patients who were wearing cosmetic soft contact lenses, a study was undertaken to determine the effi¬ cacy of soft lens disinfection in the home. It is well known that disinfec¬ tion in a controlled laboratory setting is very effective,7" although little is known about the practicality of disin¬ fection in the home environment. The purpose of this study was to evaluate Accepted for publication May 22, 1978. From the Department of Ophthalmology, Iowa Lions Cornea Center, University Hospitals, Iowa City. Dr Pitts is currently in private practice in Houston.
Reprint requests to Department of Ophthal¬ mology, University Hospitals, Iowa City, IA 52242 (Dr Krachmer).
home disinfection, and to determine if cosmetic soft contact lenses could be a source of microbial contamination. MATERIALS AND METHODS
Twenty-nine
soft contact lens wearers recruited for the study. All the patients were instructed not to wear their lenses, but to bring their unopened contact lens cases with them. They were told that they would be asked to insert their lenses immediately after the examination. No mention of disinfection was made prior to the patients being examined. Conjunctival cultures were obtained from all patients. All soft contact lens cases that were exam¬ ined had not been opened since their last disinfection. On examination the cases were meticulously opened so as not to touch the interior of the case. The solution in the case was cultured with the aid of a calcium alginate swab. Each was cultured in trypticase soy broth, on a blood agar plate, on a mycosel slant, on Sabouraud's slant, and in thioglycollate broth. A minimum of 20 separate cultures were made on each patient. Additional subculturing was ob¬ tained when deemed necessary. The patients had worn soft contact lenses for a period of six to 47 months, with the average being 22.75 months. Their present lenses were worn an average of 11.50 months. The minimum was one month and the maximum was 34 months. Previous lens replacements were for changes in dioptric strength, proteinaceous buildup on the lens, or tears in the lens. None were changed for a known contami¬ nation problem. The ages of the patients ranged from 14 to 69 years, with an average age of 30 years. Of the 55 lenses examined, seven were for aphakic correction and the remaining 48 were for myopia. There were three unilaterally aphakic patients in this study. Each was wearing a contact lens only in the aphakic eye. The patients were asked about the frequency of soft lens disinfection, as well as the methods used. They also indicated the type of saline in their irrigating solu¬ tion and how fresh the present solution was on the day of examination. Two patients were excluded from the study because they were wearing their lenses at the time of examination. Patients who were later found to have contaminated cases were asked to bring their saline solution for laboratory examination. To serve as controls for the culturing procedure, four new cases (eight eyes) were filled with sterile saline solution and then boiled in the heat disinfecting unit. The were
Downloaded From: http://archopht.jamanetwork.com/ by a University of Pennsylvania User on 05/13/2015
patients. RESULTS
The Table summarizes information from patients with positive contact lens cultures. Fourteen (25.5%) of the 55 contact lens case cultures demon¬ strated bacterial and/or fungal growth. These 14 contaminated lens cases were from ten of the 29 patients (34.5%). The spectrum of microbial organisms varied widely. Pure cul¬ tures were seen six times and mixed cultures were seen eight times. Pa¬ tient 7 had a particularly contami¬ nated case (Fig 1). Of the 55 separate conjunctival cultures, 31 (56.4%) were negative while 24 (43.6%) showed microbial growth. The most prominent orga¬ nism was Staphylococcus epidermidis, which grew in a pure culture in 19 instances. Staphylococcus epidermidis was shown in a mixed growth with Aspergillus sp in one conjunctival culture. The remaining four positive cultures grew S aureus, Acinetobacter calcoaceticus Iwoffi, Ac calcoaceticus antitratus, and Cladosporium spp. There were eight instances where both the conjunctiva and lens-case cultures were positive. Of the other factors studied, the greatest variability was shown in the frequency of making saline solution. Only six of the 29 patients indicated that they made their saline solution daily as recommended by the manu¬ facturer. Six of the patients obtained sterile liter saline bottles from the hospital and thus the frequency of fresh saline solution was prolonged. One patient had not prepared fresh saline solution in six months. In six of the patients with contaminated lens cases, the saline solution was cultured on a return visit. All six of the saline solutions demonstrated microbial growth. The results are as follows: Patient 1
Saline Solution Culture Enterobacter cloacae;
Staphylococcus epider¬ midis;
diphtheroids
meningo-
3
Flavobacterium
6 7
Pseudomonas aeruginosa Enterobacter cloacae; Fla¬ vobacterium sp; Staphy¬ lococcus epidermidis Enterobacter cloacae Acinetobacter calcoaceti¬
15 21
septicum
cus
Iwoffi
Patients tended to adhere to their disinfection schedule. Twenty-five of the 29 had disinfected their lenses in the 24 hours preceding their examina-
Ten Patients With Contaminated 'Disinfected' Soft Contact Lens Cases
Patient/Age, yr/Sex 1/18/F
Time Since
Age of Present
Time Since
Fitted,
Lens,
Disinfection,
Solution,
mo
hr 10
Days 10
Conjunctival Staphylococcus epi¬
10
10
No
mo
Eye
28
OD
of Saline
Age
Cultures
dermidis OS
3/14/M
45
OD
4/19/M
11
OD OS
10
10 10
Lens Case
Staphylococcus epidermidis, Enterobacter cloacae
Staphylococcus epidermidis,
growth
10
No
10 10
No growth Staphylococcus
Enterobacter cloacae; Cladosporium sp Flavobacterium meningosepticum No growth
growth au¬
Staphylococcus
aureus
reus
6/61/M
10
OD OS
7/24/F
31
OD
10 10
No growth Acinetobacter calcoa¬
10
Staphylococcus epi¬
No growth Staphylococcus epidermidis
ceticus Iwoffi 12
dermidis OS
17
Staphylococcus epi¬
10
dermidis 14/20/M
34
OD
72
41
OS OD
34
OS
29
Staphylococcus ep¬ idermidis. OU; Rhodotorula spp, OS
Staphylococcus epi¬
Staphylococcus epidermidis No growth Acinetobacter calcoaceticus
dermidis
15/51/F
Pseudomonas aeruginosa; Enterobacter cloacae;
72
No
48
No
48
Staphylococcus epi¬
10
No
10
Staphylococcus epi¬
growth growth
antitratus, OU; Alternaria spp, OU
dermidis
OD
16/19/F
growth
Staphylococcus epidermidis, Citrobacter freundii
OS
10
dermidis 20/24/F
21
OD
Staphylococcus epidermidis, Citrobacter freundii
10
30
Staphylococcus epi¬
Cladosporium
dermidis 21/15/M
10
OS
21
10
30
No
OD
10
10
60
No
OS
10
10
60
growth growth Staphylococcus epidermidis No No
growth growth No growth
Fig 2.—Soft contact lens with large crack.
Fig 1.—Blood agar plate
of
patient
tion. The longest duration of previous disinfection was 72 hours. All patients used the heat disinfecting unit. The eight control subjects (four lens cases) were completely free of bacteri¬ al or fungal growth.
7 with mixed bacterial
growth.
COMMENT
Recent reports of bacterial corneal ulcers in cosmetic soft contact lens wearers prompted this study.1'4 The possible reasons for these corneal ulcers are many and in this report the
case
of
patient
6
disinfection procedures for the soft contact lens are evaluated as a possi¬ ble source of microbial contamination. The frequency of bacterial corneal ulcers in cosmetic soft lens wear seems very low because of the large numbers of patients wearing the lenses and the paucity of reports in the literature. Bernstein and co-workers reported on a 21-year-old woman with bilateral
keratoconjunctivitis, limbal edema, and superficial haziness of the periph¬
eral anterior corneal stroma.' Her symptoms cleared and the cultures of her opened case were negative. Three months later she had a recurrence of conjunctivitis associated with scat-
Downloaded From: http://archopht.jamanetwork.com/ by a University of Pennsylvania User on 05/13/2015
tered
subepithelial infiltrates.
A cul¬
ture of her opened case grew Pseudo¬ monas spp. No mention was made of a
corneal culture. Freeman and
Sugar described a 20-
who wore soft lenses for refractive error in whom cultureproven bilateral Pseudomonas corneal ulcers developed.2 The soft lenses were also contaminated with aeruginosa. Her condition responded well to anti¬ biotics, and her final visual acuity was 6/6 in both eyes. The etiology of the lens contamination was not deter¬ mined, although it was postulated that there could be inadequate disinfec¬ tion, reflux of contaminants into the case, or use of contaminated saline solution. Thompson reported on two soft contact lens wearers with superficial corneal ulcération and surrounding keratitis.3 Escherichia coli was cul¬ tured from the saline solution of one patient and the other had a mixed infection of E coli and a Pseudomonas spp. After boiling the lenses, there was a positive culture of E coli in both
year-old woman
cases.
In 1976 Ruben published a report of acute eye disease in contact lens wear¬ ers." Included were six patients with soft contact lenses in whom corneal
infection developed. The specific mi¬ crobial organisms were not men¬ tioned. Cooper and Constable found eight cases of infective keratitis in soft contact lens wearers.4 Four of their cases were found in continuous soft contact lens wearers, one was in a patient wearing a therapeutic soft contact lens, and the remaining three were in patients wearing their soft lenses on a daily basis. Most were due to
Gram-negative organisms.
Another report described five cos¬ metic soft contact lens wearers in whom culture-proven bacterial corneal ulcers developed.1 In three patients the resulting visual acuity was less than 6/120. The authors speculated that poor hygiene in contact lens handling, inadequacies in disinfection technique, loose lens containers, or changes in surface characteristics with aging of the lens might be possi¬ ble sources of contamination. The question still remains as to the etiology of these bacterial corneal ulcers in cosmetic soft contact lens wearers. Laboratory studies to deter¬ mine the adequacy of the recom¬ mended disinfection procedure for soft contact lenses have shown the method to be very effective.7 s In the present study the majority, 25 out of 29, disinfected their lenses on a daily basis. The possibility still existed that
the patient's home disinfection proce¬ dure might not be totally effective. To evaluate the disinfection proce¬ dure with routine patient usage of soft contact lenses, Bernstein et al cultured previously unopened cases from 25 patients who had disinfected their lenses the night before/' Eleven of the 25 (44%) demonstrated a posi¬ tive culture. The organisms were not specifically stated in each instance, but were predominantly Gram-nega¬ tive, including Serratia, Pseudomo¬ nas, E coli, Acinetobacter, and Flavobacterium. Both Bernstein's study and the present one demonstrated that there are certain inadequacies of disinfection in the routine clinical usage. It should be emphasized, how¬ ever, that Bernstein et al did not describe their culturing techniques, detail their results, or perform a controlled study. As other authors have shown, there are numerous sources of possible contamination. Of the factors consid¬ ered in the present study, the most variable was the frequency of making fresh saline solution. Since this saline solution is not sterile, it could be a source of bacterial contamination. It is possible that with inadequate disin¬ fection in the home unit, the contami¬ nants in the saline solution would remain viable in the lens case. Six patients who had culture-posi¬ tive lens cases brought their saline solution for culturing on a return visit. Bacteria were demonstrated in the saline solutions of all six patients. Although the number of patients is very small, it does show that the saline solution can be a possible source of microbial contamination. This could create a potential hazard, especially in those patients who use the saline solu¬ tion to wet their lenses prior to inser¬ tion, a practice that is against manu¬ facturer's recommendations. Another possible source of microbial exposure could be the integrity of the soft contact lens case. The saline solu¬ tion in the case has no germicidal effects; therefore, it cannot be ex¬ posed to any outside contaminants prior to lens insertion. A loosely fitting cap could allow air to enter during the cooling process. On close examination of the cases, defects were sometimes found that ranged from small linear cracks to large holes (Fig 2). Other sources of contamination might include concurrent conjunctivi¬ tis, lens surface abnormalities, and failure to reach adequate disinfection temperature. The disinfection dura¬ tion and temperature elevation were not evaluated, but previous studies
Downloaded From: http://archopht.jamanetwork.com/ by a University of Pennsylvania User on 05/13/2015
have shown both to be adequate."1" The important question is whether this potential source of microbial contamination poses a threat to the eye. It is well accepted that once corneal epithelial integrity has been breached, the cornea becomes vulnera¬ ble to infection. If a contaminated soft contact lens is placed on an epithelial defect, then the possibility of infection certainly exists. It should be emphasized that while it is theoretically possible for ade¬ quate home disinfection to be effec¬ tive, the practical fact is that a substantial percentage of cosmetic soft lens wearers are not effectively disinfecting their lenses. It was the goal of this study to check for that possibility. It would necessitate ob¬ serving and testing each patient's home disinfecting procedure to deter¬ mine whether the inadequacy was due to failure to adhere to manufacturer's guidelines or to a flaw in the recom¬ mended procedure for home use. The purpose of this report is not to alarm those who prescribe cosmetic soft contact lenses, but to make them aware of the potential hazards. Al¬ though the chance of a bacterial corne¬ al ulcer in a soft contact lens wearer seems very low, any patient pre¬ scribed soft lenses should be followed up very closely and examined at the earliest signs of ocular inflammation. Jaci Yochum, MT, provided microbacteriological assistance. Cathi Miller and Linda Jones, RN, provided technical assistance.
References 1. Krachmer JH, Purcell JJ Jr: Bacterial corneal ulcers in cosmetic soft contact lens wear¬ ers. Arch Ophthalmol 96:57-61, 1978. 2. Freeman H, Sugar J: Pseudomonas keratitis following cosmetic soft contact lens wear. Contact Lens J 10:21-25, 1976. 3. Thompson G: Complications from wearing soft contact lenses. Med J Aust 1:29, 1973. 4. Cooper R, Constable IJ: Infective keratitis in soft contact lens wearers. Br J Ophthalnwl 61:250-254, 1977. 5. Bernstein HN, Stow MN, Maddox Y: Evalu¬ ation of the 'aseptization' procedure for the Soflens hydrophilic contact lens. Can J Ophthalmol 8:575-576, 1973. 6. Ruben M: Acute eye disease secondary to contact lens wear. Lancet 1:138-140, 1976. 7. Tragakis MP, Brown SI, Pearce DB: Bacté¬ riologie studies of contamination associated with soft contact lenses. Am J Ophthalmol 75:496-499, 1973. 8. Mote EM, Filipi JA, Hill RM: Does heating arrest organisms in hydrophilic cases? J Am Optom Assoc 43:302-304, 1972. 9. Busschaert SC, Szabocsik JM, Good RC, et al: Challenging the efficacy of the Soflens Asepter—Patient Unit for disinfection of the Soflens (polymacon) contact lens. J Am Optom Assoc 45:701-705, 1974. 10. Phares RE, Hall NC: Microbiology of soft and hard contact lens care, in Bitonte JL, Keates RH (eds): Symposium on the Flexible Lens. St Louis, CV Mosby Co, 1972, pp 206-207.
Evaluation of Soft Contact Lens
Disinfection in the Home Environment R. Edwin
Pitts, MD, Jay H. Krachmer,
MD
• Recent reports of bacterial corneal ulcers in cosmetic soft contact lens wear¬ ers prompted an evaluation of one possi¬ ble source of contamination, inadequate home disinfection of the lenses. Twentynine patients were asked to come for an early morning examination. They were told not to wear their lenses so their usual home disinfection procedure could be observed. On arrival, extensive bacterial and fungal cultures were taken of the solution in the previously unopened cases. Ten of the 29 patients (34.5%) had contaminated cases. Some patients did not follow the manufacturer's disinfection guidelines. The current disinfection pro¬ cedure has repeatedly proven adequate in the laboratory. However, the practical fact is that a substantial percentage (34.5% in this study) of soft lens wearers are inade¬ quately disinfecting their lenses. This serves as a possible source of contamina¬ tion leading to bacterial corneal ulcers.
(Arch Ophthalmol 97:470-472, 1979)
contact lenses have become a ÇJoftpopular modality for the correction
of refractive
errors.
The ease of
tation, comfort, and prolonged
adap¬
wear¬
ing time make them very appealing to patient. Approximately 1,300,000 patients are presently wearing soft contact lenses (C. Titus, MD, oral the
communication, March 1977). Few reports have appeared in the
literature concerning the possibility that cosmetic soft contact lenses are a potential source for corneal and con¬ junctival infection. Because of recent articles1-'4 concerning bacterial corneal ulcers in patients who were wearing cosmetic soft contact lenses, a study was undertaken to determine the effi¬ cacy of soft lens disinfection in the home. It is well known that disinfec¬ tion in a controlled laboratory setting is very effective,7" although little is known about the practicality of disin¬ fection in the home environment. The purpose of this study was to evaluate Accepted for publication May 22, 1978. From the Department of Ophthalmology, Iowa Lions Cornea Center, University Hospitals, Iowa City. Dr Pitts is currently in private practice in Houston.
Reprint requests to Department of Ophthal¬ mology, University Hospitals, Iowa City, IA 52242 (Dr Krachmer).
home disinfection, and to determine if cosmetic soft contact lenses could be a source of microbial contamination. MATERIALS AND METHODS
Twenty-nine
soft contact lens wearers recruited for the study. All the patients were instructed not to wear their lenses, but to bring their unopened contact lens cases with them. They were told that they would be asked to insert their lenses immediately after the examination. No mention of disinfection was made prior to the patients being examined. Conjunctival cultures were obtained from all patients. All soft contact lens cases that were exam¬ ined had not been opened since their last disinfection. On examination the cases were meticulously opened so as not to touch the interior of the case. The solution in the case was cultured with the aid of a calcium alginate swab. Each was cultured in trypticase soy broth, on a blood agar plate, on a mycosel slant, on Sabouraud's slant, and in thioglycollate broth. A minimum of 20 separate cultures were made on each patient. Additional subculturing was ob¬ tained when deemed necessary. The patients had worn soft contact lenses for a period of six to 47 months, with the average being 22.75 months. Their present lenses were worn an average of 11.50 months. The minimum was one month and the maximum was 34 months. Previous lens replacements were for changes in dioptric strength, proteinaceous buildup on the lens, or tears in the lens. None were changed for a known contami¬ nation problem. The ages of the patients ranged from 14 to 69 years, with an average age of 30 years. Of the 55 lenses examined, seven were for aphakic correction and the remaining 48 were for myopia. There were three unilaterally aphakic patients in this study. Each was wearing a contact lens only in the aphakic eye. The patients were asked about the frequency of soft lens disinfection, as well as the methods used. They also indicated the type of saline in their irrigating solu¬ tion and how fresh the present solution was on the day of examination. Two patients were excluded from the study because they were wearing their lenses at the time of examination. Patients who were later found to have contaminated cases were asked to bring their saline solution for laboratory examination. To serve as controls for the culturing procedure, four new cases (eight eyes) were filled with sterile saline solution and then boiled in the heat disinfecting unit. The were
Downloaded From: http://archopht.jamanetwork.com/ by a University of Pennsylvania User on 05/13/2015
patients. RESULTS
The Table summarizes information from patients with positive contact lens cultures. Fourteen (25.5%) of the 55 contact lens case cultures demon¬ strated bacterial and/or fungal growth. These 14 contaminated lens cases were from ten of the 29 patients (34.5%). The spectrum of microbial organisms varied widely. Pure cul¬ tures were seen six times and mixed cultures were seen eight times. Pa¬ tient 7 had a particularly contami¬ nated case (Fig 1). Of the 55 separate conjunctival cultures, 31 (56.4%) were negative while 24 (43.6%) showed microbial growth. The most prominent orga¬ nism was Staphylococcus epidermidis, which grew in a pure culture in 19 instances. Staphylococcus epidermidis was shown in a mixed growth with Aspergillus sp in one conjunctival culture. The remaining four positive cultures grew S aureus, Acinetobacter calcoaceticus Iwoffi, Ac calcoaceticus antitratus, and Cladosporium spp. There were eight instances where both the conjunctiva and lens-case cultures were positive. Of the other factors studied, the greatest variability was shown in the frequency of making saline solution. Only six of the 29 patients indicated that they made their saline solution daily as recommended by the manu¬ facturer. Six of the patients obtained sterile liter saline bottles from the hospital and thus the frequency of fresh saline solution was prolonged. One patient had not prepared fresh saline solution in six months. In six of the patients with contaminated lens cases, the saline solution was cultured on a return visit. All six of the saline solutions demonstrated microbial growth. The results are as follows: Patient 1
Saline Solution Culture Enterobacter cloacae;
Staphylococcus epider¬ midis;
diphtheroids
meningo-
3
Flavobacterium
6 7
Pseudomonas aeruginosa Enterobacter cloacae; Fla¬ vobacterium sp; Staphy¬ lococcus epidermidis Enterobacter cloacae Acinetobacter calcoaceti¬
15 21
septicum
cus
Iwoffi
Patients tended to adhere to their disinfection schedule. Twenty-five of the 29 had disinfected their lenses in the 24 hours preceding their examina-
Ten Patients With Contaminated 'Disinfected' Soft Contact Lens Cases
Patient/Age, yr/Sex 1/18/F
Time Since
Age of Present
Time Since
Fitted,
Lens,
Disinfection,
Solution,
mo
hr 10
Days 10
Conjunctival Staphylococcus epi¬
10
10
No
mo
Eye
28
OD
of Saline
Age
Cultures
dermidis OS
3/14/M
45
OD
4/19/M
11
OD OS
10
10 10
Lens Case
Staphylococcus epidermidis, Enterobacter cloacae
Staphylococcus epidermidis,
growth
10
No
10 10
No growth Staphylococcus
Enterobacter cloacae; Cladosporium sp Flavobacterium meningosepticum No growth
growth au¬
Staphylococcus
aureus
reus
6/61/M
10
OD OS
7/24/F
31
OD
10 10
No growth Acinetobacter calcoa¬
10
Staphylococcus epi¬
No growth Staphylococcus epidermidis
ceticus Iwoffi 12
dermidis OS
17
Staphylococcus epi¬
10
dermidis 14/20/M
34
OD
72
41
OS OD
34
OS
29
Staphylococcus ep¬ idermidis. OU; Rhodotorula spp, OS
Staphylococcus epi¬
Staphylococcus epidermidis No growth Acinetobacter calcoaceticus
dermidis
15/51/F
Pseudomonas aeruginosa; Enterobacter cloacae;
72
No
48
No
48
Staphylococcus epi¬
10
No
10
Staphylococcus epi¬
growth growth
antitratus, OU; Alternaria spp, OU
dermidis
OD
16/19/F
growth
Staphylococcus epidermidis, Citrobacter freundii
OS
10
dermidis 20/24/F
21
OD
Staphylococcus epidermidis, Citrobacter freundii
10
30
Staphylococcus epi¬
Cladosporium
dermidis 21/15/M
10
OS
21
10
30
No
OD
10
10
60
No
OS
10
10
60
growth growth Staphylococcus epidermidis No No
growth growth No growth
Fig 2.—Soft contact lens with large crack.
Fig 1.—Blood agar plate
of
patient
tion. The longest duration of previous disinfection was 72 hours. All patients used the heat disinfecting unit. The eight control subjects (four lens cases) were completely free of bacteri¬ al or fungal growth.
7 with mixed bacterial
growth.
COMMENT
Recent reports of bacterial corneal ulcers in cosmetic soft contact lens wearers prompted this study.1'4 The possible reasons for these corneal ulcers are many and in this report the
case
of
patient
6
disinfection procedures for the soft contact lens are evaluated as a possi¬ ble source of microbial contamination. The frequency of bacterial corneal ulcers in cosmetic soft lens wear seems very low because of the large numbers of patients wearing the lenses and the paucity of reports in the literature. Bernstein and co-workers reported on a 21-year-old woman with bilateral
keratoconjunctivitis, limbal edema, and superficial haziness of the periph¬
eral anterior corneal stroma.' Her symptoms cleared and the cultures of her opened case were negative. Three months later she had a recurrence of conjunctivitis associated with scat-
Downloaded From: http://archopht.jamanetwork.com/ by a University of Pennsylvania User on 05/13/2015
tered
subepithelial infiltrates.
A cul¬
ture of her opened case grew Pseudo¬ monas spp. No mention was made of a
corneal culture. Freeman and
Sugar described a 20-
who wore soft lenses for refractive error in whom cultureproven bilateral Pseudomonas corneal ulcers developed.2 The soft lenses were also contaminated with aeruginosa. Her condition responded well to anti¬ biotics, and her final visual acuity was 6/6 in both eyes. The etiology of the lens contamination was not deter¬ mined, although it was postulated that there could be inadequate disinfec¬ tion, reflux of contaminants into the case, or use of contaminated saline solution. Thompson reported on two soft contact lens wearers with superficial corneal ulcération and surrounding keratitis.3 Escherichia coli was cul¬ tured from the saline solution of one patient and the other had a mixed infection of E coli and a Pseudomonas spp. After boiling the lenses, there was a positive culture of E coli in both
year-old woman
cases.
In 1976 Ruben published a report of acute eye disease in contact lens wear¬ ers." Included were six patients with soft contact lenses in whom corneal
infection developed. The specific mi¬ crobial organisms were not men¬ tioned. Cooper and Constable found eight cases of infective keratitis in soft contact lens wearers.4 Four of their cases were found in continuous soft contact lens wearers, one was in a patient wearing a therapeutic soft contact lens, and the remaining three were in patients wearing their soft lenses on a daily basis. Most were due to
Gram-negative organisms.
Another report described five cos¬ metic soft contact lens wearers in whom culture-proven bacterial corneal ulcers developed.1 In three patients the resulting visual acuity was less than 6/120. The authors speculated that poor hygiene in contact lens handling, inadequacies in disinfection technique, loose lens containers, or changes in surface characteristics with aging of the lens might be possi¬ ble sources of contamination. The question still remains as to the etiology of these bacterial corneal ulcers in cosmetic soft contact lens wearers. Laboratory studies to deter¬ mine the adequacy of the recom¬ mended disinfection procedure for soft contact lenses have shown the method to be very effective.7 s In the present study the majority, 25 out of 29, disinfected their lenses on a daily basis. The possibility still existed that
the patient's home disinfection proce¬ dure might not be totally effective. To evaluate the disinfection proce¬ dure with routine patient usage of soft contact lenses, Bernstein et al cultured previously unopened cases from 25 patients who had disinfected their lenses the night before/' Eleven of the 25 (44%) demonstrated a posi¬ tive culture. The organisms were not specifically stated in each instance, but were predominantly Gram-nega¬ tive, including Serratia, Pseudomo¬ nas, E coli, Acinetobacter, and Flavobacterium. Both Bernstein's study and the present one demonstrated that there are certain inadequacies of disinfection in the routine clinical usage. It should be emphasized, how¬ ever, that Bernstein et al did not describe their culturing techniques, detail their results, or perform a controlled study. As other authors have shown, there are numerous sources of possible contamination. Of the factors consid¬ ered in the present study, the most variable was the frequency of making fresh saline solution. Since this saline solution is not sterile, it could be a source of bacterial contamination. It is possible that with inadequate disin¬ fection in the home unit, the contami¬ nants in the saline solution would remain viable in the lens case. Six patients who had culture-posi¬ tive lens cases brought their saline solution for culturing on a return visit. Bacteria were demonstrated in the saline solutions of all six patients. Although the number of patients is very small, it does show that the saline solution can be a possible source of microbial contamination. This could create a potential hazard, especially in those patients who use the saline solu¬ tion to wet their lenses prior to inser¬ tion, a practice that is against manu¬ facturer's recommendations. Another possible source of microbial exposure could be the integrity of the soft contact lens case. The saline solu¬ tion in the case has no germicidal effects; therefore, it cannot be ex¬ posed to any outside contaminants prior to lens insertion. A loosely fitting cap could allow air to enter during the cooling process. On close examination of the cases, defects were sometimes found that ranged from small linear cracks to large holes (Fig 2). Other sources of contamination might include concurrent conjunctivi¬ tis, lens surface abnormalities, and failure to reach adequate disinfection temperature. The disinfection dura¬ tion and temperature elevation were not evaluated, but previous studies
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have shown both to be adequate."1" The important question is whether this potential source of microbial contamination poses a threat to the eye. It is well accepted that once corneal epithelial integrity has been breached, the cornea becomes vulnera¬ ble to infection. If a contaminated soft contact lens is placed on an epithelial defect, then the possibility of infection certainly exists. It should be emphasized that while it is theoretically possible for ade¬ quate home disinfection to be effec¬ tive, the practical fact is that a substantial percentage of cosmetic soft lens wearers are not effectively disinfecting their lenses. It was the goal of this study to check for that possibility. It would necessitate ob¬ serving and testing each patient's home disinfecting procedure to deter¬ mine whether the inadequacy was due to failure to adhere to manufacturer's guidelines or to a flaw in the recom¬ mended procedure for home use. The purpose of this report is not to alarm those who prescribe cosmetic soft contact lenses, but to make them aware of the potential hazards. Al¬ though the chance of a bacterial corne¬ al ulcer in a soft contact lens wearer seems very low, any patient pre¬ scribed soft lenses should be followed up very closely and examined at the earliest signs of ocular inflammation. Jaci Yochum, MT, provided microbacteriological assistance. Cathi Miller and Linda Jones, RN, provided technical assistance.
References 1. Krachmer JH, Purcell JJ Jr: Bacterial corneal ulcers in cosmetic soft contact lens wear¬ ers. Arch Ophthalmol 96:57-61, 1978. 2. Freeman H, Sugar J: Pseudomonas keratitis following cosmetic soft contact lens wear. Contact Lens J 10:21-25, 1976. 3. Thompson G: Complications from wearing soft contact lenses. Med J Aust 1:29, 1973. 4. Cooper R, Constable IJ: Infective keratitis in soft contact lens wearers. Br J Ophthalnwl 61:250-254, 1977. 5. Bernstein HN, Stow MN, Maddox Y: Evalu¬ ation of the 'aseptization' procedure for the Soflens hydrophilic contact lens. Can J Ophthalmol 8:575-576, 1973. 6. Ruben M: Acute eye disease secondary to contact lens wear. Lancet 1:138-140, 1976. 7. Tragakis MP, Brown SI, Pearce DB: Bacté¬ riologie studies of contamination associated with soft contact lenses. Am J Ophthalmol 75:496-499, 1973. 8. Mote EM, Filipi JA, Hill RM: Does heating arrest organisms in hydrophilic cases? J Am Optom Assoc 43:302-304, 1972. 9. Busschaert SC, Szabocsik JM, Good RC, et al: Challenging the efficacy of the Soflens Asepter—Patient Unit for disinfection of the Soflens (polymacon) contact lens. J Am Optom Assoc 45:701-705, 1974. 10. Phares RE, Hall NC: Microbiology of soft and hard contact lens care, in Bitonte JL, Keates RH (eds): Symposium on the Flexible Lens. St Louis, CV Mosby Co, 1972, pp 206-207.
