Glaucoma can cause permanent blindness if left untreated

Glaucoma is a common progressive eye disease caused by damage to the optic nerve that connects the eye to the brain. Left untreated, glaucoma can lead to complete loss of sight. 

Anyone can have glaucoma at any age but it is commonest in older adults. It is one of the leading causes of blindness in people over the age of 60.

Causes

There are several types of glaucoma. Open-angle glaucoma is the commonest. It is caused by damage to the filter in the eye’s drainage canals.

Angle-closure glaucoma is caused by a rapid blockage of the eye’s drainage canals due to a closed or narrow angle between the iris and cornea where the filter is located.

Low-tension or normal-tension glaucoma is a type in which damage occurs to the optic nerve without the eye pressure exceeding its normal range.

• Glaucoma the thief of sight

Congenital glaucoma occurs in infants when there are incorrect or underdeveloped drainage canals in the eye during the prenatal period.

Inflammatory or uveitic glaucoma is caused by autoimmune and inflammatory disorders.

Neovascular glaucoma is a type of glaucoma associated with poorly controlled diabetes and other conditions that damage the blood vessels in the body.

Risk factors

Anyone can develop glaucoma. However, some people are at higher risk than others. Risk factors for glaucoma include your race. Glaucoma is the leading cause of blindness for people of African descent.

People aged 60 and older are more at risk of developing glaucoma than those who are younger. People with a family history of glaucoma have a higher risk of developing glaucoma, especially if a sibling has the condition.

Those with high fluid pressure inside the eyes or a thinner than normal cornea have an increased risk as well.

Symptoms

Most people with glaucoma do not notice symptoms until they begin to lose their eyesight. As glaucoma damages optic nerve fibres, small blind spots may begin to develop. These spots usually occur on the side or within the eye’s peripheral vision.

Many people do not notice the blind spots until significant optic nerve damage has already occurred. Blindness can result when the entire nerve is destroyed.

The symptoms of glaucoma also depend on the type and stage of your condition. There are no symptoms in the early stages of open-angle glaucoma. Gradually you start having patchy blind spots in your side or peripheral vision. In later stages, you will have difficulty seeing things in your central vision.

Acute angle-closure glaucoma, a type of open-angle glaucoma, has symptoms that include severe headache, severe eye pain, nausea or vomiting, blurred vision, halos or coloured rings around lights and eye redness.

Normal-tension glaucoma has no symptoms in its early stages. Gradually you experience blurred vision.

In later stages, you lose your side vision.

Symptoms of glaucoma in children include a dull or cloudy eye and tears without crying. This is more common in infants. Other symptoms include blurred vision, near-sightedness that gets worse and headaches.

Diagnosis

Your eye health care provider may ask you for your complete medical history before examining your eyes. There are a variety of tests that can be done.

The most common is the visual acuity test. This is an eye chart test that measures how well you can see at various distances. A pupil dilation test can also be performed. The pupil is widened with eye drops to allow a close-up examination of the eye’s optic nerve and retina.

Visual field tests measure your side or peripheral vision. Lost peripheral vision may mean you have glaucoma. A tonometry test can be done to determine the fluid pressure inside your eyes. Optic nerve imaging involves taking images of the optic nerve to indicate areas of damage.

A gonioscopy can also be done. A lens is placed on the eye to look at the area called the drainage angle. This is where fluid drains from the eye. This test determines whether the drain is open or closed and if any damage has occurred.

Treatment

Although there is no lasting treatment for glaucoma, early treatment can often control it. There are various medicines that can be used to cause the eye to make less fluid, while there are  others that lower pressure by helping fluid drain from the eye.

Surgery can be done to create a new opening for fluid to leave the eye. This can be done by creating a passage for drainage or by implanting a shunt to help drain the fluid. There are also several types of surgery using a laser that are used to treat glaucoma.

Cataract surgery has been shown to reduce eye pressure in most cataract patients. In some situations it may be used as a treatment for glaucoma.

Sometimes a single operation is not enough to slow down the progress of glaucoma. Repeat surgery and/or continued treatment with medicines may be necessary.

Prevention

There are several steps that may be taken to help detect and manage glaucoma in its early stages. These steps may help to prevent vision loss or slow its progress.

Start by having regular comprehensive eye screening. Glaucoma tends to run in families so you must gather as much knowledge as you can about your family's eye health history. If you are at increased risk, you may need more frequent screening.

If you are prescribed eye drops, take them regularly as they can significantly reduce the risk that high eye pressure will progress to glaucoma. Use eye drops as prescribed, even if you have no symptoms.

Make use of eye protection as serious eye injuries can lead to glaucoma. You should make sure you wear eye protection when using power tools or playing some sports.

• The information in this article is provided as a public service by the Cimas iGo Wellness programme, which is designed to promote good health. It is provided for general information only and should not be construed as medical advice. Readers should consult their doctor or clinic on any matter related to their health or the treatment of any health problem. — igo@cimas.co.zw or WhatsApp 0772 161 829 or phone 024-2773 0663.