In this article we herein report an interesting vitreo-macular interface abnormality associated with chronic diabetic cystoid macular edema. It is an observational case study of three diabetic patients examined in the diabetic clinic. All the patients had proliferative diabetic retinopathy with chronic macular edema. A serial cross sectional OCT examination and tracking of both the longitudinal progression of macular thickening and vitreo-macular interface revealed cystoid macular edema with a characteristic hyperreflective vitreous shadow emerging from the vitreofoveal interface. All the patients had dehiscence of inner retinal layers. This particular morphological feature at the vitreo-foveolar interface, which we name as "volcano sign", has not been described earlier. The probable mechanism of such a finding probably could be due to slow progressive leakage of chronic cytoid fluid into the vitreous with condensation of the overlying vitreous. Vitreo-macular traction followed by posterior vitreous detachment probably would have contributed to such a morphological event.
Keywords: Diabetic cystoid macular edema; Optical coherence tomography; Posterior vitreous detachment; Retinal morphology; Vitreo-macular interface.