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H. Sheng, E. Parker, M.A. Bullimore; Factors Affecting Corneal Endothelial Morphology . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2362.
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Corneal endothelial morphology is influenced by age and long term contact lens wear. The effect of refractive error, particularly high myopia has not been established. People with higher myopia are more likely to wear contact lenses and for longer, so age, contact lens wear, and degree of myopia may act independently or interact to change corneal endothelial morphology. We investigated the effects of age, race, years of contact lens wear, and degree of myopia on three key aspects of corneal endothelial morphology: endothelial cell density (ECD), polymegathism, expressed as the coefficient of variation (CoV), and pleomorphism, expressed as the proportion of hexagonal cells (%Hex).
A total of 149 subjects with a broad variation in age (19 to 71 years, mean = 33.2 years), refractive error (39.6% had myopia over –5.00 D), and contact lens history (13.4% had worn lenses for >20 years) were examined. The majority of subjects were white, but one third were Asian. The Konan NonCon Robo 9000 specular microscope was used to capture corneal endothelial images from one eye of each subject. The images were analyzed with the KSS–300 center method. Multiple regression analysis was used to build models of endothelial cell density, polymegathism, and pleomorphism as a function of age, race, refractive error (Rx), and contact lens wear (CLyears).
Age and race significantly affected endothelial cell density, but refractive error or years of contact lens wear did not (model: ECD = 3274 – 12.7*Age + [164 if Asian]). Years of contact lens wear, age, and their interaction significantly affected polymegathism (model: CoV = 24.3 + 0.72*CLyears + 0.18*Age – 0.011*interaction), but refractive error did not. Years of contact lens wear, age, and refractive error all significantly affected pleomorphism, independently (model: %Hex = 70 – 0.29*CLyears – 0.21*Age + 0.4*Rx).
The three key aspects of corneal endothelial morphology are not influenced by the same factors. Endothelial cell density is significantly affected by age and race. In contrast, polymegathism and pleomorphism are affected by age, years of contact lens wear and, in the case of pleomorphism, the degree of myopia. Therefore, in studying of the influence of drugs, intraocular devices, or disease on the corneal endothelium, polymegathism and pleomorphism might be more sensitive than cell density. This is the first study to find that degree of myopia correlates with corneal endothelial shape changes. The underlying mechanism needs further investigation.
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