PUBLICATION EXCLUSIVE: Medical and surgical innovations expected to transform treatment of presbyopia

Presbyopia is the most common refractive error in the world, impacting about 40% of the population. All of us who are in the presbyopic age group appreciate the fact that it represents a significant functional disability.

Most of us living in the so-called advanced countries manage our presbyopia with glasses or, in a minority of cases, a contact lens. It should be remembered that in many developing countries spectacles of any kind, including simple inexpensive reading glasses, are simply not available. While on a cataract surgery mission trip with my now-deceased good friend John Pearce of England, he made the astute observation that presbyopia-correcting IOLs were not just for the affluent but ideal for emerging countries where readers are not available or unaffordable. An inexpensive widely available bifocal IOL would be a welcome addition for the cataract surgeon treating those with no access to glasses after cataract surgery.

In the advanced countries, significant human and financial capital is being invested to provide the more affluent with both medical and surgical alternatives to reading glasses, bifocals, progressive lenses and presbyopia-correcting contact lenses. I would like to disclose that the medical and surgical treatment of presbyopia has been a special interest of mine for more than 30 years and that I consult widely in this field of invention. I have participated in research and development on each of the products I will mention in my commentary. Here are a few thoughts to add to those of the excellent panel in the accompanying cover story.

First, the optical principle of small-diameter aperture optics is being applied successfully to the medical and surgical treatment of presbyopia. We are all aware that reducing the f-stop on a camera increases the depth of focus. In the eye, creating pupillary miosis with a topical drop can effectively treat presbyopia. Those of us in ophthalmology during the era in which glaucoma was primarily treated with pilocarpine, carbachol, eserine and phospholine iodide are familiar with emmetropic presbyopes or pseudophakes on strong miotics seeing well at distance, intermediate and near. They also enjoyed a relatively seamless range of vision from far through intermediate to near, a distinct advantage of small-diameter aperture optics. To achieve a meaningful improvement of more than two lines at near, the pupil must be reduced to less than 2 mm in diameter.

Much research using small-diameter aperture optics in corneal inlays and IOLs has been performed by AcuFocus, resulting in an FDA-approved device, the Kamra inlay. Optical bench research and patient clinical trials helped select an aperture diameter of 1.6 mm at the corneal plane with a slightly smaller aperture near 1.4 mm needed at the pupillary and IOL plane. Of note, the increased depth of focus created by small-diameter aperture optics allows one to target mild myopia of –0.75 D to –1 D and still retain excellent distance vision. This is the exact same optics that are incorporated into the widely used disposable cameras, and in that application, mild near focus with a small-diameter aperture has been defined as hyperfocality. I find hyperfocality a useful term and hope it becomes familiar and useful to other ophthalmologists and optical scientists.

As an aside, there is much for ophthalmology to learn from research done by our optical colleagues designing cameras, telescopes and microscopes, including the fact that the best possible optical resolution can be obtained using diffractive optics, not refractive optics. Some of the principles learned in advanced optical devices have been applied to create my current favorite presbyopia-correcting IOL, the Symfony from J&J Vision. Significant clinical data support the conclusion that inducing hyperfocality in one eye and leaving the other at emmetropia creates a functional visual system for patients, with significant advantages over the very popular monovision.

Click here to read the full publication exclusive, Lindstrom's Perspective, published in Ocular Surgery News U.S. Edition, April 25, 2017.