RT Journal Article
SR Electronic
T1 Aqueous humour dynamics and biometrics in the ageing Chinese eye
JF British Journal of Ophthalmology
JO Br J Ophthalmol
FD BMJ Publishing Group Ltd.
SP 1290
OP 1296
DO 10.1136/bjophthalmol-2016-309883
VO 101
IS 9
A1 Tao Guo
A1 Sruthi Sampathkumar
A1 Shan Fan
A1 Nathan Morris
A1 Fang Wang
A1 Carol B Toris
YR 2017
UL http://bjo.bmj.com/content/101/9/1290.abstract
AB Aims This study evaluates ocular biometrics and aqueous humour dynamics (AHD) in healthy Chinese volunteers to determine how the various ocular parameters interact to maintain physiological intraocular pressure (IOP) at all ages.Methods Sixty-nine volunteers enrolled in this cross-sectional study and were categorised into young (20–30 years) and old (≥50 years) groups. Measurements included IOP, ocular biometrics and AHD. Data were analysed using mixed model with random sampling to account for both eyes from the same individual. Spearman’s rank correlation with bootstrap resampling was used to find associations between parameters.Results Compared with young subjects, old subjects had significantly (p<0.05) thinner corneas (CCT; 549.7±5.7 vs 530.6±5.3 µm; mean±SEM), shallower anterior chambers (3.14±0.05 vs 2.37±0.05 mm) and slower aqueous flow (Fa; 3.0±0.1 vs 2.7±0.1 µL/min). Uveoscleral outflow slowed (Fu; 1.0±0.2 vs 0.7±0.1) but not significantly. A positive linear association between IOP and episcleral venous pressure was found (young: R2=0.16; old: R2=0.08). Negative correlation between Fa and CCT (R2=0.06) and positive correlation between Fa and outflow facility (R2=0.08) was found in old participants.Conclusions In the healthy ageing Chinese eye, IOP remains unchanged, while Fa slows, which is counterbalanced by slowing of Fu. Aqueous humour exits the eye preferentially through the trabecular route at all ages. Ageing is also associated with shallowing of the anterior chamber and thinning of the cornea. A slower Fa with lower outflow facility supports existence of autoregulatory mechanisms.