Glaucoma

Glaucoma is the name given to a group of eye conditions that cause permanent sight loss by damaging the optic nerve. Glaucoma occurs when the optic nerve (connecting the eye to the brain) becomes damaged by the pressure of the fluid inside of the eye. It is one of the world’s leading causes of blindness with around 2% of the population over 40 in the UK having the condition. Despite it being a common condition many people will not realise they have glaucoma as it doesn’t carry any symptoms in the early stages.

Although any vision that has been lost due to glaucoma cannot be reversed, with early diagnosis, careful monitoring and regular treatment, further damage is preventable and most patients can retain useful eyesight.

Symptoms

The two most common types of glaucoma are primary open-angle glaucoma (POAG) and angle-closure glaucoma (ACG). Many refer to open-angle glaucoma as the “sneak thief of sight” because it shows no symptoms until significant sight loss has occurred.

Symptoms of Open-Angle Glaucoma

In open-angle glaucoma, the angle in your eye where the iris meets the cornea is as wide and open as it should be, but the eyes drainage canals become clogged over time, this causes an increase in internal eye pressure and subsequent damage to the optic nerve.

Unfortunately, there are typically no early symptoms or warning signs of open-angle glaucoma. The condition tends to develop slowly and sufferers may not notice their sight deteriorating for many years.

The majority of people with ACG will feel fine and will not notice any early changes in their vision as the initial loss of sight is of side or peripheral vision, a sharpness of vision is also maintained until late in the disease.

When a patient begins to become aware of vision loss, the disease is normally in a quite advanced stage.

Because the disease has few warning signs or symptoms before damage starts to occur, it is vital to receive regular eye examinations. If glaucoma is detected during an eye exam, your eye doctor is able to prescribe a preventative treatment to help protect your vision.

Symptoms of Angle-Closure Glaucoma

Angle-closure glaucoma, commonly known as narrow-angle glaucoma, is caused by block drainage canals in the eye, resulting in a sudden rise in intraocular pressure. This is a rarer form of glaucoma, which develops fast and requires urgent and immediate medical attention.

Unlike open-angle glaucoma, symptoms of angle-closure glaucoma are extremely noticeable and damage often occurs quickly. If you experience any of the symptoms below, please contact your ophthalmologist immediately.

• Hazy or blurred vision
• Severe head and eye pain
• Nausea and vomiting (accompanying severe eye pain)
• Sudden sight loss
• The appearance of rainbow-like ‘halos’ around bright lights

Diagnosis, Screening and Tests

It is vital that you attend regular eye tests to ensure conditions such as glaucoma are identified as early as possible. Early treatment can help stop your vision from becoming severely affected.

Tests for Glaucoma

Please do not worry, there are several quick and painless tests that can be carried out to diagnose and monitor glaucoma:

Eye Pressure Test

A tonometry (eye pressure test) uses an instrument known as a tonometer to measure the pressure inside of the eye.

To perform the test, a small amount of anaesthetic and dye is placed onto the front of the eye. A light from the tonometer is gently held against the eye to measure the pressure inside.

High pressure in the eye can indicate that you have glaucoma or are at a higher risk of developing it.

Gonioscopy

Gonioscopy is the examination of the front outer edge of the eye, between the cornea and the iris. It is in this area that fluid should drain out of your eye.

A gonioscopy is performed to determine whether or not this area (commonly known as the “angle”) is open or closed (blocked), which can have an effect on how fluid drains from your eye.

Visual Field Test

A visual field test (often known as a perimetry) checks for missing areas of vision.

You may be shown a sequence of light spots and asked which ones you are able to see. Some dots will appear in your peripheral vision, which is often affected by glaucoma, to begin with.

If you are unable to see the spots in your peripheral vision, it may indicate that glaucoma has damaged your vision.

Optic Nerve Assessment

Glaucoma can cause the optic nerve (the nerve that connects your eye to your brain) to become damaged, so an assessment may be carried out to check if it is healthy.

For the test, eye drops are used to enlarge your pupils. Your eyes are then examined using a slip lamp to assess the optic nerve.

The eye drops used may cause temporary blurred vision, for this reason, it is advised that you do not drive until the effects have fully disappeared.

Optical Coherence Tomography

Optical coherence tomography is a type of scan using special rays of light to scan the back of your eye and produce an image of it.

This can help to detect any damage to the retina (the light-sensitive layer at the back of the eye) or optic nerve caused by glaucoma.

Referral to a Specialist

If glaucoma is detected during an eye test you will be referred to an ophthalmologist for further tests.

The ophthalmologist will be able to confirm whether or not you have the condition and find out:

• How far the condition has developed
• How much damage the condition has done to your eyes
• The factors that may have caused the glaucoma

Treatments

Glaucoma can be treated in several different ways, including eye drops, laser treatment and surgery. The treatment you receive will depend upon your personal circumstances.

Unfortunately, treatment is unable to reverse any sight loss that has already taken place but it can help to stop your eyesight deteriorating any further.

Your treatment generally depends on which type of glaucoma you have.

• Primary open angle glaucoma is normally treated with eye drops. If eye drops have little or no effect then laser treatment or surgery will be used.
• Primary angle closure glaucoma often requires immediate medical attention in a hospital with medication to reduce the pressure in the eye, this is often followed by laser treatment
• Secondary glaucoma can be treated with eye drops, laser treatment or surgery, depending on the underlying issue
• Childhood glaucoma often requires surgery to correct the problem in the eye that led to the build-up of fluid and pressure

All patients will be required to attend regular follow-up appointments to monitor your eyes and check that the treatment is working. It’s essential not to miss any of these follow-up appointments.

Eye Drops

Eye drops are the main treatment for glaucoma and several different types can be used. All eye drops work by reducing the pressure in your eyes.

Unfortunately, eye drops can have negative side effects, such as eye irritation, and some are unsuitable for people with certain underlying conditions.

Some patients may need to use more than one type of eye drops at the same time. Eye drops are normally taken between one and four times a day.

Laser Treatment

If your condition cannot be improved using eye drops, laser treatment may be recommended.

Laser treatment involves a high-energy beam of light being carefully aimed at a part of your eye, to stop fluid building up inside it.

There are several different types of laser treatment:

• Laser iridotomy – A laser is used to produce holes in your iris, allowing fluid to drain from your eye
• Laser trabeculoplasty – A laser is used to open up the drainage tubes in your eye, allowing more fluid to drain out of your eye and reducing the pressure inside it.
• Cyclodiode laser treatment – A laser is used to destroy some of the tissue in the eye that produces aqueous humour, reducing pressure in the eye

Laser treatment is generally carried out under local anaesthetic. Throughout the treatment, you may feel a brief period of pain or heat.

Eye drops may still have to be administered after treatment is completed.

Surgery

In some cases, surgery is recommended as an alternative to laser treatment.

There are several different types of surgery including:

• Trabeculectomy – The most common type of glaucoma surgery. Trabeculectomy involves removing part of the eye drainage tubes to allow fluid to drain more easily
• Trabeculectomy- Similar to the surgery above, but an electric current is used to remove a small part of the eye drainage tubes
• Viscocanalostomy – Creates an opening for insertion of a highly pliable, gel-like material known as viscoelastic, which helps provide enough space for adequate drainage and eye pressure relief.

Prevention

You are at an increased risk of glaucoma if your parents or siblings have the condition. People of African, Afro-Caribbean or Asian origin are also at increased risk of developing certain types of glaucoma. Other medical conditions such as short and long sightedness and diabetes is also believed to heighten your risk of glaucoma. The risk of glaucoma also increases with age.

If you are at risk of developing the condition, medical experts suggest a healthy lifestyle that includes regular exercise and eating a well-balanced diet. Receiving regular eye tests will ensure that any early signs of glaucoma will be detected and preventive action can be taken.

The following suggestions may help lower your risk of developing glaucoma:

• Maintaining a healthy body weight
• Keeping your blood pressure at a normal level
• Quitting smoking
• Limiting your caffeine intake
• Regular exercise
• Preventing overexposure to sunlight (wearing sunglasses, large brim hats etc.)

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