The plastic lens used in cataract surgery (Image: Mayo-Klinik)
About half of those over the age of 70 suffer from cataracts, also known as cataract, due to age-related clouding of the eye. The only therapy is the surgical replacement of the lens by a plastic lens. With around 600, 000 operations per year in Germany, the procedure has long been routine. He is usually outpatient. A look through frosted glass makes it clear how people with cataracts perceive their environment. Their surroundings are murky, the contours are blurred. With increasing opacity of the eye lens, a soon opaque gray veil would spread over the world: the patient goes blind. But the cataract does not initially come as a disease: "Everyone gets a lens opacity with age, " said Alf Reuscher, eye surgeon in Esslingen am Neckar and in the professional association of ophthalmologists Germany's head of eye surgery.

The clouding of the lens is a symptom of aging like the graying of the hair. Similar to how the hair turns into gray or white over a longer period of time in middle-aged years, a clouding of the lens is also subtle. It varies greatly from person to person. Sometimes the lens hardly becomes cloudy, but more and more frequently it becomes a problem at a higher age: around half of the seventy-year-olds suffers from the cataract, also called cataract. The fact that around 600, 000 cataract surgeries are being performed in Germany this year is simply due to the higher age of humans, "says Reuscher. But the patient clientele is getting younger, says Reuscher. The reason for this lies in the more demanding viewing habits such as the work on the screen.

If the lens becomes cloudy, its replacement with a plastic lens is the only therapy. With so many surgeries a year, it's routine. The Esslingen physician Reuscher, for example, operates 2, 000 eyes a year. Average operating time: 15 minutes. Together with the preparation and aftercare as well as a local anesthetic, the outpatient treatment lasts two hours.

"Of course, there are initially inhibitions in the patients, " says Reuscher. After all, vision is one of the most personal things a patient has. But in the high numbers of operations almost every person affected has a relative or acquaintance who can report on the routine intervention. Various studies also show positive effects beyond the restoration of vision. On the one hand, the better visibility reduces the risk of falling in the elderly. On the other hand, the mood brightens with the look. Moreover, if the brain is challenged more by reading, it can prevent dementia. display

"We used to say: The cataract must be mature, " explains Reuscher. Today, patients are operated on earlier. However, due to the degree of cloudiness, the suffering of the patient and the recommendation of the respective ophthalmologist, there is a great amount of time.

During surgery, the eye surgeon removes the old clouded lens. He introduces a small ultrasonic head into the eye. Lenticular tissue near the matchstick liquefies and is aspirated. The capsule shell of the eye lens is retained. This can later support the artificial lens.

In its shape, the new lens resembles a paragraph symbol (§): The round center part is made of acrylic plastic and has a diameter of six millimeters. It is fixed in the eye with the two curved hooks. During surgery, the lens is gently pushed into the eye in a cannula over a three millimeter access.

If the lens has unfolded, it aligns the eye surgeon. A small injection into the entrances closes them. It is not sewn. Easily dulled by tranquilizers, the patient can get up and be picked up straight away. He was supposed to save himself there a while longer and to visit his ophthalmologist several times in the following days. "After three weeks, then there's still glasses, then the matter is complete, " says Reuscher.

Each patient gets his own customized lens. Ophthalmologists use ultrasound to assess the eyes in the preliminary discussion. A computer program calculates the desired shape. Namely, the patient has one wish: Since the eye can no longer accommodate with the artificial lens, ie its ability to flexibly adjust the focus for near and distant vision is missing, the lens can only be focused on a fixed distance. This fixed distance, for which no glasses are needed, the patient can choose. For example, "normal sighted", then no glasses are needed for the distance view, but for reading.

Most commonly, however, a slight myopia of minus 0.5 to minus 1.0 diopters is chosen. This is almost the housewife or do-it-yourself distance: in the range of a short arm length to the worktop in the kitchen or hobby cellar, the view without glasses is okay. A progressive lens opens up the near field for reading and the long-distance vision for driving a car.

ddp / science.de Martin Sch fer

science.de

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