Macular degeneration

The central part of the retina (the macula) is responsible for perceiving fine details and colors. This is made possible because the largest concentration of contrast and color vision cells (the cones) is present in the center. Macular degeneration is a condition in which these cones die.

Age-related macular degeneration (AMD)

This form is by far the most common. Age-related macular degeneration usually starts after the age of fifty. In the Western world, including the Netherlands, AMD is the main cause of permanent vision deterioration in people over 65 years of age.

The quality of vision can also decrease because, for example, straight lines (bathroom tiles) become crooked.

As the number of older people continues to increase, AMD will become an increasing public health problem. Two main forms can be distinguished:

1. The ‘dry’ AMD

This form begins as small pale yellow deposits called ‘drusen’ that begin to accumulate in the macula. The occurrence of these drusen is associated with a reduction in the number of cones in the macula, which will deteriorate vision. This is an insidious and very slow process, and it can take many years before vision deteriorates. Usually both eyes are affected more or less equally.

With dry AMD it is important that you monitor whether distortion occurs in the images of the environment, such as a bend in a window frame or line of a notebook. This may indicate the development of the ‘wet’ form.

Treatment and monitoring of dry AMD

It is common to start treatment by means of lifestyle advice and possibly nutritional supplements. The prevention of progression is checked (half) annually. It is important that a straight line test is performed regularly (daily/weekly/monthly) for monitoring purposes.

2. The ‘wet’ AMD

This form of AMD is also called exudative AMD, wet AMD, discoid AMD or Junius‐Kuhnt disease. With wet AMD, vision loss occurs much more quickly.

Wet AMD occurs when blood vessels grow behind the macula, causing fluid and blood to end up in or under the retina (that is why it is called ‘wet’ AMD). This leakage damages the light-sensitive cells in the retina, causing rapid and severe vision deterioration. Ultimately, a scar develops in the macula, resulting in loss of central vision. It is striking that the other eye can remain good for a long time.

How does AMD affect vision?

With dry AMD, small parts of the image gradually disappear and image distortion may also occur. Very slowly, vision will deteriorate. In the wet form of AMD, the images become distorted and new blood vessels form under/in the retina (subretinal neovascularization). These new vessels are weak and bleed easily, causing visual acuity to decrease rapidly. Ultimately, AMD leads to a blind spot in the center of the field of vision. Most people with AMD retain reasonable peripheral vision. Complete blindness, being unable to see anything, therefore rarely occurs with AMD.

Risk factors for AMD include:

  • Age – In the Netherlands, it is estimated that approximately 14% of people between the ages of 55 and 64 suffer from some form of AMD. This rises to almost 20% in the group of 65 to 75 year olds and to 37% among the over 75s.
  • Heredity – You have a higher risk of developing the condition if one or more of your blood relatives has AMD.
  • Smoking – AMD is five times more likely to occur in people who smoke more than a pack of cigarettes per day. An increased risk remains even up to 15 years after someone has stopped smoking.
  • Alcohol and Nutrition – Alcohol also removes antioxidants from the body. Furthermore, high concentrations of saturated fats and cholesterol, which are known to be harmful to blood vessels, may also be involved in the development of free radical damage to the macula.
  • Gender – A woman over 75 years old is twice as likely to develop AMD as a man of the same age. Low levels of estrogen (a hormone in the blood) in women after menopause increases the risk of the condition.

Diagnosis

To determine AMD, the ophthalmologist will first test your visual acuity. Furthermore, they can test (at home) with a checkered page or by means of the straight lines of the bathroom tiles whether there are distortions or other abnormalities in your vision. If you notice distortions, you should be seen by an ophthalmologist as soon as possible within a week, if necessary by referral from your family doctor.

After dilating the pupil by instilling drops in the eyes, the ophthalmologist can examine the entire retina and in particular the macula with a lamp and a magnifying glass. This examination is called “mirroring”. Additional examination is usually necessary, such as Fluorescence Angiography or a scan (OCT scan).

Treatment and monitoring of wet AMD

A direct The treatment of AMD is usually only possible in the early stages of the ‘wet’ form of AMD. Although visual acuity improves in a minority of patients, in most cases a stabilisation of the vision can be achieved. In approximately 50% of cases an improvement occurs with the treatment.

Treatment is possible with medicines that reduce the fluid. The treatment is done by injecting a very small amount of medicine into the eye every month. In some cases a one-off laser treatment of the leaking fluid spot is also possible. The condition can often be chronic in nature, so that monitoring and treatment is required for years (intermittently).

to Treatment of Mascular Degeneration