BLOG: Hyper hopes for hyperopes
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In this issue of Healio/Ocular Surgery News, the cover story explores evolving trends in LASIK and what to expect for the future. But all this may hinge on other developments in lens-based surgery.
More than one company is working on technology to reverse both presbyopia and cataract formation. This is a challenging task because of the multifactorial contributors to these conditions. Novartis learned an expensive lesson with the failed clinical trials of UNR844, the lipoic acid choline ester-based eye drop that failed to meet clinical endpoints in a U.S. phase 2b clinical trial to reverse presbyopia, despite promising evidence in a mouse model. Another good idea in the dustbin of history.
Visus, known for the presbyopia-treating combination drop candidate containing carbachol and brimonidine, recently announced the acquisition of ViewPoint Therapeutics. This brings Visus a library of compounds purporting to stabilize the dimer configuration of alpha-crystallin proteins in the lens, which contribute to an orderly arrangement of beta- and gamma-crystallins that maintain lens clarity. Primates with age-related cataracts, which are biochemically analogous to human cataracts, have already demonstrated improved lens clarity when exposed to the intravitreal delivery of at least one of these drug candidates.
This is a long way from curing human cataract or presbyopia for that matter. If pandemic-related vaccine hesitancy taught us one thing, it’s that consumers are not fond of needles. To choose an eyeball needle stick over a pair of readers, our patients would need some convincing proof. Moreover, how will eye care providers react to a treatment that will reduce the need for cataract surgery, our bread-and-butter procedure?
As technology advances, barriers recede; improvement in the formulation of these drugs is likely, eventually allowing topical or other more tolerable delivery. And if that happens, think of the implications. Hyperopes, who make up roughly half the Western population, would be the biggest beneficiaries. Except at the extremes, all hyperopes start as low or latent hyperopes — the kids with the best vision in their classes. As their lenses mature in adulthood, they frustratingly experience near difficulties, eventually resorting to readers and finally bifocals far earlier than their contemporaries. Hyperopic LASIK procedures create spherical aberration and only across a limited range of correction. We resort to lens-based procedures much earlier in these patients, compromising accommodation, because no other treatment offers much hope. A medical treatment for cataract/accommodation is, therefore, a medical treatment for hyperopia, at least in the largest population of hyperopes who need smaller corrections.
Surely there is a place for drugs that treat cataract, and I believe even we cataract surgeons should welcome them. In a population that’s living longer, it’s likely that cataract will eventually occur, which means we’ll be treating more 60-year-old cataracts in 80-year-old patients.
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