ABSTRACT
This form of glaucoma invokes a different mechanism to the more slowlyprogressive glaucomas as its name implies. It usually affects smaller eyes (hyperopic eyes) and occurs due to a crowding phenomenon within the eye, wherein the peripheral iris is forced against the peripheral cornea to deny aqueous humour access to the trabecular meshwork drains. The blockage of the passage of aqueous humour through the pupil is the initiating mechanism, for even a relative block at that site will cause an accumulation of aqueous humour behind the flexible iris diaphragm, pushing it forward to create a vicious cycle of events resulting in an acute rise of pressure in the eye. Symptoms include pain, redness of the eye and rapid loss of vision. The cause of pupil block may be related to an increase in size of the crystalline lens, which is a natural phenomenon (see crystalline lens, page 23). This circumstance classically occurs in small (hyperopic) eyes, for when the pupil dilates naturally in dim-light conditions (or iatrogenically by the instillation of mydriatic, or pupil-dilating, eye drops), then the crowding of the iris into the angle of the anterior chamber can initiate the above cycle of events
Symptoms
Pain, blurred vision, coloured haloes around lights, frontal headaches, nausea and vomiting. The symptoms may occur in isolation or in combined form. Vomiting may cause the unwary physician to suspect an abdominal rather than an eye problem.
