Abstract
Purpose:
Diabetic retinopathy (DR) is a leading cause of preventable blindness. Evidence suggests that retinal neurodegeneration (ND) plays a role in the genesis of DR. Our aim is to study ND process and long-term effect of neuroprotection with electrophysiological methods in patient with diabetes (DM).
Methods:
24 patients with DM (without diabetic macular edema and severe DR) are involved in this study (age: 34-65 ys). 12 patients have taken probiotic vitamin supplements with supposed neuroprotective effect (Group 1), while the other 12 patients remained on their previous diet (Group 2). Beside routine ophthalmological examinations, electrophysiological tests (RetiPort/RetiScan, Roland Consult GmbH) and optical coherence tomography (OCT - Topcon 3D 2000, Topcon Inc.) are performed at baseline and every 6 months. Electophysiological test are repeated within 1 week and average values are analyzed. The observed parameters are best corrected visual acuity (BCVA), central retinal thickness (CRT), retinal nerve fiber layer thickness (RNFL), multifocal ERG (mfERG) implicit times, pattern ERG (PERG) P50 and N95 amplitudes, visual evoked potential (VEP) P100 amplitude and latency. The changes from the baseline of these parameters are compared between the two groups.
Results:
After 6 months, there were no change in the BCVA in any the patients. Changes of the OCT parameters (CRT, RNFL) were within ±5 mm, thus considered absent. The overall changes from baseline in mfERG implicit time were 0.03 and 0.04 ms in Group 1 and 2, respectively. PERG P50 amplitudes became 0.15 and 0.23 mV lower, while there was a decrease of 0.11 vs 0.19 mV in the N95 amplitudes in Group 1 and 2, respectively. The changes in VEP amplitudes were -0.39 and -0.62 mV in the two groups. None of these changes or the differences were statistically significant (p>0.05).
Conclusions:
In the first 6 months of follow-up no statistically significant changes were detected in either parameters. This time is definitely too short to detect significant changes, however a tendency of worsening parameters was observed. These changes were slightly more remarkable in the control group and above the expected normal progression. The design of the study seems suitable for the long term evaluation of ND and neuroprotection in patients with early diabetic retinopathy, so continuation of the follow-up and enrollment of more patients are in prospect.