Stereoscopic and photogrammetric study of the disc cup in open-angle glaucoma reveals several morphological changes. The ovalisation of the cup, upwards, downwards or on the temporal side, appears early. It can be detected at the onset of the disease, even in the absence of visual field defects. It results in a localised thinning of the nervous rim, which is a characteristic sign of beginning glaucoma, but the depth of the cup is not increased even when perimetry already reveals important defects. The aim of this paper is to study, on the one hand, the morphological changes of the disc cup and on the other, the functional defects in open-angle glaucoma, and then to compare the results of the investigations.
The depth of the anterior chamber is measured with a coincidence ocular placed on the Haag-Streit slit lamp. The accuracy of the method is approximately 0.l ram. The thickness of the lens, its position in the eye, and the length of the globe are measured by ultrasonic echography. The depth of the anterior chamber depends on the biometric characteristics of the cornea and of the lens. The height of the corneal apex depends on the diameter and on the curvature radius of the cornea. The role of the lens is determined by its thickness and its position. In 2,395 normal eyes the depth of the anterior chamber is influenced by age, sex and refraction. Its depth is 2.5 ram. at birth, it reaches 3.25 mm. at the end of the growth and decreases to values smaller than 2.65 ram. after the age of 60. This evolution depends on two factors which act in opposite directions: longitudinal growth of the eye increases the depth of the anterior chamber. This growth terminates at the age of 20. Increase of the lens thickness decreases the depth of the anterior chamber; this increase continues until deat]h. The depth of the anterior chamber is increased in axial myopia and decreased in hypermetropia. Different pathological factors increase the depth of the anterior chamber.The increase of the ocular volume in high myopia is mostly retroequatorial and does not increase in the same proportion as the depth of the anterior Adresse des auteurs: Clinique ophtalmologique de l'universit6 de Liege, H6pital de Bavi~re, 4000 Liege, Belgique.
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