What is macular degeneration?
Macular degeneration is a kind of macular lesion. The macula is a small area in the center of the retina, located in the back wall of the eye, in charge of our fine vision. With fine vision, we can see clearly when we read, drive, etc. If the macula does not work properly anymore, our central vision will become blurred, dark areas will appear in the center of the visual field, and seeing things may be distorted and deformed. Macular degeneration can therefore affect both our distance vision and our near vision, and can make it difficult or even impossible to perform certain operations – such as threading a needle or reading.
Macular degeneration is the most common cause of severe vision loss in people over the age of 50.
Although macular degeneration can cause a loss of central vision, peripheral vision is usually unaffected. For example, you may be able to see the outer edge of a clock on one side, but not the exact time. Macular degeneration alone does not usually cause total blindness. Even people with advanced macular degeneration are usually able to retain some useful vision and live on their own. Some macular degeneration may have little effect on vision, while others may cause rapid vision loss.
Why does macular degeneration occur?
Macular degeneration occurs in many older adults as part of the natural aging process throughout the body. Of the many types of macular degeneration, age-related macular degeneration (AMD or ARMD) is the most common.
Throughout our lives, our bodies continue to react with oxygen in the environment, and over time, more and more oxygen free radicals are produced in the body. These oxygen free radicals can affect and even damage the body’s cells, called oxidative stress, and play a major role in the formation of AMD. At the same time, many people also have genetic alterations (about 1/3 of Caucasians and relatively low in the Chinese) that make them more susceptible to oxidative stress and thus more likely to develop AMD.
Risk factors for AMD include
Age greater than 50 years.
A family history of AMD.
Smoking.
Hypercholesterolemia.
The main fundus feature in patients with AMD is a subretinal deposit called a vitreous wart. The presence of vitreous warts alone does not usually lead to vision loss, but the risk of developing advanced AMD increases greatly as vitreous warts grow larger and more numerous.
AMD is mainly divided into dry AMD and wet AMD.
Dry macular degeneration
Dry AMD, which occurs in 90% of AMD patients, is caused by damage from oxidative stress and can lead to atrophy and thinning of the macular tissue. Vision usually declines gradually and many patients have difficulty adjusting to changes in light. As an example, when you enter a house through the door, it may take ages to see inside.
Wet macular degeneration
Ten percent of people with AMD have wet AMD, and most will experience severe vision loss. Wet AMD is caused by the formation of abnormal blood vessels under the retina. These new blood vessels leak fluid and blood, which leads to central vision loss, and the loss of vision is rapid and severe.
What are the symptoms of macular degeneration?
Symptoms can vary from patient to patient. Some patients almost never notice their eye symptoms in the early stages of AMD. This is because sometimes vision is lost in only one eye, while the other eye can still maintain clear vision for many years. It is only when both eyes are involved that they notice a significant loss of central vision.
Symptoms of AMD include.
Finding it difficult to read when reading.
A darkened or missing patch in the center when looking at something.
Straight lines become distorted, as shown below.
How is macular degeneration diagnosed?
It is difficult for many patients to realize that they have macular degeneration until there is a significant loss of vision. Regular eye exams can detect AMD early.
Examinations include.
Asking you to look at a chart of squares (called an Amsler square).
Examining your macula with a special fundoscope.
Having special ophthalmic imaging tests, including optical coherence tomography (OCT) and fundus fluorescence angiography (FFA). ffa reveals abnormal blood vessels under the retina with fluorescein dyes. oCT shows the level of abnormal blood vessels in the macula in fine detail.
How to treat macular degeneration?
Nutritional supplements
Antioxidant vitamins and zinc may slow the progression of AMD in some patients. A large multicenter study showed that a combination of the following high-dose medications reduced the risk of developing advanced AMD by 25 percent
Vitamin C (500 mg).
Vitamin E (400 IU).
Beta-carotene (15mg).
Zinc (80mg).
Copper (2mg).
Another study in women with AMD showed that taking folic acid, vitamin B6 and B12 was beneficial. There is also a large study evaluating the effects of lutein and fish oil (omerga-3).
However, in patients without AMD or very early AMD, studies have shown that these medications are not beneficial. Therefore, please consult with your ophthalmologist before self-administering any of these medications.
It is also important to highlight here that medications such as vitamin supplements do not cure AMD and will not restore your vision. Also, for certain patients, there may be some risks associated with supplementation. However, for patients who are at high risk of developing advanced AMD, supplementation with specific doses of medication does help maintain their vision. Therefore, before using medications, please visit an eye exam to see if you are at high risk of progression and if medication supplementation is right for you.
Anti-VEGF therapy, laser and PDT
The most common treatment for wet AMD is vitreous cavity injection, which blocks the growth of new blood vessels and bleeding by injecting anti-VEGF drugs into the eye. There is a special chemical in the body called vascular endothelial growth factor (VEGF) that causes abnormal blood vessels to grow under the retina. Anti-VEGF drugs work specifically against VEGF, blocking the growth of new blood vessels by blocking VEGF, thus improving vision in patients with wet AMD.
Some specific types of wet macular degeneration can also be treated with a general laser, which can be done in a short time on an outpatient basis, to slow or block the leakage of abnormal blood vessels.
Photodynamic therapy (PDT), on the other hand, is a combination of a special drug and laser to slow or block leakage of abnormal blood vessels.
These treatments can preserve or even partially improve vision, but they do not cure AMD and usually do not restore vision to normal. Moreover, even with aggressive treatment, many patients continue to lose vision.
Making the most of your existing vision
To help you make the most of your existing vision, your eye doctor may prescribe low vision aids to help you with your daily tasks or refer you directly to a low vision specialist or low vision center. There are many supportive devices and rehabilitation programs available to help people with AMD maintain their independence in life. Because your peripheral vision is usually unaffected, this residual vision is very useful. By using low vision aids such as various magnifying glasses, portable electronic devices, special televisions, large print reading materials and audible devices, you can continue to do the activities you enjoy.
Test your visual function with an Amsler chart
You should check your visual function daily with an Amsler chart. This way, you may notice changes in your vision that you would not normally notice. Putting this chart on your refrigerator door is a good way to remind yourself to keep checking it every day.
How to apply the chart.
In a brightly lit area, put on your presbyopic glasses and place the table 30-40 cm in front of you.
Cover one eye.
Look at the black dot in the center of the table with the uncovered eye.
While looking at the central black dot, observe whether all the lines on the form are straight and whether any parts are distorted, blurred, or invisible.
Cover the other eye and complete the same steps.
If you notice any new distorted, blurred or invisible parts of the form, go to the eye immediately.