According to the National Eye Institute, a cataract is defined as a clouding of the lens in the eye that affects your vision.

Tim Johnson, MD, a University of Iowa Hospitals and Clinics ophthalmologist, said that while most cataracts are the result of aging, there are other things that can cause cataracts. “Trauma, including other eye surgery, can cause cataracts to develop rapidly. People with eye inflammation known as uveitis often develop cataracts. Certain medications, specifically steroids given as eye drops or taken orally, can cause cataracts. And people with diabetes, especially, have cataracts that develop at an early age and they tend to grow more rapidly.”

What causes a cataract? The lens is a type of epithelium similar to the skin. The cells of the lens rapidly turn over, and unlike the skin where old cells are lost into the air, there’s no place for the lens cells to go except to the middle of the lens which is called the nucleus. Over time this leads to a loss of clearness to the lens, and that’s what a cataract is.

Johnson says cataracts impair a lot of daily vision functions, such as reading, watching television, and especially driving. Night driving and driving on sunny days are common complaints of cataract patients. There can be a glare or halos from the lights and it makes it difficult to read road signs.

“Pretty much everybody is at risk of developing cataracts if you live long enough, if you’re in your 60s or older, you’re going to get a cataract to some degree. Whether or not it’s severe enough to require surgery differs from person to person and those with the conditions mentioned earlier are at especially high risk.

Johnson says people with cataracts complain of blurry vision, or dimness to the vision, and the glare and halos that we talked about before with headlights or sunny days. And it becomes difficult to read a paper or a menu and see the print, other than the largest type of print.

“If someone has symptoms of a cataract, they should have an eye check-up,” says Johnson. “The physician can check the patient’s vision and examine the lens to diagnosis the cataract. During that examination it’s also important to look for other eye diseases that could cause vision loss, such as glaucoma and macular degeneration, to be sure that it’s a cataract that’s causing the problem and not something else.

“Usually cataracts develop in both eyes, but it can be at a different rate between one eye and the other. If someone has had an eye injury or an eye disease, the cataract would develop more rapidly in that eye.

“There’s only one treatment for cataracts and that is surgery, where you remove the natural lens and replace it with an artificial lens implant,” says Johnson.

There are several types of cataract surgery. There are some older techniques still in use, Johnson says, but by far the most common method of removal is what we call Phacoemulsification. That involves making a very small opening about three millimeters into the eye to allow a probe to be passed into the eye. This probe vibrates at a very high ultrasound frequency and that vibration breaks the lens into small particles that are then vacuumed out of the eye. Many people think that a laser is used to remove the lens. A few lasers have been developed to remove cataracts, but that technique is not as successful or as popular as the ultrasound technique.

“Most patients are extremely happy with the improved vision they receive after the surgery. They say their vision hasn’t been this good in many years. But the artificial lens implants that we use aren’t a perfect solution or a perfect substitute for the natural lens. Most lens implants don’t focus, and so someone who has good distance vision would typically need reading glasses for their up close vision,” he says. “There are new lenses that are called focusing or multi-focal lenses that are designed to improve vision both far away and up close and these are very successful.

Cataracts don’t redevelop after treatment. Some of the cells that are typically left behind can grow along the back surface of the artificial lens and cause it to cloud up again but the entire lens doesn’t grow back. “That’s what we call a secondary or after-cataract,” says Johnson. “The modern lens implants we use are designed to prevent this from happening, but it still occurs about 10 percent of the time. If that does happen, there is a simple laser procedure that can clear those cells from behind the implant”

UI Hospitals and Clinics is involved with cataracts research. One area of interest is in restoring vision in patients who have severe trauma or developmental abnormalities of the eye. There are several devices and special implants being studied to restore the vision in these patients, and Iowa is one of the study centers investigating these devices.

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Tim Johnson, MD