24-HOUR INTRAOCULAR PRESSURE IN SUBJECTS WITH PRIMARY OPEN-ANGLE GLAUCOMA: A POPULATION- BASED ASSESSMENT

Purpose. To assess the distribution of the 24-hour intraocular pressure (IOP) in subjects with primary openangle glaucoma (POAG) in a population-based study in rural West Bengal. Methods. All untreated POAG patients (n = 132) identified by a door to door survey in the Hugli District of West Bengal were invited to attend a follow-up study in which IOP was tested with a Goldmann Applanation tonometer at 10 AM, 1 PM, 4 PM, 7PM, 10 PM, 1 AM, and 6 AM. Results. 72 subjects with untreated POAG (72/132; 88.6%) attended the study. Of them, 59 (83.0%) had a peak IOP ≤ 21 mm Hg. The peak IOP (mean ± SD) was 16.4 ± 4.2 mm Hg. Peak IOP occurred in early morning in approximately 78.5% of the subjects (6 AM to 10 AM), and the trough occurred during night time in 72.2% of the subjects (10 PM to 1 AM). The 24-hour IOP (mean ± SD) was 14.2 ± 4.4 mm Hg and the mean fluctuation was 4.0 ± 6.8 mm Hg (range, 2–11 mm Hg). In the 32 persons with unilateral glaucoma, no significant differences were found in mean 24-hour IOP, peak IOP, trough IOP, or IOP fluctuation when comparing the glaucomatous eye with the non glaucomatous eye (P > 0.05). Conclusions. Twenty-four–hour IOP was similar between glaucomatous and Controls (contralateral nonglaucomatous) eyes suggesting that factors other than IOP may play a role in the development of glaucomatous optic neuropathy in these eyes.