Phentolamine mesylate ophthalmic solution may have utility in presbyopia
Phentolamine mesylate ophthalmic solution improved distance corrected near visual acuity and reduced pupil diameter in patients with glaucoma and presbyopia, according to a study.
“Presbyopia has a significantly negative impact on quality of life. ... Currently, there are no pharmacological therapies approved for presbyopia, but there is some evidence that decreasing pupil diameter, optimally to a size of 1.6 mm to 2 mm to create a ‘pinhole’ effect, can improve visual acuity by increasing the depth of focus via pseudoaccommodation,” Jay S. Pepose, MD, PhD, and colleagues wrote. “This trial studied the safety and efficacy of 1% PMOS, an alpha-1 antagonist, as a drug candidate to lower IOP in glaucoma patients and, in parallel, to modulate pupil diameter and improve visual acuity in refractive conditions such as presbyopia and [dim light vision disturbances].”
In the ORION-1 double-masked, placebo-controlled, multiple-dose phase 2b trial, researchers randomly assigned 39 patients with elevated IOP 1:1 to receive one evening dose of either 1% phentolamine mesylate ophthalmic solution (PMOS) (19 patients) or placebo (20 patients) for 14 days. Treatment study visits occurred on day 8, day 15 and day 16; study outcomes included mean change in diurnal IOP as well as changes in pupil diameter, distance corrected near visual acuity (DCNVA) and conjunctival hyperemia.
PMOS did not significantly decrease diurnal IOP compared with placebo, but it did yield a mean 20% reduction in pupil diameter sustained for 36 hours after dosing.
Further analysis showed PMOS demonstrated an IOP decrease in patients with lower IOP baseline measurements at day 8 (P = .049), but the difference was not significant at day 15.
Compared with placebo, patients in the study arm achieved one or more lines of DCNVA improvement at day 8 (P = .0018), day 15 (P = .0072) and day 16 (P = .0163) under both mesopic and photopic conditions. There was no statistical difference in conjunctival hyperemia between the study arm and the placebo arm.
“This trial found that 1% PMOS did not reduce IOP in patients with glaucoma or [ocular hypertension]. However, statistically significant decreases in pupil size and improvements in DCNVA were seen, which may be clinically relevant in ocular diseases with pupil modulation as a solution, such as presbyopia and [dim light vision disturbances],” Pepose and colleagues wrote. “PMOS has been studied in patients ranging from 18 to 81 years of age, and further trials should be explored to use PMOS eye drops for pupil modulation indications or potentially [normotensive glaucoma].”