Mechanics of pupil block.

Abstract

PUPIL block is widely regarded as one ofthe factors in the initiation of closed-angle glaucoma (Barkan 1953, 1954; Chandler 1952, 1955). Whilst the occurrence of pupil block is an established fact, statements as to its mechanism are uniformly vague; e.g. both Barkan and Chandler consider it to be produced by contact between the iris and lens, Sugar (1964) states that the posteriorly directed vector of force exerted by the iris sphincter is responsible, and Lowe (1966) gives an explanation of pupil block (caused by mydriatics) that depends on an incorrect resolution of forces. The mechanics of pupil block are explained below in accordance with clinical observation.