Sunday, November 20, 2011

Cataract

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A cataract is the clouding of the eye’s lens. It is not a growth or a film that can be peeled off. Located inside the eye, cataracts cannot be seen without a special microscope. Thus, they do not change the appearance of the eye; they do not cause discomfort. Changes may be so gradual that you are not aware of a cataract's effect at first. Although this clouding usually causes blurry vision, it is not painful. Normally, the blurring increases gradually over months or years. As the cataract grows, the patient may experience dimmed vision, blurriness, glare or light sensitivity, altered colour perception and increased nearsightedness.
 
Most cataracts occur in people over 60 years of age, but the disease can develop at any age and babies may be born with congenital cataracts. Cataracts can also be caused by eye injury, diabetes, certain medications (such as corticosteroids), radiation treatment, and ultraviolet light.Although there is no medicine or diet to cure cataracts, surgical removal of the cataract and replacement with a permanent artificial lens implant can restore lost vision.

Symptoms of Cataract ?

The first sign is usually a blurring of vision which cannot be corrected by glasses. Opacification, or clouding, nearly always develops at the edges of the lens and if progressive, impairs vision as it spreads inwards. Other symptoms may include seeing multiple images, poor vision in bright light, seeing a large black spot in front of the eye or haloes around lights.
 
Cataracts cause visual symptoms only; they do not cause pain, discomfort, tearing, or redness. The visual symptoms can vary. Blurriness, hazy vision, or increased glare from sunlight and headlights may be present. Some cataracts turn yellow, causing fading of color. Reading may take more effort, and you may tire prematurely. Vision progressively worsens over a period of years or sometimes after only a few months.
  
Some Frequently Asked questions about Cataract?

What Causes cataract ?

Some cataracts are caused by birth defects, injuries, diabetes, or prolonged use of certain medications, such as steroids. Highly nearsighted patients may develop cataracts at a young age. However, most cataracts result simply from the natural aging process of the human lens. Like grey hair, cataracts are not a disease, nor do they occur at the same age or rate in everyone.

When should cataracts be removed ?
 
The decision to have a cataract removed is elective. Because cataracts do not harm the other parts of the eye, nothing needs to be done if you are not significantly bothered by the symptoms. However, as activities such as driving and reading become increasingly affected by cataract, surgery becomes a logical option to consider.
 
With the success of the modern implant, waiting for cataracts to "ripen" is no longer necessary. Since cataracts will not improve and will eventually worsen, there is no advantage in delaying treatment if vision is sufficiently affected and the prognosis of surgery is good. You are never "too old" to have cataract surgery, just as you are never "too old" to enjoy better vision or a better quality of life.

How is the surgery performed ?
 
Cataract surgery is microsurgery; it utilizes an operating microscope and is performed inside the eye through an incision. One can think of the human lens as having a thin, transparent "wrapper" which holds the lens in the center of the eye. This delicate, cellophane-like skin is called the lens "capsule". A hole is made in the front of this wrapper, and the cloudy lens is removed in several delicate stages, leaving behind an empty, clear capsule. The implant is then inserted into this empty wrapper, occupying the original place of the natural lens.

What is a "lens implant" ?
 
To take the place of the clouded human lens, a tiny, delicately engineered artificial lens is implanted into the eye. The modern intraocular lens "implant" does not change the appearance or sensation of the eye. The implant is permanent. Unlike a contact lens, it cannot fall out and does not require cleaning.
The "prescription" or power of each patient's implant is selected based on computer calculations that use a series of precise eye measurements performed in the hospital prior to surgery. The distance between the front of the eye and the retina can be measured precisely using medical sonar (ultrasound). This painless test is called the "A scan".

What is a "small incision" cataract surgery ?
 
Removing the solid core of the cataract as a single piece requires a large incision with multiple sutures. Physical activities must be limited to avoid straining the large incision, which takes several months to stabilize.
Using the technique of "small incision surgery" with specialized technology called phacoemulsification, the firm cataract core is fragmented into small particles that can be gently sucked out through a tiny three mm incision (1/8 inch). Modern foldable lens implants can fit through incisions this small, and sutures are not required. Physical activities are not restricted after small incision surgery, and the vision stabilizes faster than with the conventional large incision method.

 
What is the success rate of surgery and how long does it take to recover ?
 
Cataract microsurgery is usually highly successful and more than 90% of patients are able to regain good vision. Surgery is done under topical or local anesthetic and it takes only 15 to 30 minutes. Following the procedure, the patient wears an eye patch for up to a day. It may take several weeks for the eye to heal completely and for the vision to stabilize, but some patients experience good vision on the day after surgery.

Is the surgery performed with a laser ?
 
For small incision surgery, the primary microsurgical tool used to ultrasonically remove the cataract is called a "phacoemulsifier". Lasers may be an appropriate adjunct in some cases. The YAG laser is sometimes employed months to years following the cataract surgery for a non-surgical treatment. Although the cataract cannot recur, the capsule behind the implant may later cloud and affect vision. This is not a complication. Thanks to the YAG laser, this can be painlessly corrected in the hospital without surgery.
 
What are the risks of cataract surgery ?
 
There is some risk with any surgical procedure. Fortunately, in experienced hands, severe complications that could worsen the vision are rare. The chances of eyelid, cornea, retina, and ocular pressure problems may depend on individual circumstances, but all may occur even without surgery - i.e. with aging alone. With modern advances in technique, more than 98% of patients with otherwise healthy eyes will gain significant visual improvement following surgery.

For More Informations Vist Shekar Nethralaya

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