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S. M. Tick, B. ElMathari, C. Bachelin, J.-F. Girmens, J.-A. Sahel, M. Paques; Clinical and Experimental Neuroglial Remodelling Following Resolution of Post-Retinal Vein Occlusion Macular Edema. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2694. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Resolution of macular edema, either spontaneously or following specific treatment, may leave to a permanent visual loss despite the presence of a normal macular profile. The aim of this study is to analyze by high resolution optical coherence tomography (OCT) the retinal structure of the macula of patients having recovered from post-retinal vein occlusion (RVO) macular edema and to compare it to histology of experimental RVO in rats.
In 12 patients (mean age 53 years) with RVO having recovered from macular edema (duration 0.5-6 months), OCT cross-scan averaged images were acquired (3D-OCT, Topcon® Corp, Tokyo, Japan) in both eyes. All had a central foveal thickness between 160 and 200 microns and a normal macular profile. The aspect of retinal layering was analyzed and compared to that of fellow eyes, and to immunohistochemical data from experimental laser-induced branch RVO in rats.
In cases with normal visual function, disorganization of the layers presumably corresponding to the outer plexiform layer (OPL)could be detected. With increasing severity of functional deficit, aditional retinal damage was evidenced by disruption of the outer segments (OS) reflectance which preceded their disapearance. Loss of central vision occurred only in cases with disruption of the OS reflectance, and was strongly correlated to its extent. In 2 eyes having recovered from central RVO with perivenular whitening, a presentation associated to acute and transient hypoperfusion, thinning of the inner retina was present in the temporomacular area, together with disorganization of the OPL. None had pigment alteration and 488 nm autofluorescence was normal in all cases, suggesting limited or no alteration of the retinal pigment epithelium. Similar lesions could be reproduced in rats after transient RVO, showing by order of increasing severity: disorganization of the OPL with retraction of presynaptic elements and loss of horizontal cells, shortening and disappearance of OS, thinning of the outer nuclear layer, and global retinal thinning.
Post-RVO macular edema induces neuroglial remodeling primarily affecting the OPL. Functional alteration was strongly correlated to photoreceptor OS loss. Deafferentation may participate to photoreceptor cell death during macular edema due to RVO.
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