En Face Optical Coherence Tomography Illustrates the Trizonal Distribution of Drusen and Subretinal Drusenoid Deposits in the Macula

Abstract

Purpose: To analyze the topographic distribution of macular drusen and subretinal drusenoid deposits (SDDs) using single-capture en face spectral domain optical coherence tomography (SD-OCT) imaging.

Design: Retrospective case series.

Methods: Analysis of 33 eyes of 20 patients with evidence of SDDs. Structural en face OCT images were reconstructed using a 40-µm-thick slab positioned from 48 to 88 µm above the Bruch membrane. The Early Treatment of Diabetic Retinopathy Study (ETDRS) grid and a rod/cone density map were overlaid on the en face OCT images, and the distribution of different subtypes of SDDs and macular drusen were assessed.

Results: A total of 31 eyes (94%) showed a trizonal distribution pattern of drusen and SDDs. Whereas small to large drusen tended to aggregate in the central circle, dot SDDs predominated in the inner ring and the inner portion of the outer ring of the ETDRS grid and ribbon SDDs localized to the outer ring and outside the ETDRS grid. Of note, drusen colocalized to the region of greatest cone density, whereas ribbon SDDs colocalized to the area of greatest rod density. The dot SDDs mapped to the intermediate region with mixed rod and cone representation.

Conclusion: Dot and ribbon subtypes of SDDs and macular drusen show a characteristic trizonal distribution. The locations of these lesions colocalize according to the different densities of the cones and rods in the retina and may reflect varying pathophysiological activities of these photoreceptor subtypes.