BLOG: Four reasons we can’t beat presbyopia (yet)
When Bette Davis said, “Old age ain’t for sissies,” she might have been referring to the challenge of correcting presbyopia.
So many treatments, from optical ones to pharmaceutical to surgical, have fallen short of our hopes of them being accurate, effortless and tolerable, giving a wide range of vision. We still don’t have a presbyopia treatment that works as well as young eyes. Here are four reasons why presbyopia is such a tough foe.
1. Each patient brings a different perspective. Treatment is effective when it satisfies the patient, but circumstances vary widely between different types of patients. Age (and degree of hyperopia) determine how big a problem we have to solve for each patient. Previous refractive error determines baseline uncorrected vision. What satisfies a 50-year-old emmetrope with a clear lens is very different from what satisfies a 68-year-old myope undergoing cataract surgery. If we had a perfect presbyopia treatment, it would work for every patient.
2. Pupil size influences outcomes. Shrinking the pupil, of course, is the strategy taken by all current presbyopia drops, the Apthera small aperture implant (Bausch + Lomb) and arguably by other extended depth of focus lenses like Vivity (Alcon). Pupil size varies moderately by patient characteristics, medications taken and the outcome of prior surgery. And variations in pupil size yield variations in the result of every treatment. Small pupils are almost always the doctor’s friend, at least after surgery.
3. Effort greatly influences results. Patients with even advanced presbyopia can read when they try hard enough. That’s why treatments that eventually fail can show positive results in clinical trials. Until we can standardize the amount of guessing and frustration the clinical subject endures, we will have somewhat fuzzy endpoints to our trials.
4. Near acuity and real-world reading speed can be very different. The amount of effort by the patient is just one element influencing reading speed. Dry eye, significant vitreous opacity, macular disease and so many other factors, which are all excluded from participation in clinical trials, can make or break the effectiveness of a “proven” treatment. Satisfaction with multifocal IOLs is generally incredibly high in clinical trials among the rare perfect patient who is allowed to participate.
A result of these challenges is that most of our presbyopia corrections depend on either some element of monovision, which is its own subject, or imperfect optics. While we continue to look for the “free lunch” of a treatment that navigates all these obstacles, we can be cautiously optimistic about some of the accommodating implants that are in development. At least for patients with cataract or advanced presbyopia, these technologies could be the next best thing to being young with healthy eyes.
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For more information:
John A. Hovanesian, MD, FACS, an ophthalmologist specializing in cataract, refractive and corneal surgery at Harvard Eye Associates in Laguna Hills, California, can be reached at drhovanesian@harvardeye.com.
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