As of Tuesday, March 25, 2014
DEAR DOCTOR K: I’m having cataract surgery in a few weeks. There are so many options for replacement lenses. Which one should I choose?
DEAR READER: I can’t tell you which you should choose, since I don’t know the specifics of your cataract. But I can suggest how you should think about several options that your ophthalmologist is likely to discuss with you.
First, the basics. A cataract is a clouding of the normally clear lens of the eye. Over time, it can cause a disabling loss of vision. Surgical removal of the clouded lens is the only effective cure for a cataract. In most cases, the surgeon replaces the clouded lens with an artificial intraocular lens (IOL).
As you noted, there are several options for replacement lenses. The most popular are monofocal IOLs. These lenses are designed to focus at one set distance: far, intermediate or near. (On my website, AskDoctorK.com, I’ve put a figure that illustrates these “zones of vision.”) Standard monofocal IOLs lack the ability to accommodate. That’s the ability to change focus from near to far and back again.
Many people choose a monofocal IOL that allows for clear distance vision after cataract surgery. Other people choose a lens that’s good for reading. Still others choose a lens that focuses about 18 to 36 inches away because they spend a lot of time at a computer, and that’s about how far away the screen is from their eyes.
If, like most people, you choose a lens that’s good for distance vision, you probably will need to use reading glasses. And vice versa if you choose a lens that’s good for close vision.
If you need cataract surgery on both eyes, and choose monofocal IOLs but hope to be less dependent on glasses, consider a technique called monovision. Monovision involves implanting an IOL for near vision in one eye and an IOL for far vision in the other eye. For many years I did this — but with contact lenses, not IOLs (I didn’t have cataracts then). It worked fine for me.
Many people find the adjustment to monovision quite challenging, if not impossible. That’s because reducing your binocular vision (your ability to use both eyes together) changes your depth perception. If you are considering monovision, try it out with contact lenses before your cataract surgery. Monovision is not an ideal option if you require crisp, detailed vision.
One approach is to forgo traditional monofocal IOLs. Instead, consider specialized, non-monofocal IOLs. There are several options in this category. For example, accommodating IOLs allow you to change focus between middle and distance vision, but they aren’t as reliable for near vision.
Another option, multifocal IOLs, is similar to bifocals or progressive eyeglasses. These lenses include different areas designed for distance, intermediate and near vision. Just as people with progressive eyeglasses require just one pair of glasses for seeing things at all distances, the same is true with multifocal IOLs.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.