Abstract
Purpose :
Psychophysical and electrophysiological measurements have provided evidence for photoreceptor dysfunction in patients with diabetic retinopathy (DR). The purpose of this study is to conduct quantitative optical coherence tomography (OCT) analysis of outer retina, and thus to verify the feasibility of noninvasive OCT detection of photoreceptor abnormality in early DR.
Methods :
OCT images were acquired from normal eyes, diabetic eyes with no diabetic retinopathy (no DR) and with mild DR. Nine quantitative features, including inner and outer retinal thicknesses, photoreceptor inner and outer segment bandwidths, reflectance intensities of the external limiting membrane (ELM), inner segment ellipsoid (ISe), and retinal pigment epithelium (RPE) were measured and intensity ratios of ELM/ISe and RPE/ISe were determined. Comparative parafoveal and perifoveal features (Figure 1a) were analyzed within retinal quadrants, i.e., superior, inferior, temporal, and nasal regions (Figure 1b). The quantitative features were determined using the averaged A-line reflectance intensities (Figure 1c).
Results :
Outer retinal thickness was observed to have significant differences (p<0.05) among the normal controls, no DR, and mild DR groups within the superior and inferior quadrants. Reflectance abnormalities of the ELM and ISe (p<0.05) were observed within the temporal and nasal quadrants. Similarly, reflectance abnormality of the RPE was observed in the parafovea region of the nasal quadrant (p<0.05). Comparative analysis consistently revealed decreased reflectance intensity of the ISe compared to that of the RPE, and the relative intensity ratio ISe/RPE discloses significant differences among the cohorts (p < 0.001) in the parafoveal region of all quadrants.
Conclusions :
Quantitative OCT analysis consistently revealed outer retina changes in diabetic patients with no DR and with mild DR. The abnormalities of outer retinal thickness and OCT reflectance are retinal region/quadrant dependent. The normalized ISe/RPE measurement reveals retinal abnormalities in all quadrants, promising a sensitive biomarker for OCT detection of early DR.
This is a 2021 ARVO Annual Meeting abstract.