Inter-relationship between ageing, body mass index, diabetes, systemic blood pressure and intraocular pressure in Asians: 6-year longitudinal study

Background To investigate the biological effect of ageing on intraocular pressure (IOP) and risk factors in a population-based cohort study of Malay and Indian adults. Methods Participants aged 40-80 years were recruited for baseline and 6-year follow-up visits between 2004-2009 and 2010-2015, respectively. Blood pressure (BP) was measured with an automatic BP monitor and IOP were obtained by Goldmann applanation tonometry. Main outcome was change in IOP, defined as the difference between the 6-year IOP and the baseline IOP. Linear regression models were used to investigate the association of changes in IOP with risk factors. Results Participants without a history of glaucoma or cataract surgery at baseline were included (n = 3188; mean age: 54 +/- 9 years) . Their average IOP was reduced (-0.5 +/- 3.1 mm Hg), except for those who developed hypertension at follow-up (0.0 +/- 3.1 mm Hg). After adjusting for covariates, changes in IOP were negatively associated with age (beta=-0.07, 95% CI -0.13 to -0.01) and positively associated with body mass index, diabetes, hypertension (normotensive as reference group; newly developed hypertensive (beta=0.67, 95% CI 0.39 to 0.95) and chronic hypertensive (beta=0.46, 95% CI 0.22 to 0.70)), baseline systolic BP (SBP) (beta=0.20, 95% CI 0.14 to 0.26) and diastolic BP (DBP) (beta=0.33, 95% CI 0.22 to 0.44), as well as with 6-year increases in SBP (beta=0.27, 95% CI 0.21 to 0.33) and DBP (beta=0.52, 95% CI 0.41 to 0.63). Conclusions Normal ageing and reduced systemic BP are associated with reduced IOP in Malay and Indian adults. Given that high IOP is a risk factor for glaucoma, our finding highlights the importance of controlling hypertension in older adults, where hypertension and glaucoma incidences are on a rise.