Glaucoma is the second leading cause of blindness in the world and the leading cause of irreversible blindness. It is a result of an increase in the pressure of the eye (intraocular pressure) which causes progressive damage to the optic nerve. The optic nerve is responsible for carrying visual impulses to the brain and its damage results in loss of vision. In most cases the condition progresses slowly and insidiously, and the patient is not often aware of the condition until a late stage. By the time the patient notices a deterioration of vision, there is often already moderate to severe damage to the nerve. This is why this disease has been called the “silent thief of sight”.
Different Types of Glaucoma
Most glaucomas present as a slowly progressive disease, with the common forms being Primary Open-Angle Glaucoma and Chronic Angle-Closure Glaucoma. These usually affect the middle-aged or elderly people. Glaucoma may be inherited, which means that relatives of people with glaucoma have a higher risk.
Primary Open-Angle Glaucoma
This is the commonest type of glaucoma in most countries. The glaucoma progresses slowly and in the initial stage has no obvious symptoms.
Chronic Angle-Closure Glaucoma
Angle-closure glaucoma occurs commonly among Asians. Singapore has the highest reported incidence of angle-closure glaucoma in the world. In the chronic form, similar to Primary Open-Angle Glaucoma, this type of glaucoma progresses gradually, and often goes unnoticed for a long time. It results from progressive blockage of the drainage channels of the eyeball, resulting in a prolonged rise in eye pressure.
Acute Angle Closure Glaucoma
This type of glaucoma usually affects women in the middle or elderly ages. It develops because of a blockage of the fluid drainage pathway located in the angle of the eye, resulting in a rapid rise in the fluid pressure within the eye. The symptoms are sudden and dramatic requiring patients to seek medical attention urgently.
Glaucoma may arise when there is inflammation of the eyeball or when a cataract becomes too advanced and swollen. Other causes are eye surgery and injury to the eye.
Symptoms of Glaucoma
Patients with Primary Open-Angle Glaucoma and Chronic Angle-Closure Glaucoma often do not have any symptoms in the early stage, because the peripheral vision is affected first and the disease is slowly progressive. Most patients do not realise they have glaucoma until it is more severe when the central vision starts being affected. By which time, there may already be significant irreversible nerve damage.
Acute angle-closure glaucoma presents with sudden severe eye pain, redness, blurring of vision and haloes around lights. This is an eye emergency and the patient should be seek medical consultation immediately.
Diagnosis and Treatment
Early detection and treatment of glaucoma is the key to preventing further nerve damage and visual loss. The patient should see an eye specialist who will be able to detect if the patient has glaucoma. The assessment for glaucoma involves measuring the intraocular pressure, examining the optic nerve head and carrying out a visual field examination, which is a sensitive test for nerve function.
There is no cure for glaucoma but in most cases it can be successfully controlled with medical or surgical treatment. Newer and safer medication can more effectively treat glaucoma, meaning that fewer patients need to undergo surgery.
Laser treatment can help certain forms of glaucoma, particularly angle-closure glaucoma. In this case, a small opening in the coloured part of the eye (iris) is made using lasers to create a bypass channel for fluid to exit. When medication alone cannot control the glaucoma, surgical treatment in the form of a filtering operation (trabeculectomy) may be required.
The adequacy of glaucoma control can only be determined by your eye doctor, and regular follow-up is essential in ensuring that the glaucoma control is optimal.