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G. Somfai, E. Tatrai, Má. Ferencz, C. A. Puliafito, D. Cabrera; Quantifying Retinal Layer Thickness Changes in Eyes With Diabetic Diffuse Macular Edema Using Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1426.
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© ARVO (1962-2015); The Authors (2016-present)
To assess which retinal sublayers show thickness changes in diffuse diabetic macular edema (dDME).
Six eyes from patients with background diabetic retinopathy and diffuse macular thickening as seen on Optical Coherence Tomography (OCT) images along with six control eyes were enrolled in our study (median age (interquartile range): 51 (35-67) years and 41.5 (38-44) years, respectively). Standard OCT scanning using the six radial lines protocol was performed in the macular area of all subjects. The OCT raw data were exported and analyzed using an automated computer algorithm of our own design capable of segmenting the various cellular layers of the retina. Then, thickness and volume analysis was performed for the automatically extracted retinal layers (retinal nerve fiber layer (RNFL), ganglion cell layer and inner plexiform layer (GCL+IPL), inner nuclear layer (INL), outer plexiform layer (OPL) and outer nuclear layer (ONL)). The results were analyzed using Mann-Whitney U test. For all analyses p≤0.05 was considered to be statistically significant.
A significant thinning of the NFL (28.94 ± 3.91 vs. 43.24 ± 4.15 µm, p=0.002) and thickening of the GCL+IPL and ONL was found in dDME eyes (73.14 ± 6.16 vs. 62.41 ± 3.60 µm and 98.22 ± 9.96 vs. 85,39 ± 3.21 µm, respectively, p=0.026 in both cases). Overall volume was significantly higher only in the ONL of dDME eyes (2.57 ± 0.33 ± 0.13 vs. 2.14 mm3, p=0.015).
Retinal layer thickness changes between patients with dDME and normals can be detected by segmenting the subretinal layers on images obtained by the current commercial OCT system. We demonstrated that the NFL, GCL+IPL and the ONL layers may be affected in diffuse diabetic macular edema. Significant thickening both in overall thickness and volume per layer was found only in the ONL layer. Our results support the view that there may be a neuronal loss in NFL in eyes with diabetes, while the GCL+IPL and mostly the ONL layers may be responsible for retinal thickness increase in diffuse edema. We believe that the methodology presented could permit both a better detection and follow-up of layer injury as well as understanding of diabetic retinal changes, and also contribute to the advancement of the early detection and diagnosis of diabetic retinopathy when using OCT measurements. However, a further study is needed with a larger sample size to validate our results.
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