Three Dimensional (3D) Segmentation Of Normal And Glaucomatous Optic Nerve Heads In 1050nm Optical Coherence Tomography (OCT) Datasets

Abstract

 

Purpose:

 

The aim of this study was to segment the structures of the human optic nerve head (ONH) and determine if changes in lamina cribrosa (LC) structure in high resolution 1050nm OCT datasets could be identified.

 

Methods:

 

Optic nerve heads of glaucoma (n=6) and healthy controls (n=3) were imaged using a laboratory 1050nm spectral domain OCT device, operating at 47,000 a-scans/sec, with 7-8µm axial and 15-20µm transverse resolution. OCT volumes of 512x512 a-scans, centred on the ONH were acquired and post-processed using ImageJ. Manual delineation and segmentation were performed using Amira (Version 5.4).

 

Results:

 

1050nm OCT produced high quality 3D datasets allowing delineation of retinal and ONH structures. Structures, including the neural canal defined by Bruch’s membrane opening, anterior scleral surface, prelamina and LC have been successfully delineated in healthy and glaucomatous ONHs. 3D segmentation of cup volume, BMO and cribriform plates within the LC are shown in Figure 1a. Additionally, segmentation of individual pores within regions of LC was achieved (Figure 1b). Marked changes in ONH and LC structure were visualised in glaucoma. The pores of lamina cribrosa from healthy and early, moderate and advanced glaucomatous optic nerve heads will be presented (Figure 1c-f respectively) showing change in pore number and shape at different stages of glaucoma.

 

Conclusions:

 

Improvements in OCT allowing the imaging of deeper structures within the ONH, raises the possibility that alterations in LC structure can be used as a marker of glaucomatous damage. 3D delineation and segmentation of glaucomatous retina and ONH at different stages of disease progression is possible, permitting the evaluation of LC pores, posterior displacement of anterior LC surface and excavation of the ONH. This raises the possibility that LC structure in vivo can be analysed to quantify glaucomatous optic neuropathy.  

 

Keywords: lamina cribrosa • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)