Variable phenotypes in patients diagnosed with idiopathic multifocal choroiditis.

PURPOSE: To report investigations in a case series of patients diagnosed with idiopathic multifocal choroiditis (MFC) in order to determine whether or not a new clinical phenotype could be identified and to determine the long-term visual prognosis. METHODS: Twenty-eight patients were identified from the clinic database of approximately 1200 and subsequently reviewed. After ocular examination, which included fluorescein angiography, 20 of these patients were determined to have idiopathic MFC. Visual outcome, patient demographics, presenting symptoms, the distribution of inflammatory cells, the pattern of chorioretinal lesions and the development of peripapillary atrophy, choroidal new vessels or cystoid macular oedema were compared. RESULTS: The range of follow up was 1-27 years (mean 10 years). A Kaplan-Meier plot showed that approximately 60% of patients maintained their best-corrected visual acuity for 10 years after diagnosis. Poor vision at final review was associated with eyes having choroidal new vessels or cystoid macular oedema. Oral steroids were used to treat 11 patients, of which 10 responded with a visual improvement. The one non-responsive patient had foveal ischaemia angiographically. Generally the idiopathic phenotype was variable and only four patients showed some overlap with known subgroups of MFC. Unusual vascular features were observed in two patients. CONCLUSIONS: No specific phenotype was seen to emerge from this cohort of patients diagnosed with idiopathic MFC, although most were significantly different from the retinal white dot syndromes currently described. The visual prognosis was relatively good and most cases responded to oral steroids.