The Stats don’t lie: after age 65, most people will struggle to focus visually on close-up objects. You might have seen this among your friends and relatives or even experienced it yourself, holding books, magazines, or your phone farther away from your face to try to bring words and pictures into focus. Many of those affected start using reading glasses. But a new treatment could become available: eye drops.
This deterioration of vision is called presbyopia. It is not a disease but a natural, physiological change caused by aging—specifically by the loss of elasticity and flexibility of the crystalline lens at the front of the eye, which impairs the ability of the eye to change the curvature of the lens to bring objects into focus. This stiffening begins in middle age and tends to stabilize around age 65. For people with shortsightedness, or myopia, who struggle to see faraway objects clearly, the onset of presbyopia may at first lead to improved vision by compensating for their existing condition. For those with farsightedness, or hyperopia, the effects of presbyopia often present earlier than in the rest of the population.
Living with presbyopia can cause fatigue and headaches, and in rare cases double vision, but generally it isn’t something to be worried about. But correcting it can make daily activities easier and help maintain good quality of life. The classic means of correction are reading glasses, though in some cases people opt for eye surgery—either laser refractive surgery to reshape the cornea to compensate for the loss of flexibility of the lens or intraocular surgery to replace the lens with an artificial one. The latter is often proposed when there is also some clouding in the lens (a cataract).
But recently, researchers have been working on eye drops that, in different ways depending on the active ingredient used, improve near focus. Two types have been approved by the US Food and Drug Administration: one based on a substance called aceclidine, the other on pilocarpine.
Pilocarpine is the star molecule, with multiple trials of new formulations underway. It is a natural alkaloid that interacts with parts of the nervous system, which has the effect, in the eye, of inducing miosis—the narrowing of the pupil diameter—and contraction of the ciliary muscle, the ring of muscle that controls the shape of the lens. The two effects combined improve the elasticity of the lens and the ability to focus on nearby objects.
A recent trial conducted in Argentina has tested a pilocarpine eye drop at different concentrations (1 percent, 2 percent, 3 percent) in combination diclofenac, a nonsteroidal anti-inflammatory that soothes the adverse effects of pilocarpine such as irritation and discomfort. (The FDA-approved pilocarpine eye drops are concentrated at 1.25 percent.)
In a two-year retrospective study of 766 people, average age 55 years, the researchers found that the eye drops enabled the majority of patients to improve their vision. “Our most significant result showed rapid and sustained improvements in near vision for all three concentrations,” said lead researcher Giovanna Benozzi when presenting the research at the 43rd Congress of the European Society of Cataract and Refractive Surgeons.
“One hour after having the first drops, patients had an average improvement of 3.45 Jaeger lines. The treatment also improved focus at all distances,” Benozzi said. If you’ve visited an optician, you’re probably familiar with a Jaeger chart. It’s a tool for assessing near visual acuity, consisting of small blocks of text printed at different sizes.
Specifically, 99 percent of the 148 patients in the group treated with pilocarpine at 1 percent achieved optimal near vision and were able to read two or more additional lines; in the group of 248 patients treated with pilocarpine at 2 percent, 69 percent were able to read three or more additional lines on the Jaeger chart; while in the group treated with pilocarpine at 3 percent, 84 percent of the 370 patients were able to read three or more additional lines. The patients’ vision improvement was maintained for up to two years, with a median duration of 434 days. Patients took the eye drops two to three times per day.
Pilocarpine does have some potential side effects—eye redness, tearing, blurred vision, reduced night vision, sensitivity to light, difficulty changing focus between objects, and seeing flashes of light or “flying flies”; retinal detachment is also possible in rare cases. Those recorded by Benozzi’s trial, however, were mild (irritation and headache) and occurred in 32 percent of cases. No patient decided to discontinue the treatment.
“Nearly all patients experienced positive improvements in near visual acuity, although the magnitude of the improvement depended on the status of their vision before treatment at baseline,” Benozzi said, going on to suggest that in future treatments could be tailored to people depending on need. “Patients with less severe presbyopia responded best to 1 percent concentrations, while those with more advanced presbyopia required higher 2 percent or 3 percent concentrations to achieve significant visual improvement.”
So will eye drops for presbyopia make us say goodbye to reading glasses or corrective surgeries? Probably not. But as more studies test these eye drops in larger populations to further evaluate their safety and efficacy, they may become a viable alternative for those people who just can’t stand wearing glasses or for whom surgery isn’t an option.
