Evaluation of Ocular Pulse Amplitude-Related Parameters Measured by Dynamic Contour Tonometry and Ocular Blood Flow Analyzer
Narrative Responses:
Purpose
To compare ocular pulse amplitude (OPA) measurements by dynamic contour tonometry (DCT) with measurements using an ocular blood flow analyzer (BFA) with regard to their relationship with other ocular and systemic factors, and to investigate any relationship between OPA-derived parameters and the severity of glaucoma.
Methods
In total, 77 eyes in 77 normal and normal tension glaucoma (NTG) patients were enrolled in this cross-sectional and retrospective study. OPA was measured using DCT. Pulse amplitude (PA), pulse volume (PV), and pulsatile ocular blood flow (POBF) were measured using BFA. Ocular rigidity-related factor (ORF) was calculated from OPA and PV, measured with both devices, based on the Friedenwald equation. The severity of glaucoma was estimated by both visual field (VF) tests and Stratus optical coherence tomography (OCT) in NTG patients.
Results
DCT OPA correlated well with POBF and BFA PA. OPA correlated significantly with intraocular pressure (IOP) but PA did not. PA and OPA correlated significantly with the spherical equivalent of refractive error but not with central corneal thickness. OPA and PA did not correlate with blood pressure or glaucoma severity. Lower POBF and higher ORF correlated significantly with decreased inferior and average retinal nerve fiber layer thickness, as measured by OCT in NTG patients.
Conclusion
Although both OPA and PA measure the same ocular phenomenon, they showed different relationships with IOP. POBF and ORF, derived from measurements of ocular pulsatile components, could be related to the severity of glaucoma in NTG patients.