Waterfall… a beautiful sight but not when it is on your eye
Patients with severe cataract sometimes describe their vision as if they are looking through a waterfall.
The most commonly performed surgery in the United States is cataract surgery. Several million individuals undergo cataract surgery each year. At the same time, cataract remains the number one cause of blindness in the world because so many people lack access to adequate care.
The human eye has a lens, just as a camera does. It sits right behind the iris, the colored part of the eye. The lens focuses images onto the retina, where the image is transformed into an electrical signal that can be transmitted to and interpreted by the brain. When we are born, the lens is completely clear and colorless. As we age, the proteins in the lens become less transparent, and the lens takes on a cloudy, hazy appearance and becomes yellowed. When the lens is no longer clear, we say the patient has a cataract. Many people have the misconception that a cataract grows over the lens; in fact, it is the lens itself that becomes cloudy. (Factoid: cataract comes from the Greek word for “waterfall,” as patients with severe cataract sometimes describe their vision as if they are looking through a waterfall). Left untreated, the lens may eventually turn completely white, like a piece of marble, or it could even turn black.
Symptoms of Cataract
The symptoms of cataract depend upon the part of the lens affected by the cataract. The earliest symptoms of cataract are often glare or halos around oncoming headlights while driving at night. Other patients notice blurry vision, such as difficulty reading street signs or reading. Other patients may notice daytime glare from the sun or distortions in color. Because cataract is painless and because they tend to progress very slowly, most people do not realize how much vision they’ve lost until the cataract is removed from one eye. Patients then can compare the sight in the eye that’s had cataract surgery, to the un-operated eye.
Causes of Cataract
The most important cause of cataract is age. Genetic factors inherited from one’s family also likely influence the development of cataract. Certain medications, especially steroids, are also an important cause of cataract. Injuries to the eye from blunt trauma or infrared exposure are less common causes of cataract. There is no known way to prevent cataract, and unlike the lens in a camera, there’s no way to fix, clean, or polish the natural lens once it develops a cataract. The only way to treat a cataract is to completely remove the natural lens and replace it with an artificial lens.
Cataract Surgery
Cataract surgery had crude beginnings. For hundreds of years, the treatment for cataract was “couching”: a sharp, pointed instrument was used to enter the eye (often without the benefit of anesthesia) and the entire lens was forcefully pushed into the back of the eye, where it would remain. Couching resulted in some improvement in vision, especially for patients who had become blind. But the loss of the focusing power of the lens left patients with extremely blurry vision.
In the 1800’s cataract “extraction” became the preferred technique: using anesthesia, an incision was made in the eye and the lens was pulled out of the eye. Patients would then use extremely strong spectacles to compensate for the loss of the natural lens. As late as the 1960’s, cataract surgery required a hospital stay of two weeks with patients confined to strict bed rest. With the advent of surgical microscopes, microsurgical instruments, and sutures fine enough to be used in the eye, the technique was refined so that patients could leave the hospital after a day or two of recovery. However, patients still had to use extremely strong spectacles or contact lenses to see clearly.
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The Artificial Intraocular Lens
The invention of the artificial lens is attributed to Sir Harold Ridley. During World War II, Sir Harold served as an ophthalmologist in the Royal Air Force. Occasionally, pilots in their haste to get airborne would forget to wear their protective goggles. If the plastic windshield protecting the pilot was damaged by gunfire, pieces of the plastic could penetrate the eyes of the pilot. When a foreign object enters the eye, it usually initiates an intense inflammatory reaction, but Sir Harold noted that these pieces of plastic from the airplane windshields did not cause inflammation in the eye. This observation gave Ridley the idea that the plastic used to make the windshields, polymethylmethacrylate (PMMA), could be used to make an artificial lens that could be inserted into the eye after the natural lens had been removed during cataract surgery. It took nearly 40 years to manufacture an artificial lens that could be safely used in cataract surgery, but these implants have restored sight to millions all over the world.
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Unquestionably, the biggest advance in modern cataract surgery has been the invention of the artificial lens. Following removal of the lens, an artificial lens can now be placed inside the eye, markedly reducing the need for glasses.
Modern cataract surgery is an outpatient procedure and patients rarely have to stay in the hospital. Patients do not need to be put to sleep for cataract surgery. The patient is given light sedation to reduce anxiety and an anesthetic jelly is placed on the eye. Surgery usually takes 30-45 minutes and patients are sent home to recover. Patients often note improved vision within one to seven days after surgery, but attain their best vision about one to two weeks after surgery. For safety reasons, both eyes are not operated on at the same time. Most surgeons require patients to wait at least one to two weeks before proceeding with surgery on the other eye.
Providing Cataract Surgery Around the World
Some ophthalmologists travel to the third world to provide free surgery to patients suffering from cataract. Surgeons also use these opportunities to help train local eye doctors in the techniques of modern surgery. Surgeons at the Moran Eye Center at the University of Utah in Salt Lake City travel to Ghana, Kenya, Nepal, and Bhutan to perform hundreds of free surgeries to patients blinded by cataract and other eye diseases.
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"Waterfall… a beautiful sight but not when it is on your eye"
authored by:
Dr Katz is an assistant professor of ophthalmology at the John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah, in Salt Lake City. He specializes in comprehensive ophthalmology and neuro-ophthalmology. His res...
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