Corneal Inlays Better Than Monovision, Researchers Say

Print 28 October 2016
Marcia Frellick / MedScape

CHICAGO — One of the biggest misperceptions about corneal inlays is that the end result is monovision, experts said here at the American Academy of Ophthalmology (AAO) 2016 Annual Meeting.

This is not true, according to Greg Parkhurst, MD, chief executive officer of Parkhurst NuVision in San Antonio, Texas, who is a principal investigator on clinical trials of the Raindrop Near Vision Inlay (ReVision Optics) (NCT01373580).

Patients effectively have monovision in the first week, he explained, but "as the epithelial remodeling occurs, the near point of focus shifts out to a more comfortable reading distance, and while that occurs, the distance vision is stabilizing."

Raindrop is a clear hydrogel corneal inlay that is placed in the nondominant eye during a 10-minute outpatient procedure. It was approved for the treatment of presbyopia earlier this year by the US Food and Drug Administration (FDA).

With both eyes open, the minimum visual acuity achieved with the Raindrop inlay at all three ranges — distance, middle, and near — was 20/25 for 85% of patients, Dr Parkhurst reported.

"There's much less of a trade-off, compared with monovision," he explained. "These patients can gain back their intermediate and near vision, and they don't have to give up much distance vision to accomplish that."

In terms of range — in which intermediate range is the distance while watching a computer screen or selecting grocery items on a shelf — corneal inlays improve both intermediate and near vision, said Jay Pepose, MD, PhD, medical director of Pepose Vision Institute in St. Louis, Missouri, who is a principal investigator on the KAMRA trials (NCT01895088).

Unlike monovision, he explained, corneal inlays change the focusing power of the eye, and both eyes still have the same power.

Raindrop Trials

Raindrop inlays, which are indicated for people aged 41 to 65 years, function best when patients are slightly farsighted, Dr Parkhurst said.

"In fact, the sweet spot on my patients has been about plus three quarters, or maybe even plus one. This is where patients do the best at all ranges — distant, intermediate, and near," he said.

Prospective, nonrandomized, 24-month trials conducted for Investigational Device Exemption showed that the early myopic shift resolved from months 1 to 3; refractive stability was achieved in 6 months and was maintained for 2 years.

Before receiving the inlay, no patients had the near equivalent of 20/20 visual acuity, and only 0.3% of patients had 20/40 acuity or better for near vision, Dr Parkhurst said.

"At 24 months out, 98% of the treated eyes were at the 20/40 equivalent, and 88% were 20/25 or better," he reported. Intermediate vision improved as well.

"We're able to tell these patients that they should be able to gain about 5 lines of near, about 2.5 lines of intermediate, and give up only about 1 line of distance in the treated eye," he explained. "Looking binocularly, they don't have to give up any significant distance vision."

The procedure is simple, and patients are able to see up close in a couple of days, he said. Complications are manageable, and if the inlay does have to be removed, best-corrected vision comes back, "so that gives people peace of mind," Dr Parkhurst added. 

Results From KAMRA

The other implant approved for presbyopia by the FDA is the KAMRA Inlay (AcuFocus), as previously reported by Medscape Medical News. It is indicated for patients aged 45 to 60 years and works by blocking unfocused peripheral light.

"The sweet spot is on the myopic side," Dr Pepose reported. "The inlay functions best when a patient is at -0.75 diopters, whether naturally or surgically achieved."

The best candidates for the inlay are patients who require near vision between +1 and +2.5 diopters, he explained. They, like most presbyopic patients, are typically people who view the loss of near vision as a disability, dislike reading glasses, feel constrained by having to take readers on and off, or are unhappy with their appearance in glasses.

Recipients should be patient during the recovery process, "because it can take a few weeks or months before they see the full effect of the inlay," he added.

Dr Pepose described the difference between rates of inlay explantation and monovision reversal in LASIK.

"Approximately 7% of patients in most studies have asked for reversal of LASIK monovision, which is much higher than the explant rate of either of these inlays," he said. KAMRA explantation rates are about 2% in the United States and about 2% worldwide.

Prospective KAMRA trials conducted for Investigational Device Exemption involved 507 patients at 24 sites.

At least 75% of patients had achieved unaided near vision of 20/40 at 12, 24, and 36 months, Dr Pepose reported. At 5 years, mean distance vision was 20/20, intermediate was 20/25, and near was 20/30.

Jeff Machat, MD, chief medical director for Crystal Clear Vision in Toronto, Canada, who received a KAMRA inlay himself 4 years ago and is a consultant for AcuFocus, said he will be implanting Raindrop as well as KAMRA in his practice.

He said he does not see the choice as being either/or when patients come in. "Anybody who does corneal inlays sees them as complementary," he explained.

"I've been doing refractives for more than 25 years now. I was one of the early people to do LASIK," Dr Machat told Medscape Medical News. "Every new procedure, every new option, I evaluate it and embrace it. It gives me one more tool.

"If a patient comes in at plus one, which is very common, that's an ideal Raindrop patient, because all we have to do is create a flap, place the inlay, and we're done," he explained. "If someone comes in and they have a complicated prescription, then I need to do LASIK. If someone has more dry eye, I might tend to go KAMRA. There are many, many factors that we consider."

The Raindrop study was sponsored by ReVision Optics. The KAMRA trial was sponsored by AcuFocus. Dr Parkhurst is a consultant for ReVision Optics, STAAR Surgical, and Alcon and is a principal investigator on Raindrop clinical trials. Dr Pepose is part of the medical board of AcuFocus. He was a clinical investigator for and has a financial interest in AcuFocus. Dr Machat is a consultant for AcuFocus, Abbott Medical Optics, Allergan, Bausch + Lomb, ClariaVision, and EndVision.

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