Presby-LASIK – Correction for Reading Vision
PresbyLASIK is an advanced form of LASIK vision surgery designed to correct presbyopia as well as nearsightedness, farsightedness and/or astigmatism.
The term PresbyLASIK (or PresbyLASIK or presby-LASIK) often is used synonymously with multifocal LASIK. But the latter is the more generic term to describe this type of presbyopia correction surgery.
PresbyLASIK is not yet FDA-approved for use in the United States, but it has been performed for several years in Canada and a similar multifocal LASIK surgery has been performed in Europe since 2002.
How PresbyLASIK Works
PresbyLASIK and other variations of multifocal LASIK treat presbyopia in a way that is similar to vision correction provided by multifocal contact lenses. Multiple power zones are created across the surface of the eye to provide a greater depth of focus for clear vision at all distances. This is accomplished by applying different curves to the contact lens (or to the cornea itself, in the case of PresbyLASIK) in a concentric fashion.
In PresbyLASIK, the center of the cornea can be shaped to correct the patient's distance vision or near vision, depending on the type of multifocal ablation pattern applied by the excimer laser.
Researchers are evaluating both "center-distance" and "center-near" ablation patterns for PresbyLASIK. In the center-distance approach, the excimer laser ablation creates an aspheric cornea that is flatter in the center for good distance vision, and steeper away from the center for good intermediate and near vision. (Center-distance PresbyLASIK is also called peripheral PresbyLASIK.)
In center-near PresbyLASIK, the cornea is made steeper in the center for good near vision and flatter in the mid-periphery for clear intermediate and distance vision. (Center-near PresbyLASIK is also called central PresbyLASIK.)
PresbyLASIK can be performed on both eyes or on only one eye to create a modified monovision correction of presbyopia. In this latter approach, one eye is treated with standard or custom LASIK for good distance vision in that eye (or is left untreated, in the case of a person who needs no corrective eyewear for distance vision and only needs reading glasses). The other eye is treated with PresbyLASIK to improve near vision in that eye, while also preserving some distance in that eye (compared to traditional monovision LASIK, where the distance vision of the "near eye" is quite blurred).
Advantages of Different PresbyLASIK Designs
Some experienced PresbyLASIK 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 PresbyLASIK correction.
Other surgeons prefer the center-near PresbyLASIK design, saying it provides better near vision than the center-distance approach and therefore gives patients greater freedom from reading glasses.
The best PresbyLASIK 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.
PresbyLASIK Success Rates
Initial clinical studies of PresbyLASIK show encouraging outcomes and high patient satisfaction with the procedure.
In a 2006 Canadian study, 82 eyes of 49 farsighted and presbyopic patients were treated with the PresbyLASIK procedure. One year after surgery, all patients were able to see 20/25 or better in the distance and could read normal newspaper print without reading glasses.
In a study published in the May 2008 issue of Journal of Refractive Surgery, 44 eyes of 22 patients with presbyopia and mild farsightedness were treated with a distance-center variation of PresbyLASIK called Peripheral Multifocal LASIK (PML). Six months after surgery, the average uncorrected visual acuity for distance vision among these patients was 20/20 and the average binocular near vision was approximately 20/25 without reading glasses.
In another study published in 2008 in the Journal of Refractive Surgery, 103 patients who had presbyopia in combination with nearsightedness or farsightedness had their vision corrected with a modified monovision approach with PresbyLASIK. The average age of patients in the study was 53.3 years, and preoperative refractive errors ranged from -9.75 diopters (D) of nearsightedness to +2.75 D of farsightedness. All patients were wearing bifocals or reading glasses prior to surgery.
For patients who wore bifocals prior to surgery, their dominant eye was treated with standard LASIK, wavefront LASIK or limbal relaxing incisions (LRI) to optimize distance vision in that eye. The other eye received a peripheral (center-distance) PresbyLASIK treatment for improved distance and near vision in that eye.
Patients who needed only reading glasses prior to surgery were treated with just the center-distance PresbyLASIK procedure in their non-dominant eye.
At the patients' final follow visit (conducted at least one year after surgery), 91 percent reported having no need for prescription eyeglasses or reading glasses, and 7.8 percent said they needed glasses less than one hour per week.
Realistic Expectations Are Essential
Despite the excellent results reported in these studies, people considering PresbyLASIK should be aware that they may still need reading glasses for certain tasks after the procedure. A realistic expectation for the outcome of PresbyLASIK is that you will be less dependent on reading glasses and that you frequently will be able to see adequately well to read and perform many close-up tasks without glasses.
PresbyLASIK after Other Eye Surgery
In most cases, PresbyLASIK can be performed after other eye surgery, including cataract surgery, LASIK, PRK and other refractive surgery procedures. PresbyLASIK may be particularly attractive to a people who have had successful LASIK surgery when they were in their 20s or 30s but are now over age 40 and have became 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.
