Abstract
Purpose :
To determine whether a phase-sensitive optical coherence tomography (PhS-OCT) system can be used to identify and quantitate differences in pulsatile motion of the trabecular meshwork (TM) in healthy control subjects vs. primary open-angle glaucoma (POAG) patients.
Methods :
In this prospective pilot study, 6 healthy control subjects (11 eyes) and 2 POAG patients (4 eyes) were enrolled. A laboratory-based prototype PhS-OCT system was designed to measure pulsatile TM motion. Intraocular pressure (IOP) was obtained by iCare rebound tonometry before the procedure. PhS-OCT images were captured at a single cross-sectional position centered on the temporal limbus of both eyes in all participants. Consistent positioning was achieved as follows. Patients’ faces were oriented in a straight-ahead position. Patients then looked at a fixation target without moving their head, placing the eye in an optimal position for the PhS-OCT to acquire images with an identical protocol for each patient. A digital pulsimeter recording captured the signal from the cardiac pulse. A trigger synchronized the pulsimeter and PhS-OCT data. PhS-OCT images were analyzed to determine both maximum velocity (MV) and cumulative displacement (CD).
Results :
The mean age of control and POAG subjects was 63.5±4.2 years (range 59-71 years) and 65±25.5 years (range 47-83 years), respectively. Mean IOPs for the control and POAG subjects were 13.3 ± 2.3 mmHg and 15.9 ± 3.2 mmHg, respectively. A pulsatile TM tissue motion waveform synchronous with the digital pulse was observed using PhS-OCT in both control and POAG eyes (Fig. 1). The mean MV of control eyes was 21.38± 5.85 μm/s, whereas mean MV in POAG eyes was significantly lower (14.76 ± 2.85 μm/s, P=0.013). The mean CD in control eyes was 0.39 ± 0.28 μm whereas the mean CD in POAG eyes was also significantly lower at 0.17 ± 0.058 μm (P = 0.027).
Conclusions :
POAG patients had reduce pulsatile movement of TM compared to control subjects, which may be due to the altered tissue stiffness or other biomaterial properties of the TM in POAG eyes. This pilot study suggests measurement of pulsatile movement of the TM with PhS-OCT may be a mechanism of characterizing outflow pathway abnormalities. If further studies confirm the initial findings, the differences may be of use clinically in identifying, monitoring and making management decisions in glaucoma.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.