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What is a cataract?

When cataracts are mentioned, people often think of a film that grows on their eyes causing them to see double or blurred images. However, a cataract does not form on the eye, but rather within the eye.


Eye without a cataract

Eye with a cataract


A cataract is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images. The lens is contained in a sealed bag or capsule. As old cells die they become trapped within the capsule. Over time, the cells accumulate causing the lens to cloud, making images look blurred or fuzzy. For most people, cataracts are a natural result of aging.


In fact, they are the leading cause of visual loss among adults 55 and older. Eye injuries, certain medications, and diseases such as diabetes and alcoholism have also been known to cause cataracts.


Normal Vision
Illustration by Mark Erickson


Illustration by Mark Erickson



The Self-Sealing Incision


hanks to medical and surgical advancements in recent years, cataract surgery has become one of the most gentle medical procedures performed today. The restoration of precious eyesight is accomplished every day at St. Luke's through tiny incisions that do not even require stitches. The chances of developing astigmatism (distorted vision) after surgery are significantly decreased by eliminating stitches, which tend to pull the eye's surface slightly out of its natural shape. Most patients are now able to enjoy their best possible vision with minimal recovery time.

This is possible thanks to a tiny, beveled incision commonly called the "self-sealing" incision. It is called "self-sealing" because the eye's natural internal pressure holds the incision tightly closed allowing the eye to heal without stitches. The self-sealing is made at the edge of the "clear cornea," and is less than 2.5 mm in length. The clear cornea is the transparent covering of the front of the eye.

The cataract is situated inside the lens capsule, which is like an elastic bag that holds the lens in place. To remove the cataract, the front portion of the lens capsule is carefully opened. The cataract is gently broken apart using ultrasonic vibrations and vacuumed out of the lens capsule. This technique is called phacoemulsification. The lens capsule is left undisturbed so a tiny lens implant can be inserted in place of the original lens.


Many types of lenses are used; most are made of either hard plastic or soft, foldable silicone. Patients will receive the lens best suited for them.


Selecting the Best Implant
For Your Needs

After the cataract is removed, an intraocular lens is required to replace the focusing power of the natural lens. The implant provides clearest vision at a single focal distance. This means that an eye focused for distance will have sharpest vision for distance activities such as driving, but would still require glasses for reading. Conversely, an eye focused for close range activities such as reading, will see best close-up rather than at a distance.

Most patients undergoing cataract surgery on their first eye receive an implant that provides distance to intermediate vision. If surgery is required on the second eye, the patient can elect to have better distance or near vision in that eye depending on their needs. Patients can reduce their need for glasses by electing to have what is called "monovision". With monovision, one eye is focused for near vision and the other for distance to intermediate vision. Over time, the brain gets used to "looking through" whichever eye is necessary, and therefore eliminates the need for glasses.