cortical cataract


Also found in: Dictionary, Thesaurus, Legal, Encyclopedia, Wikipedia.
Related to cortical cataract: Posterior Subcapsular Cataract, Nuclear sclerosis, subcapsular cataract

cataract

 [kat´ah-rakt]
opacity of the lens of the eye or its capsule. adj., adj catarac´tous.
Causes and Symptoms. Some cataracts result from injuries to the eye, exposure to great heat or radiation, or inherited factors. The great majority, however, are “senile” cataracts, which are apparently a part of the aging process of the human body.

Blurred and dimmed vision are often the first symptoms. The patient may find that a brighter reading light is needed, or objects must be held closer to the eyes for better vision. Continued clouding of the lens may cause double vision; eventually there may be a need for frequent changes of eyeglasses. These symptoms do not necessarily indicate cataract, but if any of them are present, an ophthalmologist should be consulted immediately.
Treatment. The only known effective treatment for cataract is surgical removal of the lens (lens extraction or cataract extraction). The procedure of choice was formerly intracapsular extraction, with total removal of the lens within its capsule. This may be done by forceps or by cryoextraction using a supercooled metal probe that forms a bond with the lens capsule. The inner portion of the lens can be removed by emulsification and aspiration. More recently the removed cataract has been replaced with a plastic intraocular lens. In this procedure the inner portions of the lens (the nucleus and cortex) may be all that is removed; the capsule is retained and the intraocular lens is placed inside it.

The lens of the eye serves only to focus light rays upon the retina. After cataract extraction the loss of the natural lens is compensated for by either special eyeglasses or contact lenses. Implantation of a permanent artificial lens, either during cataract surgery or later, is an alternative to use of cataract spectacles and a removable contact lens.
Patient Care. Eye drops are administered to produce mydriasis and vasoconstriction. Because these patients may have extremely poor eyesight, care should be taken that they do not injure themselves. (See also vision.) Local anesthesia is usually preferred for the surgical procedure and preoperative medications are given to produce drowsiness. Ambulatory care surgery with same-day admission and discharge is becoming increasingly routine. Careful observation of the patient on follow-up visits is important. One needs to be on the alert for a complaint of pain in the eye followed by nausea and vomiting. These could be signs that the patient has increased intraocular pressure within the operative eye and measures need to be taken to reduce the pressure.
after-cataract any membrane of the pupillary area after extraction or absorption of the lens. See also secondary cataract.
atopic cataract cataract occurring, most often in the second to third decade, in those with longstanding atopic dermatitis.
brown cataract (brunescent cataract) senile cataract appearing as a brown opacity.
capsular cataract one consisting of an opacity of the capsule of the lens.
complicated cataract secondary cataract.
cortical cataract an opacity in the cortex of the lens.
hypermature cataract one in which the entire lens capsule is wrinkled and the contents have become solid and shrunken, or soft and liquid.
immature cataract (incipient cataract) an incomplete cataract; the lens is only slightly opaque and the cortex clear.
intumescent cataract a mature cataract that progresses; the lens becomes swollen from the osmotic effect of degenerated lens protein, and this may lead to secondary angle closure (acute) glaucoma.
lenticular cataract opacity of the lens not affecting the capsule.
mature cataract a cataract that produces swelling and opacity of the entire lens; cataracts are removed before maturity.
presenile cataract a subcapsular senile cataract in a person under 40 years of age.
secondary cataract a cataract, usually posterior subcapsular, that arises from either disease (especially iridocyclitis), degeneration (such as chronic glaucoma or retinal detachment), or surgery (such as glaucoma filtering or retinal reattachment).
senile cataract cataract with no obvious cause occurring in persons over 50 years old.

cor·ti·cal cat·a·ract

a cataract in which the opacity affects the cortex of the lens.
Synonym(s): peripheral cataract

cor·ti·cal cat·a·ract

(kōr'ti-kăl kat'ăr-akt)
A cataract in which the opacity affects the cortex of the lens.

cataract

opacity of the lens of the eye or its capsule or both. Cataract may result from injuries to the eye, exposure to great heat or radiation, or inherited factors. Rare in cattle and swine, common in dogs. Treatment consists of surgical removal of the lens (lens extraction or cataract extraction). May affect the entire lens or be localized, e.g. posterior polar cataract.

acquired cataract
any non-congenital cataract; usually the result of trauma, systemic disease or another eye disorder.
after-cataract
1. any membrane of the pupillary area after extraction or absorption of the lens.
2. secondary cataract (below).
capsular cataract
one consisting of an opacity of the capsule of the lens.
complicated cataract
a cataract occurring secondarily to other intraocular disease.
congenital cataract
present at birth; often not progressive. See also white eye calf syndrome.
cortical cataract
an opacity in the cortex of the lens. The common form of cataract in dogs; inherited in many breeds, often in association with progressive retinal atrophy.
developmental cataract
one that occurs at any age before the animal becomes an adult.
diabetic cataract
one associated with diabetes mellitus.
electric cataract
one caused by electrical current as in electrocution.
embryonal cataract
one caused by prenatal influences.
focal ring cataract
a perinuclear opacity with normal lens fibers surrounding it. Usually the result of an in utero or neonatal insult to the lens.
galactosemic cataract
hyaloid cataract
a focal opacity at the point where the hyaloid artery meets the posterior lens capsule. See also mittendorf's dot.
hypermature cataract
one in which the lens has begun to liquefy.
immature cataract
incomplete opacity.
incipient cataract
a very early stage of development with no impairment of vision.
inherited cataract
occurs in a number of breeds of cattle, often in combination with other abnormalities of the eye. Affected calves are usually normal in other respects and can be reared if the inconvenience of their blindness can be overcome. Also occurs in dogs, often with late onset and in association with other inherited ocular defects such as progressive retinal atrophy.
intumescent cataract
a mature cataract that has become swollen.
juvenile cataract
one developing in very young animals, for example dogs less than 6 months of age.
lenticular cataract
opacity of the lens not affecting the capsule.
mature cataract
one in which the lens is completely opaque.
morgagnian cataract
liquefaction, except the nucleus which drops to the bottom of the lens, and shrinkage of the capsule.
nuclear cataract
one involving the nucleus of the lens; the common form of congenital cataracts.
nuclear Y cataract
a form of congenital cataract in which small opacities outline the Y suture of the nucleus.
nutritional cataract
radiation cataract
one caused by radiation, as in radiotherapy.
reduplication cataract
a capsular opacity covered by another layer of epithelium.
secondary cataract
1. one that forms after most of the lens has been removed.
2. complicated cataract.
senile cataract
occurs in the aged of all species, preceded by nuclear sclerosis.
subcapsular cataract
may be anterior or posterior. Inherited in several breeds of dogs.
toxic cataract
one caused by exposure to a toxic substance.
traumatic cataract
one caused by trauma.
References in periodicals archive ?
Compared to rural residents with nitrate-nitrogen exposure of less than 5 parts per million (ppm), rural residents whose well water had concentrations of nitrate-nitrogen of 10 ppm (OR; 95% CI) had higher odds of developing cortical cataract (1.
However, after adjusting for age and sex, an interaction between sun-sensitizing medication use and UV-B exposure was associated with the development of cortical cataract.
29,30) The aetiology of cataract is multifactorial, although it has been estimated that 6-38% of cortical cataract occurs due to sunlight exposure.
Optometrists are in a prime position to advise about the link between UV-B and cortical cataract, particularly in those patients with cortical opacity or with a family history of the disease.
The incipient anterior cortical cataracts observed in this study possibly will progress with age and result in vision deficits.
5 times more likely to develop cortical cataracts than those whose intakes averaged between 101 and 185 g per day.
The second study found that higher carbohydrate intakes were associated with an increased risk of one type of cataract called cortical cataracts.