Original Article Interrelations among Smoking Habits, Casual Blood Pressure and Intraocular Pressure in Middle and Old-Aged Japanese Residents

Objectives: To investigate the association of smoking habits with blood pressure (BP) and intraocular pressure (IOP), and to examine whether the smoking-BP association is related to the IOP level. Methods: This study was conducted on the basis of a cross-sectional design using annual health check-up data during one-year between August, 1999 and August, 2000 for 611 middle and old-aged Japanese residents living in Ibaraki prefecture, Japan. Results: After adjustment for age, gender, body mass index and alcohol intake score, the proportion of hypertensives, and the mean systolic and diastolic blood pressure (SBP and DBP) of the subjects without antihypertensive medications were the highest (50.4%, 129.6 mmHg and 75.9 mmHg, respectively) in the “smokers of 25 or more cigarettes per day with intraocular pressure (IOP) 15 mmHg ” of six subgroups crossed by three smoking categories (non-smokers, 1 to 24 cigarettes per day, and 25 or more cigarettes per day) and two IOP categories (less than 15 mmHg, and 15 mmHg or greater). On the other hand, the adjusted proportion of hypertensives, and the adjusted mean SBP and DBP decreased with increasing smoking category in the individuals with less than 15 mmHg of the IOP (p for trend=0.028 for proportion of hypertensives, 0.008 for the SBP, and 0.001 for the DBP, respectively). Conclusions: Heavy smoking may be specifically related to ‘high BP accompanied by high IOP’, although the BP may be inversely associated with smoking under the condition without high IOP. Key words: smoking, intraocular pressure, casual blood pressure, effect modification, health check-u