Multifocal LASIK Surgery – Correction for Reading Vision
Multifocal LASIK is an advanced form of LASIK vision surgery designed to correct presbyopia as well as nearsightedness, farsightedness and/or astigmatism.
This specific type of presbyopia correction surgery treats presbyopia in a way that is similar to vision correction with multifocal contact lenses: Multiple power zones are created across the corneal surface of the eye to provide a greater depth of focus for clear vision at all distances.
The center of the cornea can be shaped to correct the patient's distance vision or their near vision, depending on the type of multifocal ablation pattern created with the excimer laser.
Multifocal LASIK is not yet FDA-approved for use in the United States, but it has been performed for several years in Canada and in Europe since 2002.
Multifocal LASIK Terminology
The terminology used to describe multifocal LASIK can be a bit confusing.
"Center-distance" multifocal LASIK creates an aspheric cornea that is flatter in the center to provide for good distance vision and is steeper away from the center to create clear intermediate and near vision. "Center-near" multifocal LASIK does just the opposite: It creates an aspheric corneal profile that is steeper in the center to provide for good near vision and flatter in the mid-periphery to create clear intermediate and distance vision.
In addition to center-distance and center-near classifications, a term often used interchangeably with multifocal LASIK is PresbyLASIK (or presbyLASIK or presby-LASIK). While this may continue for some time, it is likely that PresbyLASIK will emerge as one specific (and patented) brand of multifocal LASIK, and other variations of the procedure will be developed as competing brands.
For example, a specific multifocal LASIK technique being developed and currently in use in Europe is called Presbyopic Multifocal LASIK, or PML. The PML procedure is a center-distance multifocal approach, and can correct nearsightedness, farsightedness and astigmatism as well as presbyopia.
To complicate matters further, center-near multifocal LASIK is sometimes called "central presbyLASIK" and center-distance multifocal LASIK is also called "peripheral presbyLASIK."
Advantages of Different Multifocal LASIK Designs
Some experienced multifocal LASIK surgeons prefer the center-distance design, saying that it typically provides better distance vision while offering acceptable near vision for most routine daily activities. They also point out that a center-distance multifocal design may be easier to convert to a monofocal distance correction with a retreatment, in case a person is unhappy with the multifocal LASIK correction.
Other surgeons prefer the center-near multifocal LASIK design, saying it provides better near vision than the center-distance approach and therefore gives patients greater freedom from reading glasses.
Both types of multifocal LASIK can be performed bilaterally (on both eye) or on one eye only for what is called a "modified monovision correction." In bilateral treatment, the surgeon may elect to use the same design on both eyes or perhaps use a center-distance multifocal design on one eye and a center-near design on the other.
With modified monovision, the patient's dominant eye is given a monofocal distance correction, usually with wavefront-guided LASIK. The other eye is then given either a center-distance or center-near multifocal correction, depending on their visual needs.
The best multifocal LASIK design and method of correction (bilateral or modified monovision) for a person depends on many factors, including their visual needs, pupil size and other considerations. Each case must be considered individually during a thorough pre-operative consultation with the LASIK surgeon.
Who is a Candidate for Multifocal LASIK?
Candidates for multifocal LASIK should meet the same criteria established for candidates of any LASIK procedure: They should have healthy eyes, a stable eyeglasses prescription and show no signs of eye disease, such as cataracts and dry eye. This last criterion is especially important for multifocal LASIK candidates, as there is a greater risk of these problems among older adults.
And, of course, candidates for multifocal LASIK must already have presbyopia and need bifocals or reading glasses. Younger adults who have previously undergone cataract surgery or refractive lens exchange (RLE), which cause a person to prematurely lose their near focusing ability, may also be good candidates for multifocal LASIK.
It's also important for anyone considering multifocal LASIK to have realistic expectations about the outcome of the surgery. Multifocal LASIK cannot restore a person's near vision to the same level it was prior to presbyopia, but it can significantly reduce the need for bifocals or reading glasses.
A realistic expectation for the outcome of multifocal LASIK surgery is that you will be less dependent on reading glasses and will often be able to read and do other close-up tasks without them.
Multifocal LASIK after Other Eye Surgery
In most cases, multifocal LASIK can be performed after other eye surgery, including cataract surgery, standard or custom (wavefront) LASIK and other refractive surgery procedures. Multifocal LASIK may be particularly attractive to a person who has had successful LASIK surgery in their 20s or 30s and has enjoyed good vision without glasses, but are now over age 40 and have become presbyopic.
Note: This information is for general education purposes only. It is not to be used as a substitute for medical advice from your eye doctor or refractive surgeon.
