U.S. clinical trial investigating efficacy of presbyopia treatment approach

The device is based on the use of small-aperture optics to increase depth of focus. It is doughnut-shaped, ultrathin (approximately 10 μm thick), and constructed of an opaque biocompatible polymer that contains microperforations to permit nutrient flow.

"This device is approaching presbyopia treatment with a new principle that involves changing the optics of the eye instead of the power," Dr. Durrie said.

"The U.S. trial is designed to study efficacy and safety of the corneal inlay in exhaustive detail and is including multiple parameters of quality of vision," he continued. "When it is completed, we will know how well this device works in a large number of patients."

Preliminary results

Speaking at the refractive subspecialty day meeting sponsored by the International Society of Refractive Surgery of the American Academy of Ophthalmology, Dr. Durrie presented preliminary results from a multinational study of the corneal inlay conducted at eight sites in three countries outside of the United States. That trial involved 57 patients with a mean age of 50 years (range, 45 to 60) who were emmetropic (natural or post-LASIK) and received the implant in the non-dominant eye. With follow-up available for up to 9 months in some patients, results showed mean distance uncorrected visual acuity (UCVA) was unchanged while there were improvements in both mean near and intermediate UCVA that appeared to increase over time.

"There might be some cortical adaptation involved with this approach as there is with monovision or perhaps vision improves over time in association with postoperative healing. Those and many other questions remain to be answered," he said.

Dr. Durrie also presented a simple experiment designed by Jack T. Holladay, MD, of Houston, that demonstrates the principles of small-aperture optics for improving depth of focus. Working in his backyard, Dr. Holladay placed a series of eye charts on sticks at different distances and determined how many were legible when the camera focus and f-stop were changed. When the f-stop was set to simulate a 4-mm pupil and the camera focused at 20 feet, four charts were in focus. However, as the focus was brought in closer, first to 12 feet and then 8 feet, the number of charts able to be seen clearly decreased to three and then to two. In contrast, when the f-stop was changed to simulate a 1.6mm pupil, 10 charts could be read when the camera was focused at 20 feet, and the number of charts legible increased as the focus was brought in closer.

Other investigators participating in the U.S. trial of the corneal inlay include Richard L. Lindstrom, MD; Vance M. Thompson, MD; George O. Waring III, MD; Perry S. Binder, MD; Dr. Holladay; and Jay McDonald, MD.