Twenty-four Hour Ambulatory Blood Pressure Monitoring in Open Angle Glaucoma Suspects: A cross-sectional descriptive study.

Purpose: To compare glaucoma suspects' 24-hour blood pressure pattern with healthy subjects and the Retinal Nerve Fibre Layer (RNFL) thickness among dippers and non-dippers.

Materials and methods: We included 100 patients diagnosed as glaucoma suspects in the study group and 100 age and gender-matched controls. Twenty-four-hour ambulatory blood pressure (BP) was measured using an automated BP monitoring device for mean systolic BP (SBP), mean diastolic BP (DBP), and mean arterial pressure (MAP). We classified patients into non-dippers, dippers, and overt dippers based on reduction in nocturnal MAP. Structural damage to the optic nerve head was studied by measuring the superior, inferior, and average RNFL thickness on Optical Coherence Tomography (OCT).

Results: Glaucoma suspects showed lower values of day, night, and mean SBP values but higher values of day, night, and mean DBP values when compared with controls, and these were statistically significant. ANOVA and Post Hoc test (Bonferroni) analysis among glaucoma suspects showed that overt dippers had statistically significant superior, inferior, and average RNFL thinning (average 86.20 ± 12.200 µm) as compared to non-dippers and dippers (average 105 ± 11.183 and 102.19 ± 9.582 µm respectively). Pearson's correlation, used to assess the relationship between the nocturnal dip in BP and average RNFL thickness, showed a negative correlation (r = -0.396, p < 0.001).

Discussion: Our study found a statistically significant decrease in systolic blood pressure day and night and an increase in diastolic blood pressure day and night in glaucoma suspects compared to normal. Mean arterial pressure did not show any significant difference, and the data obtained is comparable with previous studies. The corresponding retinal nerve fiber layer changes noted in dippers and non-dippers were also similar to those in the existing literature. This study, however, has a shortcoming of not including intraocular pressure-related nerve head changes.

Conclusion: Nocturnal BP reduction was associated with structural damage to the optic nerve head in glaucoma suspects, suggesting systemic vascular etiology in the damage progression. ABP monitoring can help detect those glaucoma suspects who are mainly likely to progress so that they can be on close follow-up.