Safety and Efficacy of Nyxol (0.75% Phentolamine Ophthalmic Solution) in Subjects With Dim Light Vision Disturbances

Inclusion Criteria: 1. Males or females ≥ 18 years of age 2. Subject-reported DLD (likely subjects with a history of multifocal IOLs, post-laser-assisted in situ keratomileusis \[LASIK\], corneal scars, and keratoconus) 3. Ability to comply with all protocol-mandated procedures independently and to attend all 4. Otherwise healthy and well-controlled subjects 5. Able and willing to give written consent to participate in this study 6. Able to self-administer study medication 7. PD ≥ 6 mm under mesopic conditions (prior to illumination) in at least one eye 8. ≤ 20 (20/100 Snellen or worse) ETDRS letters in mLCVA score 9. ≥10 ETDRS letters ( ≥2 lines) improvement in mLCVA in at least one eye during illumination of the contralateral eye with a BAT system on low setting Exclusion Criteria: Ophthalmic: 1. Prior history of dry eye diagnosis, taking prescription drops for dry eye, or taking artificial tear drops occasionally for dry eye 2. Prior history of fluctuating vision 3. Clinically significant ocular disease as deemed by the Investigator that might interfere with the study 4. Known hypersensitivity to any topical alpha-adrenoceptor antagonists 5. Known allergy or contraindication to any component of the vehicle formulation 6. History of cauterization of the punctum or punctal plug (silicone or collagen) insertion or removal 7. Ocular trauma, ocular surgery (e.g., IOLs) or laser procedure (e.g., LASIK, photorefractive keratectomy \[PRK\]) within 6 months prior to screening 8. Use of any topical prescription or over-the-counter (OTC) ophthalmic medications of any kind within 7 days of screening 9. Recent or current evidence of ocular infection or inflammation in either eye. Subjects must be symptom free for at least 7 days. 10. History of diabetic retinopathy, diabetic macular edema, or dry or wet macular degeneration 11. History of any traumatic (surgical or nonsurgical) or nontraumatic condition affecting the pupil or iris 12. Unwilling or unable to discontinue use of contact lenses at screening until study completion, except for keratoconus subjects who may wear contacts up to 24 hours prior to their scheduled visits Systemic: 1. Known hypersensitivity or contraindication to alpha- and/or beta-adrenoceptor antagonists 2. Clinically significant systemic disease that might interfere with the study 3. Initiation of treatment with or any changes to the current dosage, drug, or regimen of any systemic adrenergic or cholinergic drugs within 7 days prior to screening or during the study 4. Participation in any investigational study within 30 days prior to screening and during the conduct of the study 5. Females of childbearing potential who are pregnant, nursing, planning a pregnancy, or not using a medically acceptable form of birth control 6. Resting HR outside the specified range (50-110 beats per minute) 7. Hypertension with resting diastolic BP \> 105 mmHg or systolic BP \> 160 mmHg