Material and Methods: Sixty-three diabetics and 30 control subjects were enrolled in this study. Diabetic patients without retinopathy were allocated to NDRP group, patients with mild to moderate diabetic retinopathy into the NPDR group.The control group consisted of 30 healthy subject.RNFL, GCL, IPL, INL, OPL, ONL, PL-RPE, Sum of IRL and ORL were analyzed by automated segmentation software of spectral domain optical coherence tomographyª and thickness of each retinal layer was compared between the groups. Measurements were analyzed from paracentral and peripheral area of the standard ETDRS circles.

Results: Mean thickness of the RNFL,GCL and IPL layers in the paracentral area (21.4±2.5 m,47.4±5.3 m and 39.1±3.2m) was thinner edilein the NDRP group than the control group (23.1±3.1m,51.5±3.9m,41.9±3.1m). In the NPDR group, mean thickness of GCL and IPL layers in the paracentral area (41.5±7.5m and 35.5±4.8m) were thinner than the control group (51.5±3.9m and 41.9±3.1m),while ONL layer (78.4±9.3m) was thicker than the control group (69.1±11.1m).Mean thickness of the IRL of the paracentral area in the NDRP and NPDR groups was detected as thinner than the control group.Mean thickness of the ORL of the paracentral and peripheral areas in the NDRP group,were thicker than the control group.

Conclusion: While a thinning in the RNFL and GCL layers of the diabetic patients who did not yet develop any retinopathy was observed, retinal thickness seemed to be thicken in the outer retinal layers accompanying to thinning in the inner retinal layers in the stage of mild to moderate diabetic retinopathy. Keywords : Diabetic retinopathy, retinal layer, optical coherence tomography