Preoperative Brimonidine on IOP of Patients Undergoing RALP

With completed informed consent, study participants will undergo a pre-operative comprehensive ophthalmic evaluation to document best corrected visual acuity (VA), IOP measurements, visual field assessments (VF), optical coherence tomography measurements (OCT) of the retinal nerve fiber layer, optic disc photography and screening for other ophthalmologic abnormalities. Height and weight measurements will also be recorded. Using opaque envelopes with the aid of Sequentially Numbered Opaque Sealed Envelopes (SNOSE) schemes, each patient will be randomized to either right eye or left eye. Thereafter patients will be randomized to placebo (carboxymethylcellulose) or drop (Brimonidine tartrate 0.2%) which will be given 30 minutes before the start of surgery with the patient in horizontal supine position. Eyes randomized to receive a drop will be treated with one drop of Brimonidine tartrate 0.2% while eyes randomized to receive placebo will receive one drop of Carboxymethylcellulose eye drops (Control group). IOP measurements will be recorded for both eyes pre-operatively in the upright seated position (baseline), pre-anaesthetized in supine horizontal position, intra-operatively in anaesthetized supine horizontal position, hourly intra-operatively in anaesthetized sTBURG, awake post-operatively in supine horizontal position and at 1 month postoperatively in the upright seated position. Three IOP measurements will be recorded, each with 5% confidence interval (CI). Blood pressure and end tidal carbon dioxide will be recorded hourly intra-operatively. The following surgical data will also be recorded: procedure duration, angle of inclination of surgical bed, anesthetic agents used, fluid volume given, transfusions given, blood loss volume and complications. Best corrected VA, IOP, VF, OCT and optic disc photography will also be recorded for each patient at the 1-month post-operative visit.