Visualization of the Lamina Cribrosa Microvasculature in Normal and Glaucomatous Eyes: A Swept-source Optical...

The purpose of this study was to investigate the lamina cribrosa (LC) microvasculature using swept-source optical coherence tomography angiography (OCTA) images that have been processed using multiple image averaging and a projection-resolved algorithm. OCTA has recently gained popularity for assessing retinal and choroidal microvasculature. However, it is not known if the LC microvasculature, which likely holds important information for further understanding of glaucoma, can be visualized with OCTA.

One normal subject and 1 glaucomatous subject were enrolled and optic disc 3×3 mm swept-source OCTA cubic images were obtained for each subject. Anterior LC slab frames were developed, and the averaged images were created using 3 frames. Images were examined both with and without removal of projection artifacts.

The OCTA images of anterior LC slabs before projection artifact removal contained information on superficial and deep layer vessel blood flow. However, after projection artifact removal, fewer blood flow signals remained. These en face OCTA images showed flow signals on or immediately adjacent to lamina beams, but not inside lamina pores. The glaucomatous eye had a sectoral reduction in LC microvasculature blood flow that was not detected in normal eye.

This is the first demonstration of imaging of the inner LC microvasculature, which, in agreement with previous histologic reports, was arranged in a polygonal pattern. Furthermore, glaucomatous eye had decreased flow signals in comparison with normal eye. Therefore, future imaging studies with OCTA may be helpful for identifying and better understanding LC pathologic changes associated with glaucoma.