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Dr Katie Mortlock 


Research Topics and Related Projects:

Recent research has investigated structural changes within the optic nerve head (ONH), more specifically the lamina cribrosa and inner retina in open angle glaucoma using novel laboratory 1050nm optical coherence tomography (OCT).  OCT is an imaging technique which can provide high resolution, three dimensional images of ocular structures in vivo.  The use of longer wavelength light sources, such as 1050nm, increases tissue penetration and this enables the examination of deeper ocular structures such as the lamina cribrosa and choroid, which until recently have been virtually impossible to image in vivo.  The lamina cribrosa is a key structure in the pathogenesis of glaucoma, as it is thought to be the initial site of ganglion cell axonal damage.  Using 1050nm OCT, we have been able to examine and identify changes in the lamina cribrosa in subjects with early and advanced glaucoma. 

20° x 20° 3D rendered view of ONH of healthy control subject, showing surrounding retinal layers, choroid and inner sclera.  Deeper structures within the ONH are revealed, showing the prelaminar and laminar regions.  The extracted rendered section shows detail within the lamina cribrosa, including pore pathways and laminar beams.

Figure 1. 20° x 20° 3D rendered view of ONH of healthy control subject, showing surrounding retinal layers, choroid and inner sclera.  Deeper structures within the ONH are revealed, showing the prelaminar and laminar regions.  The extracted rendered section shows detail within the lamina cribrosa, including pore pathways and laminar beams.  

 

The images shown below are en face OCT images of the right eye of two subjects, a healthy control subject (left) and a subject with advanced glaucoma (right), at the level of the anterior lamina cribrosa.  Structural changes are clearly evident in the advanced glaucoma subject, with significant pore enlargement in the central and superior regions and marked deformation of the inferior lamina cribrosa.  

Healthy control subject

 

The three dimensional capabilities of the OCT system have also permitted visualisation of the pores of the lamina cribrosa, presenting further opportunities to understand how this structure is altered during the development of glaucoma.  The image below represents a 500 x 500 x 300 µm section of lamina cribrosa in a subject with early glaucoma, showing connections between pores as bundles of nerve fibres travel through the optic nerve head.  

The three dimensional capabilities of the OCT system have also permitted visualisation of the pores of the lamina cribrosa, presenting further opportunities to understand how this structure is altered during the development of glaucoma.  The image below represents a 500 x 500 x 300 µm section of lamina cribrosa in a subject with early glaucoma, showing connections between pores as bundles of nerve fibres travel through the optic nerve head.

 

Analysis of the ganglion cell complex – the three innermost layers of the retina – using OCT scans, has allowed assessment of retinal ganglion cell and nerve fibre layer loss in glaucoma.  The image below shows segmentation of the three individual inner retinal layers, with resulting retinal thickness maps in a control and glaucoma subject from these layers shown below.  

Healthy control subject

 

This research has been undertaken as part of the work of the Optic Nerve Head Group led by Dr Julie Albon, with Prof Rachel North and Prof James Morgan and imaging support from Nick White and Dr James Fergusson from VSBL