Abstract
Purpose :
Retinal neuronal damage occurs in both preclinical and clinical diabetic retinopathy (DR). However the extent of ocular neuronal damage that co-exists with established peripheral diabetic neuropathy (DN) (in the feet) is not very well known. We explored the relationship between the markers of early retinal neuronal damage and neuropathy. A cross sectional study examined structural retinal and visual functions in patients with DN.
Methods :
Data were collected from 888 type 2 diabetic subjects without retinopathy and with early (mild and moderate) DR. Visual function assessments included visual acuity, contrast sensitivity (CS), color vision (CV), retinal sensitivity (RS) using microperimetry. Retinal structural assessment was carried out by optical coherence tomography. Neuropathy was measured by the vibration perception thresholds (VPT) using a biothesiometer probe. Statistical analysis was performed using Independent t test, Pearson’s correlation and multivariate logistic regression with an alpha error set at 5%.
Results :
248 subjects had neuropathy (VPT>/=20µv); 185 (74.6%) had no retinopathy and 63 (25.4%) had retinopathy. Subjects with DN were relatively older (63.95 SD 9.3years) and had longer duration of diabetes (9.96 SD 6.4) compared to no DN (56.92 SD 8.8years and 6.96 SD 4.6, p=0.0001). When compared to patients who had no neuropathy or retinopathy, patients with neuropathy but no retinopathy showed retinal nerve fiber layer thinning (5.33 SD 3.6µm vs 6.39 SD 5.57µm, p=0.04), increased foveal thickness (173.59 SD 26.9µm vs169.77 SD 18.88µm, p=0.06), reduced CS (9.35 SD 1.4 log vs 10.15 SD 1.8, p=0.0001), reduced RS (13.56 SD 3.65 dB vs 14.78 SD 3.17 dB, p=0.03) & impaired CV (total error scores:228.5 SD 117.5 vs 189.6 SD 94.92, p=0.04). Multivariate logistics showed a significant association between the mean retinal sensitivity and DN in subjects without DR (adjusted odds ratio (95%CI): 0.76 (0.60-0.95), p=0.01), also in subjects who had early DR (adjusted odds ratio (95%CI): 0.65 (0.49-0.86), p=0.03). A significant negative correlation existed between the RS and the VPT in both no DR (r = -0.16, p=0.01) and early DR (r = -0.35, p=0.004).
Conclusions :
The presence of DN significantly affects the structural retina and visual functions even before the onset of clinical retinopathy. Retinal sensitivity could possibly serve as a predictor for early neural changes in diabetic subjects.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.