Cataract Definition

Cataract – colloquially called cataract – (synonyms: cataract; cataracta; cataracta senilis; cortical cataract; senile cataract; ICD-10-GM H25.-: Cataracta senilis) is the name given to any form of opacification of the lens of the eye.

Cataract is by far the most frequent cause of vision loss. There are about 150,000 operations per year in Germany due to this disease.Cataracta senilis (senile cataract) represents the most common form of the disease with about 90%. Cataract can also be congenital (congenital), although this is very rare. The cause may be, for example, a prenatal infection.

The following forms of cataract senilis are distinguished:

  • Cataracta corticalis (cortical cataract).
  • Cataracta subcapsularis posterior (subcapsular posterior cortex opacity).
  • Cataracta nuclearis (nuclear cataract)

The lens of the eye consists of a cortex and nucleus. In cataracta corticalis (cortical cataract), the outer area of the lens, the cortex, is affected by the opacity. If cortical cataract progresses slowly, visual acuity may improve briefly because light can pass through occasional spaces between the widening spokes. Later, however, cortical cataract causes problems in both near and distance vision.In cataracta subcapsularis posterior (subcapsular posterior corneal opacification), a thin layer of fluid is found subcapsularly beneath the posterior portion of the lens. This form of cataracta senilis usually progresses rapidly. Near objects are seen significantly worse than distant objects due to near vision miosis (constriction of the pupil). Often a so-called nyctalopia is present, i.e. the patient can often see better than in daylight due to the dilating pupil in twilight, as it looks past the central opacity.In cataracta nuclearis (nuclear cataract) the lens nucleus gradually hardens. This age-related change, which is not pathological in itself – predominantly beginning in the 4th decade of life – first shows up as a yellowish-brown (cataracta nuclearis brunescens), later blackish (cataracta nuclearis nigra), colored central opacity. The increase in refractive power of the hardened lens leads to myopia of the eye, i.e. the patients can partially read again without near glasses, possibly even to double vision (diplopia). The phenomenon of nyctalopia described above may also occur in nuclear cataract.There are different stages of cataract, which gradually merge into each other:

  • Incipient cataract – slight opacity of the lens.
  • Advanced cataract – significant opacity of the lens.
  • Premature cataract – far advanced lens opacity.
  • Maturer (mature) cataract – both the lens cortex, but more so the nucleus are opacified.
  • Hypermature (overripe) cataract – the soft lens cortex material is absorbed, the lens capsule is shrunken; risk of phacolytic glaucoma (glaucoma).

Frequency peak: the disease occurs predominantly in older age (> 60 years).

The prevalence (disease frequency) is about 50% in people over 60 years (in Germany). Worldwide, about 17 million people suffer from a cataract, which is about half of all visually impaired people.

Course and prognosis: The course of a treated cataract is good. Full visual acuity can be restored by surgery. Rarely, the cataract as well as the surgery of it is associated with complications.