Novel optical approaches drive cornea-based presbyopia correction

Corneal inlays and refined laser techniques maximize near vision, minimize the loss of distance vision and largely preserve cosmetic appearance.

Roger F. Steinert

Innovative optical concepts, corneal implants and evolving laser techniques are providing surgeons with many choices for presbyopia correction at the corneal plane.

Three distinct optical approaches potentially optimize near vision and minimize loss of distance vision in presbyopia treatment. The three approaches are near power in the pupil center, distance power in the pupil center and the pinhole effect.

“The three different types of inlays with three different mechanisms of action consist of Flexivue Microlens (Presbia), which creates a bifocal optical system at the nondominant eye of presbyopic, emmetropic patients; Kamra (AcuFocus) that utilizes the pinhole effect, increasing depth of focus; and PresbyLens (ReVision Optics), which changes the anterior curvature of the cornea when placed under a superior hinged lamellar LASIK corneal flap. All the inlays are implanted only in the nondominant eye,” Ioannis G. Pallikaris, MD, PhD, OSN Europe Edition Editorial Board Member, said in an interview with Ocular Surgery News.

Other options are laser-based, such as presbyLASIK and femtosecond laser IntraCor (Technolas Perfect Vision). Surgeons may also use a monovision option with conductive keratoplasty.

Cornea-based treatments offer differing and multiple benefits to patients who want presbyopia correction, he said.

“Intracorneal inlays represent the less invasive technique for presbyopia correction and it is the only reversible approach,” Dr. Pallikaris said. “Presby-laser creates a multifocal pattern on the surface of the cornea and improves near vision in presbyopic, non-emmetropic patients, also offering customized ablations at various optical zones. Conductive keratoplasty improves near vision in hyperopic, emmetropic patients and offers the advantage of easy repetition if needed.”

New technologies are being developed for each optical approach. In studies, refractive corneal inlays and a pinhole inlay yielded visual outcomes largely comparable to those of new and established laser refractive procedures, according to a presentation by Roger F. Steinert, MD, OSN Cornea/External Disease Board Member, at the American Society of Cataract and Refractive Surgery meeting in San Diego.

“All of the procedures gave good, clear improvement in uncorrected near acuity,” Dr. Steinert said. “The long-term biocompatibility, of course, is going to be the subject of extensive ongoing testing. So far, so good, but time will tell.”

Refractive and pinhole inlays

The PresbyLens provides near power in the pupil center. Placed under a LASIK-like flap, the inlay steepens the corneal curvature and generates plus power in the pupil center.

“The inlay itself does not have intrinsic optical power. Basically, it’s the same index of refraction as the cornea, so it’s the change in curvature that makes it work,” Dr. Steinert said.

The intracorneal Flexivue Microlens provides refractive power from +1.50 D to +3.5 D.

“The center does not have power,” Dr. Steinert said. “This means that the distance is through the center for emmetropes, and the peripheral plus power or steepening basically acts like a donut to create plus power through changing the corneal curvature.”

The Kamra intracorneal inlay is designed to improve accommodation via the pinhole effect by limiting the amount of light entering the eye and minimizing glare.

The body of the Kamra inlay is fenestrated with 8,400 randomly placed holes to permit the flow of nutrients and minimize excessive incoming light, which can cause glare, Dr. Steinert said.

Comparing visual outcomes

All three corneal inlays yielded favorable results compared to presbyLASIK, PRK and the IntraCor femtosecond laser-based intrastromal ablation procedure for presbyopia, according to Dr. Steinert. In published studies, the PresbyLens yielded monocular uncorrected near visual acuity of J1 or better in 90% of patients and J2 or better in 100% of patients. The mean uncorrected near visual acuity in the operated eye for Flexivue Microlens improved considerably, from J8 preoperatively to J1 at 6 months for the 32 patients included in recent post-market surveillance studies.

IntraCor offered uncorrected near visual acuity of J1 or better in about 38% of patients, J2 or better in about 54%, J3 or better in about 68% and J5 or better in about 91%, Dr. Steinert said.

“Is J3 really good enough or is it J2 or J1 that makes patients happy? The PresbyLens is probably the strongest of them based on just published results,” he said.

Reversibility, cosmetics

Refractive inlays and the pinhole inlay are refractively reversible; presbyLASIK and PRK are not reversible.

“Reversibility of pinholes is attractive but, again, biocompatibility needs to be studied as well as whether there’s some impact to the patient from the loss of light getting back to the retina,” Dr. Steinert said.

In terms of maximizing available light, refractive inlays and procedures including presbyLASIK or PRK, and IntraCor proved most effective.

Refractive inlays and IntraCor offer rapid visual improvement.

The best cosmetic results are attained with refractive inlays, presbyLASIK or PRK, and IntraCor.

“Again, there are some questions as to whether the pinhole inlays are going to be visible and bothersome or not. Mixed reviews on that,” Dr. Steinert said. “The others are essentially invisible.”

IntraCor has shown promising results but merits long-term scrutiny, Dr. Steinert said.

“The use of a femtosecond laser in the IntraCor procedure is clearly pretty interesting. It’s got everybody’s attention. Long-term stability remains to be determined,” he said. – by Erin L. Boyle and Matt Hasson

References:

• Assil KS, et al. Photopic pupillometry-guided laser in situ keratomileusis for hyperopic presbyopia. J Cataract Refract Surg. 2008;34(2):205-210.
• Holzer MP, Mannsfeld A, Ehmer A, Auffarth GU. Early outcomes of IntraCor femtosecond laser treatment for presbyopia. J Refract Surg. 2009;25(10):855-861.
• Seyeddain O, et al. Refractive surgical correction of presbyopia with the AcuFocus small aperture corneal inlay: Two-year follow-up. J Refract Surg. 2010;26(10):707-715.
• Uy E, Go R. Pseudoaccommodative cornea treatment using the Nidek EC-5000 CXIII excimer laser in myopic and hyperopic presbyopes. J Refract Surg. 2009;25(1):S148-155.

• Ioannis G. Pallikaris, MD, PhD, can be reached at the University Hospital of Heraklion, Ophthalmological Clinic, P.O. Box 1352, Voutes, Heraklion, CR-71003 Crete, Greece; 30-81-3923-51; fax: 30-81-39-46-53; email: pallikar@med.uoc.gr.
• Roger F. Steinert, MD, can be reached at the Gavin Herbert Eye Institute at University of California, Irvine, 118 Med Surge I, Irvine, CA 92697-4375; 949-824-8089; fax: 949-824-4015; email: steinert@uci.edu.
• Disclosures: Dr. Steinert is a consultant to ReVision Optics. Dr. Pallikaris is medical director of Presbia.

Patient selection, preparation key to presbyopic treatment plan

Ioannis G. Pallikaris

For emmetropic presbyopic patients between 45 years and 60 years of age, Ioannis G. Pallikaris, MD, PhD, opts for corneal inlays due to the minimally invasive character of the technique and its reversibility. This option enables the surgeon to remove the implant when needed without tissue loss and replace it with another lens. Implantation of corneal inlays is an easy procedure for an experienced surgeon, lasting a few minutes, according to Dr. Pallikaris. Using a femtosecond laser with special software to create pockets simplifies the procedure further. Photoablation of the cornea is avoided, so there is no reduction of corneal thickness.

For ametropic patients between 40 years and 50 years of age, Dr. Pallikaris prefers corneal laser procedures, mostly monovision with a target of no more than 1.25 D to 1.50 D.

For emmetropic presbyopic patients older than 50 years, he chooses intraocular procedures with implantation of multifocal or monovision lenses. Besides the procedure itself, the most critical steps in the surgical treatment of presbyopia according to Dr. Pallikaris are appropriate patient selection, detailed explanation of possible outcomes and preoperative trial simulation of postoperative results using eyeglasses or contact lenses when possible.

• Disclosure: Dr. Pallikaris is medical director of Presbia.