Repeatability of In-Vivo Measurement of Lamina Cribrosa’s Biomechanics

Abstract

Purpose : The lamina cribrosa (LC) is a porous structure within the optic nerve head (ONH) and longitudinal alterations in its biomechanics have been suggested to contribute to the glaucomatous damage. Previous works have used a Thirion’s demon algorithm to estimate ex-vivothe 3D displacement of the LC at varying IOP levels to determine its biomechanical properties. The purpose of this study is to determine the repeatability of LC biomechanics measurement using this analysis method on in-vivo LC imaging.

Methods : Anterior chamber cannulation of the eye was performed in 3 healthy rhesus macaques to control IOP level. Two consecutive sets of OCT scans (Bioptigen Envisu; Leica, Chicago, IL) were acquired in both 15mmHg and 30mmHg IOP levels. A non-rigid Thirion’s demon algorithm was used to compute the 3D LC displacement field of each set at the varying IOP levels. 3D Green-Lagrange strains were calculated from the displacement field from which the right Cauchy stretch tensor was computed. Maximum Principal Values of the right Cauchy stretch tensor were subsequently calculated and plotted (Figure 1).

Results : First principal stretch distribution plots generated from the two OCT scans for each eye show marked overlap and near identical distribution (Figure 1). Differences between the median values and the first and third quantiles measurements obtained in each scans in each animal were as small as 0.60% up to 5.66%.

Conclusions : Good repeatability was observed for first principal stretch measurements generated from in-vivo OCT scans.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.