• Alternative names
• Defination
• Causes, Incidence and Risk Factors

• Prevention
• Symptoms
• Signs & Tests
• Treatment

• Expectations
• Complications
• Calling Your health care provider

Alternative Names
Lens opacity

Defination
A cataract is a clouding of a part of the eye known as the crystalline lens. The lens is a clear tissue located behind the pupil - the dark circular opening in the middle of the iris or colored part of the eye. The lens works with the transparent cornea, which covers the eye's surface, to focus light on the retina at the back of the eye. When the lens becomes cloudy, or cataractous, light cannot pass to the retina properly, and vision is blurred and decreased.

Causes, Incidence and Risk Factors

The lens of an eye is normally clear. If the lens becomes cloudy or is opacified it is called a cataract. Cataracts may be present at or shortly after birth in which case they are called congenital cataracts. Adult cataract develops with advancing age, tends to run in families, and the appearance may be accelerated by environmental factors. Cataract may develop at any time throughout life following an eye injury in which the capsule of the lens is damaged. Cataract may also develop in response to metabolic diseases such as diabetes.

Congenital cataracts are cataracts which are present from birth (or appear shortly after). They may be familial (autosomal dominant inheritance), or they may be caused by congenital infections such as rubella, or associated with metabolic disorders such as galactosemia. Risk factors include inherited metabolic diseases, a family history of cataract, and maternal viral infection.

Adult cataract is generally associated with aging. It develops slowly and painlessly with a gradual loss of vision. Visual problems may be heralded by difficulty seeing at night, halos around lights or glare when looking at lights, and finally, decreased visual acuity, even in daylight.

Adult cataracts are classified as immature, mature, or hypermature. A lens that has some remaining clear areas is referred to as an immature cataract. A mature cataract is completely opaque; a hypermature cataract has a liquefied surface that leaks through the capsule and may cause inflammation.

Most people develop some clouding of the lens after the age of 60. About 50 percent of Indian ages 65 to 74 have cataract and about 70 percent of those age 75 and over have it. Most people with cataract have it in both eyes, although one eye may be worse than the other. Many people with cataract don't even know they have it. Other factors that may contribute to cataract development are low serum calcium levels, diabetes, long-term use of corticosteroids, and other inflammatory and metabolic disorders.

Other causes include trauma, radiation exposure, and excessive exposure to ultraviolet light (sunlight). In many cases, the cause of cataract is unknown.

Prevention
The primary prevention involves controlling associated diseases and avoiding exposure to factors known to promote cataract formation. Wearing sunglasses when you are outside during the day can reduce the amount of UV light your eyes are exposed to. Some sunglasses do not filter out the harmful UV. The optician or salesperson at your optical shop should be able to tell you which sunglasses filter out the most UV.

Symptoms

• Cloudy, fuzzy, foggy, or filmy vision
• Changes in the way you see color
• Frequent changes in your eyeglass prescription
• Impaired vision at night, especially while driving, caused by effects of bright lights
• Problems with glare from lamps or the sun
• Halos around lights
• Double vision
• White spot or cloudy spot in the lens of the eye (the pupil, instead of being black appears milky or white)
  

Signs & Tests

• Standard ophthalmic exam
• Slit lamp examination
• Ultrasonography of the eye

Other tests that may be done (rarely) include:

• Glare test
• Contrast sensitivity test
• Potential vision test
• Specular photographic microscopy

Treatment

OVERVIEW:
Cataract treatment is done simply to improve vision. For some people changing their glasses, getting stronger bifocals, or using a magnifying lens is helpful enough. Others choose to have cataract surgery.

If you are not bothered by a cataract, then treatment is usually not necessary. On occasion, there may be an additional eye problem that the doctor needs to see or treat and the cataract impairs the doctors view. In these cases, cataract surgery may be required to allow proper treatment of the other eye problem.

SURGERY:
Cataract surgery consists of removing the lens of the eye and replacing it with an artificial one. Your doctor will discuss the options with you and together you will decide which type of removal and lens replacement is best for you.

LENS REMOVAL
There are 3 different types of surgery that can be used to remove lenses that have a cataract.

Extracapsular surgery consists of surgically removing the lens, but leaving the back half of the capsule (the outer covering of the lens) intact.

Phacoemulsification is done by softening the lens with sound waves and then removing it through a needle. The back half of the lens capsule is left behind.

Intracapsular surgery involves surgically removing the entire lens, including the capsule. This is done very rarely.

LENS REPLACEMENT
People who have cataract surgery usually get an artificial lens at the same time. The artificial lens is a plastic disc called and intraocular lens. It is placed in the lens capsule inside the eye.

Other options include contact lenses and cataract glasses. You and your doctor will decide which choice is best for you.

Surgery can be done in an outpatient center or hospital, and you can leave when your doctor says you are fit to go. Most people do not need to stay overnight in a hospital. You will need a friend or family member to take you home and someone will need to stay with you for a day or two to help you follow your doctor's instructions.

It takes a few months for an eye to heal totally so your doctor should check your progress periodically and make sure you have the care you need until your eye fully recovers.

Expectations (Prognosis)
For most people, cataract surgery is associated with a relatively low risk. With implanted artificial lenses, some people no longer need corrective lenses for distance vision, but they are usually necessary for reading and near vision.

Complications
Vision may not improve after cataract surgery if other eye diseases such as macular degeneration are present. Unfortunately, it is not always possible to evaluate for such diseases before the surgery. In infants, amblyopia and decreased visual development may occur as a result of cataract. Early diagnosis and treatment is essential.

Disclaimer