Abstract
Purpose: :
to study the relationship between foveal thickness assessed by optical coherence tomography (OCT) and foveal function measured with multi focal electroretinography (mfERG) in patients with non–proliferative diabetic retinopathy, and with no previous laser treatment.
Methods: :
Eighteen eyes of 13 diabetic patients (9 men), aged 61, (range 28–79) years, diabetesduration 9, (range 2–27) years, with a macular thickness between 200–600µ were evaluated by mfERG, visual acuity (ETDRS score) and OCT. Mean amplitudes and implicit times of the mfERG response were analyzed within the three innermost (27degrees) of the five concentric rings (the summed response from the first and second ring was analyzed), which corresponds to the area measured by the OCT (6 mm).
Results: :
There was a negative correlation both between retinal thickness assessed with OCT and mean amplitude values measured by the mfERG –0.51; p=0.035 and between OCT values and visual acuity, –0.49; p=0.045, in the first concentric ring. No correlation was found in the second and third concentric ring from fovea. Furthermore, no correlation was found between retinal thickness and implicit time or values measured by mfERG and visual acuity. When retinal thickness exceeded 280 microns a more pronounced decrease of retinal function measured by mfERG was seen.
Conclusions: :
Macular response density of the mfERG and best–corrected visual acuity were inversely correlated with foveal thickness. A foveal retinal thickness of 280 microns seems to be a critical point regarding retinal function.
Keywords: diabetic retinopathy • electrophysiology: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)