Clinical outcomes of combined versus separate carbachol and brimonidine drops in correcting presbyopia

Abstract

BackgroundTo test and compare in a masked fashion the efficacy of using a parasympathomimetic drug (3% carbachol) and an alpha-2 agonist (0.2% brimonidine) in both combined and separate forms to create optically beneficial miosis to pharmacologically improve vision in presbyopia.MethodsA prospective, double-masked, randomized, controlled clinical trial was conducted. Ten naturally emmetropic and presbyopic subjects between 42 and 58 years old with uncorrected distance visual acuity of at least 20/20 in both eyes without additional ocular pathology were eligible for inclusion. All subjects received 3% carbachol and 0.2% brimonidine in both combined and separate forms, 3% carbachol alone and 0.2% brimonidine (control) alone in their non-dominant eye in a crossover manner with one week washout between tests. The subjects’ pupil sizes and both near and distance visual acuities will be evaluated pre- and post-treatment at 1, 2, 4, and 8 h, by a masked examiner at the same room illumination.ResultsStatistically significant improvement in mean near visual acuity (NVA) was achieved in all subjects who received combined 3% carbachol and 0.2% brimonidine in the same formula compared with those who received separate forms or carbachol alone or brimonidine alone (P < 0.0001).ConclusionBased on the data, the combined solution demonstrated greater efficacy than the other solutions that were tested. Improving the depth of focus by making the pupil small caused statistically significant improvement in near visual acuity, with no change in binocular distance vision.Trial registration ACTRN12616001565437. Registered 11 November 2016.

Presbyopia: Effectiveness of correction strategies

“…Pharmaceutical treatments for presbyopia include stimulating the contraction of the ciliary muscles in the presence of different miotics(Abdelkader, 2015;Abdelkader and Kaufman, …”

Pharmacological Therapy for Presbyopia in Patients with Previous Corneal Refractive Surgery: A Pilot Study

“…The UNVA was measured with the Jaeger scale, and all the treated subjects abandoned the use of near glasses. He also compared the monocular instillation of 3% carbachol and 0.2% brimonidine in combined and separate forms, demonstrating a significant improvement in mean near visual acuity in the combined solution group [7]. Benozzi et al [10] reported that 100% of patients achieved near vision of J1 after the topical instillation of pilocarpine 1% and 0.1% diclofenac.…”

“…Accommodation can be pharmacologically stimulated by the contraction of the ciliary muscle. Some topical treatments have been studied [6][7][8][9][10], reporting an improvement in near vision with the topical application of muscarinic cholinergic agonists. We previously reported our results with a new pharmacological therapy (FOV tears) for presbyopia [8,9].…”

Overview of pharmacological treatments for presbyopia

“…On the 1 hand, brimonidine, an α2-receptor agonist used in glaucoma, induces pupillary action, producing significant miosis, mainly under low light conditions [48]. Brimonidine binds to receptors on the presynaptic nerve endings of the dilator muscle and obstructs further release of the neurotransmitter into the synaptic cleft, thus reducing the activity of the dilator muscle, generating a more miotic pupil [37]. In contrast, carbachol, unlike pilocarpine, is a full parasympathomimetic agent that stimulates the muscarinic and nicotinic receptors on the iris sphincter muscle to produce miosis, increase the depth-of-focus [34], and promote acetylcholine release from parasympathetic nerve endings.…”