Optical coherence tomographic hyperreflective foci: a morphologic sign of lipid extravasation in diabetic macular edema.

PURPOSE: To analyze hyperreflective foci typically seen in diabetic macular edema (DME) in optical coherence tomography (OCT).
DESIGN: Prospective clinical trial. PARTICIPANTS: Twelve consecutive patients with treatment-naïve, clinically significant DME.
METHODS: During a same-day examination, a standardized visual acuity assessment (Early Treatment of Diabetic Retinopathy Study protocol), infrared fundus imaging, color fundus photography, and biomicroscopy were performed. Additionally, all patients were scanned using Stratus, Cirrus, and Spectralis OCT and results correlated. MAIN OUTCOME MEASURES: Morphologic changes secondary to DME.
RESULTS: In all eyes with DME, distinct hyperreflective foci distributed throughout all retinal layers were found in the OCT scans of all 3 OCT devices. These deposits could not be identified by infrared imaging, fundus photography, or biomicroscopy as long as they were not confluent. Accumulations of such foci at the border of the outer nuclear and in the outer plexiform layer were recognizable clinically as hard exudates showing the same hyperreflective features in OCT. The hyperreflectivity of these foci did not correspond with intraretinal hemorrhage, nor did the lesions cause the characteristic OCT laser beam scattering phenomena typically seen secondary to intraretinal bleedings or microaneurysms. Further, they were detected within the walls of intraretinal microaneurysms.
CONCLUSIONS: Well-demarcated, hyperreflective foci were identified in the retina of patients with DME. The deposits were located within walls of intraretinal microaneurysms and scattered throughout all retinal layers, forming confluent plaques in the outer plexiform layer. It is suggested that the foci represent extravasated lipoproteins and/or proteins being a very early subclinical barrier breakdown sign in DME.