Morphologic Features of Buried Optic Disc Drusen on En Face Optical Coherence Tomography and Optical Coherence Tomography Angiography

Abstract

To evaluate and compare the morphologic characteristics of buried optic disc drusen (ODD) and optic disc edema (ODE) by using en face optical coherence tomography (OCT) and OCT angiography (OCTA). Retrospective, cross-sectional study. We reviewed the medical records of 61 patients (92 eyes) with buried ODD, 45 patients (62 eyes) with ODE, and 42 normal-appearing fellow eyes examined at 1 referral center between November 1, 2017 and April 30, 2019. Characteristic en face OCT and OCTA findings of buried ODD compared to those of ODE and normal optic discs were investigated. On en face OCT, all buried ODD were visualized as hyperreflective kidney-shaped masses well demarcated from the optic nerve axons, whereas ODE was visualized as ill-defined boundaries confluent with the retinal nerve fibers. On OCTA, 25.0% of the eyes with buried ODD showed a C-shaped vessel density decrease in the nasal radial peripapillary capillary layer, while 40.3% of the eyes with ODE had nonspecific focal vessel density decrease around the optic nerve head. Larger ODD were significantly associated with a vessel density decrease on OCTA (P= .009). The disc diameter positively correlated with the ODD area (r= 0.245; P= .018) and negatively correlated with the ODD height (r=-0.237; P= .023). En face OCT showed the characteristic features of buried ODD compared to those of ODE or normal optic discs. The demarcation of buried ODD from the optic nerve axons on en face OCT and the poor vascular perfusion of buried ODD on OCTA suggest that buried ODD are materials deposited around the optic disc rather than the herniated optic nerve axon fibers.