## 2 Materials and Methods  
Figure 1 is a schematic of the experimental study's setup used to image and quantify dynamic TM motion in response to pressure transient [20]. The setup has four components: (1) a PhS-OCT system for imaging the TM motion, (2) an anterior segment perfusion system for controlling the mean pressures, (3) a perfusion pump controlling pulse transients, (4) a  
PowerlabTM processing unit for real-time pressure monitoring and synchronization with the PhS-OCT imaging system during data acquisition. (1) Eyes and anterior segment perfusion setup  
A nonhuman primate eye (Macaca nemestrina, female, 9-year-old) was obtained from the University of Washington Primate Center and harvested within 0.5 h of experiment initiation. A normal postmortem human eye (Caucasian, female, 70-year-old, Caucasian) with no history of ocular disease was provided by the SightlifeTM eye bank within 24 h after the donor's death. The eyes were hemisected along the equator, followed by removing the vitreous, retina, and choroid leaving the crystalline lens and ciliary body intact. The prepared anterior segments were mounted on the eye perfusion fitting. Two 23-gauge perfusion needles were inserted into the AC--one connected by a cannula to a pressure transducer, the other to a reservoir controlling AC pressure. An additional cannula led from a perfusion fitting communicating with the posterior chamber (PC) to a valve that switched between a pressure reservoir and a perfusion pump. Baseline mean AC and PC pressure was initially experimentally controlled by establishing identical chamber pressures. The posterior chamber cannula was switched to the perfusion pump, and the pulse transient was immediately initiated. Pressure transient elevations simulating blink and eye movement were generated by controlling the perfusion pump infusion rate and duration. An anterior chamber needle connected to a pressure transducer (PowerLab, ML866) continuously monitored the mean pressure and pulse amplitudes in the anterior chamber. The mean baseline or resting pressures tested were 16, 24, 32, and 40 mmHg. The pulse amplitudes tested were 2.5, 5-, 7.5-, and 10-mmHg. The appropriate transient pulse amplitude was determined by maintaining a steady 3 mL/min infusion rate and experimentally varying the infusion volume. Controlled pulse frequencies of 30, 60, and 90 pulses/min were experimentally induced with the above variables. (2) Imaging system and scanning procedures  
A spectrometer-based, phase-sensitive optical coherent tomography (PhS-OCT) system was used for imaging the TM region of the ex vivo anterior segments. The system was coupled with a broad bandwidth light source centered at 1340 nm (~7.2 \(\upmu\)m axial resolution in air) and used a ~92 kHz A-line rate InGaAs array sensor. Tracings were acquired using 1500 repeated B-scans of 360 A-lines and 512 axial pixels at the rate of 200 f/s from the surface overlying the TM. Figure 1: Schematic of the experimental setup including the PhS-OCT system (dashed box), the anterior chamber mount, the reservoir for controlling the anterior chamber pressure, the pressure transducer for recording anterior chamber pressure, the reservoir-pump perfusion system for controlling posterior chamber pressure and inducing pulse transients. CIR: circulator; OC: optical coupler; CL: collimation lens; FL: focusing lens; DG: diffraction grating; M: mirror. (3) Data analysis  
The data were processed using a PhS-OCT Matlab algorithm to extract the structure and phase of each B-scan. The average of 5 phase frames (\(\Delta\varphi\)) was used to reduce the effect of phase noise on the final result. The instantaneous depth-resolved tissue velocity, the total displacement, and the ppTMD values were extracted as previous report [20] (Figure 2).The time constant, determined by tissue recoil in response to the removal of the IOP loading force, was calculated by the fitted exponential decay function. Descriptive statistics calculated the mean and standard deviations (mean \(\pm\) SDs).