Cystoid macular edema without macular thickening: a retrospective optical coherence tomographic study.

BACKGROUND: This is a retrospective observational case series of 37 eyes of 32 patients meeting the inclusion criteria intended to describe the appearance, prevalence, and associated risk factors for cystoid macular edema in eyes with normal foveal thickness and contour as determined by optical coherence tomography (OCT).

METHODS: A retrospective review of all patients with macular disease who underwent OCT evaluation at the New England Eye Center from January to March 2007 and met the study inclusion criteria was performed. Optical coherence tomography scans were evaluated for the presence of intraretinal cystic fluid or cystoid macular edema but with normal retinal thickness and foveal contour. Retinal thickness and contour were evaluated using OCT mapping software. The main outcome measures were as follows: OCT-defined entity based on the presence of cystoid spaces within the fovea, "normal" foveal thickness (<252 microm), normal foveal contour, and best-corrected visual acuity on the date of examination.

RESULTS: Thirty-seven eyes of 32 patients were determined to have cystoid macular edema with normal foveal thickness and contour on OCT. The overall prevalence within our patient population was 4.9%. Mean foveal thickness (standard deviation) for these patients was 201.4 microm (28.9) compared with normal mean foveal thickness (standard deviation) of 212 microm (20.0). Of the 32 patients, 17 (53.1%) had a primary diagnosis of age-related macular degeneration. The mean visual acuity (Snellen; logarithm of the minimum angle of resolution) was 20/80 (0.60).

CONCLUSION: Cystoid macular edema in the setting of normal foveal thickness and contour as determined by OCT has not been extensively described. This entity is not pathognomonic of a single diagnosis and can occur in the setting of several disparate diagnoses as seen in our cohort. Chief among these were age-related macular degeneration and diabetic retinopathy. Acute postcataract cystoid macular edema was absent.