[Optical coherence tomography and visual evoked potentials in patients with type 2 diabetes with and without...

Diabetic retinopathy remains the leading visual complication of diabetes mellitus type 2 (DM2) in productive patients. It evolves from a non-proliferative stage, occasionally asymptomatic, until a proliferative phase with neovascularization, retinal detachment and blindness. There are many reports that compare visual, biochemical or electrophysiological parameters among diabetic patients and healthy controls. However, much less information has been published comparing parameters between diabetics with and without non-proliferative retinopathy. Thus, it is essential to know what changes take place in the retina and the visual post retinal pathway as the disease progresses, but before the establishment of a proliferative process involving blindness. Therefore, the purpose of this study was to compare and correlate electrophysiological and visual parameters of diabetics with and without non-proliferative retinopathy, using modern, non invasive techniques. These data will allow us to a better understanding of the process and to determine the use of these parameters in the monitoring of diabetes and its complications.

This is an observational, prospective, transversal and analytical study. Twenty-two patients with DM2 were divided into two groups (50% on each group): group with non-proliferative retinopathy and group without retinopathy. We measured the central fovea thickness (CFT) by optical coherence tomography, the P100 wave of the Visual Evoked Potentials (VEP) and other visual and biochemical parameters.

Retinopathy patients had lower visual acuity (p < 0.047), lower P100 amplitude (p < 0.043) and lower rate of rise (p < 0.026, 1-tailed). They also showed a more biochemical disturbance with higher glycemia (p < 0.015) and HbA1c (p < 0.033), and longer disease duration (p < 0.011), compared with those without retinopathy. Visual acuity showed a negative correlation with disease duration (r = -0.65; p < 0.017) and severity of ocular damage (r = -0.76; p < 0.007) in patients with retinopathy.

Patients with retinopathy have lower visual acuity, decreased central visual fibers and a tendency to increase the ECF. Although the data favor the use of these non-invasive techniques to monitor the disease and prevent progression of visual complications, additional studies are needed with larger sample size to confirm the results obtained here.