Abstract
Purpose: :
To investigate the clinical significance of the oscillatory potentials (OPs) and photopic negative response (PhNR) of the electroretinogram (ERG) in patients with early diabetic retinopathy.
Methods: :
One hundred and two diabetic patients with diabetic retinopathy at different stages were examined. Thirty–two age–matched normal controls were also studied. Full–field maximal and photopic cone ERGs were recorded according to the ISCEV protocol. The amplitudes of the b–wave, OPs, and PhNR were compared at the different stages of diabetic retinopathy.
Results: :
The amplitudes of the a– and b–waves of the maximal scotopic ERGs remained unchanged despite advancing stages of retinopathy, but the OP amplitudes were significantly attenuated even at an early stage of diabetic retinopathy. On the other hand, the amplitudes of both the PhNR and cone b–wave were reduced at the early stage of diabetic retinopathy. Analysis of the receiver operating characteristic curves demonstrated that the OPs were more sensitive and specific than the PhNR in detecting the early changes of retinal function in diabetic patients.
Conclusions: :
The amplitudes of the OPs and PhNR progressively decrease with the progression of diabetic retinopathy. The PhNR amplitudes were reduced along with the cone b–wave, indicating that earlier change of the PhNR in diabetic patients reflects reduced input to the retinal ganglion cell from the distal retina. The OPs are better indicators than the PhNR in detecting functional abnormality in patients with early diabetic retinopathy.
Keywords: electrophysiology: clinical • diabetic retinopathy • retina: proximal (bipolar, amacrine, and ganglion cells)