Abstract
Purpose :
Ocular rigidity (OR) and vasospasm are risk factors for glaucoma. Evidence suggests that in vasospastic disorders, ocular blood flow dysregulation could occur in response to biomechanical stimuli. This may contribute to the optic nerve head’s susceptibility in glaucoma. We therefore expect OR to play a greater role in the pathophysiology of glaucoma in subjects with vasospasm.
Our group has developed a non-invasive, reliable method to measure OR in vivo. In this study, we evaluate the relationship between OR and glaucomatous damage in vasospastic and non-vasospastic (atherosclerotic) subjects.
Methods :
Forty-three subjects were recruited in this study. Vasospasticity was assessed by a 10-point questionnaire. OR was measured using a non-invasive method developed by our group. Time-lapse optical coherence tomography (OCT) imaging and automated choroidal segmentation was used to measure the pulsatile choroidal volume change and calculate OR using Friedenwald’s equation. Structural OCT-based parameters including retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) thicknesses were acquired. Correlations between OR and structural parameters were assessed in POAG patients with concurrent vasospasticity, and were compared with non-vasospatic, atherosclerotic patients.
Results :
In the vasospastic group, significant correlations were found between OR and the average RNFL thickness (rs=0.733, p=0.016), the RNFL in the temporal quadrant (rs=0.827, p=0.003) and minimum GCC thickness (rs=0.717, p=0.020), indicating more damage with lower OR. In contrast, no similar correlation was found in the atherosclerotic group (rs=0.212, p=0.208; rs=0.168, p=0.350; and rs=0.299, p=0.138 respectively).
Conclusions :
In this study, OR was strongly correlated with RNFL and GCC in the vasospastic group, contrarily to the atherosclerotic group. This may indicate more structural damage in less rigid eyes, but perhaps also that OR may play a greater role in glaucomatous eyes with vasospasm.
These findings provide insight unto the pathophysiology of OAG. Further investigation is warranted to confirm the role of OR in glaucoma, and elucidate why and how low OR may play a greater role in certain subgroups of glaucoma patients.
This is a 2020 ARVO Annual Meeting abstract.