Pathological Findings in a Case of Primary Congenital Glaucoma Compared with Normal Infant Eyes.

EARLIER studies have illustrated the gross changes which take place in the configuration of the anterior chamber with increasing age (Allen, Burian, and Braley, 1955; Maumenee, 1958; Sondermann, 1930), resulting in a marked deepening of the angle. At term the whole of the trabecular meshwork, scleral spur, and a variable portion of ciliary body lie exposed in the anterior chamber. Coincidental with the deepening of the angle, the canal of Schlemm forms from the vascular plexus in the region of the scleral spur. Interposed between the canal of Schlemm and the anterior chamber lies the trabecular meshwork, which in early foetal life consists of a solid mass of cells and fibres. By birth the meshwork appears laminated and, although it is presumed that communications exist between adjacent lamellae, these cannot be visualized in routine paraffin sections. Since paraffin sections exclusively have been employed in the past to study the angle of infant eyes, virtually nothing is known about the finer drainage channels within the meshwork. By using the microscope to examine flat preparations of the meshwork, one performs in effect a refined gonioscopy, and this makes possible a more detailed visualization of the intertrabecular spaces which are essential for the normal circulation of aqueous. A comparison of the findings in congenital glaucoma with normal eyes suggests that a defect in the development of these spaces may be responsible for obstruction to aqueous outflow. The Table (opposite) records clinical data concerning the cases used in this study. It is important to remember that the eyes which were used to establish criteria for normality were not obtained from healthy individuals. Although the eyes did not receive a detailed clinical examination, only those which were removed from a baby with a congenital corneal epithelial dystrophy were thought to be abnormal. The child with congenital glaucoma died 2 hours after a bilateral goniotomy and the eyes were fixed in osmic acid which made possible an electron microscopic examination. Conventional methods of study with meridional paraffin sections have been used to record the gross configuration of the angle. In order to visualize channels running through the meshwork, thin flat teased preparations were removed at different levels with jeweller's forceps. This technique avoids the artefacts of shrinkage and distortion associated with paraffin sectioning, but introduces artefacts of its own due to tissue disruption. It is important to examine preparations that are not too thin in order that normal tissue relationships are preserved.