Abstract
Purpose :
Diabetes progressively impairs visual function with increasing severity of retinopathy. Therefore, this study examined the relationship of impaired retinal function with OCT-defined retinal structure.
Methods :
Fifty subjects with diabetes (24 without diabetic retinopathy [DR], 26 with nonproliferative diabetic retinopathy [NPDR]) and 18 healthy controls were tested with a comprehensive exam including refraction, e-ETDRS visual acuity, and fundus photography. Macular function was assessed with frequency doubling perimetry (FDP) (Carl Zeiss Meditec) using the 10-2 algorithm, and the quick contrast sensitivity function (qCSF) method (Adaptive Sensory Technology) over a range of spatial frequencies. Macular thickness was determined in the 3mm diameter around the fovea using Spectralis HRA+OCT software. The inner retina was defined as between the inner and outer limiting membranes, and the outer retina was defined as between the outer limiting membrane and the RPE. Statistical analysis was performed using Student’s t-test, ANOVA and Pearson’s Correlation.
Results :
e-ETDRS acuity was significantly decreased in subjects with NPDR (83.9 ± 7.2 letters) and no DR (87.1 ± 7.3 letters) compared to controls (91.2 ± 2.6 letters) (p = 0.002). Mean absolute threshold sensitivities in the 10° of the FDP was reduced in subjects with NPDR (27.7 ± 3.5 dB) relative to subjects with no DR (31.0 ± 2.5 dB) and controls (31.8 ± 1.4 dB) (p < 0.0001). Area Under the Log Contrast Sensitivity Function (AULCSF) was reduced in subjects with NPDR (1.23 ± 0.3) and no DR (1.38 ± 0.3) relative to controls (1.60 ± 0.1) (p < 0.0001). There was no difference in mean total, inner and outer retinal thickness between groups. However, in the NPDR group, FDP thresholds were positively correlated with the total retinal thickness (p = 0.042) and the inner retinal thickness (p = 0.039), while AULCSF and e-ETDRS acuity both correlated with the outer retinal thickness (p = 0.014 and p = 0.015 respectively).
Conclusions :
Central macular function is reduced in patients with diabetes, especially those with NPDR. A thinner macular structure is related to the retinal dysfunction in those patients. These findings provide insight into the pathophysiology of visual impairment due to diabetes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.