Ocular Pulse Amplitude Correlates With Ocular Rigidity at Native IOP Despite the Variability in Intraocular Pulse...

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Ocular Biomechanics

Background:

• Assessing ocular coat mechanical behavior is crucial for understanding eye conditions.
• Current methods may have limitations in precisely measuring ocular rigidity.
• Nonhuman primate models offer valuable insights into ocular physiology.

Purpose of the Study:

• To evaluate the mechanical properties of the ocular coat using controlled microvolumetric injections (MVI).
• To determine if MVI can be used to measure ocular rigidity and related biomechanical parameters.
• To investigate the relationship between ocular pulse amplitude (OPA) and ocular rigidity.

Main Methods:

• Controlled ocular microvolumetric injections (MVI) of 15 µL balanced salt solution (BSS) into the anterior chamber of rhesus macaques.
• Continuous intraocular pressure (IOP) recording at 200 Hz using an implantable telemetry system.
• Calculation of ocular rigidity coefficients (K) and ocular pulse volume (PV) with statistical analysis including ANOVA and regression.

Main Results:

• MVI at native baseline IOP (10.4 ± 1.6 mm Hg) resulted in a mean IOP increase (∆IOP) of 9.1 ± 2.8 mm Hg/s.
• Average ocular rigidity (K) was 0.042 ± 0.010 µL⁻¹, and ocular pulse volume (PV) was 1.16 ± 0.43 µL.
• OPA showed significant correlation with ocular rigidity (K) at native IOP (Pearson r = 0.71–0.83, R² = 0.50–0.69).

Conclusions:

• Microvolumetric injections (MVI) provide a viable method to assess ocular coat mechanical behavior.
• The MVI-driven IOP changes and slope are effective for measuring ocular rigidity.
• OPA is a significant indicator of ocular rigidity, even with variability in PV.