Co-localization of Spectral Domain Optical Coherence Tomography (SDOCT) Deep Optic Nerve Head (ONH) Imaging to 3D Histomorphometry

Abstract

 

Purpose

 

To compare deep ONH anatomy within pre-sacrifice SDOCT and post mortem 3D histomorphometric reconstructions (HMRN).

 

Methods

 

Eighty ONH radial SDOCT B-scans (Spectralis, Heidelberg Engineering, 870 and 1050 nm - enhanced depth imaging or EDI) were obtained 30 min after manometric IOP lowering to 10 mm Hg from both eyes of 4 non-human primates (NHP) with unilateral experimental glaucoma (EG). Each animal was then sacrificed by perfusion fixation, ONHs were trephined (6 mm), embedded in paraffin and 3D reconstructed (Burgoyne, et al. IOVS 2004; 45:4388-99). SDOCT B-scans were viewed with and without adaptive compensation (Mari, et al. IOVS 2013;54:2238-47). Bruch’s Membrane Opening (BMO) was delineated in each SDOCT and HMRN volume (Strouthidis, et al. IOVS 2009;50:214-223). Each SDOCT data set was 3D co-localized to its HMRN using BMO. Co-localization was qualitatively evaluated using the delineated 3D HMRN vessel tree and the SDOCT infrared image. Each aligned 3D HMRN was digitally re-sectioned to match the associated SDOCT B-scan coordinates.

 

Results

 

Co-localization of SDOCT and 3D HMRN volumes was feasible in all 8 eyes. HMRN tissue shrinkage was substantial leading to modest to moderate anatomic distortion. When deep ONH targets including the prelaminar glial columns, anterior laminar insertion, anterior and posterior lamina cribrosa surfaces (Figure 1), anterior neural canal wall and peripapillary sclera (Figure 2) were visible within SDOCT B-scans, comparable anatomy was present within the matched 3D HMRN section. EG eye laminar thickening (Yang, et al. IOVS 2007;48:5068-5084) within matched SDOCT B-scans from the control and EG eyes, was confirmed within matched 3D HMRN sections (Figure 1). Adaptive compensation enhanced visualization of peripapillary sclera. Visualization of the lamina was modestly enhanced (Figure 2).

 

Conclusions

 

Our comparisons suggest close morphologic correspondence between SDOCT deep ONH anatomy (when visible) and matching 3D HMRNs. SDOCT EDI detection of deep ONH imaging targets including the posterior laminar surface and laminar thickening in NHP EG is supported by 3D HMRN.

 

 

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 577 lamina cribrosa • 629 optic nerve