Keywords: Glaucoma, Retinal Nerve Fiber Layer; Systolic Blood Pressure; Diastolic Blood Pressure, Intraocular Pressure; Bayesian, Prognostic Model, Prediction, Progression

Background: Few studies have evaluated the influence of baseline blood pressure (BP) on structural deterioration in glaucoma. We recently demonstrated that lower baseline diastolic BP with concurrent higher intraocular pressure (IOP) predicted macular ganglion cell complex thinning. 

Objective: To investigate the influence of baseline BP on rates of change of retinal nerve fiber layer (RNFL) in patients with central or moderate to severe glaucoma.

Design: Prospective cohort study.

Setting: Tertiary academic medical center.  

Participants: 110 eyes with ≥4 RNFL OCT scans and ≥2 years of follow-up. 

Exposures: Global and sectoral RNFL rates of change were modeled with a Bayesian hierarchical model with subject- and sector-level random effects. The influence of baseline systolic and diastolic BP measures and their interactions with IOP on global RNFL rates of change was investigated in prognostic models adjusting for relevant baseline demographic and clinical measures.

Main Outcomes and Measures: The magnitude of coefficients for BP, IOP, and their interaction for prediction of global RNFL rates. One-sided Bayesian p-values represent the posterior probability that a given regression coefficient is greater than or less than zero with p <0.025 or >0.975 defining statistical significance.

Results: Average (SD) 24-2 visual field MD, follow-up time, and number of OCT scans in the study were –8.8 (6.0) dB, 4.3 (0.5) years, and 8.3 (1.4), respectively. On multivariable analyses, female sex, Hispanic vs. White ethnicity, better baseline 24-2 mean deviation, higher contrast sensitivity at 12 cycles per degree, presence of diabetes, and thicker central corneal thickness predicted faster RNFL thinning. Adjusted for covariates, lower diastolic BP combined with higher IOP predicted faster RNFL rates of change. Parallel multivariable models incorporating systolic BP showed similar effects. Among various BP/IOP combinations, eyes with IOP at the 90th percentile and systolic (diastolic) BP at 10th percentile demonstrated the fastest RNFL thinning rates (–0.660 and –0.682 µm/year).

Conclusions and Relevance: A combination of lower BP and higher IOP at baseline predicted faster (worse) RNFL rates of change in patients with central or moderate to advanced glaucoma. The findings confirm the role of baseline BP on structural glaucoma progression and may provide additional therapeutic avenues.