How do cataracts affect eyesight?


In cataracts, the lens of the eye gradually becomes cloudy. Those affected see increasingly blurred - like through fog or a veil. Sometimes eyesight is only slightly impaired, in others it becomes worse. Only an operation will help in the long term.

At a glance

  • Cataracts is an eye disease that causes the lens of the eye to become cloudy.
  • Those affected see increasingly blurred - like through fog or a veil.
  • Sometimes eyesight is only slightly impaired, in others it becomes worse.
  • Most often, cataracts appear in people over the age of 50.

Note: The information in this article cannot and should not be used as a substitute for a doctor's visit and should not be used for self-diagnosis or self-treatment.

What is the cataract?

Cataracts is an eye disease that causes the lens of the eye to become cloudy. This causes the eyesight to decrease. In particular, subtleties can then no longer be clearly recognized. The technical term for cataract is cataract.

The disease is called "cataracts" because the lens turns gray and those more severely affected often develop a fixed stare. However, in some people with cataracts, vision is only slightly impaired. In others, the limitations are more severe and eyesight is quickly lost. How the disease progresses depends, among other things, on the type of cataract.

Cataracts usually appear in the second half of life. Mostly people over 50 get sick. The risk increases over time: between the ages of 65 and 74, it affects around 20 in 100 people. It is more than half of those over 74 years of age.

In developing countries, cataracts are the main cause of blindness. In industrialized countries, significantly fewer people go blind because of the disease, as their eyesight can often be preserved through surgery. During this procedure, the cloudy lens is removed and replaced with an artificial one.

What are the symptoms of a cataract?

In cataracts, eyesight usually disappears gradually. The gradual loss of vision is the only symptom: otherwise there are no symptoms. People with cataracts see increasingly blurred and blurred - like through fog or a veil. Over time, the image becomes less contrasted and the colors also fade. Some sufferers develop a great sensitivity to glare - for example from the sun or other bright light sources. Driving also becomes more arduous, especially at night. The impairment of vision increases the risk of injury and falls. In addition, spatial vision diminishes.

Sometimes a cataract also has unexpected consequences: some people who wear glasses can suddenly see better without glasses. The reason: The disease changes the refractive power of the eye and thus the ability to see things clearly at different distances. However, this effect does not last long.

What are the causes of a cataract?

Around 90 percent of all those affected develop what is known as gray cataracts. Doctors then speak of a senile cataract. The reason for the gradual clouding of the lens is the aging process. Normally, the lens focuses the incident light and provides a clear image on the retina - both near and distant objects then appear sharp. The function of the lens is impaired in a cataract.

For some people, the risk of developing cataracts is hereditary. The disease is very rarely congenital. For example, a child with cataracts may be born if the mother contracted measles or rubella during pregnancy.

There is evidence that certain factors can increase the risk of cataracts. These include, for example, UV light and X-rays, but also smoking. People suffering from diabetes are also more often affected.

The disease can also develop as a result of eye infections or eye injuries. In addition, eye surgery can lead to cataracts. The same applies to certain drugs, such as cortisone, if they are used over a long period of time.

How does cataract develop?

Those who have a cataract gradually see worse and worse. Initially, the impairments show up as nearsightedness. Then, previously farsighted wearers of glasses can see better for a short time without glasses. In the course of the disease, those affected see more and more cloudy and blurred. If left untreated, cataracts can lead to blindness. But this does not have to be the case. As a rule, both eyes are affected. However, cataracts can advance faster in one eye than the other.

The cataract has different courses. Sometimes people lose eyesight quite quickly. Others have little or no vision impairment. A distinction is made between the following forms:

  • Cortical cataract: Those affected by this form not only see more blurred, but also react more sensitively to blinding light, for example when driving at night.
  • Posterior subcapsular cataract: This type is more common in younger people. It progresses relatively quickly.
  • Core cataract: In people with core cataract, far vision is more impaired than close vision. Sometimes the eyesight is only slightly impaired. This form of cataract usually only worsens very slowly.

Can cataracts be prevented?

There is no scientific evidence that certain preventive measures reduce the risk of cataracts. It is believed that smoking increases the risk. If you quit smoking, you could lower it again. Radiation such as UV light could also possibly promote the development of cataracts. People who are exposed to a lot of UV light can take care of good sun protection and protect their eyes from sunlight, for example with sunglasses. In addition, certain drugs containing cortisone can increase the risk of cataracts. Anyone who uses such agents can check whether it is possible to switch to another drug.

Advertisements for certain dietary supplements claim that they can help prevent eye diseases. However, studies show that such dietary supplements are ineffective for cataracts.

How is a cataract diagnosed?

There can be many reasons for deteriorating eyesight. In order to diagnose cataracts, the ophthalmologist will therefore first rule out other possible causes. The patient is asked about the symptoms and the medical history. Eye tests and exams can help determine how badly your eyesight is impaired and what could be the reason for it.

During the examination, the eye lens is also examined with a slit lamp. The doctor can look into the eye with this special light microscope. Since the eye is illuminated with a slit-shaped light beam, the lens and the sections of the eye behind it can be assessed. This examination is painless.

To examine the back of the eye, patients usually take a drug that dilates the pupil. This medication can make people blurry and feel more blinded for a few hours. Therefore you have to do without driving for about four to five hours afterwards. But sometimes the drug works even longer: When in doubt, it is better to leave the car behind.

How is cataract treated?

Some people with cataracts can use glasses or contact lenses to compensate for their impaired vision for some time or even longer. Cataracts cannot be treated with medication.

The only effective treatment option is surgery. During this procedure, the cloudy lens is removed and replaced with an artificial lens.

Whether and when an operation makes sense depends to a large extent on how much the vision loss affects life. It also plays a role whether someone has other (eye) diseases that could affect the operation.

You can find more detailed information on cataract surgery, for example, at

  • Allen D. Cataract. BMJ Clin Evid 2011: pii: 0708. Accessed on June 14, 2020.
  • Allen D, Vasavada A. Cataract and surgery for cataract. BMJ 2006; 333 (7559): 128-132. Accessed on June 14, 2020.
  • Asbell PA, Dualan I, Mindel J, Brocks D, Ahmad M, Epstein S. Age-related cataract. Lancet 2005; 365 (9459): 599-609. Accessed on June 14, 2020.
  • Jacobs DS. Cataract in adults. UpToDate 2019. Accessed on June 14, 2020.
  • Mathew MC, Ervin AM, Tao J, Davis RM. Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract. Cochrane Database Syst Rev 2012; (6): CD004567. Accessed on June 14, 2020.
  • Olson RJ, Braga-Mele R, Chen SH, Miller KM, Pineda R, Tweet JP et al. Cataract in the Adult Eye Preferred Practice Pattern®. Ophthalmology 2017; 124 (2): P1-P119. Accessed on June 14, 2020.

In cooperation with the Institute for Quality and Efficiency in Health Care (IQWiG). Was standing: