Corneal inlay appears promising for near, intermediate vision

January 1, 2010

A corneal inlay improves near and intermediate vision without compromising functional distance vision.

Any viable presbyopia procedure needs to result in gains at near and with minimal loss of distance visual acuity, according to Dr. Slade. The corneal inlay maintains uncorrected distance visual acuity (UCDVA) compared with the monovision procedure and results in what might be called "super monovision," he said.

Enrique Barragan Garza, MD, of Monterrey, Nuevo León, Mexico, was the principal surgeon in the single-center study. Dr. Slade also performed some of the cases; he is director of the Laser Center of Houston.

The study enrolled 30 subjects with 1.5 to 2.5 D (mean 1.8 D) near add requirement with uncorrected near visual acuity (UCNVA) between J5 (20/50) and J10 (20/100) [mean J6, 20/63]. The subjects received inlay implantation under a corneal flap in the nondominant eye. Procedures were performed with both a microkeratome and a femtosecond laser.

Benefits of the procedure were seen almost immediately, according to Dr. Slade.

"The [corneal inlay] drives near visual acuity, and it drives it at Day 1," he said.

At 1 month, 73% of the patients achieved J1 (20/25) UCNVA; at 6 months, 77% of patients had achieved J1 or better, and 100% had achieved J2 or better (n = 13), he said. In other results, uncorrected intermediate visual acuity improved from an average of 20/40 preoperatively to 20/25 postoperatively.

UCDVA in the treated eye lost an average of 1.5 lines at 6 months, but no patient had worse than 20/20 binocular UCDVA, Dr. Slade said. No patients had lost 2 or more lines of best-corrected near or distance visual acuity at either 1 or 6 months postoperatively.

At 12 months, results were slightly better for the patients in the femtosecond laser group when data were analyzed by the way in which the implant was performed. All patients (n = 7) saw 20/30 or better, and there have been no complications to date, according to Dr. Slade.

The advantage of a central near procedure such as implantation of the corneal inlay is the creation of a prolate shape, which causes negative asphericity, he said.

The optical power change, which is most pronounced and uniform over the central part of the eye, may mimic the accommodation of the human lens, Dr. Slade added.

"It's important to remember that this is an additive effect," he said. "You're adding something centrally to change the curvature."

The implant is removable with probable reversibility of refractive effect, according to Dr. Slade. He described the device as a patient-friendly option for presbyopia correction. FDA trials of the corneal inlay for correction of presbyopia are expected to begin soon.