The shift of Schlemm's canal during the remodelling of the chamber angle in the developing rat eye

Abstract

A morphometric analysis of the pre- and postnatal development of the tissue components of the chamber angle was performed in the rat. One eye of each of five weight-matched littermates was evaluated by light microscopy at the following time points: prenatal days 18, 21; day 0 (= day of birth); postnatal days 5, 10, 15, 20, 40, 60. Composite photomicrographs of the entire chamber angle area at a magnification of 5776 × were prepared from each eye under investigation. Developmental stages were analysed by direct measurements between selected anatomical reference points and by computerised calculations that were obtained from geometrical constructions on the photomicrographs. A statistical analysis was performed on the correlation of measurements and calculations with the entire investigated time period. This way, a modification of the allometric growth analysis was developed. Our data indicate that Schlemm's canal undergoes a distinct forward shift from a position next to the peripheral retina towards the chamber angle recess. This forward shift is paralleled by a considerable growth of the ciliary body. In contrast, an arrest of growth of tissues between the end of Descemet's membrane and the anterior end of Schlemm's canal is observed. Thus, with the anterior chamber angle components remaining constant and the posterior ones growing in the meridional diameter, a forward and internal shift of Schlemm's canal results.