Background: Ocular surface disease (OSD) is relatively common in glaucoma patients. OSD symptoms could be linked to prolonged exposure to preservatives in anti-glaucoma medications, especially benzalkonium chloride (BAK). The OBSERVE clinical audit was designed to track the impact of intraocular pressure lowering medications in patients with evidence of OSD to test the hypothesis that BAK-free anti-glaucoma preparations offer clinical advantages over BAK-containing products. Design: Prospective clinical audit from March 2012 to April 2013, open to ophthalmologists practising in Australia. Participants: There were 375 patients enrolled, with a completion rate of 64%. The cohort was predominantly female (68%) with an average age of 71 years. Methods: Patients were screened for inclusion during a routine consultation. If eligible, they were enrolled. At the ophthalmologist's discretion, some patients were switched to BAK-free anti-glaucoma products. Data were collected via an online survey completed by the ophthalmologist during three appointments over a 16- to 30-week period for all patients. Main Outcome Measures: Intraocular pressure, tear-film breakup time, McMonnies Dry Eye Questionnaire score and reported lubricant use. Results: Patients who switched to BAK-free preparations reported a significant fall in the use of lubricants (P=<0.001). Patients in both groups experienced a significant improvement in McMonnies Dry Eye Questionnaire score (P=<0.0001). The percentage of patients with low tear-film breakup time decreased significantly in both groups (P=0.0001). There was no significant change in intraocular pressure from pre-study levels for either group (P=0.105). Conclusions: BAK-free anti-glaucoma preparations were associated with a change in lubricant use, suggesting reduction in some OSD symptoms, but more research is needed.