Abstract
Purpose :
To examine the tissue deformation within the load bearing and neurovascular components of the optic nerve head in research-consented brain-dead organ donors in response to manometric elevation of IOP.
Methods :
Research-consented brain-dead organ donors underwent an ocular examination with biometry, fundoscopy, along with optic nerve head (ONH) and retinal imaging with spectral domain optical coherence tomography and angiography (OCT/A). The anterior chamber was cannulated and OCT imaging was repeated while the eye was sequentially maintained at manometric pressures of 10, 30, and 50mmHg. The ONH scan volumes were automatically segmented by a deep learning commercial algorithm (Reflectivity; Abyss) and the 3D morpholofy was computed by a custom algorithm. Change in the thickness of the choroid and alterations in the relative depth and curvature of the lamina cribrosa (LC) and surrounding peripapillary sclera were quantified and compared across tested levels of IOP by linear mixed models.
Results :
26 eyes from 20 brain-dead organ donors (age range: 20-66, median: 45.4) were imaged and quantified. LC depth measured against a scleral-based reference plane increased with increasing IOP (Figure 1a, est.; 1.374 microns/mmHg, p<0.001); the effect sie and significance was much reduced when measure against a BM reference plane (Figure 1b; 0.245 microns/mmHg, p=0.0217). In all subjects, choroidal volume greatly reduced with elevation in IOP (Fig. 1c, est.; -0.52218 microns/mmHg, p<0.001). LC inflection (relative curvature) (Figure 1d, est., 0.00043594 microns/microns/mmHg, p<0.001). An increase in posterior curvature of the peripapillary sclera was also noticeable (Figure 1e; 6.75e-07, p<0.001). Posterior deformation of the LC was seen in all eyes.
Conclusions :
Acute manometric elevation of IOP results in significant tissue deformations that differentially impacts the load bearing and neurovascular components of the optic nerve head and the surrounding choroid and sclera. In contrast to in vivo studies, LC deformation in this cohort was universally posterior across these levels of IOP.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.