T H E MICROBIAL FLORA IN EXTENDED-WEAR SOFT CONTACT-LENS WEARERS G I L B E R T S M O L I N , M.D.,
M A S A O O K U M O T O , M.A., San Francisco,
We report herein an evaluation of the effect of the use of extended-wear soft contact lenses on the microbial flora of the eye. M A T E R I A L AND M E T H O D S
The lens that we used in this study was the Perfilcon-A lens (Cooper Laborato ries). The polymeric material of which it is composed is a terpolymer of 21 hydroxyethyl methacrylate N-vinyl-2-pyrrolidone and methacrylic acid, with ethyleneglycol dimethacrylate as a crosslinking agent. The water content of the lens, which is hydrophilic, is about 76% at 20°C. Its oxygen permeability ranges from a low of 8.1% in lenses 0.43 mm thick to a high of 13.1% in lenses 0.12 mm thick in the center. Over a period of one year we prepared a total of 857 cultures of material from the eyelids, conjunctivae, and contact lenses of our first 51 patients (20 aphakic and 31 phakic) fitted with these lenses. A moist ened, cotton-tipped applicator was used to obtain the material, with which we inoculated blood agar and Sabouraud's medium. The blood agar cultures were incubated for 48 hours at 37°C and the Sabouraud's-medium cultures for two to three weeks at 30°C. The potential path ogens were identified, their identity recorded, and their antibiotic sensitivi ties tested by the Kirby-Bauer method. From the Francis I. Proctor Foundation for Re search in Ophthalmology and the Department of Ophthalmology, University of California San Fran cisco, San Francisco, California. Reprint requests to Dr. Gilbert Smolin, M.D., Francis I. Proctor Foundation, Room 315S, Univer sity of California San Francisco, San Francisco, CA 94143.
AND R O B E R T A. N O Z I K ,
M.D.
California
We excluded Staphylococcus epidermidis and liphtheroids entirely, and excluded S. aureus if only one or two colonies were recovered only from the eyelids. Collaterally we compared 295 cultures from our aphakic contact-lens wearers with 295 cultures of material taken from preoperative cataract surgery patients dur ing about the same period of time. The preoperative cultures were taken routine ly in all of our patients one or two weeks before surgery. The eyes were otherwise undisturbed. The extended-wear soft contact lenses were routinely removed once a month by the physician immediately after obtaining the culture material. The lenses were physically cleaned, not sterilized, and re inserted. The lenses were only removed because of irritation or infection. RESULTS
Out of the 857 cultures, 44 (5%) grew pathogenic organisms. Of the 44, 24 were from the aphakic patients (24 of 295 or 8%), and 20 were from the phakic patients (20 of 562 or 3.6%), all of whom were young and myopic individuals. If the patients with only a few 5. aureus on their eyelids had been included, the rates would have been approximately 10 and 5%, respectively. The organisms recov ered are listed in Table 1. Occasionally more than one potential pathogen was recovered from the eyelids of the same patient. On 39 occasions the patients were asymptomatic but the cultures were posi tive for potential pathogens. Two of the patients from whom the material for these 39 cultures was collected were treated with an antibiotic; the rest were left un-
AMERICAN JOURNAL O F OPHTHALMOLOGY 88:543-547, 1979
543
544
AMERICAN JOURNAL OF OPHTHALMOLOGY
SEPTEMBER, 1979
TABLE 1 POTENTIAL PATHOGENS RECOVERED IN 44 OF 857 CULTURES OF MATERIAL COLLECTED FROM 51 SOFT-CONTACT-LENS WEARERS
Organism
Positive Cultures Per Total No. of Cultures
Percent
Staphylococcus aureus Alpha-hemolytic streptococcus Gram-negative rods Moraxella species Acinetobacter species Streptococcus pneumoniae Branhamella catarrhalis Nocardia species Candida albicans Rhodotorula species
11/44 13/44 10/44 2/44 2/44 2/44 1/44 1/44 1/44 1/44
25 30 24* 4 4 4 2 2 2 2
*No Pseudomonas
or Proteus species.
treated. In one of the two treated cases the cultures were positive for S. aureus be fore the patient began wearing soft con tact lenses, and gentamicin ophthalmic drops were used to eliminate the organ ism. In the second treated case the organ ism was also 5. aureus, and because it was recovered in cultures run sequentially at one-month intervals, we assumed that it had colonized on the eyelids, and we used chloramphenicol (Ophthochlor) drops to eliminate it. On more than 800 occasions the pa tients were asymptomatic and without recoverable pathogenic organisms, and on a few occasions they were symptomat ic and without recoverable pathogenic organisms. The symptoms were blurred vision, feeling the lens, red eyes, a scratchy sensation, and the like. Altering the diameter, base curve, or power of the lens usually relieved the symptoms, and artificial tears were required by several aphakic patients. We treated one patient with antibiotics. He had crusts, collaretes, scurf, and rosettes on his eyelid mar gins, and despite negative cultures, it was our clinical impression that he had staphylococcal blepharitis. He was treat ed with eyelid scrubs and systemic tetra-
cycline for one month. Both the symp toms and the condition of the eyelids improved remarkably. On five occasions, the five patients ex amined were symptomatic and the cul tures were positive for potential path ogens. Two of the five patients were aphakic and three were phakic. In one case the organism was a gram-negative rod and the conjunctiva was hyperemic. The eye was treated with chlorampheni col (Chloromycetin) ophthalmic drops four times a day for four days with the soft lens in place. Subsequent cultures were negative and the eye became asymp tomatic. In a second case the organism was Moraxella species. There was conjunctival hyperemia and the eye was treated with gentamicin ophthalmic drops after removal of the lens. After three days of treatment, the eye was asymptomatic and cultures were negative for potential path ogens. In a third case the organism was S. aureus. The patient had a peripheral corneal infiltrate that simulated a catarrhal ulcer. The lens was removed and sulfacetamide ophthalmic drops were adminis tered for four days. The infiltrate cleared
VOL. 88, NO. 3, PART II
MICROBIAL FLORA IN EXTENDED-WEAR LENSES
and cultures were negative for potential pathogens. In a fourth case the organism was a gram-negative rod. The patient com plained of excessive mucus in his eye. The lens was removed and gentamicin eye drops were used five times a day for four days. Cultures were then negative for potential pathogens and the eye was asymptomatic. In a fifth case the organism was alphahemolytic Streptococcus and the conjunc tiva was hyperemic. No treatment was instituted, and in several days the hyperemia subsided and the next culture (two weeks later) was negative for potential pathogens. In three instances, consecutive cultures were positive for the same potential path ogen. In one patient (who was one of the two treated patients that were asympto matic and had positive cultures) this oc curred twice. The organism was S. aure us. The eye was treated with an antibiotic on the first occasion but not on the sec ond. Despite this omission, however, the next cultures were negative and they have remained negative 12 months later. In the second patient, a gram-negative rod was recovered from two consecutive cultures. The patient received no antibi otic treatment but was free of the organ ism 12 months later.
545
When we compared the number of cul tures positive for pathogenic organisms in our aphakic soft-contact-lens wearers with the number in our preoperative cataract surgery patients, we found 24 cultures positive in the contact-lens wear ers (24 of 295 or 8%) and 63 positive in the preoperative patients (63 of 295 or 21%). The potential pathogens recovered from the preoperative patients are listed in Table 2. There was a higher percentage of S. aureus and Moraxella species in this group than in the group of aphakic lenswearers. DISCUSSION
There are several reports of infections in contact-lens wearers. 1,2 In our study, we hoped to: (1) collect data that would make possible a reasonable estimate of the flora of the eyelids, conjunctivae, and lenses of soft contact-lens wearers, and (2) determine the frequency of external microbial problems in these lens wear ers. By comparing the contact-lens-wear ing patients with an epidemiologically similar group of patients not wearing lenses, we hoped to see if the microbial flora had been altered in the lens-wearing patients. In an attempt to eliminate bias in pa tient selection, we used the data collected
TABLE 2 POTENTIAL PATHOGENS RECOVERED IN 63 OF 295 CULTURES OF MATERIAL FROM PREOPERATIVE CATARACT SURGERY PATIENTS Organism
Positive Cultures Per Total No. of Cultures
Percent
Staphylococcus aureus Alpha-hemolytie Streptococcus Gram-negative rods Moraxella species Acinetobacter species Streptococcus pneumoniae Haemophilus influenzae Rhodotorula species
30/63 14/63 9/63 6/63 2/63 1/63 1/63 1/63
46 22 15* 9 3 2 2 2
*Two Proteus species, one Pseudomonas
species.
546
AMERICAN JOURNAL OF OPHTHALMOLOGY
from our first 51 patients during the first year of wearing Perfilcon-A contact lens es. Most of these patients have now worn their lenses for more than 24 months, and the data have not changed significantly. Although we eliminated S. epidermidis from our study because of its pres ence on the skin and eyelids, we are aware that some strains of S. epidermidis can be mannitol-positive and produce toxins, and that these properties invest it with potential for causing ocular disease. If we find this organism in the conjunc tiva or lens, and if its growth is confluent on blood agar plates, it may be able to produce disease. It is important to differentiate between the transient localization of an organism and its colonization on ocular tissue. If the organism has colonized, it can be recovered in cultures repeatedly, can usu ally be recovered in increasingly large numbers, and can be seen in smears. There may also be such ocular alterations as eyelid crusting, collarette formation, and the like. Most of our patients who showed potentially pathogenic organisms were probably examples of transient lo calization because there was no ocular disease, and the organisms, which were present in small numbers, failed to grow when cultures were repeated. This was the case on 37 occasions. In seven cases we treated the patients with an antibiotic, and because we altered the natural course of organism growth, we had no way of knowing whether true colonization had occurred or not. In four of these cases some ocular changes could have been related to the presence of the microbe. In the three cases in which repeated cultures were positive, the organisms had probably colonized. In the two untreated cases, the orga nisms disappeared without antibiotic assistance. When transient localization of organ
SEPTEMBER, 1979
isms of minor virulence occurs in the external ocular tissues, no treatment is needed. Even when the organisms have colonized, the host's immune defense mechanisms can probably handle most of them. But if there is a break in the eye's surface barrier (for example, from a corneal abrasion), or if the patient's immune defense system is depressed by age, dis ease, medication, and the like, either the colonization of a potential pathogen or the transient localization of a virulent pathogen may require antibiotic treat ment. Although brain-heart infusion broth may yield higher organism recovery than the media we used, our media probably grew most of the potential pathogens. The higher incidence of potential pathogens in the elderly aphakic patients was antici pated, and was probably the result of their less efficient immune defense sys tems, reduced tear flow, and diminished corneal sensation. The organisms recov ered from the contact-lens-wearing pa tients were comparable to those recovered from similar groups of patients not wear ing contact lenses. Infiltrates resembling catarrhal infil trates were noted in one of our contactlens wearers. Similar lesions have been noted by other observers (W. Stark and R. Keates, personal communications, 1977) and have been attributed to anoxia. We believe they are the result of a precipita tion of staphylococcal antigen-antibody complex that binds complement and at tracts polymorphonuclear leukocytes. If the staphylococci are eliminated from the eyelids, the infiltrates disappear. Fitting a flatter lens also alleviates the problem, indicating that anoxia may be a contribut ing factor. We probably treated some patients un necessarily, but later in our study, we learned to appreciate the patient's ability to eliminate transient organisms and even
VOL. 88, NO. 3, PART II
MICROBIAL FLORA IN EXTENDED-WEAR LENSES
those colonized on the ocular tissues. If a virulent organism (for example, Pseudomonas species) was recovered, howev er, we considered treatment with an anti biotic necessary. Chloramphenicol (Ophthochlor) con tains no perservative. It can be used while the lens remains in the eye but must be changed every few weeks. If a patient has to be kept on antibiotics for more than ten to 14 days, however, the lens should be removed and the antibiotic regimen changed. Systemic tetracycline is espe cially helpful in eliminating or reducing the number of staphylococci in the oil glands of the eyelid, and during this treat ment the lens can be worn. There were more recoverable potential pathogens in the parallel group of preoperative patients than in the contact-lens wearers, which has been noted by others. 3 Also a higher proportion of 5. aureus and Moraxella species in the preoperative group was noted.
547
SUMMARY
Of 857 cultures of material collected from the eyelids, conjunctivae, and con tact lenses of 51 extended-wear softcontact-lens wearers, 44 (5%) grew poten tial pathogens. The aphakic patients wearing contact lenses had fewer recover able pathogens (24 of 295 or 8%) than a group of preoperative cataract patients (63 of 295 or 21%). On five occasions, positive cultures ac companied clinical symptoms, and on three occasions, repeated cultures grew the same potential pathogen. REFERENCES 1. Cooper, R. L., and Constable, I. J.: Infective keratitis in soft contact lens wearers. Br. J. Ophthalmol. 61:250, 1977. 2. Herbst, R. W.: Herellea corneal ulcer associat ed with the use of soft contact lenses. Br. J. Ophthalmol. 56:848, 1972. 3. McBride, M. E.: Changes in eye microflora with soft contact lens wear. Presented at poster session, American Society for Microbiology, Las Vegas, Nevada, May 16, 1978.
M A S A O O K U M O T O , M.A., San Francisco,
We report herein an evaluation of the effect of the use of extended-wear soft contact lenses on the microbial flora of the eye. M A T E R I A L AND M E T H O D S
The lens that we used in this study was the Perfilcon-A lens (Cooper Laborato ries). The polymeric material of which it is composed is a terpolymer of 21 hydroxyethyl methacrylate N-vinyl-2-pyrrolidone and methacrylic acid, with ethyleneglycol dimethacrylate as a crosslinking agent. The water content of the lens, which is hydrophilic, is about 76% at 20°C. Its oxygen permeability ranges from a low of 8.1% in lenses 0.43 mm thick to a high of 13.1% in lenses 0.12 mm thick in the center. Over a period of one year we prepared a total of 857 cultures of material from the eyelids, conjunctivae, and contact lenses of our first 51 patients (20 aphakic and 31 phakic) fitted with these lenses. A moist ened, cotton-tipped applicator was used to obtain the material, with which we inoculated blood agar and Sabouraud's medium. The blood agar cultures were incubated for 48 hours at 37°C and the Sabouraud's-medium cultures for two to three weeks at 30°C. The potential path ogens were identified, their identity recorded, and their antibiotic sensitivi ties tested by the Kirby-Bauer method. From the Francis I. Proctor Foundation for Re search in Ophthalmology and the Department of Ophthalmology, University of California San Fran cisco, San Francisco, California. Reprint requests to Dr. Gilbert Smolin, M.D., Francis I. Proctor Foundation, Room 315S, Univer sity of California San Francisco, San Francisco, CA 94143.
AND R O B E R T A. N O Z I K ,
M.D.
California
We excluded Staphylococcus epidermidis and liphtheroids entirely, and excluded S. aureus if only one or two colonies were recovered only from the eyelids. Collaterally we compared 295 cultures from our aphakic contact-lens wearers with 295 cultures of material taken from preoperative cataract surgery patients dur ing about the same period of time. The preoperative cultures were taken routine ly in all of our patients one or two weeks before surgery. The eyes were otherwise undisturbed. The extended-wear soft contact lenses were routinely removed once a month by the physician immediately after obtaining the culture material. The lenses were physically cleaned, not sterilized, and re inserted. The lenses were only removed because of irritation or infection. RESULTS
Out of the 857 cultures, 44 (5%) grew pathogenic organisms. Of the 44, 24 were from the aphakic patients (24 of 295 or 8%), and 20 were from the phakic patients (20 of 562 or 3.6%), all of whom were young and myopic individuals. If the patients with only a few 5. aureus on their eyelids had been included, the rates would have been approximately 10 and 5%, respectively. The organisms recov ered are listed in Table 1. Occasionally more than one potential pathogen was recovered from the eyelids of the same patient. On 39 occasions the patients were asymptomatic but the cultures were posi tive for potential pathogens. Two of the patients from whom the material for these 39 cultures was collected were treated with an antibiotic; the rest were left un-
AMERICAN JOURNAL O F OPHTHALMOLOGY 88:543-547, 1979
543
544
AMERICAN JOURNAL OF OPHTHALMOLOGY
SEPTEMBER, 1979
TABLE 1 POTENTIAL PATHOGENS RECOVERED IN 44 OF 857 CULTURES OF MATERIAL COLLECTED FROM 51 SOFT-CONTACT-LENS WEARERS
Organism
Positive Cultures Per Total No. of Cultures
Percent
Staphylococcus aureus Alpha-hemolytic streptococcus Gram-negative rods Moraxella species Acinetobacter species Streptococcus pneumoniae Branhamella catarrhalis Nocardia species Candida albicans Rhodotorula species
11/44 13/44 10/44 2/44 2/44 2/44 1/44 1/44 1/44 1/44
25 30 24* 4 4 4 2 2 2 2
*No Pseudomonas
or Proteus species.
treated. In one of the two treated cases the cultures were positive for S. aureus be fore the patient began wearing soft con tact lenses, and gentamicin ophthalmic drops were used to eliminate the organ ism. In the second treated case the organ ism was also 5. aureus, and because it was recovered in cultures run sequentially at one-month intervals, we assumed that it had colonized on the eyelids, and we used chloramphenicol (Ophthochlor) drops to eliminate it. On more than 800 occasions the pa tients were asymptomatic and without recoverable pathogenic organisms, and on a few occasions they were symptomat ic and without recoverable pathogenic organisms. The symptoms were blurred vision, feeling the lens, red eyes, a scratchy sensation, and the like. Altering the diameter, base curve, or power of the lens usually relieved the symptoms, and artificial tears were required by several aphakic patients. We treated one patient with antibiotics. He had crusts, collaretes, scurf, and rosettes on his eyelid mar gins, and despite negative cultures, it was our clinical impression that he had staphylococcal blepharitis. He was treat ed with eyelid scrubs and systemic tetra-
cycline for one month. Both the symp toms and the condition of the eyelids improved remarkably. On five occasions, the five patients ex amined were symptomatic and the cul tures were positive for potential path ogens. Two of the five patients were aphakic and three were phakic. In one case the organism was a gram-negative rod and the conjunctiva was hyperemic. The eye was treated with chlorampheni col (Chloromycetin) ophthalmic drops four times a day for four days with the soft lens in place. Subsequent cultures were negative and the eye became asymp tomatic. In a second case the organism was Moraxella species. There was conjunctival hyperemia and the eye was treated with gentamicin ophthalmic drops after removal of the lens. After three days of treatment, the eye was asymptomatic and cultures were negative for potential path ogens. In a third case the organism was S. aureus. The patient had a peripheral corneal infiltrate that simulated a catarrhal ulcer. The lens was removed and sulfacetamide ophthalmic drops were adminis tered for four days. The infiltrate cleared
VOL. 88, NO. 3, PART II
MICROBIAL FLORA IN EXTENDED-WEAR LENSES
and cultures were negative for potential pathogens. In a fourth case the organism was a gram-negative rod. The patient com plained of excessive mucus in his eye. The lens was removed and gentamicin eye drops were used five times a day for four days. Cultures were then negative for potential pathogens and the eye was asymptomatic. In a fifth case the organism was alphahemolytic Streptococcus and the conjunc tiva was hyperemic. No treatment was instituted, and in several days the hyperemia subsided and the next culture (two weeks later) was negative for potential pathogens. In three instances, consecutive cultures were positive for the same potential path ogen. In one patient (who was one of the two treated patients that were asympto matic and had positive cultures) this oc curred twice. The organism was S. aure us. The eye was treated with an antibiotic on the first occasion but not on the sec ond. Despite this omission, however, the next cultures were negative and they have remained negative 12 months later. In the second patient, a gram-negative rod was recovered from two consecutive cultures. The patient received no antibi otic treatment but was free of the organ ism 12 months later.
545
When we compared the number of cul tures positive for pathogenic organisms in our aphakic soft-contact-lens wearers with the number in our preoperative cataract surgery patients, we found 24 cultures positive in the contact-lens wear ers (24 of 295 or 8%) and 63 positive in the preoperative patients (63 of 295 or 21%). The potential pathogens recovered from the preoperative patients are listed in Table 2. There was a higher percentage of S. aureus and Moraxella species in this group than in the group of aphakic lenswearers. DISCUSSION
There are several reports of infections in contact-lens wearers. 1,2 In our study, we hoped to: (1) collect data that would make possible a reasonable estimate of the flora of the eyelids, conjunctivae, and lenses of soft contact-lens wearers, and (2) determine the frequency of external microbial problems in these lens wear ers. By comparing the contact-lens-wear ing patients with an epidemiologically similar group of patients not wearing lenses, we hoped to see if the microbial flora had been altered in the lens-wearing patients. In an attempt to eliminate bias in pa tient selection, we used the data collected
TABLE 2 POTENTIAL PATHOGENS RECOVERED IN 63 OF 295 CULTURES OF MATERIAL FROM PREOPERATIVE CATARACT SURGERY PATIENTS Organism
Positive Cultures Per Total No. of Cultures
Percent
Staphylococcus aureus Alpha-hemolytie Streptococcus Gram-negative rods Moraxella species Acinetobacter species Streptococcus pneumoniae Haemophilus influenzae Rhodotorula species
30/63 14/63 9/63 6/63 2/63 1/63 1/63 1/63
46 22 15* 9 3 2 2 2
*Two Proteus species, one Pseudomonas
species.
546
AMERICAN JOURNAL OF OPHTHALMOLOGY
from our first 51 patients during the first year of wearing Perfilcon-A contact lens es. Most of these patients have now worn their lenses for more than 24 months, and the data have not changed significantly. Although we eliminated S. epidermidis from our study because of its pres ence on the skin and eyelids, we are aware that some strains of S. epidermidis can be mannitol-positive and produce toxins, and that these properties invest it with potential for causing ocular disease. If we find this organism in the conjunc tiva or lens, and if its growth is confluent on blood agar plates, it may be able to produce disease. It is important to differentiate between the transient localization of an organism and its colonization on ocular tissue. If the organism has colonized, it can be recovered in cultures repeatedly, can usu ally be recovered in increasingly large numbers, and can be seen in smears. There may also be such ocular alterations as eyelid crusting, collarette formation, and the like. Most of our patients who showed potentially pathogenic organisms were probably examples of transient lo calization because there was no ocular disease, and the organisms, which were present in small numbers, failed to grow when cultures were repeated. This was the case on 37 occasions. In seven cases we treated the patients with an antibiotic, and because we altered the natural course of organism growth, we had no way of knowing whether true colonization had occurred or not. In four of these cases some ocular changes could have been related to the presence of the microbe. In the three cases in which repeated cultures were positive, the organisms had probably colonized. In the two untreated cases, the orga nisms disappeared without antibiotic assistance. When transient localization of organ
SEPTEMBER, 1979
isms of minor virulence occurs in the external ocular tissues, no treatment is needed. Even when the organisms have colonized, the host's immune defense mechanisms can probably handle most of them. But if there is a break in the eye's surface barrier (for example, from a corneal abrasion), or if the patient's immune defense system is depressed by age, dis ease, medication, and the like, either the colonization of a potential pathogen or the transient localization of a virulent pathogen may require antibiotic treat ment. Although brain-heart infusion broth may yield higher organism recovery than the media we used, our media probably grew most of the potential pathogens. The higher incidence of potential pathogens in the elderly aphakic patients was antici pated, and was probably the result of their less efficient immune defense sys tems, reduced tear flow, and diminished corneal sensation. The organisms recov ered from the contact-lens-wearing pa tients were comparable to those recovered from similar groups of patients not wear ing contact lenses. Infiltrates resembling catarrhal infil trates were noted in one of our contactlens wearers. Similar lesions have been noted by other observers (W. Stark and R. Keates, personal communications, 1977) and have been attributed to anoxia. We believe they are the result of a precipita tion of staphylococcal antigen-antibody complex that binds complement and at tracts polymorphonuclear leukocytes. If the staphylococci are eliminated from the eyelids, the infiltrates disappear. Fitting a flatter lens also alleviates the problem, indicating that anoxia may be a contribut ing factor. We probably treated some patients un necessarily, but later in our study, we learned to appreciate the patient's ability to eliminate transient organisms and even
VOL. 88, NO. 3, PART II
MICROBIAL FLORA IN EXTENDED-WEAR LENSES
those colonized on the ocular tissues. If a virulent organism (for example, Pseudomonas species) was recovered, howev er, we considered treatment with an anti biotic necessary. Chloramphenicol (Ophthochlor) con tains no perservative. It can be used while the lens remains in the eye but must be changed every few weeks. If a patient has to be kept on antibiotics for more than ten to 14 days, however, the lens should be removed and the antibiotic regimen changed. Systemic tetracycline is espe cially helpful in eliminating or reducing the number of staphylococci in the oil glands of the eyelid, and during this treat ment the lens can be worn. There were more recoverable potential pathogens in the parallel group of preoperative patients than in the contact-lens wearers, which has been noted by others. 3 Also a higher proportion of 5. aureus and Moraxella species in the preoperative group was noted.
547
SUMMARY
Of 857 cultures of material collected from the eyelids, conjunctivae, and con tact lenses of 51 extended-wear softcontact-lens wearers, 44 (5%) grew poten tial pathogens. The aphakic patients wearing contact lenses had fewer recover able pathogens (24 of 295 or 8%) than a group of preoperative cataract patients (63 of 295 or 21%). On five occasions, positive cultures ac companied clinical symptoms, and on three occasions, repeated cultures grew the same potential pathogen. REFERENCES 1. Cooper, R. L., and Constable, I. J.: Infective keratitis in soft contact lens wearers. Br. J. Ophthalmol. 61:250, 1977. 2. Herbst, R. W.: Herellea corneal ulcer associat ed with the use of soft contact lenses. Br. J. Ophthalmol. 56:848, 1972. 3. McBride, M. E.: Changes in eye microflora with soft contact lens wear. Presented at poster session, American Society for Microbiology, Las Vegas, Nevada, May 16, 1978.
