A systematic correlation between morphology and functional alterations in diabetic macular edema.

PURPOSE The aim of this study was to correlate different types of retinal morphologic alterations secondary to diabetic macular disease with their characteristic impact on retinal function. METHODS In the present cross-sectional study, 26 eyes of 26 diabetic patients with clinically significant macular edema were examined. All patients underwent complete standardized ophthalmologic examination, including SD-OCT and microperimetry. Microperimetric values were projected over the scanning laser ophthalmoscope image of the OCT device, allowing direct correlation of functional and morphologic parameters. Results over all 1066 individual areas were analyzed using a general linear model. RESULTS All the characteristic morphologic alterations demonstrated a significant effect on retinal function (P < 0.0002), except for outer nuclear layer (ONL) hyporeflectivity and small ONL cysts. Large ONL cysts (>220 μm) and serous retinal detachment had the greatest estimated negative effect on retinal sensitivity (-3.86 and -3.66 dB), followed by medium-sized ONL cysts, hard exudates associated with an extinction of the scan signal, and inner nuclear layer cysts. CONCLUSIONS In diabetic macular edema, serous retinal detachment and large ONL cysts are the two morphologic changes with the greatest negative impact on retinal function.