A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens is mostly made of water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.
But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see.
Researchers are gaining additional insights about what causes these specific types of proteins (crystallins) to cluster in abnormal ways to cause lens cloudiness and cataracts. One recent finding suggests that fragmented versions of these proteins bind with normal proteins, disrupting normal function.
A subcapsular cataract begins at the back of the lens. People with diabetes, high farsightedness or retinitis pigmentosa, or those taking high doses of steroids, may develop a subcapsular cataract.
A nuclear cataract is most commonly seen as it forms. This cataract forms in the nucleus, the center of the lens, and is due to natural aging changes.
A cortical cataract, which forms in the lens cortex, gradually extends its spokes from the outside of the lens to the center. Many diabetics develop cortical cataracts.
A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting.
Hazy or blurred vision may mean you have a cataract.
A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did.
The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called "second sight."
Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. On the other hand, a subcapsular cataract may not produce any symptoms until it's well-developed.
If you think you have a cataract, see an eye doctor for an exam to find out for sure.
No one knows for sure why the eye's lens changes as we age, forming cataracts. Researchers are gradually identifying factors that may cause cataracts — and information that may help to prevent them.
Many studies suggest that exposure to ultraviolet light is associated with cataract development, so eye care practitioners recommend wearing sunglasses and a wide-brimmed hat to reduce your exposure.
Other types of radiation may also be causes. For example, a 2005 study conducted in Iceland suggests that airline pilots have a higher risk of developing nuclear cataract than non-pilots and that the cause may be exposure to cosmic radiation. A similar theory suggests that astronauts, too, are at risk from cosmic radiation.
Other studies suggest people with diabetes are at risk for developing a cataract.
The same goes for users of steroids, diuretics and major tranquilizers, but more studies are needed to distinguish the effect of the disease from the consequences of the drugs themselves.
Some eye care practitioners believe that a diet high in antioxidants, such as beta-carotene (vitamin A), selenium and vitamins C and E, may forestall cataract development. Meanwhile, eating a lot of salt may increase your risk.
Other risk factors include cigarette smoke, air pollution and heavy alcohol consumption.
A small study published in 2002 found lead exposure to be a risk factor; another study in December 2004, of 795 men age 60 and older, came to a similar conclusion.
But larger studies are needed to confirm whether lead can definitely put you at risk and, if so, whether the risk is from a one-time dose at a particular time in life or from chronic exposure over years.*
Researchers say additional studies also are needed to confirm whether hormone replacement therapy (HRT) significantly increases chances that cataracts will form and progress to the point that surgical removal is required.
An eight-year study of more than 30,000 postmenopausal Swedish women found a 14 percent increased risk for cataract removal among those who used HRT at any time and an 18 percent increased risk for current HRT users.
HRT use combined with regular alcohol consumption appeared to create a 42 percent increased risk of cataract removal, compared with women who had never used HRT or alcohol.
The HRT study was reported in the March 2010 issue of Ophthalmology.
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When symptoms begin to appear, you may be able to improve your vision for a while using new glasses, strong bifocals, magnification, appropriate lighting or other visual aids.
Think about surgery when your cataracts have progressed enough to seriously impair your vision and affect your daily life. Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure to regain vision.
Cataract surgery is very successful in restoring vision. In fact, it is the most frequently performed surgery in the United States, with more than 3 million Americans undergoing cataract surgery each year. Nine out of 10 people who have cataract surgery regain very good vision, somewhere between 20/20 and 20/40.
During surgery, the surgeon will remove your clouded lens and in most cases replace it with a clear, plastic intraocular lens (IOL).
New IOLs are being developed all the time to make the surgery less complicated for surgeons and the lenses more helpful to patients. Presbyopia-correcting IOLs potentially help you see at all distances, not just one. Another new type of IOL blocks both ultraviolet and blue light rays, which research indicates may damage the retina.
When the lens in your eye becomes cloudy, the light reaching the retina is blurred and distorted and your vision is affected then this clouded lens is called a cataract which must be removed for vision to be restored. A clouded lens can be compared to a window that is frosted or "fogged" with steam.
Cataracts are treated as a surgical procedure that has become a fairly common practice in India.
The two most common types of cataracts are: cortical cataract and a posterior sub capsular cataract. Depending on the type of cataract, a patient will experience different visual problems, but the most common cataract symptoms include:
Blurring vision.
Sensitivity to light or glare.
Double vision in one eye.
Poor night vision.
Needing brighter light to read.
Experiencing fading or yellowing of colors
If the cloudiness is not near the center of the lens, you may not be aware that you have a cataract.
Many cataracts take years to develop to the point where vision is seriously affected. Most occur as a result of the normal aging process. The types of age-related cataracts are usually described by their location in the lens. They are: nuclear cataracts, cortical cataracts and sub capsular cataracts.
Nuclear Cataracts occur in the center of the lens and may induce other eye problems, such as Myopia.
Cortical Cataracts tend to occur in persons with diabetes, beginning from the outer portion of the lens and slowly moving inward.
Sub Capsular Cataracts develop under the capsule, often at the back of the lens. This type of cataract also occurs more in patients suffering from diabetes, but is also found in persons with high myopia, adults with Retinitis Pigmentosa and in patients who take steroids.
There are other kinds of cataracts not related to the aging process.
Traumatic Cataracts develop as a result of eye injuries. Others can develop from metabolic blood disorders, eye infections and inflammations and certain types of medications.
Another type, called Congenital Cataract, occurs at birth, particularly if the mother has had Rubella (German measles) during pregnancy.
Research continues to look for ways to prevent cataracts. Until then, good vision can be restored in 98 percent of all patients who have normal, healthy eyes after surgery.
Precise Measuring: exact measurement of the eye is possible even in cases of high ametropia, pupil size as well as state of accommodation.Non contact Technique: no requirement of local anesthesia, no risk of infection from patient to patient.Saves time: axial length, corneal curvature and anterior chamber depth of the patient's eye are measured on the same instrument saving valuable time.
Cataracts can be removed at any age. You no longer have to wait until the cataract "ripens" or until you lose your sight before surgery can be performed. In fact the placement of an intraocular lens (IOL) implant to restore vision is best done in when the cataract starts interfering with your daily activities or causes a decrease in vision.
Dr. Charles Kelmen conceived and developed phacoemulsification, a method of cataract removal by ultrasonic fragmentation and aspiration of the cataractous lens through a small wound. Phacoemulsification is advantageous for both patients and surgeon.
Greater intra operative control.
A smaller wound with no sutures possesses less risk of infection and induced astigmatism and gives better long and short term predictability of vision.
Patients are able to resume normal activity much sooner and with fewer restrictions than the traditional cataract surgery.
Phacoemulsification with sophisticated instrumentation provides options of pulse and burst mode.