Schematic depiction of the KAMRA inlay optical principle: narrowing the entrance pupil
aperture results in a reduction of the defocus blur for near targets and increase depth of focus.
Slit lamp picture of a KAMRA inlay 1 year after implantation.
Source (all): Damien Gatinel, MD, PhD
“Generally, if the patient is
unhappy 3 months after inlay
insertion, more time won’t make him or her happy. That is a good time to remove the inlay.”
—Damien Gatinel, MD, PhD
They provide another option for presbyopic patients, but careful patient selection is crucial
Inlays offer another option to patients of presbyopic age. As surgeons garner more experience with this technology, they get a better sense of the pros and cons of inlays.
On the pro side
One major advantage of inlays is that they provide a near vision solution for a universal vision problem, said John Vukich, MD, adjunct associate clinical professor, University of Wisconsin Madison School of Medicine. Although the need for better near vision has always been important, that need has increased substantially with today’s ubiquitous smartphone and computer screens. “Couple that with individuals working longer and enjoying a full life into their 60s, 70s, and beyond, and this is a need that is real,” Dr. Vukich said. Inlays offer a convenience for patients in the presbyopic age who may want to avoid reading glasses, said Dr. Vukich, who gained experience with inlays early on as part of the original U.S. Food and Drug Administration trial for the KAMRA lens (AcuFocus, Irvine, California).
Inlays also provide a gap procedure for patients between the ages of 45 and 60 who may not be ready to assume the risks of an intraocular procedure, said Jay Pepose, MD, PhD, director, Pepose Vision Institute, St. Louis, and professor, clinical ophthalmology and visual sciences, Washington University School of Medicine, St. Louis.
Inlays also can be adjusted if needed, said Damien Gatinel, MD, PhD, Rothschild Foundation, Paris, France. “Adjustability refers to the possibility of recentering the inlay postoperatively and, in some cases, fine tune refraction after inlay implantation with additive corneal surgery,” Dr. Gatinel said. “Inlays are usually implanted in one eye, but optimal refraction for distance vision of the contralateral eye may sometimes require a bilateral refractive procedure,” he said.
Reversibility as an advantage
Another advantage is that inlays are reversible in a way that LASIK is not, said Robert Maloney, MD, Maloney Vision Institute, Los Angeles. “Generally, if the patient is unhappy 3 months after inlay insertion, more time won’t make him or her happy. That is a good time to remove the inlay,” he said.
An inlay should be removed if both local medical and surgical adjunct postoperative therapies do not provide the patient with satisfactory results, Dr. Gatinel said. “Local complications such as inflammation or severe dry eye cause a decrease in vision. In my experience, this may happen in a small percentage of cases and should always be explained to the patient preoperatively,” he said. Surgeons should let patients know that the post-explantation refraction may be slightly different from the preoperative refraction, he added.
“The safety record for both the KAMRA and Raindrop [ReVision Optics, Lake Forest, California] inlays were very favorable in preservation of good best-corrected vision in patients where the inlays were removed,” Dr. Pepose said. If exuberant wound healing occurs or a patient has an immune response to an inlay associated with central haze formation around a hydrogel inlay or an amorphous deposit around a small-aperture inlay linked to a hyperopic shift, the patient should be treated with strong steroid therapy, he advised. “If they don’t respond, then early removal of the inlay generally leads to more rapid return of uncorrected and best-corrected vision,” he said.
One inlay advantage ophthalmologists may not always consider is its role as a practice builder, Dr. Vukich said. Offering inlays will bring in patients who may not otherwise come to a practice, and even those who are not candidates may be interested in other options to relieve their presbyopic symptoms, he said.
Inlays and cataract surgery
Surgeons with inlay experience also note that inlays can still function well after cataract surgery. “I have performed some cataract surgeries in patients implanted with the KAMRA, and it did not make the surgery difficult,” Dr. Gatinel said. “The target refraction should be planned to be slightly myopic (–0.75 D) for small-aperture inlays.”
Dr. Vukich has seen patients with inlays who go on to receive a monofocal IOL and retain a near visual acuity benefit. The inlays also have not hampered the ability to perform cataract surgery. “The ability to enjoy the near benefit and maintain that through the years in which cataract development is likely and after cataract surgery, maintain that ability is another distinct advantage,” he said.
As with any surgical procedure, inlays come with certain risks, including corneal haze, glare, and a drop in best-corrected visual acuity, Dr. Maloney said. However, the haze does not seem to have much effect on vision, he added.
“There’s no such thing as a surgery with a zero complication rate. We know that individuals with significant dryness in their eyes can have a diminished effect,” Dr. Vukich said.
Inlays also require some extra preoperative planning and follow-up, Dr. Gatinel said. For instance, surgeons and their staff may spend extra time explaining to patients what inlays are, as some are reluctant to have what they think will be a “foreign body” in their eyes. “Some patients think of it as a relatively bulky or electronic device, and it’s important to dissipate such misconceptions,” he said.
Sometimes, patients have a hard time tolerating inlays, and that can be another drawback, Dr. Gatinel said. This could be linked with interferences with corneal metabolism and dry eye-induced symptoms. Suboptimal results usually trace back to inappropriate patient selection, Dr. Gatinel said. “Low myopes should be regarded with caution, as no multifocal or extended depth of focus correction method can provide the crisp vision that these patients have without their distance correction,” he said.
Inlays also do not stop the onset of progressive lenticular dysfunction and opacity, Dr. Pepose said. “Small-aperture inlays may be more immune to the effects of progressive presbyopia, as their mechanism of action involves blocking unfocused peripheral light rather than the induction of dioptric change or negative spherical aberration,” he said.
Although there is a risk for damage that occurs after flap creation—something needed for inlay insertion—those risks and the ways to fix them are familiar to refractive surgeons, Dr. Vukich said. “We are very comfortable with the techniques so these problems are unusual and when they do occur, we can handle them,” he said.
Editors’ note: Dr. Vukich has financial interests with AcuFocus. Dr. Pepose has financial interests with AcuFocus and Abbott Medical Optics (Abbott Park, Illinois). Drs. Gatinel and Maloney have no financial interests related to their comments in this article.