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C.M. C. Klais, M.D. Ober, L.V. Del Priore; STRUCTURAL COMPARISON OF WRINKLING IN EPIRETINAL MEMBRANES AND CHOROIDAL FOLDS: A MORPHOMETRIC ANALYSIS . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1988.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Epiretinal membranes and choroidal folds are examples of sheer–induced wrinkling of biological tissue under tangential stress. In principle, wrinkling of such thin elastic sheets is governed by physical principles that reflect the properties of the underlying biological tissue. Herein we measure the wrinkling patterns induced in the neural retina and underlying choroid by epiretinal membranes and choroidal folds respectively and demonstrate that the wrinkling patterns reflect the physical properties of the underlying tissue. Methods:32 eyes with epiretinal membranes (group A age < 55 years; 38.4 + 9.8 years, range = 16 to 54 years; group B ≥ 55; 67.7 + 5.3 years, range = 61 to 81 years) and 8 eyes with choroidal folds were included. We determined the average peak–to–peak distance between adjacent folds and its regular periodicity from red–free photographs analyzed with IMAGEnet and Adobe Photoshop software. Results: The average peak–to–peak spacing was significantly larger for choroidal folds versus retinal folds caused by epiretinal membranes (278.2 + 62.2 vs. 81.9 + 12.2 microns; respectively; p = 0.0001) and there was very little variation in this parameter within each group (standard deviation < 8.6 %). The average fold–to–fold distance was independent of the distance of the epicenter of the epiretinal membrane from the fovea. There was no difference in the peak–to–peak spacing between patients within group A versus B (80.1 + 6.9 vs. 80.9 + 3.8 microns; respectively; p = 0.69), and there was no statistically significant correlation with patient age (p=0.25). The peak–to–peak spacing was independent of the cause of the epiretinal membrane. Conclusions: Both epiretinal membranes and choroidal folds represent wrinkling of the underlying tissue which occurs with striking regularity (spacing variation < 8.6%) and periodicity. There is a significant difference in the periodicity of retinal versus choroidal wrinkling, which reflects differences in the elasticity of the underlying tissue. Interestingly the elasticity of the retina does not change over the age range tested, although the age range of patients with choroidal folds was too narrow to allow conclusions to be drawn about the age–related changes in mechanical properties of this tissue.
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