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Related to cataract: Cataract surgery, glaucoma


in medicine, opacity of the lens of the eye, which impairs vision. In the young, cataracts are generally congenital or hereditary; later they are usually the result of degenerative changes brought on by aging or systemic disease (diabetesdiabetes
or diabetes mellitus
, chronic disorder of glucose (sugar) metabolism caused by inadequate production or use of insulin, a hormone produced in specialized cells (beta cells in the islets of Langerhans) in the pancreas that allows the body to use and store
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). Cataracts brought on by aging are most common; most individuals over 60 exhibit some degree of lens opacity. Injury, extreme heat, ultraviolet light, X rays, nuclear radiation, inflammatory disease, and toxic substances also cause cataracts. There is growing concern that further disintegration of the ozone layerozone layer
or ozonosphere,
region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12–30 mi (19–48 km) above the earth's surface.
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 will increase the incidence of cataracts. Advanced cataracts are usually treated by surgical removal of the lens and implantation of an artificial lens. After cataract surgery, which is the most common surgical procedure in the United States, most patients do not require thick glasses or contact lenses.



an opacity of the crystalline lens of the eye that prevents light from penetrating into the eye and that results in decreased visual acuity. The term “cataract” reflects the mistaken conception of the ancient Greeks that a cataract is caused by the effusion of a turbid fluid between the iris and the lens. Cataracts are distinguished according to the location of the opacity in the lens: capsular (in the capsule covering the lens), cortical (in the peripheral layers of the lens), and nuclear (in its central layers).

Cataracts may be congenital or acquired. Congenital cataracts develop in the intrauterine period, and the opacity generally does not enlarge or change with age. In congenital cataracts, parts of the lens almost invariably remain transparent, and visual acuity is not completely impaired. Depending on the site of the opacities, cataracts may be anterior or posterior polar (limited opacities of the capsule of the lens), lamellar, and so forth.

Senile cataracts constitute most of the acquired cataracts, and they are characterized by progression of the opacities of the lens. In senile cataracts, opacities appear first in the periphery of the lens (incipient senile cataract), and vision remains unimpaired. The number of opacities then increases and they coalesce, resulting in a marked decrease in visual acuity (immature cataract). As the condition develops, all the layers of the lens become cloudy and it turns grayish white or mother-of-pearl; visual acuity decreases to photoperception—that is, the eye becomes virtually blind (mature senile cataract). Also acquired are complicated cataracts that arise in some systemic diseases (diabetes, cholera, digestive disorders) or result from diseases of the eye itself (inflammation of the uveal tract, progressive myopia). Cataracts resulting from eye injuries, effects of radiation, and so forth constitute a large group of acquired cataracts.

Treatment is generally surgical. In some cases it involves transplanting an artificial lens.


Dymshits, L. A. “Bolezni khrustalika.” In Mnogotomnoe rukovodstvo po glaznym bolezniam, vol. 2, book 2. Moscow, 1960.



A waterfall of considerable volume with the vertical fall concentrated in one sheer drop.
An opacity in the crystalline lens or the lens capsule of the eye.


1. a large waterfall or rapids
2. Pathol
a. partial or total opacity of the crystalline lens of the eye
b. the opaque area
References in periodicals archive ?
Of the 570 patients that underwent cataract surgery, 527(92.
Your veterinarian will dilate the dog's pupil and examine the pupillary region or use a slit-lamp biomicroscope, which allows your veterinarian to directly examine the lens in the eye to determine if the problem is a cataract.
However, if vision cannot be corrected and is interfering with a patient's activities of daily living, cataract surgery can be considered.
In standard cataract surgery, a technique called phacoemulsification, a surgeon makes a small incision in the cornea using a blade, and inserts a probe that vibrates with ultrasound waves to emulsify the cataract and suction out the debris.
1% topical Nepafenac is effective in prevention of macular edema after cataract surgery in patients with non-proliferative diabetic retinopathy (NPDR).
The ophthalmologist performs a full eye examination for diagnosis of cataract and for making the clinical decision whether cataract surgery should be performed.
Researchers found those participants who had a higher intake of vitamin C were associated with a 33% risk reduction of cataract progression and had "clearer" lenses after the 10 years than those who had consumed less vitamin C as part of their diet.
Genetic factors were responsible for 35% of the difference in cataract progression, while environmental factors, such as diet, accounted for 65%, suggesting that genetic impact on cataract development may be less significant than previously believed.
The advent of Femtosecond Laser Assisted Cataract Surgery (FLACS) may prove to be one of the most important developments in the modern era of cataract surgery.
According to PhilHealth, at least 10 eye clinics are under investigation for possible fraud in connection with their multi-million peso claims for eye cataract surgeries.
The most common forms of cataract are still not prone to effective prevention and great efforts are therefore being made to provide sight restoring surgery; over the last 10 years new technology and techniques have improved such as surgery, including the implantation of intraocular lenses, now almost always used in patients in developed countries.