Dorzolamide+Timolol Multidose Preservative-free vs Dorzolamida+Timolol BAK Preserved Efficacy and Safety

Inclusion Criteria: * Older than 18 years old * Patients with POAG and OH * PIO \< 20 mmHg * Under treatment with Dorzolamide + Timolol BAK preserved at least 6 month after * OSDI \> 13 \& one of these ocular signs (BUT \<6sec or Schirmer test \< 5 mm/5min or corneal staining positive) * Corneal thickness between 520-580 um. Exclusion Criteria: * Patient with severe respiratory diseases (asthma, COPD and other bronchospactic diseases). * Patient with cardiovascular diseases (Sinus Bradycardia, AV Block, Cardiac Failure, Cardiogenic Shock). * Severe renal impairment (CrCl \<30 mL/min) * Progressive diseases of the retina other than glaucoma * Inflammation and/or infecctions active * Ocular surface syndrome other than Ocular Surface disease * Eyelid disorder * Systemic adminsitration of Betablockers or carbonic anhydrase inhibitors * Patient that requires another antigluacomatous eye drop other than fixed combination of Dorzolamide/Timolol * Patients who use regularly lubricant eye drops * Patient who use regularly contact lenses * Patient with autoinmune diseases * Patients who underwent kerato-refractive laser procedures, cornea or corneal surface surgery, including, but not limited to, LASIK and PRK, within 6 months prior to the baseline visit. * Patients who have undergone a laser procedure or intraocular surgery or extraocular in either eye within 6 months prior to the baseline visit. * Patients with severe central visual field loss in either eye based onclinical judgme…