Definition
The macula is the most important part of the nerve layer in the eye called the retina. It is the center of the retina, with a radius of about 1.5 millimeters, and contains a high concentration of photoreceptors that allow us to sense light. The macula is the center of the retina and is responsible for most of your vision.
Macular degeneration is a condition in which the macula degenerates. Degeneration means pathologic anatomical degeneration, regression. It refers to the change of a highly functional tissue to a less functional tissue, and when we say that degeneration has occurred in the macular area, we mean that the macular area that has a high function of detecting light has degenerated and lost the ability to see light.
Causes
There are several different types of macular degeneration. In general, the term macular degeneration usually refers to age-related macular degeneration, or degeneration caused by the aging of the retina. However, in a broader sense, it can refer to a number of conditions that cause the macula to degenerate.
First, let’s take a quick look at some of the causes of macular degeneration other than age-related macular degeneration, which are genetic in nature, such as Stargardt’s disease. It’s caused by an abnormality in the ABCA4 gene, and the macular dysfunction often begins in the teenage years. Unlike age-related macular degeneration, this is a genetically determined, predestined vision disorder, and there is currently no way to prevent or treat it.
There is also another disease that causes degeneration of the macula called myopic macular degeneration. Myopic macular degeneration usually occurs in high myopia, which is 8 diopters or more. Myopia is when the image from the outside doesn’t focus correctly on the retina, but instead focuses too far in front. It occurs when the refractive power is too great for the size of the eyeball, or when the size of the eyeball is too large for the refractive power.
Myopes with oversized eyeballs tend to have thinner, weaker eyeball walls, just like blowing up a balloon makes the surface of the balloon thinner. The retina inside the eyeball can also become thinner and more porous, and degeneration can occur in the macular area. This type of degeneration is called myopic macular degeneration.
However, the most common cause of macular degeneration is aging. Macular degeneration caused by aging is called age-related macular degeneration, senile macular degeneration, or age-related macular degeneration. In other words, age-related macular degeneration is a condition in which the macular area loses its function due to various factors related to aging. The most common cause is advanced age. The probability of occurrence increases with age. In this context, old age is generally defined as 50 years of age.
However, not everyone develops age-related macular degeneration. In some people, genetic causes, family history, smoking habits, and light damage, in addition to the expected age-related damage, can lead to macular degeneration.
Symptoms
The first symptom of macular degeneration is distorted vision. This is when objects appear to be bent. This is usually a symptom of early choroidal neovascularization. Choroidal neovascularization is the development of new blood vessels under the retina in the macular area.
The proliferation of blood vessels under the retina and the resulting hemorrhages cause the retina to become curved, which means it becomes convex. This is a vision problem caused by the bending of the retina, which should be flat.
The second is the central fovea. This is when you have a dark spot in the center of your vision, meaning that there’s a small area that’s relatively darker than the rest of your vision, or you can’t see at all. This can be detected by examining one eye while the other is covered.
Diagnosis/testing
If you visit an ophthalmologist for vision problems, he or she will first measure your visual acuity and intraocular pressure to determine the extent of your vision loss, and then perform a full eye examination using a slit lamp (a type of microscope that magnifies the eye up to 40 times for a closer look). If no abnormalities are found, the doctor may suspect that the decrease in vision is due to an abnormality in the retina and dilate the pupil, known as the dilator, to get a closer look at the retina. Several tests are performed while the eye is dilated to diagnose and monitor macular degeneration.
Arguably, the most important test performed by an ophthalmologist for routine screening of macular degeneration is optical coherence tomography. It has the advantage of being non-invasive and harmless to the body, and it is useful because it allows for accurate cross-sectional imaging of the retina, allowing for direct visualization of changes such as drusen and choroidal neovascularization in macular degeneration.
Fluorescein fundus angiography is a test in which a fluorescent dye is injected intravenously and the fundus is imaged as the fluorescent dye enters the eye, providing a precise view of the blood vessels in the retina. Indocyanine green angiography may also be performed to better visualize the choroidal vessels. It can be complementary to fluorescein fundus angiography to diagnose choroidal neovascularization, choroidal inflammatory disease, and choroidal tumors that may accompany macular degeneration.
Treatment
It is clear that macular degeneration is an incurable eye disease. However, as with any disease, early detection can help reduce risk factors, and good management can slow the rate of vision loss as much as possible.
Dry macular degeneration is classified as early, intermediate, or late depending on the presence of drusen, the size and number of drusen, and the presence and extent of mapped atrophy. The treatment of early dry macular degeneration is more about managing risk factors and having a fundus examination at least once a year by an ophthalmologist. Treatment of intermediate dry macular degeneration is aimed at slowing the progression to end-stage disease and, if end-stage disease is present, slowing the rate of vision loss.
AREDS-type dietary supplementation (lutein, zeaxanthin, vitamin C, vitamin E, zinc, and copper) can be seen as a preventive measure to slow the progression of the disease rather than a cure. To date, the only treatment for dry AMD that has been established by large-scale studies is AREDS-type dietary supplementation, which ophthalmologists can recommend to slow the progression from intermediate to end-stage macular degeneration and to slow the rate of vision loss in patients with end-stage macular degeneration who have some residual vision. It is better to take a multicomponent formulation that contains a variety of antioxidants rather than a single ingredient supplement, and even if you are taking a daily multivitamin, you may still need this type of AREDS dietary supplementation because AREDS diets contain higher levels of vitamins and minerals than multivitamins.
If wet macular degeneration has already begun, aggressive treatment is necessary to preserve vision.
Laser treatment, which involves shining a laser on weak, abnormally leaky neovascularized blood vessels so that the high energy directly destroys them and prevents further vision loss, can be performed if the boundaries of the degeneration are clearly defined.
Photodynamic therapy is a treatment for patients who have neovascularization in the center of the macula and are not suitable for laser treatment, in which a non-thermal laser is irradiated to the choroidal neovascularization with verteporfin to destroy the abnormal neovascularization, and the laser light activates the drug and the activated drug destroys the neovascularization.
The most popular treatment is the injection of anti-vascular endothelial growth factor antibodies into the eye. Lucentis, Ayla, and Avastin are some of the drugs that have been shown to be superior to other treatments, with many patients maintaining vision and some even improving vision. Intravitreal injections of anti-vascular endothelial growth factor antibodies are now the first-line treatment for wet AMD. Depending on the type of agent and the patient’s response to the agent, treatment and observation usually includes repeat injections at 4-8 week intervals and restarting treatment if the agent is discontinued or if the agent is discontinued and recurrent.
Progression/Complications
When diagnosed with early age-related macular degeneration, most patients at this stage have no self-reported symptoms and have good vision. However, as the disease progresses, the drusen become more severe, and by the time the disease reaches the end stage, vision is severely impaired.
As age-related macular degeneration progresses, the lesions can be categorized as dry or wet.
The dry form of the disease involves lesions under the retina, such as drusen and atrophy of the retinal pigment epithelium, and accounts for about 90% of age-related macular degeneration. The progression is slow, but over a long period of time, the degree of vision loss can become severe and the dry form can develop into the wet form.
The wet form accounts for about 10% of age-related macular degeneration and involves the growth of choroidal neovascularization under the retina. Progression is rapid, and these new blood vessels are weak and prone to rupture, causing exudates, hemorrhages, etc. in the macula, the most important part of the eye, reducing central vision and causing blindness.
In addition to choroidal neovascularization, there is also mapping atrophy in the later stages of age-related macular degeneration, which is associated with severe vision loss. Map atrophy is a partial atrophy of the retina in the macular area. It’s called cartographic atrophy because the atrophy seems to form a pattern. As the size of the drusen gradually increases and waste products accumulate under the retina, the retina becomes isolated, unable to receive oxygen and nutrients, and atrophies itself, causing serious vision loss.
Prevention
To prevent macular degeneration, it’s important to have regular eye exams to detect and treat macular abnormalities at an early stage. In some cases, people may think that presbyopia is inevitable as they get older, but they may not realize it until it’s too late. Therefore, it”s important to visit an ophthalmologist and have your retina examined if necessary.
Diet and lifestyle
If you have dry age-related macular degeneration, you should have regular check-ups with your doctor to see if it”s changing to wet and if it”s progressing. This can happen at any time, so it’s important to check yourself at home with an Amsler grid. Since we have two eyes, it’s not easy to notice if one eye is getting worse if we’re used to using both eyes, so it’s important to use an Amsler grid on the refrigerator, covering one eye at a time, and see an ophthalmologist without delay if you notice any abnormalities.
Smoking is an important risk factor, not just for macular degeneration, but for any disease that can affect the body. It”s especially important for people with macular degeneration to quit smoking, as it acts synergistically with many other risk factors, increasing the risk of late-stage macular degeneration.
There are also reports that exposure to ultraviolet radiation increases the risk of advanced macular degeneration. Therefore, sunglasses and hats may be helpful for people with macular degeneration if they are exposed to UV rays. High blood pressure and obesity have also been reported as risk factors for macular degeneration, so it”s important to maintain a healthy weight through diet and regular exercise.