Distribution and associations of intraocular pressure in indigenous Australians within central Australia: The Central Australian Ocular Health Study

Purpose: To determine the distribution and associations of intraocular pressure (IOP) among the indigenous Australian population living in central Australia. Design: Clinic-based cross-sectional study. Participants: 1884 individuals living in one of 30 remote communities within the statistical local area of 'Central Australia'. This equated to 36% of those aged ≥20years and 67% of those aged ≥40years within this district. Methods: Participants aged 20years or over were recruited as they presented to the eye clinic at each remote community. Of those recruited into the study, 1060 underwent IOP measurement using either a Perkins tonometer (Haag-Streit, Koeniz, Switzerland) or an ICare tonometer (Tiolat Oy, Helsinki, Finland) depending on the availability of equipment. Central corneal thickness (CCT) was also measured using ultrasound pachymetry. Main Outcome Measures: The distribution and associations of IOP from the right eye of each participant is presented. Results: Mean IOP was 12.8mmHg (SD 3.2mmHg) and CCT was 512μm (SD 36μm). IOP was strongly associated with CCT (r ²=0.14, t=3.87; P<0.0001), showing an increase of 0.4mmHg with every 10μm increase in CCT. Furthermore, IOP was strongly associated with age, decreasing by 1.9mmHg for every decade increase in age, but only for eyes with a CCT above the mean. Conclusion: IOP of indigenous Australians is lower than any other racial group previously published. This may relate to the low CCT readings found among this population. Clinicians will need to bear this in mind when examining indigenous Australians and make appropriate allowances for the measured IOP.