Cataract surgery remains the most-performed operation year after year in the United States. Virtually all of us get cataracts as we age, and three million of us choose each year to have them taken out. Many patients over the decades have needed reading glasses afterward to get clear images close up. This is because they had the blurry vision known as presbyopia. But intraocular lenses (IOLs) now give some patients a chance to lead a glasses-free life after the procedure.
The Evolution of Cataract Surgery
A doctor who removes a cataract actually takes out the natural lens of the eye. Normal healthy lenses are clear at first but become cloudy with time. So, doctors take those out, replacing them with intraocular lenses. (Learn more about this at Horizon’s Cataracts service page.)
Years ago, surgeons simply wanted to improve vision, without worrying whether patients needed glasses afterward. Later, they began to implant lenses that gave clear distance vision but left patients needing glasses for close-up work. Today, we have an array of innovative, presbyopia-correcting lens implants. This technology can’t match the optical performance of a healthy natural lens. However, it moves us closer to the goal of spectacles-free clear vision after cataract surgery.
How Intraocular Lenses (IOLs) Work
Think of the world as having three different zones of space – distant, intermediate and near. These zones are defined by the distance between your eyes and the object you’re trying to see.
A standard monofocal IOL gives clear vision without glasses in only one of these zones. Most patients select a monofocal IOL that improves distance vision, knowing the intermediate zone will be blurry and the near zone very blurry. On the other hand, a monofocal IOL chosen to give clear near vision will leave the intermediate zone blurry and the distant zone very blurry.
Patients can get clarity in more than one zone by choosing cataract surgery that provides strong distance vision in one eye and strong near vision in the other. Ophthalmologists call this monovision, because patients use only one eye at a time for any task. Sometimes their brains can ignore the blurred image from the other eye, and they adapt comfortably. But many do not.
Intraocular lenses are designed to give clear vision in more than one zone in each eye after surgery. Some implants give clear vision in two zones, either distant/intermediate or distant/near, and some give clear vision in all three. These IOLs differ according to the types of optical technology used to achieve clarity in multiple zones.
They do have limitations. They’re not covered by insurance, as traditional cataract surgery is, so patients face an extra fee. Anyone with certain ocular diseases – for instance, severe dry eye, irregular astigmatism or macular degeneration -- may not be eligible for multifocal IOLs.
Bringing more than one zone into focus at once increases the potential for optical side effects such as glare, halos, or reduced clarity of vision. Many people never experience these side effects, and most patients who notice them say reducing their dependence on glasses compensates for the mild annoyance.
The Bottom Line
If you need cataract surgery and want to reduce or eliminate the use of glasses, ask about presbyopia-correcting implants. Because not everyone will be a good candidate for them, you should discuss this option with your cataract surgeon. With newer implant technology giving clearer vision and less dependence on glasses, cataract surgery has evolved into a procedure many people actually look forward to.
To schedule a consultation at Horizon Eye Care, call 704-365-0555 Monday-Thursday, 8 a.m. to 5 p.m., or Friday, 8 a.m. to 3 p.m.