Eye drops for old eyes, plus other ophtho updates
Pinhole pupils for presbyopia? Dissolve away your cataracts?
Babylon Bee, that satirical site, recently posted this gem: “Boomer's IPhone Font Size Visible From Space” Haha. I get it. But aging lens won’t ‘accommodate’ our needs to see the damn fine print!
For those who want to toss the reader glasses, FDA approved a repurposed drug for that purpose. 1.25% pilocarpine hydrochloride ophthalmic solution, a pharmacological treatment targeted to induce temporary miosis, thus causing a pinhole effect to increase the depth of focus, via the parasympathetic pathway. Other miotic agents studied include phentolamine, a nonselective alpha-adrenergic antagonist.
Of course, there is a tradeoff. [no such thing as a free lunch]. Constricting the diameter of the pupil cut out light and also peripheral vision. Not really a good thing to have when driving in the dark of night.
Lens Softeners
Inducing miosis might be an effective mechanism for treatment of presbyopia by creating a pinhole effect, but it might not address the etiology of this condition. Lens softening, on the other hand, might make a change at its root cause of pathophysiology - loss of the lens elasticity.
Bonding the softening agent, lipoic acid, with choline allows the drug to better penetrate into the aqueous humor. 1.5% lipoic acid choline ester ophthalmic solution is currently in clinical trials showing promising results.
Overview of advantages and disadvantages of each treatment method for presbyopia
NonSurgical Cataract Removal?
Worldwide, cataracts are the leading cause of blindness. Surgery to treat cataracts involves removing the clouded lens and replacing it with a synthetic new one. But new research is looking for topical solutions to dissolve the lesions. Early research in dogs with a steroid-based eye drop, lanosterol, showed potential efficacy.
A recent paper examined the effect on the optics of the lens from treatment with an oxysterol compound in an experimental model of cataract-linked mutations that affect the gradient refractive index (GRIN) and lens opacification in mouse lenses.
Methods: A total of 35 mice including wild-type and knock-in mutants (Cryaa-R49C and Cryab-R120G) were used in these experiments: 26 mice were treated with topical VP1-001, an oxysterol, in one eye and vehicle in the other, and nine mice were untreated controls. Slit lamp biomicroscopy was used to analyze the lens in live animals and to provide apparent cataract grades. Refractive index in the lenses of 64 unfixed whole mouse eyes was calculated from measurements with X-ray phase tomography based on X-ray Talbot interferometry with a synchrotron radiation source.
Results: Heterozygous Cryaa-R49C lenses had slightly irregularly shaped contours in the center of the GRIN and distinct disturbances of the gradient index at the anterior and posterior poles. Contours near the lens surface were denser in homozygous Cryab-R120G lenses. Treatment with topical VP1-001, an oxysterol, showed an improvement in refractive index profiles in 61% of lenses and this was supported by a reduction in apparent lens opacity grade by 1.0 in 46% of live mice.
Conclusions: These results indicate that α-crystallin mutations alter the refractive index gradient of mouse lenses in distinct ways and suggest that topical treatment with VP1-001 may improve lens transparency and refractive index contours in some lenses with mutations. - K Wang et al
So there you go … the eyes have it!
REFERENCES
https://babylonbee.com/news/boomers-iphone-font-size-visible-from-space/
A Grzybowski, V Ruamviboonsuk. Pharmacological Treatment in Presbyopia. J Clin Med. 2022 Mar 3;11(5):1385. doi: 10.3390/jcm11051385
https://www.webmd.com/eye-health/cataracts/ss/slideshow-cataracts
H Armitage. Eye drops could dissolve cataracts. New therapy has already proven successful in dogs. 22 Jul 2015. doi: 10.1126/science.aac8893 https://www.science.org/content/article/eye-drops-could-dissolve-cataracts
K Wang et al. Oxysterol Compounds in Mouse Mutant αA- and αB-Crystallin Lenses Can Improve the Optical Properties of the Lens. Investigative Ophthalmology & Visual Science May 2022, Vol.63, 15. doi:https://doi.org/10.1167/iovs.63.5.15