Ocular pulse amplitude and Doppler waveform analysis in glaucoma patients

Area of Science:

• Ophthalmology
• Vascular Biology
• Medical Imaging

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Ocular blood flow plays a crucial role in glaucoma pathogenesis.
• Understanding the relationship between ocular hemodynamics and glaucoma is vital for diagnosis and management.

Purpose of the Study:

• To investigate the correlation between ocular blood flow velocities and ocular pulse amplitude (OPA) in glaucoma patients.
• To analyze these correlations using colour Doppler imaging (CDI) waveform analysis.
• To compare these relationships in healthy individuals, primary open-angle glaucoma (POAG), and normal-tension glaucoma (NTG) patients.

Main Methods:

• A prospective, observer-masked, case-control study involving 192 participants (55 healthy, 74 POAG, 63 NTG).
• OPA measured via dynamic contour tonometry.
• Retrobulbar blood flow velocities (central retinal artery/vein, ciliary arteries, ophthalmic artery) assessed using CDI.
• Univariate and multiple regression analyses performed to correlate OPA with vascular and systemic parameters.

Main Results:

• OPA was significantly lower in both NTG and POAG groups compared to healthy controls.
• Multiple regression models showed OPA variance was better explained by vascular parameters in healthy subjects and POAG patients.
• Specific associations found: CRV resistance index and NPCA systolic/diastolic velocity ratio in healthy subjects; TPCA systolic velocity in POAG patients.
• In NTG patients, OPA was associated with diastolic blood pressure and pulse rate.

Conclusions:

• Vascular factors explain OPA variance more effectively in healthy individuals than in glaucoma patients.
• The determinants of OPA differ across healthy individuals, POAG, and NTG cohorts.
• This suggests distinct pathophysiological mechanisms influencing ocular hemodynamics in different glaucoma types.