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E. Midena, F. Martini, A. Rediu, M. Casciano, S. Vujosevic; Inner versus Outer Retinal Layers Thickness Changes in Diabetic Retinopathy: Spectral Domain-OCT Automatic Detection. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4670.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate thickness changes of individual inner and outer retinal layers, automatically recorded by spectral domain-OCT (SD-OCT), in diabetes.
Ninty-eight subjects were enrolled: 68 subjects were affected by diabetes mellitus (type 1 or 2) and 30 normals served as controls. Proliferative diabetic retinopathy (DR), previous laser photocoagulation, intraocular surgery or intravitreal injection, and refractive error > 6 diopters were the main exclusion criteria. One eye of each subject was examined. Twenty patients had no diabetic retinopathy (no DR group), 22 patients had non proliferative DR without macular edema (no ME group), and 26 had non proliferative DR with macular edema (ME group). Demographic characteristics were recorded. Full ophthalmic examination, stereoscopic fundus photography, and SD-OCT (RS-3000, Nidek, Japan) were performed in all eyes. After automatic segmentation (layering) of retinal layers by SD-OCT, mean thickness of each layer was calculated in the foveal and pericentral area, and values compared among groups. All measurements were performed twice by two independent graders.
No statistically significant differences were found for age among all groups, and for diabetes duration among diabetics. In no DR and no ME groups, mean thickness of each inner retinal layer (retinal nerve fiber layer, ganglion cell/inner plexiform and inner nuclear layer) was significantly reduced compared to controls (p<.001), both in the fovea and pericentral area. But no significant difference was found for outer retinal layers (outer plexiform, outer nuclear and photoreceptor layers) (p=.10). In DME eyes, the thickness of all retinal layers was significantly increased (p<.001) compared to all other groups. Micro- and macro-cystic spaces contributed to increased thickness, without interference with automatic layering. The inter-grader agreement was at least substantial for all measurement.
Thinning of the neural retina in diabetic patients without clinically detectable retinopathy and with non proliferative retinopathy without ME is confirmed in vivo. Retinal thinning is due to a selective thinning of inner retinal layers in the central retina, strongly suggesting an early neurodegenerative processs in diabetic retinopathy. Automatic intraretinal layering by SD-OCT may be a useful tool to diagnose and monitor early intraretinal changes in diabetic retinopathy.
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