Abstract
Purpose :
The intravitreal injection (IVI) of anti-vascular endothelial growth factor (anti-VEGF) agents are a common and effective treatment for various retinal diseases. However, many studies have shown that IVIs often result in a significant acute intraocular pressure (IOP) elevation. Despite the transient nature of the IOP spike, this could lead to progression of glaucomatous optic neuropathy in affected patients.
Due to the shortcomings of current methods to measure OR in a clinical context, very few things have been evaluated in terms of the biomechanical characteristics which govern the effect of IVIs and subsequent IOP spikes. Our group has recently developed a non-invasive method to measure ocular rigidity (OR). We applied this technique to investigate the role of OR in the development of acute IOP spikes in eyes that undergo therapeutic IVIs.
Methods :
Subjects who require IVIs of Bevacizumab for a pre-existing retinal condition were enrolled in our study. OR was measured in the affected eye using our clinical method. Based on Friedenwald’s equation, this 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. IOP spikes were measured using Tono-Pen XL, before and immediately following the IVI of a set volume of fluid. The correlation between the OR coefficient and IOP spikes was calculated with SPSS.
Results :
The average IOP change following IVIs was 20±11 mmHg, with a range of 7-42 mmHg. The Spearman correlation coefficient between ocular rigidity and IOP spikes following IVIs was ρ=0.771 (p=0.003), showing higher IOP elevation in more rigid eyes.
Conclusions :
This study shows a strong correlation between the rigidity of the corneoscleral shell and acute IOP spikes following intravitreal injections of an anti-VEGF drug in subjects with retinal diseases. A major contributor to acute IOP spikes is high ocular rigidity. These findings suggest that a subject’s risk of having a large acute IOP spike following IVI can be predicted by our novel non-invasive ocular rigidity measurement.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.