An implantable corneal inlay recently approved by the FDA gives ophthalmologists a new choice in treating presbyopia. The inlay (Raindrop Near Vision Inlay, ReVision Optics) increases the prolate shape of the cornea to increase central keratometry by about 4 D while mean keratometry increases by about 1.7 D. These topographic changes translate into a 5-line improvement in near vision without compromising binocular distance vision.
“The [inlay] itself has no refractive power,” said Ralph Chu, MD, Chu Vision Institute, Bloomington, MN, and clinical investigator, ReVision Optics. “It is refractively neutral and improves near vision by altering the prolate shape of the cornea and increasing the central power of the cornea. The change in shape is very gradual and very smooth, which gives the marked improvement in near vision with very little change to distance vision.”
He evaluated visual outcomes and topographic changes in a cohort of 23 patients who were part of a multicenter trial with 373 patients that led to the approval of the device. The inlay has been used clinically in Europe and Asia for several years.
The inlay was approved for implantation in the nondominant eye in patients 41 to 65 years of age who have not had cataract surgery and need near vision correction of +1.50 to +2.50 D, but no distance correction.
The clear, lens-shaped hydrogel device is about 2 mm in diameter and 30 μm thick — about half the diameter of a human hair. The inlay is completely invisible after implantation. It is placed beneath a standard 8 to 9 mm LASIK flap cut to a depth of about 30% of the total corneal thickness.
Like other corneal inlays, the device can be removed quickly and easily if the patient is dissatisfied with the result or if there are adverse events. The FDA approval notes a number of potential side effects including foreign body sensation and pain, infection, inflammation, new dry eye or exacerbation of existing dry eye, retinal detachment and corneal scarring, swelling, inflammation, thinning, clouding, or melting.
Reports of serious adverse events have been few and far between in both investigational and clinical settings, Dr. Chu said. Inlay is completely invisible after implantation. Courtesy of ReVision Optics
“At this point, the [inlay] has only been available to clinical investigators in the United States,” Dr. Chu said. “Clinical experience outside the United States has been generally very positive.”
In his own cohort, the average near visual acuity increased from 20/63 before implantation to 20/20 eighteen months postop. Intermediate visual acuity improved from 20/40 to 20/25. Monocular distance vision in the treated eye decreased slightly from 20/20 to 20/25, but binocular distance vision improved slightly from 20/20 to 20/16.
The mean MRSE shifted to about -1.0 at six months, then stabilized about -0.75 by 18 months. There was minimal induced astigmatism and the refractive cylinder remains stable after surgery. The incidence of glare and halo was about 4%. The smooth, gradual shift in corneal topography minimizes the risk of optical side effects, Dr. Chu noted.
“The potential downside to this inlay as well as other inlays is that the technology is placed into one eye,” he continued. “Patients have to be able to tolerate and function with a one-eye procedure. The incidence of glare and halo is not 0% from any procedure, something patients need to know about. From the surgical perspective, you have to look for a healthy ocular surface. Patients need to have minimal symptoms of dry eye or have dryness appropriately managed in order to have a good visual outcome.”
Several corneal inlays have been approved worldwide for presbyopia, but there are currently only two devices in the U.S. market: the Raindrop Near Vision Inlay and the Kamra Inlay (AcuFocus). The former improves near vision by changing the physical shape of the cornea while the latter uses the pinhole effect to improve depth-of-focus.
Still, the two inlays are more complementary than competitive, Dr. Chu said. Experience outside the United States suggests the Kamra Inlay may be more suitable for patients whose refraction is around -0.75 D. The Raindrop Inlay may be more appropriate for patients whose refraction is between 0.00 and +0.25 D.
“Patients and surgeons might prefer one device [over] the other depending on their individual vision and situation,” Dr. Chu said. “The key message is that we now have another tool to treat presbyopia that uses existing femtolaser technology and familiar surgical techniques.”
This article was adapted from Dr. Chu’s presentation at the 2016 meeting of the American Society of Cataract and Refractive Surgery Symposium & Congress. Dr. Chu is a clinical investigator for ReVision Optics.