Abstract
Purpose :
To assess the changes in anterior prelaminar depth (PLD) following adduction, abduction and IOP elevation in high tension glaucoma (HTG), normal tension glaucoma (NTG), and ocular hypertensive (OHT) subjects.
Methods :
We recruited 221 subjects (Chinese ethnicity and more than 60 years old) which comprised of 93 HTG, 87 NTG, and 41 OHT subjects. For each subject, we imaged the ONH using Spectral-domain optical coherence tomography (OCT) under the following conditions: (1) primary gaze, (2) 20o adduction, (3) 20o abduction and (4) primary gaze with acute IOP elevation (to ~40 mmHg) achieved through ophthalmodynamometry. For each OCT volume, we automatically segmented the prelaminar tissue (PLT) using deep learning. We calculated the PLD for each volume with respect to the Bruch’s membrane opening (BMO) reference plane and calculated the change in PLD of each subject under loads (2)-(4) with respect to the baseline primary gaze (1).
Results :
Under IOP elevation, we observed an increase in PLD (posterior displacement) with an average change of (+12.8 ± 30.1 micron) across all subjects (Figure 1). Additionally, we found that PLD of HTG eyes were significantly more sensitive to IOP elevation (+17.24 ± 29.2 microns) as compared to PLD of NTG eyes (+7.4 ± 28.8 microns, p<0.05, Figure 2a) and OHT eyes (+7.9 ± 35.3 micron, p<0.1). Under adduction, we observed a decrease in PLD (anterior displacement) with an average change of (-15.5 ± 32.3 micron) across all subjects (Figure 1). Additionally, we found that PLD of NTG and OHT eyes were more sensitive to adduction (NTG: -18.8 ± 38.2 micron, OHT: -15.0 ± 40.3 micron) as compared to PLD of HTG eyes (-8.0 ± 29.8 micron, p<0.05, Figure 2b). Abduction did not result in significant changes in PLD (Figure 1).
Conclusions :
Using PLD changes as the mode of measurement, we found that NTG and OHT subjects were more sensitive to adduction as compared to IOP elevation and HTG subjects were more sensitive to IOP elevation as compared to adduction. These preliminary results could provide clues to the different pathophysiology of between NTG and HTG which warrants further investigation.
This is a 2021 ARVO Annual Meeting abstract.