Nangia V, Bhojwani K, Matin A, Sinha A, Jonas JB. Intraocular Pressure and Arterial Blood Pressure: The Central India Eye and Medical Study. Arch Ophthalmol. 2009;127(3):339-340. doi:10.1001/archophthalmol.2008.618
Because intraocular pressure and arterial blood pressure counteract each other with respect to the so-called ocular perfusion pressure, it was the purpose of this study to assess a potential relationship between intraocular pressure and the arterial blood pressure.
The Central India Eye and Medical Study is a population-based study in central India carried out in villages about 40 km from Nagpur.1 The medical ethics committee of Heidelberg University approved the study and all of the participants gave informed consent. We describe an interim analysis of the examination of individuals in 6 villages for which the recruitment was completed. Of 4291 individuals aged 30 years or older, 3393 participated (response rate, 79.1%). Intraocular pressure was measured by Goldmann applanation tonometry, and central corneal thickness was measured by ultrasonographic pachymetry. The intraobserver agreement expressed as a coefficient of variation was 7.2% for corneal thickness measurements, 3.1% for systolic blood pressure measurements, and 4.5% for diastolic blood pressure measurements. Statistical analysis was performed using SPSS for Windows version 16.0 statistical software (SPSS, Inc, Chicago, Illinois).
The study included 3373 subjects (99.4%) for whom intraocular pressure and blood pressure measurements were available. The mean (SD) age was 47.9 (13.8) years (range, 30-100 years) and the mean (SD) refractive error was –0.18 (1.74) diopters (D) (range, –20.0 to +14.0 D). Known arterial hypertension was present in 191 subjects (5.7%), of whom 60 (31.1%) received antihypertensive medication, 96 (49.7%) were not sure about the treatment, and 35 (18.1%) did not receive antihypertensive medication. Of the entire study population, 566 subjects (16.8%) indicated that they were current or former smokers.
In a univariate analysis, intraocular pressure was significantly correlated with higher systolic blood pressure (P < .001; correlation coefficient, r = 0.17), higher diastolic blood pressure (P < .001; r = 0.20), greater central corneal thickness (P < .001; r = 0.23), higher body mass index (calculated as weight in kilograms divided by height in meters squared) (P < .001; r = 0.11), and myopic refractive error (P = .03; r = 0.04). It was not significantly associated with age (P = .11; r = 0.03) or sex (P = .63). In a multivariate regression analysis, intraocular pressure was still significantly associated with higher systolic blood pressure (P = .001), higher diastolic blood pressure (P < .001), greater central corneal thickness (P < .001), and higher body mass index (P = .04). Similar results were obtained in a second step of the multivariate analysis in which all of the subjects with an intraocular pressure greater than 21 mm Hg were excluded, with significant associations between intraocular pressure and higher systolic blood pressure (P < .001), higher diastolic blood pressure (P = .003), greater central corneal thickness (P < .001), higher body mass index (P = .005), and younger age (P = .02).
Despite considerable scattering of the data and confirming previous reports from the Blue Mountains Eye Study,2 Beaver Dam Eye Study,3 Beijing Eye Study,4 and Los Angeles Latino Eye Study,5 the results suggest that in the central Indian population, intraocular pressure is significantly associated with higher systolic and diastolic blood pressure in addition to associations with younger age, greater central corneal thickness, and higher body mass index. Our study extends the findings from the previous investigations to the population of rural central India, which owing to its rather rural character and relatively low density of medical infrastructure may be different from the highly developed regions of the Blue Mountains Eye Study and the Beaver Dam Eye Study with mostly white populations, the Los Angeles region with a mostly Hispanic population, and the Greater Beijing area with a mostly Han Chinese population.2- 5 Since the cerebrospinal fluid pressure as the translamina counterpressure against the intraocular pressure may also depend on arterial blood pressure and because a recent clinical study suggested an association between glaucoma and cerebrospinal fluid pressure,6 the physiological and pathophysiological roles of the association between intraocular pressure and arterial blood pressure with respect to glaucoma may become the focus of further studies.
Correspondence: Dr Jonas, Universitäts-Augenklinik, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany (firstname.lastname@example.org).
Financial Disclosure: None reported.
Funding/Support: This work was supported by unrestricted grants from Heidelberg Engineering and Carl Zeiss Meditec.