A recent article presented the findings of MIRA-2 and MIRA-3, two Phase 3 trials that investigated the efficacy of 0.75% phentolamine ophthalmic solution in reversing pharmacologically induced mydriasis. The trials involved 553 healthy participants aged 12 to 80 years.

Although pupil dilation is integral to thorough eye exams, it can also have negative side effects that can affect patients’ daily lives while mydriasis is induced. These side effects include increased higher-order aberrations, blurred vision, photophobia, glare, ocular scatter, and more. In a study published in Ophthalmology, researchers looked into the potential benefits of reversing mydriasis following a dilated eye examination which could include reducing a barrier to patients seeking eye care.

Phentolamine ophthalmic solution (POS) 0.75% is a preservative-free ophthalmic non-selective alpha-adrenergic antagonist that inhibits contraction of the iris dilator muscle.

In both MIRA-2 and MIRA-3, the reversal of mydriasis occurred faster in those treated with phentolamine. At 60 minutes post-treatment, 37.5% of participants in MIRA-2 and 48% in MIRA-3 had achieved near-baseline pupil size, compared to under 2% in the placebo groups. And, at 90 minutes post-treatment, 48.9% of participants in MIRA-2 and 58% in MIRA-3 who received POS returned to near-baseline pupil size, compared to only 6% in the placebo group. By 6 hours post-treatment, nearly all POS-treated participants had fully returned to baseline pupil size, whereas many placebo-treated participants still exhibited dilation.

POS was found to be effective across all age groups in the study, with no significant difference in outcomes based on age. It was also well tolerated; the most common side effects were mild, including transient conjunctival hyperemia which was experienced in 11.2% of cases, and instillation site discomfort noted by 10.9% of study participants.

“POS can provide an overall five to six hours of time savings in terms of return of pupil dilation to its baseline,” the researchers noted. They recommended that further studies “include patients with conditions that could affect pupillary dynamics, such as pseudoexfoliation, diabetes and other conditions that may affect the autonomic nervous system, and include endpoints such as low contrast mesopic vision that can further elucidate the functional effect of POS in subjects who undergo pharmacologically induced mydriasis.”

A full list of author disclosures can be found in the published research.