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Excimer laser ablations to the cornea (PresbyLASIK) to create a multifocal cornea may be an alternative treatment for patients with presbyopia
Take-home message: Excimer laser ablations to the cornea (PresbyLASIK) to create a multifocal cornea may be an alternative treatment for patients with presbyopia.
Reviewed by Gustavo E. Tamayo, MD
Bogota, Colombia-Presbyopia can be confounding for patients who do not want to wear glasses or contact lenses. Though corneal inlays or IOLs may be standard procedures, the latter is a definitive surgical procedure with the potential for significant complications.
Advances in technology now offer a third alternative, excimer laser ablations to the cornea (PresbyLASIK) to create a multifocal cornea, said Gustavo E. Tamayo.
“This is surgery completely outside the eye,” said Dr. Tamayo, founder and partner, Bogota Laser Refractive Institute, Bogota, Colombia. “It is a variation on the LASIK, LASEK or PRK procedures that most of us are already familiar with. And with wavefront-guided instruments, the excimer laser treatment it is both reversible and repeatable.”
Using excimer laser energy to treat presbyopia is not a new concept, Dr. Tamayo noted.
In general practice, about 93% of ophthalmologists who opt for surgical treatment of presbyopia opt for excimer laser monovision and 7% choose an IOL.
But earlier excimer techniques did not always produce optimal results. Patients complained of visual symptoms, such as halos and flairs. Visual acuity did not always reach target.
“Improvements in wavefront technology, better understanding of ocular aberrations, improvements in the excimer laser itself, and the advent of femtosecond lasers to help create flaps have made this the right time to consider this technique,” he said. “It is particularly useful for younger patients with presbyopia, especially those between about 40 and 55 who are years away from needing cataract surgery.”
The key to successful presbyopia treatment is to center treatment on the visual axis, not on the pupil, he continued.
Nearly all of the patient complaints of visual symptoms and the poor visual outcomes of any presbyopia treatment are the result of decentration due to centering treatment on the center of the pupil rather than on the visual axis.
It is not possible to capture the precise visual axis using current technology, Dr. Tamayo added, but centering treatment on the Purkinje image is a useful surrogate for the visual axis.
The procedure itself creates a multifocal cornea with different powers at different points along the surface of the cornea. The surgeon creates a peripheral knee on the cornea, which creates distinct areas of negative spherical aberration and a central area of positive spherical aberration. It is this combination of positive spherical aberrations with negative spherical aberrations that creates the increase in depth of focus and improves near vision.
Correcting presbyopia by altering the cornea is not a perfect solution.
Dr. Tamayo cautioned that normal aging processes mean that presbyopia will continue to progress over time. Laser correction needs to be repeated after about seven years for most patients. In addition, the correction can be tweaked or even reversed as needed for patients in whom the procedure is not successful.
Excimer laser device manufacturers have long recognized the potential for presbyLASIK procedures, he said.
One key advantage from the ophthalmologist’s perspective is that almost any current excimer laser device can be used to correct presbyopia with a simple software upgrade.
Dr. Tamayo presented a prospective study of excimer laser presbyopia treatment of 121 eyes in 66 patients who were followed for 38 to 66 months. The mean preoperative sphere was 0.180 +- 2.2 D (-5.0 to + 5 D) and the mean preop cylinder was -0.736 +- 0.97 (-6.5 to 0.0 D). Most of the patients, 57.9%, were hyperopic, 14% were myopic myopia and 10.7% were emmetropic. Within the study group, 86.8% received presbyLASIK, 13.2% presbyLASEK and 9.9% were being re-treated.
After surgery, 97.5% had 20/40 or better uncorrected distance binocular vision and 85.9% had 20/40 or better uncorrected monocular vision. With correction, 100% of patients had 20/25 or better distance binocular vision and 96.8% had 20/25 or better monocular vision.
Near vision results were similar. A total of 95.9% had uncorrected near binocular vision of 20/25 or better and 79.4% had 20/25 or better uncorrected near monocular vision. All of the patients with emmetropia or myopia had 20/25 or better uncorrected near visual acuity compared to 78.3% of patients with hyperopia.
Patients were quite satisfied with the procedure. A total of 92.6% of patients reported they did not need to wear glasses at any time after surgery, 93.5% said they will repeat surgery when needed and 100% said surgery produced a significant positive change in their lives.
“These new techniques give us another way to correct presbyopia using noninvasive surgery that is completely reversible,” Dr. Tamayo said. “This may be the most flexible and the most successful solution we can offer to our younger patients with some accommodation present.”
Gustavo E. Tamayo, MD
This article was adapted from Dr. Tamayo’s presentation at Refractive Surgery Subspecialty Day during the 2015 meeting of the American Academy of Ophthalmology. Dr. Tamayo is a member of the Presbia medical advisory board.