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Glaucoma
Glaucoma is caused by an increase in the pressure of the fluid inside the eye. The part of the eyeball in front of the lens is divided by the iris into 2 - the Anterior and Posterior chambers, which communicate with each other through the pupil. The Aqueous humour is made by cells behind the iris. Usually it flows through the pupil and drains through channels in the angle between the front of the iris and the cornea.In ACUTE, CLOSED-ANGLE GLAUCOMA the channels suddenly become blocked. This happens in people who have a shallow anterior chamber when the pupil dilates. There is severe pain and sudden loss of vision. There may be nausea and vomiting. The eye is red and hard, the cornea swollen and the pupil fixed. There may have been warning signs such as coloured haloes seen round streetlights at night (because at night the pupil dilates). It is a medical emergency if the sight in that eye is to be saved. The other eye may also be at risk. CHRONIC GLAUCOMA occurs where there is a gradual increase in resistance in the drainage channels. The pressure builds up slowly and damages the retinal cells and optic nerve, producing defects in the visual fields, which may be severe by the time they present. It is a common cause of blindness. Surgery may be needed to reduce the pressure and preserve the residual sight. GLAUCOMA is a familial disease. Those with a family history of glaucoma should have their eye pressures checked every year. |
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