Abstract
Purpose:
In early stages of diabetic retinopathy (DR), optical coherent tomography (OCT) revealed the reduction of the thickness in ganglion cell layer and/or inner retinal layer (Sugimoto, 2005). The purpose of this study is to assess the inner retinal changes in patients with early stage type 2 diabetes mellitus using macular focal electroretinogram(fm- ERG) and OCT.
Methods:
Sixteen eyes with no DR (NDR) and thirty eyes with simple DR (SDR) were recruited to this study. Age matched fifteen healthy eyes were enrolled as normal controls. We examined the thickness of ganglion cell -inner plexiform layer (GCA) using spectral-domain optical coherence tomography (SD-OCT, Carl Zeiss, USA) and analyzed them by using the installed software. Fm-ERG was elicited by a 5 Hz rectangular 15°stimulus using ER-80(Kowa, Japan).
Results:
The GCA was 78.1±6.9 (mean±SD, µm), 181.1±5.2 and 82.2±5.7 in eyes with NDR, SDR and normal controls, respectively. GCA was significantly reduced in NDR and SDR compared to controls (p<0.05). Fm-ERG b-wave amplitude was 2.56±0.67(µV), 2.52±0.70 and 2.63±0.53 in eyes with NDR, SDR and controls, respectively. Photopic negative response (PhNR) amplitude was 1.64±0.62(µV), 1.34±0.30 and 1.56±0.37 , Oscillatory potentials (Op) amplitude were 1.01±0.44(µV), 0.65±0.26 and 1.30±0.38 in eyes with NDR, SDR and normal controls, respectively. No statistical difference was found in fm-ERG b-wave and PhNR amplitude, however, Op amplitude reached statistical difference among these groups (p<0.005).
Conclusions:
Even in early DR, the thickness of ganglion cell - inner plexiform layer and the amplitude of fm-ERG Op were reduced, neither were the amplitude of fm-ERG b-wave and PhNR. fm-ERG b - wave, PhNR and Op all were derived from inner retina but altered differently in early stages of DR.
Keywords: 499 diabetic retinopathy •
507 electrophysiology: clinical •
550 imaging/image analysis: clinical