Phentolamine Mesylate Ophthalmic Solution Provides Lasting Pupil Modulation and Improves Near Visual Acuity in Presbyopic Glaucoma Patients in a Randomized Phase 2b Clinical Trial

Pharmacological treatments for the correction of presbyopia

Presbyopia affects between 1.7 and 2 billion people worldwide. Presbyopia significantly impacts productivity and quality of life in both developed and developing countries. During accommodation, the human eye changes its dioptric power by altering the shape of the lens, but the exact nature of this change has not been fully explained. Recently, topical treatments have been marketed for the treatment of presbyopia and others are under investigation. In order to prepare a review of these novel therapies, we searched the major biomedical search engines. We found 15 randomized clinical trials and 12 reviews that met our review criteria. There are two different strategies for this purpose, the pinhole effect that increases depth of focus and "crystalline lens relaxation" for which parasympathetic mimetics and lens oxidation intermediates have been used. The results are generally favorable in terms of improvement of near visual acuity, although the follow-up period of the studies is short. These are novel strategies in the early stages of research that could be useful in the treatment of presbyopia.

A randomized phase 2 clinical trial of phentolamine mesylate eye drops in patients with severe night vision disturbances

PURPOSE

Dim light vision disturbances (DLD) comprise a wide range of symptoms affecting the quality of vision at low illumination including glare, halos, and starbursts. This exploratory study investigated 1.0% phentolamine mesylate ophthalmic solution (PMOS) as a treatment to improve vision and image quality for patients with DLD.

METHODS

In this placebo-controlled, randomized, double-masked clinical trial, 24 adult patients with severe DLD were randomized in a 2:1 ratio to receive either one dose of PMOS or placebo. Subjects were eligible if they reported experiencing severe night vision difficulty that was not eliminated by distance spectacle correction and scored ≥0.3 log units below the normal range of contrast sensitivity assessed under mesopic conditions with glare at ≥2 spatial frequencies. Key efficacy outcomes were change from baseline in pupil diameter, contrast sensitivity, and visual acuity. Safety measures including intraocular pressure, conjunctival hyperemia, and systemic effects were also assessed.

RESULTS

Eight subjects were randomized to placebo (63% female; mean age 47 years) and 16 were randomized to PMOS (75% female; mean age 42 years). Mean (SD) pupil diameter of PMOS-treated subjects decreased significantly - 1.3 mm (0 to - 2.8 mm) with p < 0.0001. Mean contrast sensitivity with glare in PMOS-treated subjects improved significantly post-treatment at spatial frequencies 3, 6, 12, and 18 cycles per degree (p ≤ 0.03). PMOS also demonstrated improvements in the numbers of letters read for mesopic and photopic, high- and low-contrast visual acuity (LCVA). Importantly, a statistically greater proportion of PMOS-treated eyes registered mesopic LCVA 5 letter (69% vs. 31%, p = 0.029) and 10 letter (34% vs. 6%, p = 0.04) improvement, with a trend at 15 letters (19% vs. 0%, p = 0.16). PMOS was well tolerated with the only reported side effect being a mild increase in conjunctival hyperemia.

CONCLUSION

PMOS was well tolerated and effectively reduced pupil size with improvements in contrast sensitivity and visual acuity in adults with severe DLD. Future Phase 3 studies should be conducted to further evaluate its potential to treat DLD.

TRIAL REGISTRATION

The trial registration number is NCT04004507 (02/07/2019). Retrospectively registered.

Glaucoma Clinical Research: Trends in Treatment Strategies and Drug Development

Purpose: To investigate the trends and progresses in glaucoma research by searching two major clinical trial registries; clinicaltrials.gov, and Australianclinicaltrials.gov.au. Methods: All clinical trials with glaucoma covered by Clinicaltrials.gov, and Australianclinicaltrials.gov.au starting the study before 1 January 2021 were included. Trials evaluating glaucoma treatment were separated from non-treatment trials and divided into three major categories: "laser treatment," "surgical treatment," and "medical treatment." In the category of "medical treatment," new compounds and their individual targets were identified and subcategorized according to treatment strategy; intraocular pressure (IOP)-lowering, neuroprotective or vascular. The phase transition success rates were calculated. Results: One-thousand five hundred and thirty-seven trials were identified. Sixty-three percent (n = 971) evaluated glaucoma treatment, of which medical treatment accounted for the largest proportion (53%). The majority of medical trials evaluated IOP-lowering compounds, while trials with neuroprotective or vascular compounds accounted for only 5 and 3%, respectively. Eighty-eight new compounds were identified. Phase I, II, and III transition success rates were 63, 26, and 47%, respectively. Conclusion: The number of clinical trials in glaucoma research has increased significantly over the last 30 years. Among the most recently evaluated compounds, all three main treatment strategies were represented, but clinical trials in neuroprotection and vascular modalities are still sparse. In addition to traditional medicines, dietary supplements and growth factors are assessed for a potential anti-glaucomatous effect. Phase II and III success rates were below previously reported success rates for all diseases and ophthalmology in general. A stricter phenotyping of patients can improve the success rates in glaucoma and ophthalmological research and gain a better understanding of responders and non-responders.

Advances in Corneal Surgical and Pharmacological Approaches to the Treatment of Presbyopia

The purpose of this article is to review the current status of presbyopia amelioration with surgical and pharmacologic procedures that partially compensate for loss of accommodation in advance of cataract surgery and lens replacement. Over the last few years, several corneal surgical and topical pharmacological approaches for the treatment of presbyopia have been introduced to the marketplace or are in the developmental pipeline. The approaches vary in invasiveness, duration of effect, reversibility, risk/benefit ratio, and clinical results. The advantages and disadvantages for each are discussed. Corneal surgical interventions aim to provide improved near and intermediate vision in patients with presbyopia through refractive means that extend ocular depth of focus through shape modification. The use of miotic drops or corneal lamellar implants extend depth of focus with the "pinhole" aperture size reduction effect. Unlike in adults younger than 40 years, the refractive status of the patient with presbyopia is not stable. Hence, procedures that provide a permanent refractive change may not provide long-term full correction; eye drops or other treatments that are self-reversing in time or are easily reversible may be used as needed. On the horizon, procedures are being explored that may add years of functional lens accommodation by preserving the deformable gel properties of the lens. [J Refract Surg. 2021;37(6 Suppl):S20-S27.].