Abstract
Purpose: :
To evaluate if retinal glial cells activation may be detected in vivo in eyes without and with nonproliferative diabetic retinopathy.
Methods: :
Eighty-eight subjects were enrolled: 58 subjects were affected by diabetes mellitus and 30 normals served as controls. Proliferative diabetic retinopathy, previous laser photocoagulation, intraocular surgery or intravitreal injection, and refractive error > 6 diopters were the main exclusion criteria. One eye of each subject was used for statistical analysis. Thirty patients had no diabetic retinopathy (no DR group) , 28 patients had non proliferative DR without macular edema (DR group). Full ophthalmic examination, stereoscopic fundus photography, and spectral domain-OCT (SD-OCT; RS-3000, Nidek, Japan) were performed in all eyes. After automatic segmentation (layering) of 5 retinal layers by SD-OCT, the thickness of these layers was automatically calculated in the foveal and pericentral area, and values compared among groups. The thickness of selected, more specific layers (inner limiting membrane, inner plexiform and nuclear layers, outer plexiform layer) was also manually quantified. All measurements were performed twice by two independent graders.
Results: :
No statistically significant differences were found for age among all groups, and for diabetes duration among diabetics. In the no DR and DR groups, using automatic layering, the mean thickness of inner retina was significantly reduced compared to controls (p<.001), no change was detected in the outer retina, both in the fovea and pericentral area. A significant increase of inner limiting membrane, inner plexiform and nuclear layers was found in DR eyes vs controls (p<0.001), versus a significant decrease of retinal ganglion cell and retinal nerve fiber layers. The inter-grader agreement was at least substantial for all measurement.
Conclusions: :
Increased thickness of retinal layers mainly corresponding to retinal glial cells , even before the appearance of clinically detectable retinopathy, confirms in vivo early glial cells activation in diabetic retina.Glial activation may be detected by spectral domain OCT using targetted analysis. These data strongly suggests a very early reactive and degenerative processs both in neural and glial cells of diabetic retina .
Keywords: diabetic retinopathy • Muller cells • glia