Racial differences in the extracellular matrix of the lamina cribrosa and the peripapillary sclera

Abstract

PurposeTo investigate the major extracellular matrix components (ECM) of the lamina cribrosa (LC) and peripapillary sclera (PPS) in human donor eyes and to determine the differences between Korean and Caucasian eyes.MethodsPosterior segment tissues obtained from nonpathologic, age and axial length‐matched 24 Caucasian and 48 Korean donors were used. Protein and mRNA expression of major ECM components were assessed by quantitative polymerase chain reaction, immunohistochemitry, and light and electron microscopy. Biomechanical analysis was performed by obtaining stress‐strain curves of the PPS and LC.ResultsCollagen and elastin were significantly more abundant in Korean eyes as measured by quantitative polymerase chain reaction and immunohistochemical staining. ECM modulating enzyme, lysyl oxidase like‐2 expression was elevated in the PPS and LC of Korean eyes. The width of PPS around the LC region was larger in Korean eyes compared to Caucasian eyes. Collagen fibers had a greater preferred directionality and smaller fibril diameter in the PPS region in Korean eyes observed by electron microscopy. The mechanical properties of the LC and PPS produced greater strain in Korean eyes measured by strain‐stress relationship. Increased strain was more pronounced in the PPS region in Korean eyes.ConclusionsThe LC and PPS are more easily deformed by similar pressures in Korean eyes compared to Caucasian eyes. Racial differences in the ECM composition and microscopic architecture may contribute to the greater deformation of the LC and PPS and this could contribute to the susceptibility for glaucoma under normal intraocular pressure range in Korean eyes.