Glaucoma

Glaucoma involves increased intraocular pressure, which damages the optic nerve and causes partial visual loss and is the third most common cause of blindness in the West. It is characterised by increased pressure within the eyeball when aqueous humour does not drain properly, reducing the blood supply to the optic nerve, firstly affecting peripheral then central vision. Open angle (chronic) glaucoma is by far the most common type: fluid outlet channels within the wall of the eye gradually narrow over a period of years bilaterally, with consistently elevated pressure slowly damaging the optic nerve. The associated loss of peripheral vision occurs so gradually that it may go unnoticed until a substantial amount of damage and visual loss has occurred. Routine eye examination is the only way for early diagnosis. Closed angle (acute) glaucoma occurs in those with a congenitally narrow angle between the iris and the cornea – the iris may slip forward and suddenly close off the exit of aqueous humour, and a sudden increase in pressure within the eye follows – symptoms of pain, redness, nausea, and vision loss develop rapidly. Secondary glaucoma is caused by eye diseases such as uveitis, systemic diseases, and drugs such as corticosteroids.