Trabecular meshwork motion reduces in eyes with normal tension glaucoma using phase-sensitive optical coherence tomography.

Purpose: To investigate alteration in pulsatile trabecular meshwork (TM) motion in normal tension glaucoma (NTG) compared with healthy controls and primary open-angle glaucoma (POAG) patients.

Methods: This cross-sectional study included 15 healthy individuals, 14 NTG patients and 15 POAG patients with asymmetric visual field defects (VFD). Eyes were categorised as mild-to-moderate VFD (GI) or severe VFD (GII). A custom-designed phase-sensitive optical coherence tomography system was used to assess TM motion in temporal and nasal regions. Parameters analysed included maximum velocity (MV) and cumulative displacement (CDisp).

Results: Mean deviation was comparable between NTG and POAG in GI eyes (p=0.944), and intraocular pressure post-treatment in POAG was similar to NTG (p=0.066). MV and CDisp in NTG were significantly lower than in healthy controls (p<0.001) but higher than in POAG (p<0.001). In POAG, temporal MV, nasal CDisp and temporal CDisp were significantly higher in GI than in GII eyes (p=0.002, 0.025 and 0.038). In NTG, no significant differences in MV or CDisp were observed between GI and GII eyes (p>0.05).

Conclusions: Pulsatile TM motion is reduced in NTG compared with healthy individuals but remains higher than in POAG. Unlike POAG, NTG shows no asymmetry in TM motion between eyes with varying VFD severity, suggesting additional factors beyond TM biomechanics contribute to NTG progression.