Pulsatile ocular blood flow measurements in healthy Asian eyes: reference values for an Indian population

Purpose: To investigate pulsatile ocular blood flow (POBF) in a healthy Indian population and use the data derived as reference values. Methods: Two hundred and fifty-two healthy subjects (121 males, 131 females) underwent intraocular pressure and POBF measurement with the Ocular Blood Flow Analyzer (Paradigm Medical Industries, Salt Lake City, UT, USA and formerly the POBF Tonograph). Before POBF measurement, subjects underwent a complete ophthalmic examination including refraction, slitlamp examination and biomicroscopic fundoscopy and Goldmann applanation tonometry (GAT). Subjects with ocular pathology were excluded from the study. Median age was 29 years (male median 32 years, female median 27 years). Results: Average POBF in males was found to be 1052 µL min−1 (95% CI: 988–1116 µL min−1) and in females to be 1293 µL min−1 (95% CI: 1222–1364 µL min−1). Median age was significantly different between males and females (Mann–Whitney U = 6685; p = 0.0311) but POBF was found to be independent of age in both sexes. As a group, mean refractive error influenced POBF (Kendall's τ = 0.24; p = 0.0017). Conclusions: Pulsatile ocular blood flow values in Indians appear to be higher than reported in studies conducted on other racial groups. The reasons for this difference could be instrumental or anatomical (i.e axial length, ocular rigidity). Care should be taken in deriving normative data using the Ocular Blood Flow Analyzer in mixed race groups.