Abstract
Purpose:
To evaluate the presence of multifocal ERG (mfERG) changes and retinal cells layers changes in eyes of patients with diabetes type 2, using Spectral Domain Optical Coherence Tomography (SD-OCT), in order to identify the correspondence between functional mfERG changes and retinal structural changes.
Methods:
211 out of 450 diabetic type 2 patients enrolled in the EUROCONDOR study (NCT01726075) and that performed SD-OCT Cirrus (Zeiss Meditec, Dublin, CA, USA) were considered for analysis: 109 patients with Diabetic Retinopathy (DR) ETDRS level 10 and 102 patients with DR ETDRS level 35. All patients performed mfERG (103 hexagons) and SD-OCT Cirrus at baseline. P1 amplitude and implicit time (IT) of mfERG central rings (rings 1, 2 and 3) were analyzed by the number of hexagons with altered z-scores (z-score ≥2 for IT and ≤-2 for amplitude). The number of altered hexagons was compared with retinal cells layers changes detected by SD-OCT.
Results:
Mean age and duration of diabetes in these patients were 63.9 and 11.3 years, respectively; 71% were males and 29% were females. In the 109 eyes classified as having ETDRS level 10 (without microaneurysms) there were central mfERG changes in 57% of eyes. A decrease of thickness in the Ganglion Cells (GC) or Retinal Nerve Fiber (RNF) layers was observed in 13% of the eyes. 64% of eyes with thinning of GC or RNF layers showed correspondence with mfERG changes. In the 102 eyes with ETDRS level 35 (mild nonproliferative DR), central mfERG response was altered in 68% of eyes and GC and RNF layers thinning was present in 12% of the eyes. Correspondence between mfERG changes and GC or RNF thinning was present in all cases (100%; p=0.011). This data shows a good correspondence between mfERG changes and thinning of the GC and RNF layers.
Conclusions:
There is good correspondence between central mfERG changes (ring 1, 2 and 3) and thinning of GC and RNF layers in the initial stages of DR in patients with diabetes type 2. Therefore, functional and structural measurements used for assessing neurodegeneration run in parallel in the early stages of DR.