A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light. Early in the development of age-related cataract the power of the lens may be increased, causing myopia, and Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated.
As a cataract becomes more opaque, clear vision is compromised. A loss of visual acuity is noted. Contrast sensitivity is also lost, so that contours, shadows and color vision are less vivid. Veiling glare can be a problem as light is scattered by the cataract into the eye. The affected eye will have an absent red reflex. A contrast sensitivity test should be performed and if a loss in contrast sensitivity is demonstrated an eye specialist consultation is recommended.
Cataracts develop for a variety of reasons, including long-term exposure to ultraviolet light, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age, or trauma (possibly much earlier); they are usually a result of denaturation of lens protein. Genetic factors are often a cause of congenital cataracts and positive family history may also play a role in predisposing someone to cataracts at an earlier age.Some drugs can induce cataract development, such as corticosteroids.
It can be associated with systemic conditions
* Chromosomal disorders
* 1q21.1 deletion syndrome
* Alport's syndrome
* Cri-du-chat syndrome
* Myotonic dystrophy
* Patau's syndrome
* Trisomy 18 (Edward's syndrome)
* Turner's syndrome
* Disease of the skin and mucous membranes
* Atopic dermatitis
* Metabolic and nutrition diseases
* Aminoaciduria (Lowe's syndrome)
* Diabetes mellitus
* Fabry's disease
* Galactosemia / galactosemic cataract
* Infectious diseases
* Congenital herpes simplex
* Congenital syphilis
* Cytomegalic inclusion disease
When a cataract is sufficiently developed to be removed by surgery, the most effective and common treatment is to make an incision (capsulotomy) into the capsule of the cloudy lens in order to surgically remove the lens. There are two types of eye surgery that can be used to remove cataracts: extra-capsular (extracapsular cataract extraction, or ECCE) and intra-capsular (intracapsular cataract extraction, or ICCE).