Pilocarpine 1.25% for the treatment of presbyopia

Dear Editor,

Vuity (pilocarpine hydrochloride 1.25%, Allergan, AbbVie Company, Dublin, Ireland) is a re-engineered formulation of pilocarpine in a proprietary vehicle, which was granted FDA approval in 2021 for the treatment of presbyopia, after phase 3 GEMINI 1 study.[1]

Continuous and regular use of pilocarpine 1.25% for the treatment of presbyopia needs to address some of the questions on the adverse effects, which may not become evident at the 30- day endpoint.[1]

Pilocarpine-induced miosis begins 15 to 30 min after instillation and lasts for 4–8 h. Hence once a daily dose in the morning will not be sufficient to have its effect on near vision in the evening.[1] Patients with lenticular opacities will have decreased vision in dim illumination and should be warned about the dangers of night driving if they use the eye drop in the evening. There can be changes in distance vision due to fluctuating myopic shifts in refraction and hence one needs to see whether an improvement in near vision is at the cost of compromised distance vision.

The direct-acting cholinergic drug can alter lens permeability, leading to a shift in lens cations and water accumulation, causing changes in the intraocular metabolism and its use may accelerate lens opacities formation.[2] Hence, the long-term adverse effect of the drug should be kept in mind. Pilocarpine binds to melanin in the iris and ciliary body and hence, iris color may influence its desired response.[3] Patients with darkly pigmented irides may require a higher concentration of pilocarpine for its maximum effect. The effect of “Vuity” on Asian Indian eyes and whether the 1.25% concentration suffices the desired effect on near vision, needs to be studied.

Careful examination of the peripheral retina is mandatory before prescribing pilocarpine. This increases the responsibility of the ophthalmologist to perform a thorough examination of the retinal periphery, before prescribing the drug. Increased permeability of the blood–aqueous barrier is another side effect of the drug, which should be kept in mind. Long-term use will cause permanent miosis from the loss of tone in the iris radial muscles and fibrosis of the pupillary sphincter and may result in posterior synechiae, causing difficulty in dilatation for examination of retinal periphery and adequate dilatation for cataract surgery, if the patient requires it in future.

Pilocarpine can also precipitate an acute angle closure attack as it causes anterior chamber depth to decrease by 12%, which is of concern in patients with narrow angles.[4] It has been suggested that prolonged therapy with pilocarpine also causes permanent ultrastructural changes in the ciliary muscle and trabecular meshwork.[5] Hence, gonioscopy should also be performed before commencing the treatment and periodically during the follow-up, which is an additional responsibility of the treating ophthalmologist.

The aforementioned adverse effects can be disabling, especially in the patients who may instill pilocarpine frequently, to have the desired effect on near work in the evening and hence, should be cautioned and monitored regularly. Future studies may address the adverse effects of long-term use of 1.25% pilocarpine, which may not become evident at the 30-day endpoint.

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Conflicts of interest

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