Brief overview
- What is macular degeneration? Progressive eye disease (AMD), onset mainly in older age, doctors distinguish dry from wet AMD.
- Symptoms: blurred vision in the central field of vision, decrease of color vision and brightness differences, straight lines appear bent or distorted. In the late stages, bright, gray or black spot in the center of the field of vision. In severe cases, extensive blindness.
- Examinations: Amsler grid, ophthalmoscopy, fluorescein angiography, optical coherence tomography, visual acuity determination.
- Treatment: Depending on the form of macular degeneration. Administration of zinc and copper oxide, vitamins, laser treatment, photodynamic therapy, laser treatment, antibody therapy, rarely surgery.
- Prognosis: Progressive, not curable disease; individual courses; dry AMD usually progresses slowly, wet AMD usually faster.
What is macular degeneration?
Doctors call macular degeneration a progressive disease of the eye, which occurs mainly in old age. The sensory cells in a certain area of the retina, the macula, are damaged and perish.
Age-related macular degeneration
There are different forms of macular degeneration. By far the most common is age-related macular degeneration (AMD), which can occur as a dry or a wet variant. Rarer are other forms of macular degeneration, where genetic defects or other factors are the cause.
In the western industrialized countries, this disease is overall the most common cause of significant visual impairment in older age. According to estimates, about 67 million people in the European Union are affected by age-related macular degeneration. Annually about 400000 new cases are added in Europe.
Dry macular degeneration
Since dry macular degeneration progresses only slowly over years, it initially affects vision only slightly. However, it can change into a wet macular degeneration at any time. This progresses faster.
Wet macular degeneration
In response, the body tries to restore the blood supply. It produces certain messenger substances known as growth factors (VEGF-A). They stimulate the formation of new small blood vessels. However, the new vessels also grow through the gaps under the retina, where they do not actually belong.
Wet macular degeneration progresses much faster and more dangerous than the dry form.
What are the symptoms of macular degeneration?
Which symptoms occur depends on how far the disease has already progressed.
Symptoms in the early stage
Often macular degeneration in the early stages is an incidental finding at the ophthalmologist, especially since it does not cause pain.
Symptoms in the further course
First symptoms appear when AMD progresses and both eyes are affected. This is the case for example when reading: The center of the text appears slightly blurred or overlaid by a gray shadow.
In addition, those affected sometimes perceive their surroundings in a distorted way (metamorphopsia). This is particularly evident when looking at straight lines, such as grid patterns or tile joints. The straight lines suddenly appear distorted or curved.
In addition, color vision suffers, since in macular degeneration a large part of the cones (visual sensory cells for color perception) in the retina is destroyed. Colors gradually fade, and those affected increasingly see only in black and white.
If AMD enters its “wet”, exudative stage, visual acuity rapidly decreases. In addition, sudden visual disturbances up to loss of vision may occur, for example in case of bleeding from the unstable vessels.
Causes and risk factors
However, since the retina around the yellow spot often remains intact, one does not go completely blind with this disease. Accordingly, in macular degeneration, the edges of the field of vision are still perceived, but not what one fixes in the center of the field of vision.
What is the macula?
Only with an intact macula is it possible to fixate and see something sharply. Without a macula, one would not be able to read, recognize faces and perceive the environment only dimly. Because the macula also stands out in color from the rest of the retina due to the many sensory cells, it is also known as the “yellow spot”.
Metabolism and degradation processes in the retina
Once the light has reached the sensory cells, the visual pigment (rhodopsin) is consumed. In addition, tiny particles (membrane discs) split off from the rods. In order to be ready for the next light stimulus, the rods must first regenerate.
Risk factors for AMD
Several risk factors can promote the development of age-related macular degeneration. These include in particular:
Smoking: Nicotine consumption worsens blood flow, including to the eye. As a result, the retina does not get enough oxygen. In addition, metabolic products in the retina are less easily removed by smoking. People who smoke for many years are therefore more susceptible to macular degeneration.
Possibly also high blood pressure (hypertension), hardening of the arteries (arteriosclerosis) and an increased BMI (body mass index) promote macular degeneration. Frequent exposure to sunlight with unprotected eyes is also suspected as a risk factor.
Sometimes patients taking the drug chloroquine for malaria prophylaxis or treatment of inflammatory rheumatic diseases develop macular degeneration in the course. However, these are exceptional cases.
Macular degeneration as a result of a genetic defect
Some people develop the typical symptoms of macular degeneration due to a genetic defect, already in childhood and adolescence. Examples for such genetic defects are Best disease (vitelliform macular degeneration) and Stargardt disease. In the case of Stargardt’s disease the photoreceptors perish due to toxic degradation products.
Macular degeneration as a consequence of myopia
Examinations and diagnosis
The first contact person in case of visual disturbances is the ophthalmologist. The typical changes in vision provide the doctor with indications of AMD, but are not sufficient on their own for a diagnosis. Other diseases of the eye can also cause similar complaints. After the doctor has inquired about the medical history, risk factors and current symptoms, detailed examinations of the eye therefore follow:
Amsler grid
A conspicuous finding is not yet a proof for a macular degeneration, but first only a general indication for a retinal damage!
The Amsler grid is also available on the internet. Whoever wants to can test himself at first in case of suspicion of macular degeneration (or retinal damage in general).
Examination of the ocular fundus (ophthalmoscopy)
In macular degeneration typical structures like drusen and degenerated, thinned out tissue are often visible. In wet macular degeneration also sprouting vessels, leaked fluid (exudate) and hemorrhages are visible.
Usually the examiner photographs the back of the eye during the ophthalmoscopy to compare the condition with later photographs. This allows the progression of the disease to be documented.
Fluorescence angiography
Optical Coherence Tomography
Optical coherence tomography (OTC) is an imaging technique used to visualize the retina. With the help of a weak and harmless laser light, the physician creates high-resolution slice images of the retina. This makes it possible to assess its thickness or fine structure. The examination is easier to perform than fluorescein angiography (no injection required) and painless for the patient.
Determination of visual acuity
Treatment
AMD is a chronic, progressive disease that cannot be cured causally. However, with the help of special therapies, it is possible to slow down the progression of the disease and improve the quality of life of those affected. How the doctor treats macular degeneration depends on whether it is wet or dry AMD and how far the disease has already progressed.
Treatment of dry macular degeneration
There are only a few treatment options for dry macular degeneration. First and foremost is the control of those risk factors that additionally worsen the disease. Doctors therefore recommend to stop smoking and to get high blood pressure and overweight under control.
Have your eyes examined regularly by an ophthalmologist! This is the only way to detect the transition from dry to wet AMD in time!
Treatment of the wet macular degeneration
The treatment of wet macular degeneration aims at preventing the formation of new vessels in the area of the macula. Vascular neoplasms are the reason that wet AMD usually progresses rapidly. There are different treatment methods available.
Photodynamic therapy
In photodynamic therapy, the physician injects a non-toxic dye into the patient’s arm vein. This accumulates in the diseased vessels. The physician then irradiates the vessels with a special laser. The laser light activates the dye and triggers a chemical reaction that specifically obliterates the vessels in the retina. Surrounding healthy tissue such as sensory cells, nerve fibers and healthy vessels are thus preserved.
Monoclonal antibodies are special drugs that can slow the progression of the disease and improve visual acuity. They bind to and thus block those proteins (VEGF-A) that stimulate the growth of new retinal vessels. Without the growth stimulus, no or at least fewer new blood vessels form. Doctors refer to these antibodies as “VEGF inhibitors.
The doctor injects the antibodies directly into the eyeball with a fine needle (intravitreal surgical drug application = IVOM). Since the effect only lasts for a certain time depending on the preparation, regular injections are necessary.
Surgical procedures
Surgical procedures such as “subretinal surgery” or “retinal rotation” (retinal rotation) with displacement of the macula are only useful in rare cases. Some of them are still being tested or further developed.
Therapeutic approaches without proven efficacy
Some people use alternative treatments for macular degeneration: Acupuncture for example can achieve positive effects in individual cases especially in dry macular degeneration.
Measures which have no proven efficacy and whose scientific background is questionable are suitable at most in addition to a treatment with proven efficacy.
Course of the disease and prognosis
Dry macular degeneration usually progresses slowly. Sometimes it can even come to a standstill for a longer period of time. Then the patients do not notice any worsening of the symptoms for months, sometimes even years. However, a complete standstill is very unlikely, although such cases have been described occasionally.
Prevention
The probability of developing AMD increases with age. Therefore it makes sense to visit the ophthalmologist regularly from the age of 40. This way he can detect and treat age-related macular degeneration at an early stage.
Nicotine consumption is moreover considered a safe risk factor. Therefore a complete stop of smoking is advisable! The same applies to high blood pressure and overweight: Try to keep your blood pressure at a normal level and to reach a normal weight!
