As we age, we must all come to terms with the inevitable changes in our bodies. How we deal with these changes is greatly influenced by the treatment options available to us. Among these changes that occur with age, presbyopia, the degeneration of the crystalline lens affecting near-field vision, is one of the most common.
A visit to any pharmacy tells the tale of medicinal options, some more effective or more preventative than others. We find anti-aging creams in the skincare aisle and denture adhesive next to the toothpaste. A common sight in nearly every pharmacy is a rack of reading glasses. While these reading glasses provide necessary relief for countless presbyopia sufferers, we often wonder if there could be a better approach to addressing this problem.
This was the issue at hand during the Presbyopia Game Changers symposium at the ESCRS Congress 2023 in Vienna, Austria. As Dr. Elizabeth Yeu emphasized in the opening lecture of the session, it is an issue of significant concern to a vast number of people.
Dr. Yeu reported that 2.1 billion people worldwide suffer from presbyopia, with an estimated 80% of the population experiencing the condition by the age of 45 to 55. In the US alone, there are about 1.8 million new cases of presbyopia each year.
“In fact, 40% of those patients are looking for an alternative beyond glasses, but there are no great solutions,” Dr. Yeu said. She cited census reports of the most impactful age-related ailments, noting that two of the top six were vision-related. “But the number one is loss of near vision,” she continued, “with 60% of patients truly concerned about it.”
Drawbacks of current alternative solutions
Dr. Yeu pointed out that “there is no ‘holy grail’ for presbyopia treatment.” In addition to the traditional reading or bifocal glasses, advanced contact lens options have been developed. However, these options come with the inconveniences and challenges associated with lens solutions. They can also lead to a reduction in depth perception over time, as well as adjustment to monovision.
Numerous surgical alternatives for presbyopia exist, but each one comes with significant drawbacks. Multifocal IOLs and refractive lens exchange do not provide a comprehensive solution, and the associated costs and risks likely outweigh the potential benefits.
Corneal inlays are both expensive and carry the risk of complications and reduced distance vision. Monovision laser correction is perhaps the most high-risk treatment option, involving irreversible sculpting of the eye. It also carries a number of potential side effects, including the loss of binocularity and depth perception.
All in all, surgical treatments often come with complications and risks, which typically outweigh the partial solutions they can provide for presbyopia sufferers. However, all of these treatments are continuously improving and may one day provide a conclusive treatment for presbyopia. As Dr. Yeu revealed, a lot of encouraging results come from the latest developments in pharmacology.
Miotic drops provide a pharmacological alternative
“Among the emerging therapeutics, the one that we currently have in the US is pilocarpine 1.25%,” continued Dr. Yeu. In March of this year, it received FDA approval for B.I.D. usage, a significant development as it extends the ability for patients to use it day to night. But it still allows reversibility, so that the pupil can go back to its nascent state by morning.
“The benefits of pilocarpine as a treatment for presbyopia are quite significant,” Dr. Yeu explained. Like all miotic drops, pilocarpine works by triggering a constriction of the pupil, thereby improving depth of focus as a result of small aperture optics. Commonly described as “the pinhole effect,” this reduction in the size of the pupil leads to a sharpening of distant and near images alike.
Though pilocarpine 1.25% is currently the only FDA-approved miotic drop, it is by no means the only one currently in the clinical development stage. Various other preparations of pilocarpine, including those prescribed in conjunction with phentolamine, as well as aceclidine and stand-alone phentolamine in a spray formulation, are also currently in the testing phase.
These applications aim to improve upon the delivery mechanics of the 1.25% pilocarpine drops, or to reduce the stress placed upon the eye, reducing the chance of harmful side effects.
Another miotic drop preparation could potentially provide an alternative treatment option. Delivering a significantly higher muscarinic agonist potency, Brimochol PF (Visus Therapeutics, WA, USA) drops are also showing great promise in phase 3 studies.
These drops bring together the longlasting miotic effect of carbachol with the unique properties of brimonidine tartrate, which has a whitening effect, by inhibiting ciliary muscle contraction, preventing pupil dilation, and acting as a vasoconstrictor.
Cautious optimism
The efficacy of the currently available pilocarpine drugs, as well as those potentially in the pipeline, is great news for individuals seeking an alternative treatment for presbyopia. However, Dr. Yeu noted that there are potential side effects that could come from the drop’s incorrect use.
“This is not a lifestyle drop that we simply prescribe without doing a proper dilation. This is a medication. We want to know if there is vitreomacular traction. We need to assess for any prolonged axial length,” she cautioned.
Careful management of these very effective drugs is vital to their future success. Dr. Yeu concluded by highlighting that the proper use of these therapeutics is something that requires close management within the eye care community in order to ensure a safe and effective alternative treatment for presbyopia.
As Dr. Yeu previously mentioned, there is no holy grail or miracle cure. However, these advances in pharmacology could go a long way in liberating millions of presbyopes from their dependence on glasses.
Editor’s Note:
- A version of this article was first published in CAKE Magazine Issue 20.
- The 41st ESCRS Congress was held in Vienna, Austria, from September 8 to 12, 2023. Reporting for this story took place during the event.
