What is glaucoma?
Glaucoma refers to a group of eye conditions that lead to damage of the optic nerve, the nerve that carries visual information from the eye to the brain. It causes irreversible but potentially preventable vision loss. It is often, but not always, associated with increased pressure of the fluid in the eye (aqueous humour). The term 'ocular hypertension' is used for cases having constantly raised intraocular pressure (IOP) without any associated optic nerve damage.
Glaucoma can be divided roughly into two main categories, "open angle" and "closed angle" glaucoma. Closed angle glaucoma can appear suddenly and is often painful; visual loss can progress quickly, but the discomfort often leads patients to seek medical attention before permanent damage occurs. Open angle, chronic glaucoma tends to progress at a slower rate and patients may not notice they have lost vision until the disease has progressed significantly.
What are the symptoms of glaucoma?
Most patients with open-angle glaucoma have no symptoms until they begin to lose vision. Vision loss is gradual and peripheral (also called tunnel vision).
In angle-closure glaucoma symptoms may come and go at first, or steadily become worse. Symptoms include sudden severe pain in one eye, decreased or cloudy vision, nausea, vomiting, rainbow like halos around light and red eye. Acute angle closure is an ocular emergency.
Who is at risk of glaucoma?
Glaucoma can aﬀect anybody from infants to adults. However the following are the conditions which put people at a higher risk:
- People over the age of 45
- People who have a family history of glaucoma
- People with abnormally high intraocular pressure (IOP)
- People of African descent
- People who have: Diabetes, Myopia (nearsightedness), long-term steroid use or a previous eye injury
How can you prevent progression of glaucoma?
There is no way to prevent open-angle glaucoma, but you can prevent vision loss from the condition. Early diagnosis and careful management are the keys to preventing vision loss. As most people with open-angle glaucoma have no symptoms, everyone over age 40 should have an eye examination at least once every 5 years, and more often if in a high-risk group.
People at high risk for acute glaucoma may opt to undergo preventive surgery before having an attack. Patients who have had an acute episode in the past may have the procedure to prevent a recurrence.
What is the treatment of glaucoma?
The main goal of glaucoma treatment is to reduce the intraocular pressure [IOP]. Each of these diagnoses, a 3 mmHg reduction in IOP roughly corresponds to a 50% reduction in the risk of the development or progression of glaucoma. Depending on the type of glaucoma, this is done either with the use of medications or surgery.
In order to decrease intraocular pressure, most glaucoma drug treatments alter either the rate of aqueous humor production (eg. beta blockers, carbonic anhydrase inhibitors) or the outflow pathway (eg. prostaglandin analogues).
Both laser and conventional surgeries are performed to treat glaucoma. However, these operations are a temporary solution, as there is not yet a cure for glaucoma.