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Subtle changes in diabetic retinas localised in 3D using OCT
Author(s) -
Arthur Edmund,
Papay Joel A.,
Haggerty Bryan P.,
Clark Christopher A.,
Elsner Ann E.
Publication year - 2018
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12578
Subject(s) - foveal avascular zone , diabetic retinopathy , retinal , ophthalmology , medicine , retina , outer nuclear layer , optical coherence tomography , foveal , optometry , optical coherence tomography angiography , physics , optics , diabetes mellitus , endocrinology
Abstract Purpose To detect and localise subtle changes in retinas of diabetic patients who clinically have no diabetic retinopathy ( DR ) or non‐proliferative DR ( NPDR ) as compared to age‐ and sex‐ matched controls. Spectral Domain Optical Coherence Tomography ( SD ‐ OCT ) and software to examine all retinal layers, including deeper layers, were used to quantify foveal avascular zone size and inner and outer retinal layer thicknesses, as well as to detect axial location of prominent lesions. Methods Diabetic subjects, 19 total with 16 having no DR and three having non‐proliferative retinopathy, were matched with 19 controls with respect to age and sex. Macular‐centred SD ‐ OCT grids of 20 × 15° were taken with the Spectralis. En face or transverse images were generated from the SD ‐ OCT data by automatically segmenting all retinal layers. The transverse images were investigated for foveal avascular zone ( FAZ ) size, retinal vessel calibre, and structural changes. The size of the FAZ was compared for diabetics vs controls using vendor software and manual marking in Photoshop. Inner retinal layer ( IRL FAZ ) and outer nuclear layer ( ONL FAZ ) thicknesses at the margins of the FAZ were measured using vendor software. Results The FAZ area was larger for diabetics (mean ± S.D. = 0.388 ± 0.074 mm 2 ) than controls (0.243 ± 0.113 mm 2 ), t 18 = 5.27, p < 0.0001, using vendor software. The mean IRL FAZ was thicker for the diabetics (86.8 ± 14.5 μm) than controls (65.2 ± 16.3 μm), t 18 = 4.59, p = 0.00023, despite lack of exudation by clinical exam. There was no significant association between FAZ area and mean IRL FAZ for the diabetics, r = 0.099, p = 0.69. Vessels not clinically detected were visible in the NFL transverse image of most diabetics, especially for a mild NPDR patient. A prominent lesion found in the en face infra‐red image of a mild NPDR subject was localised in the photoreceptor layer by SD ‐ OCT , as well as additional outer retinal changes in other subjects. Conclusions Our results demonstrate changes in inner and outer diabetic retinas not readily detectable by clinical exam. IRL FAZ had not thinned at the margins of the large FAZ s, indicating neural mass did not yet decrease despite potential ischemia.