Multifocal oscillatory potentials in type 1 diabetes without retinopathy

PURPOSE: To study multifocal recordings of oscillatory potentials (m-OPs) in diabetic (Type 1) eyes that have no visible fundus alterations, to ascertain whether topographical changes in sensitivity are evident when compared with recordings from control subjects. METHODS: The Visual Evoked Response Imaging System (VERIS; EDI, San Diego, CA) system was used to elicit m-OPs from 61 independent areas, subtending the central 30 degrees of the retina, from 24 eyes of 12 patients with diabetes without retinopathy and from 26 eyes of 14 control subjects. For each group of subjects, the mean first- and second-order (first slice) kernel components of the responses for one eye, randomly chosen from each subject, were analyzed and compared for a retinal ring analysis and for an analysis of retinal quadrants. RESULTS: Both first- and second-order kernel responses of the diabetic group show significant delays in the implicit times of some of the m-OPs, compared with those of the control group. No significant changes in amplitude were found. For the first-order component, significant differences are found for both potentials between 5 degrees and 22 degrees eccentricity, for the nasal retina, and for one of the potentials for the remaining retinal areas. In the second-order kernel responses, the differences are significant for two of the three potentials in the midperiphery between 5 degrees and 13 degrees eccentricity, with the central potential being significantly delayed in all rings and quadrants. CONCLUSIONS: Patients with diabetes without retinopathy show prolonged latencies in m-OP recordings. This indicates an alteration in inner retinal sensitivity that can be explained by an impaired rod-cone interaction.