Focusing on presbyopia
Patients with presbyopia have a number of treatments from which to choose.
Inlays (Kamra, AcuFocus; Raindrop Near Vision Inlay, ReVision Optics) are the early mainstays of treatment following spectacle correction for this patient population. Both have received FDA approval. The former relies on pinhole optics to extend the depth of focus without decreasing distance visual acuity, whereas the latter is a small clear disc that mechanically makes the cornea hyperprolate, providing an optical surface that improves near vision.
An IOL (Presbia Flexivue Microlens, Presbia) currently is under clinical trial evaluation.
The use of preserved or nonpreserved corneal tissue inlays and onlays may play a role in the future of presbyopia and hyperopia therapy.
Early European studies have reported success with this approach using SMILE lenticules. A myopic SMILE technique removes a hyperopic lenticule, and a number of case reports have shown that the inlay is well tolerated and this is effective in some patients for improving presbyopia and hyperopia, according to Dr. Hersh.
A new company, Allotex, for which Dr. Hersh is a medical monitor, is developing preserved, laser-prepared corneal tissues that can be used for corneal reconstruction and potentially as a hyperopic or presbyopic inlay or onlay.
“The potential advantage of this technology is that these corneal tissues are likely to be more biofriendly,” Dr. Hersh said. “A difficulty that patients have had over the years with corneal inlays made of a variety of polymers is that they can cause a tissue reaction or overlying stromal problems because of perturbation in metabolic transfer.”
This has been largely addressed by the thinner lens designs of current inlays, but biocompatibility problems still remain, he noted.
“Current inlays need to be placed relatively deep into the cornea and their size and thickness are limited,” Dr. Hersh said. “Tissue inlays and onlays ultimately would likely have an advantage because of the biocompatibility of actual corneal tissue.”
A clinical trial of the Allotex corneal tissue is set to begin in 2018 outside of the United States.