Glaucoma is a condition which can affect sight, usually due to build-up of pressure within the eye
- Glaucoma often affects both eyes, usually to varying degrees.
- One eye may develop glaucoma quicker than the other.
- The eyeball contains a fluid called aqueous humour which is constantly produced by the eye, with any excess drained though tubes.
- Glaucoma develops when the fluid cannot drain properly and pressure builds up, known as the intraocular pressure.
- This can damage the optic nerve (which connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).
Types of glaucoma
There are four main types of glaucoma
Primary Open Angle Glaucoma
This is the most common form of glaucoma and usually progresses slowly if not treated. Open angle glaucoma is often associated with increased pressure within the eye, but also may occur when the pressure is normal. Over time, open angle glaucoma slowly damages the field of vision, usually starting in the periphery and moving inwards. Occasionally, visual field loss may start in the centre of the vision. Visual field damage from glaucoma is irreversible. Treatment, which may consist of medicine, laser or surgery, is designed to lower the pressure within the eye in order to prevent further damage to the optic nerve and loss of vision.
Primary Angle-closure Glaucoma
Primary angle-closure is the most common form of glaucoma in Asia but may occur in any ethnic group. The typical acute form results in sudden very high pressure within the eye requiring laser iridotomy (a small laser hole in the iris to relieve the blockage) or lens extraction (cataract surgery).
Common secondary glaucomas such as pigmentary glaucoma and exfoliative glaucoma (pseudoexfoliation) are common but often result in higher eye pressures that are more resistant to medical treatment than primary open angle glaucoma.
Some secondary glaucomas result in very high pressures within the eye, often requiring surgery to prevent visual loss. These include uveitis (inflammation of the middle layer of the eye), diabetes, trauma or after surgery for other eye diseases such as corneal transplantation or retinal detachment surgery.
Developmental (Congenital) Glaucomas
These types of glaucoma are usually diagnosed within the first year of life, are blinding if not treated promptly, and are common in communities where consanguinity (marriage between close family members) is common.