RTA 408 Ophthalmic Suspension for the Prevention of Corneal Endothelial Cell Loss Following Cataract Surgery - GUARD

Inclusion Criteria: 1. Be male or female and ≥18 years of age and ≤80 years of age 2. Plan to undergo cataract extraction by phacoemulsification with the implantation of a posterior chamber intraocular lens 3. Have the potential, in the opinion of the investigator, to improve best-corrected visual acuity in the study eye after surgery 4. Have Grade 3, 4, or 5 nuclear cataract in the study eye, according to the LOCS III 5. Have corneal endothelium in the study eye that can be accurately assessed using specular microscopy 6. Have endothelial cell density of \>1800 cells/mm2 in the study eye at the Screening Visit 7. Have a pinhole visual acuity (VA) of at least 1.0 logarithm of the minimum angle of resolution (logMAR) in the study eye and fellow eye as measured using an Early Treatment for Diabetic Retinopathy Study (ETDRS) chart Exclusion Criteria: 1. Have a score \>0 on the ocular pain assessment at the Screening Visit or the Randomization Visit in the study eye 2. Have an active immunosuppressive disease or an autoimmune disease that, in the opinion of the investigator, could affect the quality of the ocular surface 3. Have active or chronic/recurrent ocular or systemic disease that is uncontrolled and will likely affect wound healing 4. Have an intraocular pressure (IOP) ≤5 mmHg in either eye 5. Have had corneal or retinal surgery (laser or incisional) within the past 6 months, or be planning to have laser or incisional surgery during the study period in the study eye 6. Have the presence of guttae Stage 2 or greater or other abnormality in the study eye that does not allow for accurate corneal endothelial cell assessments