Differences in ocular biometrics and aqueous humour dynamics between Chinese and Caucasian adults.

BACKGROUND: Glaucoma prevalence and subtype profile vary across different racial and ethnic groups. This study provides a comparative evaluation of differences in aqueous humour dynamics (AHD) and ocular biometrics in healthy Chinese and Caucasian adults of two different age groups.

METHODS: Data from two independent studies with identical designs were compared. Cohorts included young adults (20-30 years old, 32 Chinese and 39 Caucasians) and older adults (>50 years old, 37 Chinese and 46 Caucasians). Parameters of AHD and ocular biometrics were evaluated. Group comparisons were made by generalised estimating equation methods.

RESULTS: Differences in young adult Caucasians compared with similarly aged Chinese were thinner central cornea (-29.27 µm, p<0.001), lower intraocular pressure (IOP) (-2.33 mm Hg, p<0.001), larger anterior chamber volume (ACV) (28.78 µL, p<0.001) and faster uveoscleral outflow rate (Fu) (0.82 µL/min, p<0.001). Differences in older adult Caucasians compared with similarly aged Chinese were slower aqueous flow rate (Fa) (-0.28 µL/min, p=0.042), lower IOP (-1.97 mm Hg, p<0.001) and larger ACV (33.15 µL, p<0.001). Considering all subjects together by race, Caucasian subjects had slower Fa (-0.22 µL/min, p=0.035), thinner corneas (-0.52 µm, p=0.003), lower IOP (-2.11 mm Hg, p<0.001), higher ACV (30.39 µL, p<0.001) and faster Fu (0.63 µL/min, p<0.001).

CONCLUSION: Differences in AHD and biometrics between Caucasian and Chinese adults include larger ACVs which may contribute to the wider angles reported in Caucasians, and slower Fa rates coupled with faster Fu rates which may contribute to their lower IOP and lower overall risk of glaucoma.