A cataract is a clouding of the normally clear lens of the eye. It can be compared to a window that is frosted or yellowed.
The amount and pattern of cloudiness within the lens can vary. If the cloudiness is not near the center of the lens, you may not be aware that a cataract is present.
There are many misconceptions about cataract. Cataract is not:
a film over the eye; caused by overusing the eyes; spread from one eye to the other; a cause of irreversible blindness. Common symptoms of cataract include:
a painless blurring of vision; glare, or light sensitivity; poor night vision; double vision in one eye; needing brighter light to read; fading or yellowing of colors.
Left, normal vision. At right, dulled or yellowed vision.
Blurring or dimming of vision What Causes Cataract?
The most common type of cataract is related to aging of the eye. Causes of cataract include:
family history; medical problems, such as diabetes; injury to the eye; medications, especially steroids; radiation; long-term, unprotected exposure to sunlight; previous eye surgery; unknown factors. How Fast Does a Cataract Develop?
How quickly the cataract develops varies among individuals and may even be different between the two eyes. Most age-related cataracts progress gradually over a period of years.
In a normal eye, light focuses precisely on the retina.
In an eye with a cataract, light scatters throughout the eye instead of focusing precisely on the retina. Other cataracts, especially in younger people and people with diabetes, may progress rapidly over a short time. It is not possible to predict exactly how fast cataracts will develop in any given person.
How Is Cataract Treated?
Surgery is the only way a cataract can be removed. However, if symptoms of cataract are not bothering you very much, surgery may not be needed. Sometimes a simple change in your eyeglass prescription may be helpful.
No medications, dietary supplements or exercises have been shown to prevent or cure cataracts.
Protection from excessive sunlight may help slow the progression of cataracts. Sunglasses that screen out ultraviolet (UV) light rays or regular eyeglasses with a clear, anti-UV coating offer this protection.
How Is a Cataract Detected?
By performing a thorough eye examination, your ophthalmologist (Eye M.D.) can detect the presence of a cataract.
A careful evaluation will rule out any other conditions that may be causing blurred vision or other eye problems. Problems with other parts of the eye (such as the cornea, retina or optic nerve) can be responsible for vision loss and may prevent you from having much or any improvement in vision after cataract surgery. If improvement in your vision is unlikely, cataract removal may not be recommended. Your ophthalmologist can tell you how much visual improvement is likely.
When Should Surgery Be Done?
Surgery should be considered when cataracts cause enough loss of vision to interfere with your daily activities.
It is not true that cataracts need to be "ripe" before they can be removed or that they need to be removed just because they are present.
Cataract surgery can be performed when your visual needs require it. You must decide if you can see well enough to do your job, drive safely, and read or watch TV in comfort. Does your vision allow you to perform daily tasks, such as cooking, shopping, doing yard work or taking medications without difficulty?
Based on your symptoms, you and your ophthalmologist should decide together when surgery is appropriate.
What Can I Expect From Cataract Surgery?
Over 1.8 million people have cataract surgery each year in the United States, and more than 95 percent of those surgeries are performed with no complications.
During cataract surgery, which is usually performed under local or topical anesthesia as an outpatient procedure, the cloudy lens is removed from the eye. In most cases, the focusing power of the natural lens is restored by replacing it with a permanent intraocular lens implant.
Your ophthalmologist performs this delicate surgery using a microscope, miniature instruments and other modern technology.
After surgery, you will have to take eyedrops as your ophthalmologist directs. Your surgeon will check your eye several times to make sure it is healing properly.
Cataract surgery is a highly successful procedure. Improved vision is the result in over 95 percent of cases, unless there is a problem with the cornea, retina, optic nerve or other structures. It is important to understand that complications can occur during or after the surgery, some severe enough to limit vision. If you experience even the slightest problem after cataract surgery, your ophthalmologist will want to hear from you immediately.
In many people who have cataract surgery, the natural capsule that supports the intraocular lens becomes cloudy. If this occurs, your ophthalmologist can perform an outpatient laser procedure to open this cloudy capsule, restoring clear vision.
Cataracts are a common cause of decreased vision, particularly for the elderly, but they are treatable. Your ophthalmologist can tell you whether cataract or some other problem is the cause of your vision loss and can help you decide if cataract surgery is appropriate for you.