Relationship between climate, disease severity, and causative organism for contact lens-associated microbial keratitis in Australia.
OBJECTIVE
To evaluate associations between disease severity, causative organism, and climatic variation in contact lens-related microbial keratitis in Australia.


METHODS
Prospective, observational case series.


METHODS
Contact lens wearing patients (n = 236) with presumed microbial keratitis presenting to private and hospital ophthalmologists in Australia between October 1, 2003 and September 30, 2004 were identified prospectively. Clinical details, management information, and microbiology data were collected and cases were graded for severity based on lesion size and location criteria. Causative organisms were assigned to "environmental" or "endogenous" groups. Climate zone and daytime temperature and humidity were determined for the geographic location of each event. The main outcome measures were disease severity, causative organism, and climate zone.


RESULTS
Severe contact lens-related microbial keratitis was more likely to occur in warmer, humid regions of the country (P < .001), compared with smaller, increasingly peripheral corneal lesions that were more common in cooler conditions (P < .001). Culture-proven keratitis was predominantly caused by environmental organisms with Pseudomonas aeruginosa being recovered most frequently. Environmental organisms were isolated more commonly from tropical regions of the country and also accounted for nearly all cases of vision loss that occurred during the study period. Humidity did not have a significant effect on causative organism.


CONCLUSIONS
Climatic conditions play a role in disease severity and causative organism in contact lens-related microbial keratitis and therefore have implications for practitioners involved in contact lens care and contact lens wearers who live in or travel to the tropics.
Stapleton
Fiona
F
Institute for Eye Research, Sydney, Australia. f.stapleton@unsw.edu.au
Keay
Lisa J
LJ
Sanfilippo
Paul G
PG
Katiyar
Suchi
S
Edwards
Katie P
KP
Naduvilath
Thomas
T
D000293:Adolescent; D000328:Adult; D001315:Australia / Q000453:epidemiology; D001419:Bacteria / Q000302:isolation & purification*; D002980:Climate; D003261:Contact Lenses / Q000382:microbiology*; D003315:Cornea / Q000382:microbiology; D003320:Corneal Ulcer / Q000453:epidemiology / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D006813:Humidity; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D012720:Severity of Illness Index; D013696:Temperature