UNDERSTANDING RETINAL HEALTH

A healthy retina is necessary for good vision. It is a thin layer of tissue that lines the back of the eye on the inside. The purpose of the retina is to receive light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition.

AGE-RELATED MACULAR DEGENERATION

WHAT IS AGE-RELATED MACULAR DEGENERATION?

Age-Related Macular Degeneration also referred to as AMD or ARMD, is one of the leading causes of severe vision loss in people 50 years and older.

AMD affects the macular region of the retina. The retina is the light-sensitive tissue at the back of the eye that processes visual images. The macula is the central area of the retina that is needed for detailed straight-ahead vision. Reading, writing, driving and colour vision are some of the activities that depend on a healthy functioning macula.

WHAT CAUSES AGE-RELATED MACULAR DEGENERATION?

AMD is described as either dry or wet. The dry form is the most common. It results from a build-up of deposits in the layer under the retina over time. The central retina may become thin and there is a gradual loss of central vision.

The wet form of AMD is far less common and is caused by abnormal growth of blood vessels into the retina. Changes in vision with wet AMD are usually significant and sudden.

Age is a major risk factor for AMD. It is most likely to occur after the age of 60 but can occur earlier. Smoking doubles the risk of AMD and people with a family history of AMD are also more at risk.

WHAT ARE THE COMMON SYMPTOMS?

The early stages of macular degeneration may be noticed but an eye test could detect it before any visual symptoms occur. Any difficulty or change in eyesight should not be dismissed as just part of “getting older”. Early treatment is vital to saving eyesight.

Macular degeneration causes progressive macular damage resulting in loss of central vision but the peripheral vision is not affected. Common symptoms therefore include:

Difficulty distinguishing faces.

Distorted vision where straight lines appear wavy or bent.

Dark patches or empty spaces blocking the central field of vision.

Reading or activities that require close up detailed vision become difficult.

CAN IT BE TREATED?

Treatment options depend on the type and stage of the AMD. Current treatment is aimed at retaining sight for as long as possible and in some cases improving it, however, there is currently no cure. Early detection is therefore essential in saving vision.

DIABETIC RETINOPATHY

WHAT IS DIABETIC RETINOPATHY?

Diabetic retinopathy is damage to the retina caused by diabetes. It is a major cause of blindness in South Africa. Both type I and type II diabetes can cause diabetic retinopathy with over half of people diagnosed with diabetes likely to develop this condition. The risk of developing diabetic retinopathy depends on how long diabetes has been present and how well blood sugar levels are controlled. Women with gestational diabetes are also at risk of developing diabetic retinopathy.

WHAT CAUSES DIABETIC RETINOPATHY?

The eye is supplied by small blood vessels entering from behind the globe. Uncontrolled blood sugar levels, high blood pressure, high cholesterol levels and smoking may damage these blood vessels. The damaged blood vessels swell and leak fluid or become constricted, decreasing blood flow to the eye.

Diabetic Macular Oedema (DME) is a consequence of diabetic retinopathy. The leaking blood vessels cause the macula, the central part of the retina, to swell and thicken. This macula swelling results in a loss of central vision.

New, abnormal blood vessels may grow onto the retina. The presence of these blood vessels indicates severe disease and is known as proliferative diabetic retinopathy. It is the most advanced stage of diabetic retinopathy.

WHAT ARE THE COMMON SYMPTOMS?

There may be mild symptoms that go unnoticed in the early stages of diabetic retinopathy. Early detection of the disease is vital to preserve vision and diabetics should visit an ophthalmologist at least once a year. As diabetic retinopathy progresses, symptoms may include loss of vision, blurred vision, impaired colour vision and spots or dark strings known as floaters. Symptoms usually occur in both eyes, but one eye may be more affected than the other.

CAN IT BE TREATED?

Treatment of diabetic retinopathy is aimed at slowing progress and minimising loss of vision, although vision can sometimes be improved. Further blood vessel damage is prevented by medically managing blood sugar levels, blood cholesterol and blood pressure levels.

Laser treatment seals blood vessels and reduces abnormal new blood vessels, reducing the possibility of bleeding into the eye. Laser surgery is excellent for preserving sight, but it won’t restore lost vision.

Intravitreal injections are used to treat diabetic vessel leakage and blockage. Medicines are injected with a fine needle, into the eye, under local anaesthetic. These medicines dry out the fluid in the retina and reduce new vessel growth. There may be some improvement in vision.

Surgery may be necessary if there is bleeding into the eye. The procedure is called a vitrectomy and is performed under local anaesthetic. The blood-contaminated vitreous gel in the eye is removed and replaced with a clear fluid. This fluid is absorbed by the eye over time and will be replaced with natural fluids produced in the eye.

MACULAR HOLE

WHAT IS A MACULAR HOLE?

The retina is the light-sensitive tissue at the back of the eye that processes visual images. The macula is the central area of the retina needed for detailed, straight-ahead vision. Reading, writing, driving and colour vision are some of the activities that depend on a healthy, functioning macula.

A macular hole is an abnormal opening in the centre of the macula that develops slowly over time. It mostly occurs in one eye but may involve both eyes. Macular holes most often occur in older people and are more common in women. There is an increased risk of developing a macular hole if another eye condition such as severe short-sightedness or retinal detachment is present. Macular holes do not increase the risk for macular degeneration.

WHAT CAUSES A MACULAR HOLE?

The eye is filled with a gel-like substance, called vitreous humor, which resembles egg whites. With age, this gel naturally starts to contract and separate itself from the retina. This process occurs naturally and without any problems in most people. When the vitreous is attached very firmly to the retina, it begins to pull on the macula as it contracts, creating a small tear. This tear develops into a round hole over time. Fluid may seep into this hole causing vision to become blurred and distorted.

WHAT ARE THE COMMON SYMPTOMS?

Changes in vision are usually not evident in the very early stages of this condition. The first sign that a macular hole is present is often distorted or clouded vision. A black, grey or blind spot may develop in the central field of vision as the disease progresses. Peripheral vision will remain normal while central vision deteriorates. Straight lines such as street lamps or lines of text typically appear bent or wavy. There is no pain associated with macular hole formation, and the size and location of the macular hole will determine how badly vision is affected.

CAN IT BE TREATED?

Most often, surgery is required to close a macular hole and improve vision. Surgery is usually necessary by the time symptoms are noticeable. Vitreous gel is removed from the eye and replaced with gas. The gas serves to flatten out the macula defect, allowing it to heal over time. The eye absorbs the gas slowly and naturally refills with fluid.

FREQUENTLY ASKED QUESTIONS

WILL I BE ASLEEP FOR THE PROCEDURE?

No. The surgery is usually performed under local anaesthesia.

IS IT PAINFUL?

You will have a local anaesthetic which will numb your eye. Some people have some irritation and only rarely do a few have some pain during surgery.

Patients typically feel no pain following the surgery only mild to moderate redness and grittiness in the eye. The eyelid may temporarily swell and droop slightly.

HOW LONG WILL THE PROCEDURE TAKE?

It usually takes about 50 minutes. To facilitate the correct placement of the air bubble, you will need to lie in a special face-down position after the procedure.

IS IT SAFE? WHAT ARE THE RISKS INVOLVED?

Severe complications associated with this surgery are rare. However, as with all surgery, complications can occur including infection, retinal detachment, bleeding and loss of side vision.

HOW WILL I SEE AFTER THE SURGERY?

Initially, vision is limited as the gas will change the focus of the eye making everything appear out of focus. The gas placed in your eye will slowly be absorbed over 7 to 10 days, and your vision will begin to return. The final vision improvement will take up to 6 months.

WHAT WILL I NEED TO DO AFTER THE SURGERY?

A face-down position will need to be maintained for up to 2 weeks. A successful visual result is dependent on keeping the correct face-down position after surgery. This can be challenging for many people and should be discussed before surgery.

Heavy lifting, swimming and strenuous exercise should be avoided for 6 to 8 weeks following surgery to allow for full recovery.

You will not be able to fly for a couple of weeks after surgery. It will need to be confirmed that the air in your eye has been completely absorbed before you can fly again.

WHAT HAPPENS TO AN UNTREATED MACULAR HOLE?

An untreated macular hole will not cause complete blindness. The affected eye will progressively lose central vision while outer vision is maintained. It will, therefore, become more and more difficult to read, recognise faces and to perform detailed work.

CAN ANYTHING HAPPEN TO MY OTHER EYE?

There is a 10% chance of a macular hole occurring in the other eye. There is nothing that can be done to prevent a macular hole. Early detection improves prognosis, so it is a good idea to have your eyes examined regularly.

EPIRETINAL MEMBRANE (ERM)

WHAT IS AN EPIRETINAL MEMBRANE (ERM)

An ERM is a thin layer of scar-like tissue that grows over the macula, the central part of the retina. With time the scar tissue contracts and may reduce and distort vision.

WHAT CAUSES AN ERM?

The eye is filled with a gel-like substance called vitreous humor. With age, this gel naturally starts to contract and separate itself from the retina. This process occurs naturally and without any problems in most people. In some people, the vitreous is attached very firmly to the macula. When the vitreous begins to contract it causes irritation and damage to the macula, and a healing process begins. Cells migrate and group in a thin layer over the macula to heal the damaged area. With time, this layer contracts to form scar-like tissue. As it continues to contract, it pulls on the retina causing it to wrinkle, resulting in blurry or “wavy” central vision.

ERM occurs most often in people over the age of 50 following the separation of the vitreous from the retina. It is not certain why some people are more predisposed to develop the condition than others. ERM is associated with other eye conditions including diabetic eye disease, eye inflammation, retinal tear, recent eye surgery, trauma and retinal detachment.

WHAT ARE THE COMMON SYMPTOMS OF AN ERM?

ERM affect the macula which is responsible for central vision, and therefore straight-ahead visual activities such as driving and reading are most affected. There may be no obvious symptoms with mild ERM. Most people are unaware that they have developed an ERM and it may only be detected during a regular eye check. In more severe cases of ERM, the most noticeable symptoms are loss of vision, blurring and distorted vision where lines appear wavy. There may also be difficulty reading and discerning fine detail.

CAN IT BE TREATED?

It is hard to predict the progression of ERM. ERM can stay dormant for many years and not require any treatment. If vision is good and symptoms are few, then no treatment is necessary. Most ERM enlarge over time. Surgery becomes necessary when the ERM becomes large enough to cause significant changes in vision. The surgery for ERM is called vitrectomy with ERM removal. Vitrectomy is performed under local anaesthetic. The surgery takes about an hour. The jelly-like substance in the eye, the vitreous, is removed. The membrane is carefully peeled away, and the scar tissue is removed. In some cases, a gas is injected into the eye to replace the vitreous fluid and hold the retina in place.  The gas will naturally be replaced with eye fluids over time. After surgery, it will be necessary to lie in face-down position for one to two days to allow the gas bubble to press against the macula to smoothen it.

ERM surgery is very effective but only if treated before damage becomes permanent. The degree of visual improvement varies from person to person. Improvement in vision occurs slowly over time as the eye heals. Usually, the most significant improvement is in the first six weeks after surgery, but sight may continue to improve for up to a year following treatment.

Some patients may choose not to have treatment if the symptoms are few and the visual distortion is mild. An untreated ERM may lead to permanent damage to the retina that cannot be reversed with treatment.

RETINAL DETACHMENT

WHAT IS RETINAL DETACHMENT?

Retinal detachment occurs when the retina separates from the inner lining of the eye. The retina is no longer nourished by blood supply which may lead to loss of vision. Retinal detachment is not common, but it is a serious condition that is considered a medical emergency. Retinal detachment should be diagnosed and treated promptly to prevent permanent, partial or complete, vision loss.

WHAT CAUSES RETINAL DETACHMENT?

The eye is filled with a clear gel-like fluid called vitreous humor. As we age, this fluid naturally shrinks and contracts and may pull away from its attachment at the back of the eye. This process usually occurs without any problems. In some cases, the vitreous has a particularly strong attachment to the retina. When the vitreous contracts, it may pull hard enough on the retina to cause a tear. There may be one or more tears. When fluid passes through the tear, it lifts the retina from the back of the eye causing it to detach.

WHAT ARE THE COMMON SYMPTOMS OF RETINAL DETACHMENT?

Retinal detachment is usually preceded by a retinal tear, so the symptoms are also similar. There may be blurred or decreased vision which occurs suddenly or gradually happens over time. There may be bright flashes of light in the peripheral vision as well as an increase in floaters or flecks that float in the field of vision. When retinal detachment occurs, a shadow may form in the field of vision, or there may be a sudden and total loss of sight.  The effect of retinal detachment on vision depends on the location and severity of the detachment.

Retinal detachment can happen at any age, but it most frequently occurs in people over the age of 40 and more often in males. Retinal detachment most often occurs as a result of a related eye condition such as the separation of the vitreous gel from the retina. It may also be caused by trauma, diabetes or inflammatory eye conditions. People who have had cataract surgery or are severely short-sighted may have an increased risk of retinal detachment.

CAN IT BE TREATED?

Surgery is the only treatment for retinal detachment and is aimed at inhibiting the progression of vision loss. There are different surgical procedures depending on specific characteristics of the retinal detachment. The location, type of detachment and cause of the detachment will determine which surgical procedure is the best approach. If retinal detachment is left untreated, it can lead to complete and permanent loss of vision. It is critical that retinal detachment is treated promptly.

THERE ARE TWO MAIN TYPES OF SURGERY:

Vitrectomy surgery – the vitreous gel is removed from the eye and replaced with a gas bubble. If necessary, scar tissue is also removed. In cases of advanced retinal detachment, silicone oil or heavy fluid is used to secure and place pressure on the retina. The gas bubble is naturally replaced over time with the eye’s own fluids. Vitrectomy is sometimes combined with scleral buckle surgery.

Scleral buckle surgery – This is an external procedure (the vitreous is not removed). It entails closing the retinal holes from outside the sclera with silicone sponges or bands. After the procedure, there may be some discomfort. The quality of vision will vary depending on whether the macula, the area responsible for central vision, has been affected. If there is macular detachment, straight ahead vision and the ability to read and see fine detail may be impaired, and vision may not recover completely after surgery.

FLOATERS AND FLASHES

Floaters or flecks that float in the field of vision.

WHAT ARE FLOATERS?

Floaters are small specks that appear in the field of vision. Most floaters are normal, but in some cases, they may indicate an underlying problem. If you experience a sudden increase in the number of floaters or develop a sudden large floater, especially if accompanied by flashes of light, then you should seek help. Even if you have had floaters for years, you should have a check-up if you suddenly notice a new one.

WHAT CAUSES FLOATERS?

Floaters may appear to be in front of the eye, but they are actually floating in the fluid inside the eye. The fluid that fills the eye is known as vitreous humour. It is a clear, jelly-like substance that helps the eye hold its spherical shape and keep the retina in place. With age, the vitreous starts to liquefy and shrink causing it to pull away from the back of the eye. This process may result in clumps of gel and debris that move around in the vitreous and cast shadows on the retina. The shadows are what is observed as floaters.

WHAT ARE THE COMMON SYMPTOMS?

Floaters appear in a variety of sizes and shapes. Some may have a more regular shape like dots, circles or lines while others look irregular like cobwebs or clouds. Floaters are usually more obvious in bright light or when looking at a plain surface. That is why they may be noticed more easily on a sunny day or when looking at blue sky or a blank wall. Floaters may drift around or seem to hardly move at all. They tend to move as the eyeball moves and when trying to look directly at a floater, it may seem to disappear.  Large floaters can appear as decreased areas of vision, but this is uncommon.

CAN FLOATERS BE TREATED?

Floaters are common and usually don’t require any treatment. For most people, floaters become less bothersome over time as the brain learns to ignore them. Floaters may be annoying when they get in the field of vision, especially while trying to read. Looking up and down may help move the floater out of the way.

If the floaters are numerous or large then surgery may be recommended. Vitrectomy is an outpatient surgical procedure usually performed under local anaesthetic.  This procedure is performed through a small incision and does not usually require any stitches.  The vitreous gel is removed from the eye and replaced with a special saline solution that helps maintain the shape of the eye. The saline solution is replaced over time as the eye produces its own fluid.

Complications after vitrectomy are rare, but as with all surgery, there are associated risks. Possible complications include bleeding, cataract, retinal detachment and infection.

WHAT CAUSES FLASHING LIGHTS?

Flashes are lights that occur in the visual field. Flashes, unlike floaters, are usually seen at night or in low light conditions. They may appear on and off for a few months at a time and can last for a few seconds or several minutes.

Flashing lights can occur as the vitreous pulls away from the back of the eye as part of the ageing process. Detachment of the vitreous causes it to pull on the retina. The retina is stimulated by this movement which results in flashes of light or lightning streaks in the visual field.

When you see flashes of light you should make an urgent appointment at an ophthalmologist to exclude retinal tears, or holes which can lead to a retinal detachment. Flashes do not require any treatment if there is no tear in the retina, but if it continues or worsens follow-up visits are recommended.

Flashes do not require any treatment if there is no tear in the retina, but if it continues or worsens follow-up visits are recommended.