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Last updated: January 5, 2022

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Cataract is a condition characterized by clouding of the lens of the eye. This condition most frequently occurs due to age-related degenerative processes in the lens, but can also be associated with ocular trauma, metabolic disorders, side-effects of drugs, or congenital infections. The clouding causes distortion of light, as it passes through the lens, resulting in visual impairment and glare. Initially, a cataract presents discretely and may even go unnoticed, but the visual impairment worsens as the cataract grows larger. Diagnosis is typically established on the basis of a thorough history and direct visualization of the cataract (by means of slit-lamp microscopy). Surgery is indicated with significant visual impairment and involves lens extraction and implantation of an artificial lens. Untreated cataracts eventually lead to complete blindness.

  • Leading cause of visual impairment and blindness in the world
  • Prevalence of acquired cataracts: increases with age
    • > 80 years: ∼70 %
    • 40–80 years: ∼ 17.5 %
  • Sex: >


Epidemiological data refers to the US, unless otherwise specified.

Clouding of the lens may be congenital or acquired.


  • Cataracts may be classified according to etiology (as above) or morphology
  • Morphological classification .

General clinical features

Clinical features usually develop gradually and depend on the localization and cause(s) of lens clouding.

  • Reduced visual acuity: blurred, clouded, or dim vision, especially at night
  • The impairment of vision is usually painless and often bilateral.
  • Glare: in daylight, in low sunlight, and from car headlights; associated with halos around lights .
  • Second sight
  • Opacities within the red reflex, darkening of the red reflex, or obscuration of ocular fundus detail during opthalmoscopy
  • Grey, white, yellow, or brownish clouding of the lens
  • Monocular diplopia: double vision that disappears when the eye with the pathology is covered or shut
  • Hyperopia (in cortical cataract)
  • Change in color perception
  • Special features in traumatic cataract

Special features in congenital cataract

Congenital cataracts usually present with different symptoms than acquired cataracts.


References: [5]

In most cases conservative treatment and drug therapy for cataract do not exist.

  • Indications for surgical treatment
    • To improve vision in individuals with significant cataract-related visual disturbances (by far the most frequent indication)
    • Medical indication (e.g., imminent phacolytic glaucoma or in ocular fundus diseases in order to gain clear insight of the ocular fundus)

Surgical treatment

Overview of surgical techniques
Description Advantages/disadvantages
  • Small incision, sutureless surgery, lower complication rates than ECCE
  • May not be feasible for advanced cataracts, costly surgery

Extracapsular cataract extraction (ECCE)

Intracapsular cataract extraction (ICCE)
  • Involves removal of the entire lens, including the posterior capsule.
  • The IOL can be implanted in the anterior chamber, sutured to the iris, or surgically fixated in the posterior chamber.
Manual small incision cataract surgery (MSICS)
  • Involves the manual removal of the entire lens, followed by division into small pieces, removal from the eye, and placement of a foldable lens through the same small incision.
  • Fewer sutures are used than for ECCE, cost-efficient

Cataract surgery does not require any anticoagulative measures.

Congenital cataracts should be treated surgically as soon as possible to prevent amblyopia (deprivation amblyopia).


We list the most important complications. The selection is not exhaustive.

  1. Eye Health Statistics at a Glance.
  2. Vision Problems in the U.S.: Prevalence of Adult Vision Impairment and Age-Related Eye Disease in America.
  3. Cataracts Defined Tables. . Accessed: March 15, 2018.
  4. Liu Y-C, Wilkins M, Kim T, Malyugin B, Mehta JS. Cataracts. Lancet. 2017; 390 (10094): p.600-612. doi: 10.1016/s0140-6736(17)30544-5 . | Open in Read by QxMD
  5. Nizami AA, Gulani AC. Cataract. StatPearls. 2021 .