What’s on the horizon for presbyopia: the refractive surgeon’s final frontier?

Lisbon, Portugal - If presbyopia is the “final frontier” in refractive surgery, which surgical approach will stand out as the winner in treating patients with the condition? Will it be corneal surgery, intraocular surgery, or phakic-versus-pseudophakic approaches?

Samuel Masket, MD, of Los Angeles, CA, United States, attempted to answer these questions during an ESCRS symposium on the surgical correction of presbyopia. He reviewed all the approaches available to refractive surgeons and outlined where ophthalmology is now and where it is headed in the treatment of presbyopia.

Dr. Masket explained that surgical approaches have varied over the years and will continue to do so. All surgical approaches have been either laser-based on the cornea or lens-based on the cornea or within the eye. They can be pseudophakic as well as phakic.

While scleral-expansion surgery has not fared well in respect to the peer-review literature, there is still interest in this area, Dr. Masket pointed out. SurgiLight Co., Orlando, FL, United States, has developed a laser to allow scleral expansion. However, this concept of accommodation is not widely accepted, he added.

In directing his comments to the more accepted concepts for accommodation, Dr. Masket said there is a few issues surgeons need to consider when looking at the new devices. These issues will ultimately determine the winning concepts.

“We still do not have a uniform way of measuring accommodation,” Dr. Masket said. “Is true accommodation versus pseudoaccommodation better? What will give the best reading ease and speed? What allows patients to use and maintain accommodative reserve, quality of vision, or higher aberrations?”

In the area of pseudoaccommodation, the lenses are well established in ophthalmology. They are easier to implant than the lenses in the accommodative segment. The new concept under development, both in respect to phakic IOLs, is corneal ablations and corneal inlays.

“With all pseudoaccommodation, there is a variable loss of contrast sensitivity function, and perhaps induction to the optical side effects,” Dr. Masket said.

With respect to true accommodation, Dr. Masket explained that transient changes have to be instant and reversible inside the eye.

“The hope though is that true accommodation will be associated with a higher quality of vision without loss to the contrast sensitivity function,” he said.

Masket reviewed some of the laser-based surgical approaches, but refractive surgeons have the opportunity to use the cornea for an inlay. He discussed the AcriFocus Corneal Inlay, an ultra-thin device that is based on the small optical aperture, or pinhole effect.

He also pointed out that intraocular-based, pseudoaccommodating lenses such as ReSTOR (Alcon Laboratories) and ReZoom (Advanced Medical Optics) have already entered the marketplace. Both lenses have achieved better vision compared with the earlier multifocal lenses.

However, Dr. Masket asked, “Where is all this headed?” He touched on all the new concepts of accommodating lenses currently in development:

• The angle-supported “vision membrane” lens, being developed by Lee Nordan, MD, of the United States.

• The IOL-based, true accommodation lens, based on the Helmholtz theory.

• The PowerVision, a dynamic optic with fixed haptics using fluidics.

• Medennium Smart IOL, a single-piece optic that is pliable for accommodation.

• Accommodating injectable materials.

• The NuLens accommodating IOL, a multi-piece optic with fixed optics that incorporates a piston-like concept for accommodation.

• LiquiLens, a dual liquid, gravity-dependent IOL.

• Visiogen’s Synchrony lens, a dual-lens IOL.

Dr. Masket concluded that these new concepts in accommodating lenses are “a truly exciting arena” for refractive surgeons. He listed these three reasons:

• Truly accommodating IOLs are the future of refractive surgery-as they are physiologic and will likely have fewer optical side effects as compared with pseudoaccommodating IOLs.

• Single lens, rigid optic IOLs with flexible haptics have been the first of these devices to hit the marketplace, but they are limited in their accommodation function.

• True accommodative function depends on many factors, including the IOL design concept, and may require long-term flexibility of the lens capsule.