A Phase 2 interventional study of Phentolamine Mesylate Ophthalmic Solution 1% and Phentolamine Mesylate Ophthalmic Solution Vehicle (Placebo) in Mydriasis and Dilation, sponsored by Opus Genetics, Inc. Completed at 4 sites in United States. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-30.
Sponsored by Opus Genetics, Inc · Phase 2, Interventional, and Treatment
The objectives of this study are:
Randomized, 2-arm cross-over, double-masked Phase 2b study in approximately 32 healthy subjects, evaluating safety and efficacy of Nyxol in subjects with pharmacologically induced mydriasis.
At the first visit subjects will be screened for study eligibility.
After screening, eligible subjects will be randomized 1:1 to one of the two treatment sequences:
Treatment sequence 1: Placebo (Visit 1), Nyxol (Visit 2).
Treatment sequence 2: Nyxol (Visit 1), Placebo (Visit 2).
Randomization will be stratified by mydriatic agent (2.5% phenylephrine or 1% tropicamide). Approximately one half of the randomized subjects will receive 2.5% phenylephrine and one half will receive 1% tropicamide. Subjects will receive their mydriatic agent 1 hour before treatment. Each subject will receive the same mydriatic agent throughout the study.
At each visit, pupil diameter (PD), accommodation, near and distance visual acuity (VA) and redness in each eye will be measured before (-1 hour/baseline) and 1 hour after (maximum/0 minutes) the mydriatic agent instillation in each eye (i.e., right before the study treatment is administered), and at 30 minutes, 1 hour, 2 hours, 4 hours and 6 hours after treatment dosing.
As needed, two hours post treatment, subjects may request the administration of Lumify® in the non-study eye.
37 studies on the registry are indexed under Mydriasis; 4 are open to participants now.
This study's enrollment of 32 is below the median of 61 across 35 interventional studies indexed under Mydriasis.
Browse Mydriasis studies →Opus Genetics, Inc is the lead sponsor of 17 studies on the registry; 4 are open to participants now.
Of its 13 completed or terminated interventional studies of FDA-regulated products, 13 (100%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
1 drop in each eye, 1 hour post medically-induced mydriasis
Drug: Phentolamine Mesylate Ophthalmic Solution 1%
1 drop in each eye, 1 hour post medically-induced mydriasis
Other: Phentolamine Mesylate Ophthalmic Solution Vehicle (Placebo)
1% phentolamine mesylate ophthalmic solution (Nyxol), a non-selective alpha-1 and alpha-2 adrenergic antagonist
Also known as: Nyxol®, Nyxol
Topical Sterile Ophthalmic Solution
Pupil Diameter (Change From Max)
Change in pharmacologically-induced mydriatic (maximum) pupil diameter at 2 hours post-treatment in the study eye.
Time frame: 2 hours
Pupil Diameter (Change From Max)
Change in pharmacologically-induced mydriatic (maximum) pupil diameter at remaining timepoints (30 min, 1 hours, 4 hours, 6 hours)
Time frame: 30 min, 1 hours, 4 hours, 6 hours
Pupil Diameter Return to Baseline
Percent of Subjects Achieving Pupil Diameter No More Than 0.5 mm Above Baseline by Time Point with either phenylephrine or tropicamide
Time frame: 0 min, 1 hour, 2 hours, 4 hours, 6 hours
Accommodation Measured by the Near Point Rule (Diopters) (Change From Baseline), Percent With Unchanged Accommodation
Change from baseline (-1 hour) in accommodation at each time point (0 min, 2 hours, 4 hours) with Tropicamide and Phenylephrine Worsening of accommodation is defined as an amplitude decrease of greater than 1 diopter compared to baseline
Time frame: 0 min, 2 hours, 4 hours
Conjunctival Hyperemia (Eye Redness) Assessed Visually With the Brien Holden Vision Institute (Formerly Corneal and Contact Lens Research Unit, or CCLRU) Bulbar Redness Scale (0-3)
Conjunctival hyperemia at each timepoint (0 min, 30 min, 1 hour, 2 hours, 4 hours, 6 hours), for study eye; in all subjects. Scale 0-3 (None, Mild, Moderate, Severe)
Time frame: 0 min, 30 min, 1 hour, 2 hours, 4 hours, 6 hours
Best Corrected Distance Visual Acuity (BCDVA) Measured by Early Treatment Diabetic Retinopathy Study (ETDRS) Light Box Chart (Letters) at 4 Meters (Change From Baseline)
Change from baseline (-1 hour) in Best Corrected Distance Visual Acuity at each time point (0 min, 30 mins, 1 hour, 2 hours, 6 hours) in Study Eye
Time frame: 0 mins, 30 mins, 1 hour, 2 hours, 4 hours, 6 hours
Distance-Corrected Near Visual Acuity (DCNVA) Measured by Standard Reading Card (Original Series Sloan Letter ETDRS Card at 16 Inches, LogMAR Units) (Change From Baseline)
Change from baseline (-1 hour) in Distance Corrected Near Visual Acuity at each time point (0 min, 30 mins, 1 hour, 2 hours, 6 hours) in Study Eye
Time frame: 0 mins, 30 mins, 1 hour, 2 hours, 4 hours, 6 hours
| Milestone | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% |
|---|---|---|
| Started | 16 | 16 |
| Completed | 16 | 15 |
| Not completed | 0 | 1 |
| Withdrew: Pregnancy | 0 | 1 |
Change in pharmacologically-induced mydriatic (maximum) pupil diameter at 2 hours post-treatment in the study eye.
| mm | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| Pupil Diameter (Change From Max) | -1.69 ± 0.117 | -0.69 ± 0.117 |
Change in pharmacologically-induced mydriatic (maximum) pupil diameter at remaining timepoints (30 min, 1 hours, 4 hours, 6 hours)
| mm | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| 30 minutes | -0.06 ± 0.039 | -0.13 ± 0.039 |
| 1 hour | -0.77 ± 0.072 | -0.29 ± 0.072 |
| 4 hours | -2.83 ± 0.145 | -1.69 ± 0.146 |
| 6 hours | -3.24 ± 0.132 | -2.54 ± 0.133 |
Percent of Subjects Achieving Pupil Diameter No More Than 0.5 mm Above Baseline by Time Point with either phenylephrine or tropicamide
| Participants | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| 0 min | 2 | 3 |
| 1 hour | 6 | 3 |
| 2 hour | 11 | 6 |
| 4 hour | 24 | 12 |
| 6 hour | 31 | 28 |
Change from baseline (-1 hour) in accommodation at each time point (0 min, 2 hours, 4 hours) with Tropicamide and Phenylephrine Worsening of accommodation is defined as an amplitude decrease of greater than 1 diopter compared to baseline
| Participants | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| Dilated with Tropicamide, 0 min — Unchanged Accommodation | 3 | 2 |
| Dilated with Tropicamide, 0 min — Changed Accommodation (≥1 D) | 13 | 14 |
| Dilated with Tropicamide, 2 hr — Unchanged Accommodation | 7 | 3 |
| Dilated with Tropicamide, 2 hr — Changed Accommodation (≥1 D) | 9 | 13 |
| Dilated with Tropicamide, 4 hr — Unchanged Accommodation | 11 | 7 |
| Dilated with Tropicamide, 4 hr — Changed Accommodation (≥1 D) | 5 | 9 |
| Dilated with Phenylephrine, 0 min — Unchanged Accommodation | 10 | 11 |
| Dilated with Phenylephrine, 0 min — Changed Accommodation (≥1 D) | 5 | 4 |
| Dilated with Phenylephrine, 2 hr — Unchanged Accommodation | 11 | 13 |
| Dilated with Phenylephrine, 2 hr — Changed Accommodation (≥1 D) | 4 | 2 |
| Dilated with Phenylephrine, 4 hr — Unchanged Accommodation | 12 | 13 |
| Dilated with Phenylephrine, 4 hr — Changed Accommodation (≥1 D) | 3 | 2 |
Conjunctival hyperemia at each timepoint (0 min, 30 min, 1 hour, 2 hours, 4 hours, 6 hours), for study eye; in all subjects. Scale 0-3 (None, Mild, Moderate, Severe)
| score on a scale (0-3) | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| Baseline (-1 hr) | 0.45 ± 0.568 | 0.35 ± 0.486 |
| 0 min | 0.23 ± 0.497 | 0.29 ± 0.461 |
| 30 min | 1.52 ± 0.677 | 0.42 ± 0.502 |
| 1 hr | 1.55 ± 0.675 | 0.45 ± 0.568 |
| 2 hr | 1.42 ± 0.620 | 0.45 ± 0.568 |
| 4 hr | 1.10 ± 0.539 | 0.42 ± 0.564 |
| 6 hr | 0.81 ± 0.654 | 0.35 ± 0.486 |
Change from baseline (-1 hour) in Best Corrected Distance Visual Acuity at each time point (0 min, 30 mins, 1 hour, 2 hours, 6 hours) in Study Eye
| Letters Read | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| 0 mins | -0.45 ± 2.142 | -0.81 ± 2.182 |
| 30 mins | -0.55 ± 2.188 | -0.55 ± 1.690 |
| 1 hour | 0.29 ± 1.774 | -0.10 ± 2.797 |
| 2 hours | 0.65 ± 2.727 | 0.16 ± 2.162 |
| 4 hours | 1.06 ± 2.205 | 0.10 ± 2.119 |
| 6 hours | 0.45 ± 3.982 | 0.90 ± 2.399 |
Change from baseline (-1 hour) in Distance Corrected Near Visual Acuity at each time point (0 min, 30 mins, 1 hour, 2 hours, 6 hours) in Study Eye
| LogMar | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| 0 mins | 0.14 ± 0.194 | 0.13 ± 0.216 |
| 30 mins | 0.09 ± 0.156 | 0.09 ± 0.217 |
| 1 hour | 0.05 ± 0.146 | 0.07 ± 0.142 |
| 2 hours | 0.03 ± 0.113 | 0.00 ± 0.087 |
| 4 hours | 0.00 ± 0.075 | 0.01 ± 0.079 |
| 6 hours | -0.02 ± 0.083 | 0.00 ± 0.055 |
Collected over 2 weeks.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Phentolamine Mesylate Ophthalmic Solution 1% | 0/31 (0%) | 0/31 (0%) | 11/31 (35.5%) |
| Phentolamine Mesylate Ophthalmic Solution Vehicle | 0/32 (0%) | 0/32 (0%) | 1/32 (3.1%) |
| Event | Phentolamine Mesylate Ophthalmic Solution 1% | Phentolamine Mesylate Ophthalmic Solution Vehicle |
|---|---|---|
| Conjunctival HyperemiaEye disorders | 11/31 | 0/32 |
| Abdominal Pain, UpperGastrointestinal disorders | 0/31 | 1/32 |
| NauseaGastrointestinal disorders | 0/31 | 1/32 |
Subjects baseline values are included in the column to which they were randomized first in this crossover design trial. One subject in the PMOS Vehicle First, Then PMOS group was found to be pregnant after their first visit and was withdrawn from the trial and did not crossover to receive PMOS, resulting in an analytical sample of n = 31.
| Age, Continuous(years) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Mean | 27.6 ± 8.18 | 28.5 ± 8.54 | 28.0 ± 8.23 |
| Sex: Female, Male(Participants) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Female | 9 | 10 | 19 |
| Male | 7 | 5 | 12 |
| Race and Ethnicity Not Collected(Participants) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Count of participants | — | — | 0 |
| Iris Color(Participants) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Brown | 16 | 15 | 31 |
| Non-Brown | 0 | 0 | 0 |
| Mydriatic Agent Recieved(Participants) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Phenylephrine | 8 | 7 | 15 |
| Tropicamide | 8 | 8 | 16 |
| Baseline Pupil Diameter (Study Eye)(mm) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Mean | 4.5 ± 0.80 | 4.5 ± 0.79 | 4.5 ± 0.78 |
| Maximum Dilated Pupil Diameter (Study Eye)(mm) | PMOS 1% First, Then PMOS Vehicle | PMOS Vehicle First, Then PMOS 1% | Total |
|---|---|---|---|
| Mean | 7.3 ± 1.04 | 7.2 ± 1.04 | 7.3 ± 1.02 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Aug 2019 to primary completion in Sep 2019, 1 month.
Results were first posted in Aug 2022, 2 years 10 months after primary completion.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Aug 2022. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Phentolamine
Opus Genetics, Inc