Macular Degeneration

At the back of the eye lies a thin layer of light-sensitive cells. It absorbs incoming light and converts it into signals for the brain. In the center of this layer there is a tiny area that is especially densely packed with such cells. Only there can one really see sharply, for instance when reading or recognizing a face. In macular degeneration, cells gradually die off precisely in this small area. The result is a blurred or dark spot in the middle of the field of vision, while some vision remains at the periphery.

The most common cause of blindness in old age

According to estimates, several million people in Germany live with an early form of the disease. Among those over 75, roughly one in three is affected in some form. In wealthy countries, macular degeneration is thus the most common reason why older people largely lose their eyesight. Because the population continues to age, these numbers keep rising.

Of all things, the loss affects precisely those abilities that make everyday life independent. Reading, driving, cooking, recognizing acquaintances on the street: all of this depends on sharp central vision. Complete blindness, on the other hand, almost never occurs, because vision at the edge of the field remains intact. Those affected can therefore still find their way around a space, but can no longer make out a book or a price tag.

The disease is also relevant to the economy because treatment is expensive. Drugs for the aggressive form have for years been among the best-selling products in the pharmaceutical industry worldwide. At the same time, ophthalmology is one of the fields in which artificial intelligence was put to practical use early on.

Dry and wet form

Two courses of the disease are distinguished. In the dry form, metabolic waste products build up beneath the retina in the form of small yellowish deposits. The supply to the photoreceptor cells deteriorates, and they slowly die off over the years. Around 85 percent of all cases belong to this group. It progresses slowly, and so far there are hardly any effective medications against it.

The wet form is rarer but more dangerous. Here, new, leaky blood vessels grow into the retina. Fluid leaks out of them, the tissue swells, and vision can deteriorate significantly within weeks. Treatment involves injections directly into the eye that slow the growth of these vessels. The injections must be repeated regularly, often for years.

A common misconception: macular degeneration is not the same as cataracts. In cataracts, the lens at the front of the eye becomes clouded, and surgery usually restores vision. In macular degeneration, by contrast, nerve tissue is destroyed, and it does not regrow. The progression can be slowed, but the loss cannot be reversed.

Retinal images as a testing ground for diagnostic software

During an eye examination, images of the retina are produced, including cross-sectional scans that show the individual tissue layers. Deposits and fluid accumulations can be identified in these images. Precisely such images are well suited to programs that have learned to recognize patterns from many thousands of examples. Several systems of this kind have already been approved as medical devices in Europe.

For this reason, the disease regularly appears in reports from the tech industry. A collaboration between Google's AI subsidiary DeepMind and a London eye clinic became well known, in which software analyzed retinal images and provided recommendations on the urgency of treatment. Other projects attempt to predict which patients will progress from the dry to the wet form. The practical benefit lies in pre-sorting: ophthalmologists are in short supply, and the number of examinations is growing faster than the number of specialists.

In everyday life, one also encounters the topic through a simple self-test, the Amsler grid. With one eye, one looks at a grid pattern with a dot in the center. If the lines appear wavy or sections are missing, this is a warning sign. Risk factors include advanced age, smoking, and family predisposition.