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Edmund Arthur, Joel A Papay, Bryan P Haggerty, Christopher Anderson Clark, Ann E Elsner; Subtle changes in diabetic retinas localized in 3D using OCT. Invest. Ophthalmol. Vis. Sci. 2017;58(8):98.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetic patients who clinically have no diabetic retinopathy (DR) or mild non proliferative DR (NPDR) nevertheless have extensive retinal vascular changes. We used Spectral Domain Optical Coherence Tomography (SD-OCT) to detect and localize in three dimensions, subtle changes in retinas of diabetic patients who clinically have no DR or mild NPDR as compared to age- and gender- matched controls.
17 diabetic subjects with 16 clinically diagnosed as having no DR and 1 having mild NPDR were matched with 17 controls with respect to age (56.9 ± 9.72 and 56.6 ± 10.4 yr) and gender. Macular-centered 20×15 degree SD-OCT grids were analyzed using en face or transverse software (Spectralis, Heidelberg), and also using automatic segmentation to obtain thicknesses of retinal layers. A custom algorithm (Matlab, Mathworks) reduced unwanted noise. The transverse images at the level of the nerve fiber layer (NFL) were quantified for the foveal avascular zone (FAZ). The size of the FAZ was compared for diabetics vs. controls using two methods: custom Spectralis software that also provided focal retinal thickness measurements at the FAZ margins and manual delineation from transverse images (Photoshop). We measured the inner retinal layer (IRL) thickness from the boundary of the inner limiting membrane to the outer plexiform layer (OPL), and the outer nuclear layer (ONL) thickness from the boundary of the OPL/ONL to the external limiting membrane. Paired t tests were used to compare the area of FAZ, IRL and ONL thicknesses of diabetics vs. controls.
The FAZ was significantly larger for diabetics (0.385 ± 0.0768 mm2) than controls (0.246 ± 0.119 mm2) using the Spectralis software, agreeing with the manual delineation, t(16) = 4.75, p<0.0001 and t(16) = 4.7, p<0.0001 respectively. This was true even when the diabetic subject with mild NPDR and age-matched control were excluded, t(15) = 4.6, p <0.0001. The IRL measured at the edges of the FAZ was significantly thicker in the diabetics (87.2 ± 15.3 microns) than in controls (68.1 ± 14.3 microns), p = 0.001. The ONL did not differ, 97.8 vs 102 microns for diabetics vs controls respectively, p = 0.45.
Our results suggest that early in the course of retinal changes with diabetes, there is retinal vascular remodeling at the FAZ. In our subjects, the IRL had not thinned to decrease the neural mass at the margins of the larger FAZs.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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