Emerging prevalence of microsporidial keratitis in Singapore: epidemiology, clinical features, and management.
OBJECTIVE
To investigate the incidence and epidemiologic factors involved in the development of microsporidial keratitis. The association of host immune status and clinical pattern, clinical features, and the role of fluoroquinolone monotherapy in treatment are also examined.


METHODS
Retrospective, noncomparative case series.


METHODS
All cases (124 patients, 134 eyes) of microsporidial keratitis confirmed with modified trichrome stain positive of corneal scrape over a 4-year period.


METHODS
Epidemiologic factors were observed. Host immune status with human immunodeficiency virus (HIV) serology and CD4/CD8 analysis was performed when consent was obtained. Visual acuity (VA) and slit-lamp examination throughout the course of keratitis was recorded. Treatment used included topical fluoroquinolones (ciprofloxacin 0.3%, moxifloxacin 0.5%, gatifloxacin 0.5%, levofloxacin 0.5%, or norfloxacin 0.3%) as monotherapy or in combination with topical fumagillin and/or systemic albendazole. Where corneal edema developed, ultrasound corneal pachymetry was recorded.


METHODS
Demographic features and epidemiologic factors, including host immune status. Clinical features and disease course, including the response to different therapeutic regimes.


RESULTS
Patients ranged in age from 11 to 68 years (mean, 31.9; median, 30) with a male:female ratio of 8:1 (females n = 17 [13.7%]). We performed HIV serology and CD4/CD8 in 45.9% of cases (n = 57); all the cases tested were negative with normal T-cell indices. Epidemiologic factors included soil exposure (50%), contact lens wear (21.1%), and topical steroid treatment (17.1%). The VA on presentation ranged from 20/20 to 20/100 (median, 20/30) with no loss in lines of VA on resolution. Common features were follicular papillary conjunctivitis and coarse punctate epithelial lesions in 3 patterns--diffuse, peripheral, and paracentral--evolving into nummular keratitis before resolution. Resolution occurred in 99% of cases on topical fluoroquinolone monotherapy. Four patients had recurrent disease that resolved with repeat fluoroquinolone or fluoroquinolone/oral albendazole combination. Two new clinical features were identified--diffuse endotheliitis (19.4%) with corneal edema and limbitis.


CONCLUSIONS
This study identifies an increasing incidence of microsporidial keratitis in Singapore with a strong correlation with prior soil exposure. Diffuse endotheliitis and limbitis have not been described and resolves with topical steroid therapy. Topical fluoroquinolone monotherapy is a valid treatment option.
Loh
Raymond S
RS
Singapore National Eye Centre, Singapore, Singapore.
Chan
Cordelia M L
CM
Ti
Seng Ei
SE
Lim
Li
L
Chan
Kian Sing
KS
Tan
Donald T H
DT
D000287:Administration, Topical; D000293:Adolescent; D000328:Adult; D000368:Aged; D000935:Antifungal Agents / Q000008:administration & dosage; D016516:CD4-CD8 Ratio; D002648:Child; D003320:Corneal Ulcer / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D003510:Cyclohexanes / Q000008:administration & dosage; D004359:Drug Therapy, Combination; D015821:Eye Infections, Fungal / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage; D005260:Female; D024841:Fluoroquinolones / Q000008:administration & dosage; D015528:HIV Seroprevalence; D006801:Humans; D015994:Incidence; D008297:Male; D016816:Microsporida / Q000302:isolation & purification*; D016881:Microsporidiosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D012717:Sesquiterpenes / Q000008:administration & dosage; D012846:Singapore / Q000453:epidemiology
D000935:Antifungal Agents; D003510:Cyclohexanes; D005231:Fatty Acids, Unsaturated; D024841:Fluoroquinolones; D012717:Sesquiterpenes; C026211:fumagillin