Quantification of Pulse-Dependent Trabecular Meshwork Motion in Normal Humans Using Phase-Sensitive OCT

Abstract

PurposeThe purpose of this study was to characterize the pulsatile motion of trabecular meshwork (TM) in normal subjects and demonstrate its changes in accommodation with phase-sensitive optical coherence tomography (PhS-OCT).MethodsA new PhS-OCT laboratory prototype was designed to measure pulsatile TM motion in 13 healthy humans. Two sets of images were captured in 10 subjects, first with best corrective refraction and the other with an additional 3.0 diopters of accommodation. In each image, both maximum velocity (MV) and cumulative displacement (CD) in two selected regions of TM, the internal (IMV and ICD) and external (EMV and ECD) region, were measured.ResultsFor all parameters the intraclass correlation coefficient was >0.75. Neither MV nor CD was significantly different between eyes in individual subjects (PIMV = 0.967, PEMV = 0.391, PICD = 0.603, PECD = 0.482). In 26 eyes, with best corrective refraction, the EMV was higher than the IMV (23.9 ± 9.8 vs. 18.9 ± 8.08 μm/s; P = 0.0001), as was the ECD compared with the ICD (0.340 ±0.125 vs. 0.264 ± 0.111 μm; P = 0.000004). With accommodation, MV and CD significantly increased (PIMV = 0.0003, PEMV = 0.0003, PICD = 0.019, and PECD = 0.007), whereas MV and CD in the external region were still larger than those in the internal area (PEMV vs. IMV = 0.009, PECD vs. ICD = 0.023).ConclusionsThis study demonstrates the differences in TM motion between the internal and external regions of TM and displays its change with accommodation. The findings and good reproducibility suggest PhS-OCT helps to understand TM function in regulation of IOP, and, with further refinements, it may be useful in clinical management of glaucoma.

Pulsatile Trabecular Meshwork Motion: An Indicator of Intraocular Pressure Control in Primary Open-Angle Glaucoma

“…In this study, we firstly demonstrated the good reliability and repeatability of TM motion quantification, as previously reported [ 15 ]. PhS-OCT was used to characterize the TM motion change with accommodation [ 15 ]. Our results showed that pulsatile TM motion was reduced in glaucoma compared with normal subjects.…”

Pulsatile Trabecular Meshwork Motion: An Indicator of Intraocular Pressure Control in Primary Open-Angle Glaucoma

“…In this study, we firstly demonstrated the good reliability and repeatability of TM motion quantification, as previously reported [ 15 ]. PhS-OCT was used to characterize the TM motion change with accommodation [ 15 ]. Our results showed that pulsatile TM motion was reduced in glaucoma compared with normal subjects.…”

Reduced Pulsatile Trabecular Meshwork Motion in Eyes With Primary Open Angle Glaucoma Using Phase-Sensitive Optical Coherence Tomography

“…Previously, PhS-OCT was used to characterize the parameters of pulse-dependent TM motion and demonstrate its change with accommodation in healthy subjects. 12 The newly observed difference between healthy eyes and eyes with POAG found in this study may be useful in understanding the functional behavior of the AH outflow pathways and in the evaluation and management of glaucoma in clinical practice.…”

“…Moreover, the ICCs of IMV, ICDisp, EMV, and ECD, which were analyzed twice on 2 separate sessions over an interval of 2 weeks, were 0.98, 0.972, 0.979, and 0.97, respectively, which also represented a high-level of reproducibility. Because of the high repeatability and reproducibility of the measurements in both our present study and a previous study, 12 we felt that it was satisfactory to use data obtained by one observer (K.G.). Figure 2 shows the difference in MV and CDisp between a representative healthy subject and an eye with POAG.…”

Aqueous outflow regulation – 21st century concepts

“…A recent study by Xin demonstrates excellent reliability and repeatability ( Fig. 6 ) ( Xin et al, 2018 ). The resolution of motion is sufficiently sensitive to identify movement differences in the inner and outer locations of the TM, as well as motion changes resulting from accommodation efforts.…”

Pulsatile Trabecular Meshwork Motion: An Indicator of Intraocular Pressure Control in Primary Open-Angle Glaucoma

“…In this study, we firstly demonstrated the good reliability and repeatability of TM motion quantification, as previously reported [ 15 ]. PhS-OCT was used to characterize the TM motion change with accommodation [ 15 ]. Our results showed that pulsatile TM motion was reduced in glaucoma compared with normal subjects.…”

Reduced Pulsatile Trabecular Meshwork Motion in Eyes With Primary Open Angle Glaucoma Using Phase-Sensitive Optical Coherence Tomography

“…Previously, PhS-OCT was used to characterize the parameters of pulse-dependent TM motion and demonstrate its change with accommodation in healthy subjects. 12 The newly observed difference between healthy eyes and eyes with POAG found in this study may be useful in understanding the functional behavior of the AH outflow pathways and in the evaluation and management of glaucoma in clinical practice.…”

“…Moreover, the ICCs of IMV, ICDisp, EMV, and ECD, which were analyzed twice on 2 separate sessions over an interval of 2 weeks, were 0.98, 0.972, 0.979, and 0.97, respectively, which also represented a high-level of reproducibility. Because of the high repeatability and reproducibility of the measurements in both our present study and a previous study, 12 we felt that it was satisfactory to use data obtained by one observer (K.G.). Figure 2 shows the difference in MV and CDisp between a representative healthy subject and an eye with POAG.…”

Aqueous outflow regulation – 21st century concepts

“…A recent study by Xin demonstrates excellent reliability and repeatability ( Fig. 6 ) ( Xin et al, 2018 ). The resolution of motion is sufficiently sensitive to identify movement differences in the inner and outer locations of the TM, as well as motion changes resulting from accommodation efforts.…”

Pulsatile Trabecular Meshwork Motion: An Indicator of Intraocular Pressure Control in Primary Open-Angle Glaucoma

“…In this study, we firstly demonstrated the good reliability and repeatability of TM motion quantification, as previously reported [ 15 ]. PhS-OCT was used to characterize the TM motion change with accommodation [ 15 ]. Our results showed that pulsatile TM motion was reduced in glaucoma compared with normal subjects.…”

Reduced Pulsatile Trabecular Meshwork Motion in Eyes With Primary Open Angle Glaucoma Using Phase-Sensitive Optical Coherence Tomography

“…Previously, PhS-OCT was used to characterize the parameters of pulse-dependent TM motion and demonstrate its change with accommodation in healthy subjects. 12 The newly observed difference between healthy eyes and eyes with POAG found in this study may be useful in understanding the functional behavior of the AH outflow pathways and in the evaluation and management of glaucoma in clinical practice.…”

“…Moreover, the ICCs of IMV, ICDisp, EMV, and ECD, which were analyzed twice on 2 separate sessions over an interval of 2 weeks, were 0.98, 0.972, 0.979, and 0.97, respectively, which also represented a high-level of reproducibility. Because of the high repeatability and reproducibility of the measurements in both our present study and a previous study, 12 we felt that it was satisfactory to use data obtained by one observer (K.G.). Figure 2 shows the difference in MV and CDisp between a representative healthy subject and an eye with POAG.…”

Aqueous outflow regulation – 21st century concepts

“…A recent study by Xin demonstrates excellent reliability and repeatability ( Fig. 6 ) ( Xin et al, 2018 ). The resolution of motion is sufficiently sensitive to identify movement differences in the inner and outer locations of the TM, as well as motion changes resulting from accommodation efforts.…”