An intraocular lens (IOL) is the artificial lens surgeons implant to replace the eye's crystalline lens that must be removed once it becomes cloudy. The main job of the IOL is to focus light onto the back of the eye (or retina), just as a natural, healthy eye lens would.
From here, the light rays are converted into electrical impulses that travel to the brain, where they are then converted into images. If the light isn't focused correctly on the retina, then the brain can't process the images accurately.
IOLs share the same basic construction as earlier versions—a round, corrective central portion of the lens with 2 arms, or haptics, to keep it in place in the eye—but other than these shared characteristics, modern IOLs can vary widely in design, being made of plastic, silicone, or acrylic.
Most of today's IOLs are about a quarter of an inch or less in diameter and soft enough to be folded so they can be placed into the eye through a very small incision.
About 2 million people per year in the United States have cataract surgery, and almost all of them receive an intraocular lens. There are many different kinds of intraocular lenses. Your doctor can decide which lens is right for you only after a careful examination of your eye.
Intraocular lenses can be divided into two main groups: non-foldable and foldable. Intraocular lenses were originally made from a hard plastic material, but materials were later invented to make soft lenses that could be folded in half. This type of intraocular lens can be inserted through a smaller opening in the eye, which can be better for the patient because smaller incisions usually heal faster than larger ones.
What happens in the operation to implant intraocular lenses?
Intraocular lenses are usually implanted during cataract surgery, which is usually performed with local anesthesia. That is, the patient is awake but does not feel the procedure. In a few cases, the surgeon will use general anesthesia (the patient is “asleep”).
The surgeon will make a very small opening in the front of the eye so the cloudy lens can be removed. There are two ways to remove the lens. One way is to remove it whole and the other is to use a special instrument to break the lens into pieces, then remove those pieces through a small incision.
Most cataract surgery is done with an instrument that breaks up lenses with ultrasound: sound waves that are too high in frequency for humans to hear. The energy from these ultrasound waves breaks up the lens in a process called phacoemulsification.
After the natural lenses have been removed, the intraocular lenses are placed into the eye. Usually, the intraocular lens goes where the natural lens had been. This area of the eye is called the posterior chamber. Sometimes, however, that might not be the best place for the intraocular lens so some lenses are designed to be placed in the anterior chamber, the area in front of the colored iris of the eye. Both types of lenses work well at putting the eye back into focus. Depending on which method of lens removal is used, the opening in the eye might not even need stitches. The patient is usually ready to go home about an hour after surgery.
Cataract surgery is sometimes performed without implanting intraocular lenses. It is usually possible to implant an intraocular lens at a later time.
How successful are intraocular lenses?
More than 90% of the people who have cataracts removed see better after surgery than they did before. An important part of successful cataract surgery with an intraocular lens implant is following your doctor's instructions after surgery. Eye drops are prescribed after surgery to help the eye heal better and to prevent infection. We will have to examine your eye after surgery to make sure it is healing properly and to check your vision.
Does anyone need to wear eyeglasses or contact lenses after receiving an intraocular lens?
Most intraocular lenses are chosen to focus at what doctors call “distance” vision. By “distance,” they mean anything farther than 2 or 3 feet away from the eye. If the lenses are focusing at distance, eyeglasses will be needed to see clearly close-up. Many people who have cataract surgery are already used to wearing bifocals, so they are familiar with this type of vision.