Clinical Research Directory

Inclusion Criteria: 1. 18 to 45 years of age experiencing severe night vision difficulty (as reported subjectively) 2. 0.3 log improvement at least 1 eye using the Holladay Automated Contrast Sensitivity System (HACSS™) test at 2 of 4 spatial frequencies (3, 6, 12, and 18 cycles per degree) under low and high mesopic room illumination with glare 3. Photopic visual acuity (corrected or uncorrected) of 20/25 or better 4. Able and willing to give informed consent and comply with all protocol-mandated procedures Exclusion Criteria: 1. Cataracts (nuclear sclerosis or anterior subcapsular) of 1+ or greater 2. Contact lens wear within 4 weeks of enrollment 3. Ocular trauma within the past 6 months, or ocular surgery or laser treatment within the past 3 months 4. Refractive surgery or cataract surgery in either eye 5. Use of ocular medication within 4 weeks of Visit 1 6. Clinically significant ocular disease (e.g., corneal edema, uveitis, severe keratoconjunctivitis sicca, glaucoma, retinal degenerative disease) which might interfere with the study 7. Any abnormality preventing reliable applanation tonometry of either eye 8. Central corneal thickness greater than 600 µ 9. Known hypersensitivity or contraindication to PM, or any component of the formulation, or to topical anesthetics. 10. Contraindications to phentolamine (including history of myocardial infarction, cerebrovascular spasm, cerebrovascular occlusion, coronary insufficiency, angina, or other evidence suggestive of coronary artery disease) 11. Low blood pressure: systolic \< 100 mm Hg or diastolic \< 60 mm Hg 12. A history of heart rate abnormalities, such as tachycardia or arrhythmias. 13. Clinically significant systemic disease (e.g., uncontrolled diabetes, myasthenia gravis, hepatic, renal, cardiovascular, or endocrine disorders) which might interfere with the study 14. Use of any systemic alpha adrenergic antagonists up to 4 weeks prior to screening or during the study 15. Changes of systemic medication that could have a substantial effect on ocular autonomic pupil tone 4 weeks prior to screening, or anticipated during the study 16. Participation in any investigational study within the past 30 days 17. Women of childbearing potential who are pregnant, nursing, planning a pregnancy, or not using a medically acceptable form of birth control. An adult woman is considered to be of childbearing potential unless she is 1 year post-menopausal or 3 months post-surgical sterilization. All females of childbearing potential must have a negative serum pregnancy test result at the screening examination and must not intend to become pregnant during the study