Six-year review of Acanthamoeba keratitis in New South Wales, Australia: 1997-2002.
OBJECTIVE
To assess the incidence and risk factors for Acanthamoeba keratitis (AK), the diagnostic interval, and the efficacy and outcome of current treatment among the population of New South Wales, Australia.


METHODS
A retrospective review was carried out of all cases of AK treated at the Sydney Eye Hospital between January 1997 and December 2002.


RESULTS
Twenty patients were identified with a mean follow up of 24.8 +/- 21.5 months. Acanthamoeba keratitis constitutes 4.7% of severe infective keratitis treated at Sydney Eye Hospital. The mean interval from first presentation to diagnosis was 26.6 +/- 35.1 days overall; 17.2 +/- 33.1 days for those presenting directly to our unit (69% being diagnosed within 72 h of presentation), and 44.1 +/- 34.0 days for those first presenting elsewhere. Of those with a diagnostic delay >1 month, 57% had been mistakenly diagnosed with Herpes simplex keratitis. Sixteen (80%) wore contact lenses, and eight (40%) had additional risk factors including poor lens hygiene. Complications occurred in 16 (80%), with seven (35%) requiring surgical intervention. Visual acuity improved in 18 (90%), worsened in two patients (10%), and 75% achieved 6/12 or better at last follow up.


CONCLUSIONS
Acanthamoeba keratitis is a rare infection, and contact lens wear remains the commonest association, with poor hygiene constituting significant additional risk. The visual outcome has improved with the availability of effective amoebicidal agents, but patients with a diagnostic delay and non-contact lens wearers are at increased risk of recurrent disease. A high index of clinical suspicion remains the most effective strategy in implementing early treatment, and enabling a favourable outcome.
Butler
Tom K H
TK
Department of Clinical Ophthalmology and Save Sight Institute, University of Sydney and Sydney Eye Hospital, Sydney.
Males
John J
JJ
Robinson
Lyon P
LP
Wechsler
Alfred W
AW
Sutton
Gerard L
GL
Cheng
Joanna
J
Taylor
Peter
P
McClellan
Kathleen
K
D015823:Acanthamoeba Keratitis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D003261:Contact Lenses / Q000469:parasitology / Q000706:statistics & numerical data; D003315:Cornea / Q000469:parasitology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014792:Visual Acuity
D000981:Antiprotozoal Agents