Macular Degeneratione

Macular degeneration is the name given to the group of degenerative retinal diseases that cause progressive loss of central vision, leaving only peripheral or side vision intact. It is most commonly related to aging, hence the name, age-related macular degeneration (ARMD or AMD).

Less commonly, degeneration of the macula occurs in younger people. This can be due to inherited conditions called retinal or macular dystrophy, short-sightedness called myopic macular degeneration, and other rarer disease processes such as choroidal polyps, angioid streaks, central serous retinopathy, eye inflammation and medication toxicities.

Macular degeneration is usually progressive, meaning that it worsens with time. Although it never causes complete blindness, it affects central vision, impairing a person’s ability to do many daily tasks, such as reading, recognising faces, driving and shopping. The ability to recognise colours and contrasts is also affected.

Early stage AMD

This is the most common form and is present in one in 20 people aged 50 years or over. Typically there is no noticeable vision loss but some people may gradually become aware of increasing difficulty with reading in dim light and delayed adaptation to seeing in the dark. As the disease progresses, mild distortion or a blurry patch in the central vision may develop.

In this early stage, there is accumulation of debris in the retina at the level above, within or below the retinal pigment epithelium (RPE), a specialised layer of cells that nourishes the nerve cells in the retina. Over a period of many years, this debris, also called drusen, accumulates and causes RPE damage. As the disease progresses to the late stage, nerve cells in the retina will become injured or die resulting in loss of vision.

Late stage AMD

This is the stage at which most people with AMD will present to an eye doctor because of vision loss due to nerve cell injury or death within the retina. There are two types of late stage AMD: geographic atrophy and neovascular (or new vessel growth, also commonly known as the wet form).

In some people, increasing difficulty with reading or face recognition may be the first symptom of geographic atrophy. In this type of late AMD, there is progressive, patchy loss of nerve cells and RPE in the retina resulting in the formation of several blind spots in the vision. This affects recognition of all the letters in a word or details in a face. Over a period of several years, the ability to read may be completely lost due to blurriness in the central vision. This type of late AMD may be seen in up to one per cent of those aged 55 years or over.

Independent of geographic atrophy formation, some people may also develop abnormal new blood vessels from beneath the retina. Upon entry into the retina, these new blood vessels often grow wildly, and may bleed or leak fluid under the retina and hence it is often referred to as the “wet” form of AMD. If untreated, this causes scarring of the retina and severe loss of vision over a period of months. This type of late AMD may also be seen in up to one per cent of those aged 55 years or over.

People with AMD may develop new blood vessels followed by onset of geographic atrophy or geographic atrophy first followed by new blood vessels formation. Geographic atrophy and new blood vessels can also each occur alone without the other.

Macular degeneration not due to AMD

There are other forms of macular degeneration that are not related to aging. These can occur at a younger age and they are due to a variety of causes such as short-sightedness (also called myopic macular degeneration), leakiness of blood vessels (also called central serous retinopathy), balloon- like bulge in the blood vessel wall (also called choroidal polyps), genetic eye disease and medication side effects.

Many of these conditions can also lead to central vision loss through the development of geographic atrophy or new blood vessel formation. It

is important that special tests are performed to distinguish these conditions from AMD because their treatments may be very different.

What causes Macular Degeneration?

The causes and mechanisms of macular degeneration are not fully understood. The major risk factor for AMD is increasing age. This disease can cluster in certain families, suggesting that some persons are more genetically susceptible to the disorder than others. Cigarette smoking is known to increase the risk of AMD. Racial, dietary, hormonal and vascular factors appear also to play a role in an individual’s risk of developing AMD. Choroidal polyps cause 10 to 20 per cent of the abnormal new blood vessels seen in Caucasians but up to 50 per cent of the new blood vessels seen in the Asian population. You cannot change your parents, your race, your sex (AMD is more common in females) or your age, but you can reduce your risk of developing AMD.

Things you can do:

• Stop smoking

• Eat a diet rich in fresh fruit and dark green leafy vegetables

• In consultation with your doctor, supplement your diet with vitamins, minerals and antioxidants

• Check your vision regularly

It is important to realise that using the eyes for reading and other daily tasks will not cause or worsen macular degeneration. Risk factors for other types of macular degeneration vary significantly. Increasing short-sightedness is associated with increasing risk of developing myopic macular degeneration. Central serous retinopathy is more likely to develop in people who are long-sighted. Retinal dystrophy and angioid streaks are usually inherited from parents.

What are the symptoms of Macular Degeneration?

The symptoms are visual and there is no associated pain or discomfort. Many patients note difficulty with reading as words become blurred or crowded. There may be a blurred, dark, or empty spot in the central vision, similar to the after-effect of a flashbulb. Distortion is a frequent and notable symptom. Straight lines such as door frames or telephone poles may appear bent or wavy. One eye may be affected more than the other. Blurred vision in one eye alone sometimes goes unnoticed for a long period of time because the other seeing eye compensates for the vision deficit.

Macular degeneration does not lead to total blindness even if both eyes are affected. The peripheral, or side, vision is unaffected by the condition and almost all patients can see well enough to take care of themselves and continue activities that do not require detailed vision.

Optical coherence tomography (OCT)

An optical coherence tomography (OCT) scan captures a detailed picture of the retina similar to ultrasound. It is completely non- invasive and provides a very high resolution image of the various layers of nerve cells in your macula. This scan will allow your ophthalmologist to compare measurements over time and assess how the treatment is working and whether more frequent administration is required. It may even detect fluid build-up due to new blood vessels before you become aware of vision impairment.

Fundus autofluorescence (FAF)

Fundus autofluorescence (FAF) imaging is a non-invasive photograph of the retina that allows doctors to see those RPE cells under metabolic stress.

This test is critical in differentiating yellow flecks due to genetic retinal disease from drusen in AMD. Repeated FAF photography allows the doctor to measure how fast cells are deteriorating because areas of dead RPE cells are easily seen as dark patches in the macula on FAF photography.

Fundus fluorescein and indocyanine green angiography (FFA & ICGA)

Angiography enables doctors to study blood vessel structures in the retina to assist with accurate diagnosis. Fluorescein and indocyanine green are commonly used dyes that are injected into the vein of the arm which then circulate to the eye to highlight blood vessels within the retina during angiography. Different dyes are required to see different layers of circulation in the back of the eye and to distinguish between choroidal polyps, central serous retinopathy and AMD- related new blood vessels.

What is the treatment for Macular Degeneration?

There is currently no cure for macular degeneration. Treatment efforts are directed at maintaining useful central vision for as long as possible. The treatment varies depending on the cause and stage of macular degeneration. Many factors will be considered by your ophthalmologist when determining the best treatment for you.

Macular Degeneratione

Macular degeneration is the name given to the group of degenerative retinal diseases that cause progressive loss of central vision, leaving only peripheral or side vision intact. It is most commonly related to aging, hence the name, age-related macular degeneration (ARMD or AMD).

Early stage AMD

All individuals with early signs of AMD must stop smoking. Recent studies suggest that some vitamins, minerals and antioxidants may slow the progression of early AMD into late AMD. Your ophthalmologist can advise whether these preparations may be helpful and discuss new clinical trials in novel treatments aiming to reduce the harmful effects of drusen. Periodic examinations to monitor you for signs of progression may be recommended.

Late stage AMD

There have been major advances in the treatment of new blood vessels in the late stage of AMD that have enabled many patients with this type of complication to regain lost vision. The majority of patients with active new blood vessels can now be offered treatment with drugs that are injected into the vitreous cavity of the eye. These drugs reduce leakage from the abnormal blood vessels under the retina when they are administered regularly at monthly intervals. Once OCT scans show absence of fluid

in the macula, the time between retreatments may gradually extend by one to two weeks until the 12 week interval is reached. In many patients, lifelong treatment every 12 weeks may be sufficient to keep the vision stable. In a significant proportion of patients, a prolonged course of four to six weekly retreatment regimens may be required because retinal fluid returns or vision loss occurs when the retreatment interval is extended. Your doctor will discuss possible alternative treatments in such situations with you. There are also new drugs being developed for treating new blood vessels that may have stronger action or longer-lasting effects.

The results of large, multi-centre randomised controlled trials demonstrated that up to half of all patients treated with intravitreal injections achieve improvement in vision. Ranibizumab (Lucentis®) and Aflibercept (Eylea®) treatment achieved similar results in vision gain. Bevacizumab (Avastin®) was developed as an intravenous infusion to treat patients with advanced bowel cancer. Its potential for treating patients with eye diseases was recognised early. It has been used to successfully treat patients with abnormal new vessels in the macula and other eye diseases by injection of a far smaller dose into the vitreous cavity of the eye. However, several studies have demonstrated that Lucentis® is superior to Avastin® in AMD so that Lucentis® and Eylea® are now accepted worldwide as the gold standard treatments for patients with wet form of late AMD, and their use has given patients with this disease real hope of retained or even improved vision.

In patients who have new blood vessels due to myopic macular degeneration, retinal inflammation and other similar conditions not classified as AMD, Avastin remains the only available drug to treat abnormal blood vessels. Myopic macular degeneration complicated by new blood vessels tends to respond differently compared with AMD and hence monthly monitoring and a “treat-as-required” regimen may be more suitable than an “injection at every visit” approach.

A major drawback of intravitreal drug treatment is the need for continuous multiple injections in order to maintain vision. Most patients with abnormal blood vessels due to AMD are judged to be suitable for treatment and they will receive an initial loading dose of three or more injections, once per month. The retreatment interval will be determined based on assessment of fluid status on the OCT scan by your ophthalmologist at each treatment visit. If there is no fluid, your doctor may decide to extend the interval by one to two weeks. If there is recurrence of fluid, your doctor may shorten the interval by one to two weeks or go back to a monthly loading regimen to control the leakage aggressively.

A significant proportion of patients may not achieve a fluid-free macula on OCT even with 4-weekly injections. It is important that you discuss with your ophthalmologist alternative treatment strategies if this situation persists into the second year of treatment. One option for treatment resistance or failure to extend retreatment interval is to switch from Eylea® to Lucentis® or vice versa. In some patients, switching drugs may be the solution to successfully extending the retreatment interval.

In situations where choroidal polyps or central serous retinopathy are suspected based on FAF photography or OCT scans, further investigation using indocyanine green (ICG) angiography may be required to confirm these diagnoses. Both choroidal polyps and central serous retinopathy can mimic the wet form of AMD but, unlike AMD, they can be effectively treated by photodynamic therapy (PDT) with verteporfin, or sometimes laser photocoagulation alone. Both treatments are performed as an outpatient procedure. Neither treatment is suitable for every patient with choroidal polyps or central serous retinopathy, and your retinal specialist will determine if any treatment can be recommended after examination and review of the OCT scan, FAF photograph and ICG angiography. Neither treatment is a cure, and both aim to preserve central vision for as long as possible.

In PDT, a drug called verteporfin (Visudyne®) is infused into the patient’s bloodstream. The drug has been designed to selectively target the leaky abnormal blood vessels under the macula. A non-thermal laser (a laser that does not burn the retina) is directed at the leaky blood vessels and activates the drug. This in turn seals the leaky vessels without causing damage to other parts of the retina. Because of its selectivity, PDT with verteporfin is typically used when the leaky blood vessel is underneath the centre of the macula. PDT may become a course of therapy, and sometimes several treatments are needed to keep the leaking blood vessels closed and stop the progression of choroidal polyps or recurrence of central serous retinopathy. Close follow-up evaluations with your retinal specialist are needed to determine if retreatment is required. Sometimes, reactivation of the new blood vessels may respond to another course of injections and therefore combining PDT with injections may be necessary to achieve long-term control of the leakage particularly in choroidal polyps.

Self Monitoring with the Amsler Grid

It is important for patients with AMD and other types of macular degeneration to regularly monitor central vision in each eye. The object of self monitoring is to detect any change in vision as early as possible, since this may signify progression to the late stage of AMD. Because treatment of abnormal blood vessels is generally more successful if given earlier in the course of the disease, it is essential that patients attend for examination as soon as possible after noticing any significant change in vision. Self-monitoring can be as simple as covering each eye in turn while looking at a familiar object, or TV screen. The Amsler Grid provides a simple method for patients to monitor their own central vision. An Amsler Grid is provided in this brochure for your convenience. Patients should wear their normal reading glasses and hold the Amsler Grid at normal reading distance in good light. Each eye should be examined in turn by covering the opposite eye. The patient should attempt to look at the central dot of the grid to determine whether all the surrounding lines are straight and regular or whether any areas of the grid are blurred, distorted, or missing. Any change in the appearance of the grid should be reported to your ophthalmologist as soon as possible.

Will glasses help?

Patients will gain some benefit from wearing the correct glasses. However, a change in prescription is unlikely to significantly improve vision in most people. In late stage AMD special magnifying spectacles and various optical instruments are available to help people continue their usual activities. Known as low-vision aids, these devices enable patients to use their remaining vision to its fullest.