A cataract is a clouding of the normally clear lens of the eye. Cataracts are made from a protein that has altered from its natural state, distorting and eventually prohibiting required light from entering into the retina. The retina is the eye's sensitive layer that sends visual signals to the brain. To produce a sharp image, the lens must remain clear. Clouding of the lens is a normal part of getting older The name cataract stems from an ancient conception of something cascading from the "brain of humors" and depositing itself in front of the lens.



About half of Americans older 65 have some degree of clouding of the lens. After age 75 there are as many as 70 percent of Americans have cataracts that are significant enough to impair their vision.

Types of cataract are-

1. Secondary cataract. Cataracts can form after surgery for other eye problems, such as glaucoma.

2. Traumatic cataract. Cataracts can develop after an eye injury, sometimes years later.

3. Congenital cataract. Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect vision.

4. Radiation cataract. Cataracts can develop after exposure to some types of radiation.

Causes

A cataract can develop in one or both eyes. However, in most cases those caused by injury or trauma in both eyes. Certain medications like steroids and cigarette smoking also cause cataracts. Excessive long-term exposure to sunlight and exposure to heavy doses of radiation, as in cancer therapy can also result in a cataract. Trauma or a fall can dislocate a far advanced cataract as it has weak zonules. Sometimes cataract changes appear as polychromatic crystals within the lens; it is then called a 'Christmas Tree a cataract.

Congenital cataracts can also be caused by infections of the mother during pregnancy such as rubella or associated with metabolic disorders such as galactosemia.

People with diabetes are at increased risk for cataracts, particularly the posterior subcapsular type, and these cataracts tend to occur at an earlier age in people with diabetes than in the general population.

Symptoms

A cataract starts out small, and at first has little effect on your vision. A cataract may make light from the sun or a lamp seems too bright or glaring. Colors may not appear as bright as they once did. Symptoms of developing cataracts include double or blurred vision, sensitivity to light and glare, less vivid perception of color, and frequent changes in eye-glass prescriptions.

Treatment

In the old technique of this illness by which a 12mm incision is performed in the eye to extract the lens as a whole in the eyes. The lens' capsule is left in place to hold an intraocular lens. Multiple sutures are required to seal the eye after surgery.

Surgery is often not necessary or can be delayed for months or years. A cataract surgeon will discuss the options with the patient, and together they will decide which type of removal and lens replacement is best.