What is a Cataract?
A cataract is a clouding of the normally clear lens of your eye. For people who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window. Clouded vision caused by cataracts can make it more difficult to read, drive a car — especially at night — or see the expression on a friend’s face.
Most cataracts develop slowly and don’t disturb your eyesight early on. But with time, cataracts will eventually interfere with your vision.
At first, stronger lighting and eyeglasses can help you deal with cataracts. But if impaired vision interferes with your usual activities, you might need cataract surgery. Fortunately, cataract surgery is generally a safe, effective procedure.
Signs and symptoms of cataracts include:
- Clouded, blurred or dim vision
- Increasing difficulty with vision at night
- Sensitivity to light and glare
- Seeing “halos” around lights
- Frequent changes in eyeglass or contact lens prescription
- Fading or yellowing of colors
- Double vision in a single eye
At first, the cloudiness in your vision caused by a cataract may affect only a small part of the eye’s lens and you may be unaware of any vision loss. As the cataract grows larger, it clouds more of your lens and distorts the light passing through the lens. This may lead to signs and symptoms you’re more likely to notice.
When to see a doctor
Make an appointment for an eye exam if you notice any changes in your vision. If you develop sudden vision changes, such as double vision or blurriness, see your doctor right away.
Most cataracts develop when aging or injury changes the tissue that makes up your eye’s lens. Some cataracts are caused by inherited genetic disorders that cause other health problems and increase your risk of cataracts.
How a cataract forms
The lens, where cataracts form, is positioned behind the colored part of your eye (iris). The lens focuses light that passes into your eye, producing clear, sharp images on the retina — the light-sensitive membrane on the back inside wall of your eyeball that functions like the film of a camera. A cataract scatters the light as it passes through the lens, preventing a sharply defined image from reaching your retina. As a result, your vision becomes blurred.
As you age, the lenses in your eyes become less flexible, less transparent and thicker. Aging-related changes to the lens cause tissues to break down and to clump together, clouding small areas of the lens. As the cataract continues to develop, the clouding becomes denser and involves a greater part of the lens.
A cataract can develop in one or both of your eyes.
Types of cataracts
Cataract types include:
- Cataracts that affect the center of the lens (nuclear cataracts): A nuclear cataract may at first cause you to become more nearsighted or even experience a temporary improvement in your reading vision. But with time, the lens gradually turns more densely yellow and further clouds your vision. Nuclear cataracts sometimes cause you to see double or multiple images. As the cataract progresses, the lens may even turn brown. Advanced yellowing or browning of the lens can lead to difficulty distinguishing between shades of color.
- Cataracts that affect the edges of the lens (cortical cataracts): A cortical cataract begins as whitish, wedge-shaped opacities or streaks on the outer edge of the lens cortex. As it slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens. Problems with glare are common for people with this type of cataract.
- Cataracts that affect the back of the lens (posterior subcapsular cataracts): A posterior subcapsular cataract starts as a small, opaque area that usually forms near the back of the lens, right in the path of light on its way to the retina. A subcapsular cataract often interferes with your reading vision, reduces your vision in bright light and causes glare or halos around lights at night.
- Cataracts you’re born with (congenital cataracts): Some people are born with cataracts or develop them during childhood. Such cataracts may be the result of the mother having contracted an infection during pregnancy. They may also be due to certain inherited syndromes, such as Alport’s syndrome, Fabry’s disease and galactosemia. Congenital cataracts, as they’re called, don’t always affect vision, but if they do they’re usually removed soon after detection.
Cataract surgery is a procedure to remove the lens of your eye and, in most cases, replace it with an artificial lens. Cataract surgery is used to treat a cataract — the clouding of the normally clear lens of your eye. Cataract surgery is performed by an eye doctor (ophthalmologist) on an outpatient basis, which means you don’t have to stay in the hospital after the surgery. Cataract surgery is very common and is generally a safe procedure.
Cataract surgery is performed to treat cataracts. Cataracts can cause blurry vision and increase the glare from lights. If a cataract makes it difficult for you to carry out your normal activities, your doctor may suggest cataract surgery.
When a cataract interferes with the treatment of another eye problem, cataract surgery may be recommended. This may be the case in people who have other conditions, such as age-related macular degeneration or diabetic retinopathy, since a cataract makes it difficult for your eye doctor to examine the back of your eye to monitor your other eye problems.
In most cases, waiting to have cataract surgery won’t harm your eye, so you have time to consider your options. If your vision is still quite good, you may not need cataract surgery for many years, if ever. Approach the decision with these questions in mind:
- Can you see to safely do your job and to drive?
- Do you have problems reading or watching television?
- Is it difficult to cook, shop, do yard work, climb stairs or take medications?
- Do vision problems affect your level of independence?
- Do you have difficulty seeing faces clearly?
- Do bright lights make it hard to see?
Complications after cataract surgery are uncommon, and most can be treated successfully.
Cataract surgery risks include:
- Retinal detachment
- Secondary cataract
Your risk of complications is greater if you have another eye disease or a serious medical condition affecting any part of your body. Occasionally, cataract surgery fails to improve vision because of underlying eye damage from other conditions, such as glaucoma or macular degeneration. If possible, it may be beneficial to evaluate and treat such eye problems before making the decision to have cataract surgery.
Cataract surgery, usually an outpatient procedure, takes an hour or less to perform. Eye drops placed in your eye dilate your pupil. You’ll receive local anesthetics to numb the area, and you may be given a sedative to help you relax. If you’re given a sedative, you may remain awake, but groggy, during surgery.
Typically, two things happen during cataract surgery — the clouded lens is removed, and a clear artificial lens is implanted. In some cases, however, a cataract may be removed without implanting an artificial lens.
Surgical methods used to remove cataracts include:
- Using an ultrasound probe to break up the lens for removal: During a procedure called phacoemulsification (fak-o-e-mul-sih-fih-KA-shun), your surgeon makes a tiny incision in the front of your eye and inserts a needle-thin probe. Your surgeon then uses the probe, which transmits ultrasound waves, to break up (emulsify) the cataract and suction out the fragments. The very back of your lens is left in place to serve as a place for the artificial lens to rest. In this procedure stitches may or may not be used to close the tiny incision.
- Making an incision in the eye and removing the lens: A less frequently used procedure called extracapsular cataract extraction requires a larger incision than is made during phacoemulsification. Through this incision your surgeon uses surgical tools to remove the cloudy portion of your lens and suctioning tools to remove additional portions of the lens. The very back of your lens is left in place to serve as a place for the artificial lens to rest. This procedure usually requires stitches to close the incision.
Once the cataract has been removed by either phacoemulsification or extracapsular extraction, a clear artificial lens is implanted into the empty lens capsule. This implant, known as an intraocular lens (IOL), is made of plastic, acrylic or silicone. You won’t be able to see or feel the lens. It requires no care and becomes a permanent part of your eye.
A variety of IOLs with different features are available. Some IOLs are rigid plastic and implanted through an incision that requires several stitches (sutures) to close. However, many IOLs are flexible, allowing a smaller incision that requires no stitches. The surgeon folds this type of lens and inserts it into the empty capsule where the natural lens used to be. Once inside the eye, the folded IOL unfolds, filling the empty capsule.
Some types of IOLs block ultraviolet light and other types of IOLs work like bifocals to provide multifocal vision — both near and distant vision. Discuss the benefits and risks of the different types of IOLs with your eye surgeon to determine what’s best for you.
After cataract surgery
After cataract surgery, expect your vision to begin improving within a few days. Your vision may be blurry at first as your eye heals and adjusts.
You’ll typically see your eye doctor a day or two after your surgery, the following week and then again after a month to monitor healing.
It’s normal to feel itching and mild discomfort for a couple of days after surgery. Avoid rubbing or pressing on your eye. Your doctor may ask you to wear an eye patch or protective shield the day of surgery. Your doctor may prescribe eye drops or other medication to prevent infection, reduce inflammation and control eye pressure. After a couple of days, all discomfort should disappear. Often, complete healing occurs within eight weeks.
Contact your doctor immediately if you experience any of the following:
- Vision loss
- Pain that persists despite the use of over-the-counter pain medications
- Increased eye redness
- Light flashes or multiple spots (floaters) in front of your eye
- Nausea, vomiting or excessive coughing
Most people rely on glasses, at least some of the time, after cataract surgery. Your doctor will let you know when your eyes have healed enough for you to get a final prescription for eyeglasses.
If you have cataracts in both eyes, your doctor typically schedules a second surgery a month or two later to remove the cataract in your other eye. This allows time for the first eye to heal before the second eye surgery takes place.