Collagen Fibril Diameter and Cross-Band Interval of Myopic Eye Sclera

Abstract

Morphometrical tests of the sclera of six normal and nine myopic eyes were carried out using electron microscopy. The average collagen fibril cross-band interval was 64 nm, but the range for the myopic eyes was larger (60–70 mn) than that for normal eyes (62–67 nm). With myopia the interval length in the direction of the posterior sclera (PS) increases. The range of fibril interval variation in the myopic PS is notably larger (63.0–70.0 nm) than that in the normal sclera (63.0–66.5 nm). There is a wide range of variation of fibril diameter in the anterior sclera (AS) of the myopic eye but in the PS the range is narrower than that in normal sclera. There are notably more thin fibrils in the myopic PS than in the normal PS, but very thick-less. For middle-stage myopia thin fibrils comprise about 60%, with medium thick fibrils accounting for the rest (about 40%). There are no fibrils thicker than 120 nm in the PS, but the AS fibrils of this size comprise up to 40%. With high myopia the fibril diameter decrease in the PS is more pronounced than in those with low or middle-stage myopia. The mechanical stability of the sclera depends largely on the collagen fibril cross-band interval and diameter.