Keeping up with the corneal inlays
Kamra is still the leader, but Raindrop’s fate could be decided soon. Two others are in the wings.
By Martin L. Fox, MD, and OM Staff
Last year, the Kamra inlay (AcuFocus) received FDA approval for the treatment of presbyopia, the first corneal inlay to achieve this status in the United States. For presbyopes who want a viable — and removable — option to improve their reading vision, the FDA’s decision provides an effective alternative.
More than a few people want the benefits of reading without glasses, and don’t mind paying the full ride. In the first six months of its U.S. approval, which occurred in spring 2015, Kamra was implanted in at least 1,300 people, according to the company. But in the five years since Kamra appeared on the worldwide market, 20,000 have been implanted, the company says.
Jodhbir Mehta, MBBS, FRCOphth, FRCS (Ed), head, Corneal and External Eye Disease Service, Senior Consultant Refractive Service, Singapore National Eye Centre, co-authored a 2015 review of the four corneal inlays; all have CE approval. Only the Kamra has U.S. approval.
They work differently, but that doesn’t seem to affect efficacy, the authors wrote.
“The evolution in design and understanding of the optics, combined with the precision and safety of femtosecond laser technology, make corneal inlays a viable alternative for presbyopia correction,” wrote Dr. Mehta and Singapore Eye Centre colleague Aris Konstantopoulos in Expert Reviews.1
Meet the four
• Kamra (AcuFocus). The Kamra, the oldest of the group, is a small-aperture inlay that improves vision by increasing depth of focus.
• Raindrop (ReVision Optics). The Raindrop’s space-occupying inlay reforms the corneal surface’s central anterior. By doing so, it creates a hyper-extended area that increases focal power for near and intermediary vision. ReVision filed a premarket approval submission with the FDA in November for Raindrop. The agency, which accepted the filing, has until mid-May to decide the inlay’s fate.
• Flexivue Microlens (Presbia). The Microlens is a refractive inlay. It has a bifocal design that allows for separate near and distance focal points.1 Presbia recently enrolled more than 330 patients at 11 sites. These patients, after the Microlens is inserted, will be followed for three years, according to clinicaltrials.gov.
• Icolens (Neoptics AG). The Icolens, installed via a preloaded delivery system, has a peripheral zone for near vision correction and a central one for distance. It is also a refractive inlay.
Drs. Mehta and Konstantopoulos found that, despite their efficacy, the inlays had common-denominator problems, such as occasional losses of unaided distance vision and corrected distance vision. These losses, wrote Dr. Mehta in an e-mail, couldn’t be predicted in terms of common characteristics among the patients. “It was really dependent on those patients that developed hyperopic shift.”
Learning and expanding
George O. Waring IV, MD, associate professor of ophthalmology and director of refractive surgery, Medical University of South Carolina, Charleston, was involved in the early research of Kamra and its development. So, he’s a good person to ask: has AcuFocus learned anything new about the Kamra from all the trials and implants around the world?
What AcuFocus has found, says Dr. Waring, is that this is a flexible technology that can benefit different types of patients. Although the device is labeled for plano or near-plano presbyopes, patients with congenital refractive error can also benefit with a dual procedure off label, for example with combined PRK. Furthermore, patients who have had LASIK surgery in the past who have become presbyopic, or pseudophakic patients who need reading glasses, can benefit from this technology. Furthermore, trials are under way outside the United States with the IC-8 small aperture IOL, and preliminary results have been promising.
A Kamra specialist shares a pearl or two
By Martin L Fox, MD
Kamra makes use of the well-documented principle of small-aperture optics to improve depth of focus, bringing intermediate and near distances into focus.
Kamra’s reversibility claim was confirmed with an early case that required explantation because of the development of corneal haze attributed to excessive femtosecond laser pocket energy. When we could not clear the cornea with higher-dose steroids, we elected for explantation and vision cleared to 20/25 uncorrected in 10 days. Our patient requested re-implantation.
I have learned several essential factors that help to ensure success in Kamra presbyopia surgery, including:
• Using the AcuTarget HD. This AcuFocus technology is an essential piece in ensuring successful surgery as it evaluates objective scatter index (OSI). Patients with excessively elevated OSI scores are not likely to appreciate the benefits of Kamra surgery. Also, AcuTarget evaluates prospective candidates and identifies those with potential tear film issues, assesses accommodative reserve and response following surgery and identifies the first Purkinje reflection/line of sight landmark for accurate inlay placement and postoperative verification.
• Demonstrating the Kamra effect. To show patients how small-aperture optics will improve visual function, place a lorgnette occluder over the candidates’ nondominant eye. If prospective candidates are unable to appreciate improved reading vision with the superimposed pinhole, they undoubtedly have light scatter or anatomical issues and will not do well with the inlay.
• Considering combined surgeries due to refractive status. Patients with preoperative hyperopia, astigmatism and excessive post-LASIK higher order aberration (>30%) or myopia greater than 1.00D will not be satisfied with Kamra. These patients will require laser vision correction ahead of implantation or in combined photorefractive keratectomy-Kamra or LASIK-Kamra procedures. These combined surgery patients have been the happiest. Patients who fall within the “sweet spot” of -0.50D to -0.75D with little or no astigmatism do the best. I started the combined surgeries after the first five implants. Outcomes improved substantially and recovery was much faster.
• Managing tear film problems. Candidates with elevated OSI/tear film studies (>3.00), especially those with a “saw-tooth” or upwardly sloping pattern, require pre-operative treatment with lubricants, silicone outflow plugs and cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan) to improve their OSI results. Also, the 1.6-mm Kamra aperture demands a robust clear corneal tear film in order to function best. So, Kamra recipients need to be encouraged postoperatively to lubricate frequently, especially when performing tear tasks (post-Kamra patients experience tear film dysfunction more than symptomatic dry eye). We instruct patients to instill lubricants and blink 10 times to ensure adequate tear film distribution over the inlay. The response to this has been stellar, especially when performed prior to and during near visual tasks.
• Addressing patient expectations. Although 25% of our Kamra recipients say they see better immediately, the remaining 75% take four to six weeks to reach that point. When you make patients aware of this reality, postoperative management becomes much more relaxed and patients are happy to measure their gradual, functional improvement with you.
“The potential uses of this technology — it’s much wider than it’s labeled for,” says Dr. Waring. OM
REFERENCE
1. Konstantopoulos, S and Jodhbir M. Surgical compensation of presbyopia with corneal inlays. Expert Rev. Med. Devices. Early online, 1-12 (2015).
About the Author | |
| Dr. Martin L. Fox is medical director at the Cornea and Refractive Surgery Practice of New York and at Clarity Refractive Services of West Orange, New Jersey. Contact him at foxmd@laserfox.com or by phone at 917-207-3147. His website is www.laserfox.com.
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