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Diane N Sayah, Denise Descovich, Javier Mazzaferri, Renaud Duval, Flavio Rezende, Santiago Costantino, Mark R Lesk; Validation of a Non-Invasive OCT-based Method to Measure Ocular Rigidity using Intravitreal Injections of Bevacizumab. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2025.
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Biomechanical factors such as ocular rigidity (OR) are thought to be involved in the development of many ocular diseases, such as open-angle glaucoma. Our group has recently developed a direct, non-invasive method to measure OR in vivo (Beaton et al., 2015). The current study aims to validate this novel technique using an invasive procedure involving intravitreal injections (IVI) of Bevacizumab.
Subjects who require IVIs of Bevacizumab for a pre-existing retinal condition were enrolled in our study, according to a priori sample size calculations. OR coefficient was measured in the affected eye using both the OCT-based technique and the invasive technique. Based on Friedenwald’s equation, the non-invasive method uses video-rate OCT imaging and automated segmentation of the choroid, as well as dynamic contour tonometry to measure the pulsatile ocular volume change and pulsatile intraocular pressure (IOP) change respectively. The invasive procedure involves IOP measurements using Tono-Pen XL before and within 30 seconds following the IVI of 50 µL of anti-vascular endothelial growth factor (VEGF) agent.The correlation between OR coefficients obtained for the same eye using both methods was calculated with SPSS.
The Spearman correlation coefficient comparing both methods was 0.89 (p=0.007), demonstrating a strong, direct correlation between OR coefficients obtained non-invasively and invasively.
Our findings show a strong correlation between OR coefficients obtained using our optical method and the invasive procedure involving IVIs. While additional testing will be carried out to further confirm this relationship, this study suggests that our novel technique can be used to reliably measure OR coefficients in living human eyes non-invasively. This will permit further investigation of the role of OR in the pathogenesis of potentially-blinding ocular diseases by permitting OR measurements in a large cohort.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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