Corneal inlay allows presbyopia correction either paired with or after LASIK
High-volume experience demonstrates the safety and efficacy of presbyopia correction using a small-aperture corneal inlay (Kamra, AcuFocus) placed at the time of LASIK or in eyes for postLASIK.
By Cheryl Guttman Krader; Reviewed by Minoru Tomita, MD, PhD
Tokyo-Simultaneous LASIK and implantation of a small-aperture corneal inlay (Kamra, AcuFocus) is a safe and effective method for treating ametropic presbyopes.
Minoru Tomita, MD, PhD, presented the outcomes from a series of 3,015 eyes that underwent the combined procedure between August 2009 and August 2012 at Shinagawa LASIK Center, Tokyo. In addition, he noted excellent results from a group of 3,782 postLASIK eyes with the small-aperture corneal inlay implanted in the nondominant eye to correct presbyopia. The latter operations were performed between November 2010 and August 2012.
The small-aperture corneal inlay is commercially available in Japan. The device is investigational in the United States; the manufacturer submitted its premarket approval for FDA approval in March 2013.
“This small-aperture corneal inlay increases depth of field so that patients can achieve improved near and intermediate vision with minimal effect on distance vision and has been reported to be a safe and effective treatment in emmetropic presbyopes,” said Dr. Tomita, executive medical director of Shinagawa LASIK Center. “The patients who come to our center are ametropes interested in LASIK, and this inlay offers an opportunity to treat presbyopia at the same time.
“Simultaneous LASIK and implantation of this intracorneal inlay is very easy for the refractive surgeon to perform and it has resulted in high patient satisfaction,” Dr. Tomita added. “However, careful preoperative evaluation is important to ensure patients are good candidates and that they have realistic expectations for their postoperative outcomes.”
Patients are eligible for the combined procedure if they are appropriate candidates for LASIK, 45 to 65 years of age, and have SE between –9 and + 3 D with <3 D cylinder in the inlay eye. Other inclusion criteria require a corneal thickness >470 μm, an estimated residual bed thickness >280 μm, keratometry between 39 and 47 D, regular topography, and endothelial cell density >2,000 cells/mm2.
The procedure involves creation of a 200-μm flap with a femtosecond laser (Femto LDV Z6, Ziemer; iFS, Abbott Medical Optics) in the inlay eye, which is treated for a target refraction of -0.75 D using one of two excimer laser systems (Wavelight Allegretto, Alcon Laboratories; Amaris, Schwind). The dominant eye is treated with a target postoperative refraction of plano after creation of a 100-μm flap.
The 3,015 patients who underwent the combined procedure had a mean age of almost 52 years and mean SE of –2.84 D; 75% of patients were myopic. Mean uncorrected distance visual acuity (UDVA) improved from 20/125 preoperatively to 20/20 at 1 year (n = 1757) when 74% of patients achieved 20/20 or better UDVA in their inlay eye and 82% were 20/25 or better.
Mean uncorrected near visual acuity (UNVA) improved from J6 to J2 at 1 year when 77% of patients achieved J2 or better in the inlay eye and 56% could read J1. Results of a survey administered at 1 year showed 93% of patients were satisfied with their vision without reading glass, 7% of patients indicated they sometimes needed reading glasses, and only 3% said they needed reading glasses often.
Dr. Tomita’s method for inlay placement in the postLASIK eye involves use of a femtosecond laser to create a corneal pocket below the level of the LASIK flap. Pocket creation is performed with optical coherence tomography (OCT) guidance with the new Femto LDV Z6. Some patients may also need to undergo simultaneously a minor enhancement procedure with lifting of the prior LASIK flap in order to achieve a plano refraction.
The same inclusion criteria are used to determine eligibility for postLASIK inlay placement as for the simultaneous surgery except that patients must also have corrected distance visual acuity (CDVA) better than 20/25 in both eyes, UNVA worse than J3 in the implanted eye, and be at least 1 month postLASIK with a corneal thickness of at least 450 μm.
The patients included in the postLASIK inlay placement series had undergone primary LASIK for a mean attempted correction of –3.37 D and with an average flap thickness of about 100 μm. At the time of the inlay procedure, they had a mean age of about 53 years and mean SE was close to plano (–0.12 D), but ranged from –2.38 to +2.38. Mean CDVA was 20/12.5 and mean corrected near visual acuity was J1.
Data from follow-up to 6 months was available for 1,938 patients. Mean UDVA changed from 20/16 preoperatively to 20/20 with 80% of patients achieving 20/20 or better in the inlay eye and 86% being 20/25 or better. Mean UNVA improved from J6 to J2, with two-thirds of patients achieving J2 or better in the inlay eye and 80% being J3 or better.
As in the simultaneous LASIK-inlay group, 93% of patients were satisfied with their vision without reading glasses and the rest were equally divided between needing reading glasses sometimes and often.
Minoru Tomita, MD, PhD
Dr. Tomita is a consultant to AcuFocus and Ziemer. This article is adapted from Dr. Tomita’s presentation during Refractive Surgery 2012 at the annual meeting of the American Academy of Ophthalmology.