Association of Postural Blood Pressure Response with Disease Severity in Primary Open Angle Glaucoma

Abstract

Précis: Primary open angle glaucoma (POAG) patients demonstrated exaggerated postural blood pressure dip in recumbency that was positively correlated with severity of glaucomatous optic neuropathy (GON). Postural dip testing can be used clinically as a marker of systemic vascular dysregulation in GON risk assessment. Purpose: To investigate whether POAG patients demonstrated abnormal postural blood pressure response to recumbency and whether such abnormal postural response correlated with GON severity. Patients and Methods: This is a prospective observational study where 47 POAG patients underwent intraocular pressure (IOP) and systemic arterial blood pressure (SABP), systolic (SBP) and diastolic (DBP), measurement in seated and after twenty-minute recumbency positions. Mean arterial blood pressure (MABP) was calculated for seated and recumbent positions. Percentage difference between seated and recumbent SBP, DBP and MABP was calculated according to which participants were divided into three groups i.e. non-dippers, normal dippers and exaggerated dippers with percentage dips of <10%, >=10%<=20%, >20% respectively. Participants underwent optical coherence tomography of optic nerve head to measure retinal nerve fiber layer thickness (RNFLT) which was used as a structural biomarker of GON. Results: RNFLT was lower in exaggerated dippers than non-dippers and normal dippers. There was negative correlation between postural dip and average RNFLT. Linear regression showed that postural dip was associated with lower RNFLT independent of age and IOP. Chi-square independence test demonstrated strong relation between corresponding dip groups for SBP, DBP and MABP. However, it showed no significant relation between hypertension and postural dip. Fisher’s exact test showed no relation between antihypertensive medication and postural dip. Conclusions: POAG patients demonstrated abnormal postural blood pressure response comprising exaggerated recumbent dip which was positively correlated with disease severity. Postural dip assessment may serve as a simple clinic-based test of systemic vascular dysregulation as part of GON risk evaluation.