Glaucoma is one of the leading causes of blindness in the world. It is a silent disease and can damage vision gradually with no warning signs, until permanent damage has already occurred.

Normally, the amount of fluid produced inside the eyeball is the same as the amount of fluid draining out into the bloodstream. But, if the fluid cannot escape, or if too much is produced, the pressure inside the eye will rise.

There are two main types of glaucoma. Signs of open-angle glaucoma (late stage) include gradual loss of peripheral (sideways) vision. In angle-closure glaucoma (usually occurring as an emergency situation and treated as such) signs include blurred vision, reddening of the eye, pain in the eye or eyebrow, and seeing coloured rainbow effects around lights. The likelihood of having (open angle) glaucoma increases when we become 40, have a close relative with glaucoma. are short-sighted and are of African origin. We cannot prevent glaucoma from happening, and damage to the eye by glaucoma cannot be reversed. However, early diagnosis and careful treatment can stop it in its tracks or slow it down.

Treating glaucoma

Glaucoma treatments reduce the pressure inside the eye by improving the outflow of fluid, and/or by reducing the production of fluid. This prevents further damage to the eye.

Treatment usually begins with medicated eye drops, included in the following groups:

Beta blockers such as betaxolol (Betoptic), levobunolol (Betagan) and Timolol (Timoptic). People with asthma, breathing and heart problems should use these treatments with caution as they may trigger their illnesses.

Alpha agonists, like Cannabis sativa derivatives (Canasol - a product unique to Jamaica, and prepared from ganja), and brimonidine (Alphagan) are examples.

Carbonic anhydrase inhibitors like dorzolamide (Trusopt) and brinzolamide (Azopt). A tablet form exists as acetazolamide (Diamox), but it has greater side effects than the drops.

Prostaglandins like latanoprost (Xalatan), bimatoprost (Lumigan) and travoprost (Travatan). These are hormone-like substances which keep blood vessels widened so that more fluid can flow through them. Side effects include mild reddening or stinging of the eye, darkening and lengthening or eye-lashes and/or darkening of the eye colour.

Mitotics like pilocarpine which have side effects of pain around or inside the eye, brow ache and blurred vision.

Sympatho-mimetics like dipivefrine (Propine).

If we are using more then one eye drop in one sitting, we should allow at least five minutes between applying each.

Glaucoma surgery may be done nowadays right here in Jamaica, if medications cannot be tolerated or if they are not effective. It is usually an office procedure lasting no more than 30 minutes.

Dahlia McDaniel is a pharmacist and final year doctoral candidate in public health at the University of London; email: yourhealth@gleanerjm.com.