Purpose: To study recordings of oscillatory potentials (OPs) of the electroretinogram (ERG) in diabetic eyes that have no visible fundus alterations, to ascertain whether changes in sensitivity are evident when compared with recordings from age-matched controls.

Methods: OPs of the ERG were measured from 68 eyes of 34 patients with diabetes without retinopathy and from 30 eyes of 15 normal subjects.

Results: A reduction in the amplitude of each oscillatory potential, as well as delayed implicit time of each oscillatory potential peak could be found in diabetic patients without retinopathy although not all significant. Decrease in the amplitude of OP1 and summed OP (OP-sum) and also delayed the implicit time of OP1 were seen between diabetic patients with no observable diabetic retinopathy.

Conclusion: Patients with diabetes without retinopathy show prolonged latencies in OPs recordings and decreased in amplitudes of OP-1 and OP-sum. This indicates an alteration in inner retinal sensitivity or ischemic change of overall retinal layer that can be explained by an impaired rod-cone interaction.