Surgery for Presbyopia
Eye surgery is one of many options available to correct presbyopia, a focusing problem that no one escapes beginning at around age 40.
Eye doctors disagree about what causes presbyopia. Most believe stiffening of the eye's lens contributes to the condition. Other theories suggest presbyopia also could be related to continued growth of the lens or atrophy of the muscles controlling the lens.
In the past, the usual remedy was to wear reading glasses or special multifocal lenses (bifocal or progressive) for presbyopia. But in modern times, surgical remedies also have been developed for qualified candidates who have presbyopia.
One effective surgical option for presbyopia correction is monovision LASIK, with one eye corrected for near vision and the other for far. But other surgical procedures such as conductive keratoplasty or CK (see below) also have received FDA approval, which gives eye surgeons additional options for correcting this common vision problem.
Several other experimental devices and procedures also are being studied, but are not yet FDA approved. Here is a rundown.
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Monovision and LASIK
Monovision produced by LASIK can be effective for presbyopia, but you need to make sure you can tolerate this approach.
Normally, both your eyes work together equally when you look at an object, to produce what's called binocular vision. But you probably have a dominant eye that your brain tends to favor for "sighting." Most right-handed people are right-eye dominant, for example.
Contact lens fitters often take advantage of this "one-eye dominance" to produce monovision. With this approach, the dominant eye usually is fitted for distance vision and the non-dominant eye is fitted for near vision.
So in most situations with monovision and depending on where you fix your gaze, one eye does more work (sighting) than the other. If one of your eyes is set for distance vision and the other is set for near vision, the distance eye will do most of the work when looking at objects in the distance, and the near vision eye will do most of the work when looking at near objects.
Some LASIK surgeons produce monovision in their presbyopic patients by purposely leaving the non-dominant eye slightly nearsighted so they can see up close without glasses (with that eye). But many eye surgeons are wary of this technique, because not everyone becomes accustomed to the reduced binocular vision caused by monovision. It's better to try monovision with contact lenses or trial lenses in the doctor's office first to be sure you can adapt.
Initially, monovision LASIK was used off label, meaning it had not received official FDA approval, as an approach to correcting presbyopia. But in 2007, the FDA announced approval of the Advanced Medical Optics (now Abbott Medical Optics) CustomVue excimer laser for performing the monovision LASIK procedure.
How CK works: Using a tiny probe, the surgeon applies radio waves in a circular pattern to shrink some of the collagen in the cornea. The circular treatment pattern acts like a belt that tightens around the cornea, increasing its curvature for better near vision. (Images: Refractec)
Monovision and Conductive Keratoplasty (CK)
Conductive keratoplasty uses low-level, controlled radio-frequency energy to shrink collagen fibers in the periphery of the cornea. This steepens the central cornea, in effect lengthening a too-short eyeball.
CK was FDA approved in 2002 for temporary reduction of farsightedness, then received approval in 2004 to improve near vision temporarily in people with presbyopia.
CK is another monovision technique, because one eye is made nearsighted by the procedure for improved close-up vision while the other eye remains untouched.
Again, it's a good idea to try monovision with contact lenses or a trial lens in the doctor's office before proceeding with CK, to make sure you'll adapt. After the three-minute procedure, you'll likely notice some improvement in your near vision. But it can take several weeks before you reach the final level of vision correction.
One attractive feature of CK is that it is minimally invasive. Some people experience tearing, foreign-body sensation or vision fluctuation, but this is normally temporary.
Artificial Lenses (Refractive Lens Exchange or RLE)
One currently available option for presbyopia correction involves removing the eye's natural lens and inserting an artificial one in a procedure identical to cataract surgery.
Although this surgical procedure is not FDA approved specifically for presbyopia correction, it may be available off label for qualified candidates.
Refractive lens exchange, also called clear lens extraction, is becoming more popular because of the recent availability of FDA-approved multifocal and accommodative artificial lenses capable of correcting presbyopia.
Multifocal LASIK (PresbyLASIK)
Different zones in a multifocal artificial lens correct vision at near, intermediate and far ranges. In multifocal or presbyLASIK, zones are established in a similar way on the eye's clear front surface (cornea) to correct presbyopia.
PresbyLASIK or multifocal LASIK is an investigational procedure, which is not FDA approved. U.S. clinical trials exploring the effectiveness and safety of the procedure are being conducted.
Intrastromal correction of presbyopia, known as IntraCor, has shown promising results outside the U.S. The procedure uses a femtosecond laser to create precisely placed gas bubbles, which then reshape the interior of the cornea without penetrating the outside surface. This means less chance of infection, inflammation or other complications.
Researchers so far report significant improvement in near vision, as long as ample light is provided for tasks such as reading fine print.
Corneal Inlays & Onlays
Corneal inlays and onlays are inserts that would be placed just below your eye's cornea to provide vision correction.
Currently in FDA clinical trials, the Kamra (AcuFocus and Bausch + Lomb) corrects presbyopia by using principles similar to the aperture or opening through which light enters a camera: the smaller the aperture, the greater the range of what you see in focus.
This corneal inlay formerly was known as the ACI 7000.
At least three additional inlays are being studied, including:
- InVue intracorneal microlens (Biovision, Brugg, Switzerland), which is placed in a tiny tunnel in the center of the cornea.
- Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, Calif.), an ultra-thin lens implanted in the cornea. (This implant formerly was known as PresbyLens in the U.S. and Vue+ in Europe.)
- Flexivue Microlens (Presbia Cooperatief U.A., Amsterdam), which uses a femtosecond laser to create a tiny "pocket" into which the implant is inserted.
Corneal onlay technology under investigation includes creation of genetically engineered, collagen-like lens material that can be placed in a pocket under the outer layer of the cornea.
Combined Surgical Options for Presbyopia
Future approaches could involve innovations such as combining different presbyopia-correcting options listed above.
For example, a person who needs cataract surgery or who is considering RLE may choose to have a single vision intraocular lens (IOL) implanted in one eye for good distance vision and a multifocal IOL implanted in the other eye to decrease need for reading glasses. Or a person might choose a different type of multifocal IOL for each eye one that favors distance vision in one eye and the other that favors near vision in the other.
In refractive lens exchange, modified monovision options also are being explored, such as emphasizing distance vision in the artificial lens implanted in the dominant eye and near vision in the lens implanted in the non-dominant eye. LASIK also can enhance outcomes following a refractive lens exchange.
In investigations of presbyLASIK in which a multifocal cornea is created directly on the eye by laser, success has been noted with one modified monovision approach involving conventional distance correction for the dominant eye and multifocal correction for the non-dominant eye.
[Page updated May 2014]
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