Improved visualization of deep ocular structures in glaucoma using high penetration optical coherence tomography

Abstract

The introduction of optical coherence tomography (OCT) has revolutionized ophthalmology through the ability to non-invasively image the retina in vivo. Glaucoma is the leading cause of irreversible blindness worldwide. Despite major advances in imaging techniques, the pathogenesis of glaucoma remains poorly understood at present. The lamina cribrosa (LC) is the presumed site of axonal injury in glaucoma. Its thinning and deformation have been suggested to contribute to glaucoma development and progression by impeding axoplasmic flow within the optic nerve fibers, leading to apoptosis of retinal ganglion cells. To visualize the deep ocular structures such as the choroid and the LC, OCT imaging has been used, particularly the enhanced depth imaging (EDI)-OCT modality of spectral domain (SD)-OCT. However, the posterior laminar surface especially is not seen clearly using this method. A new generation of OCTs, swept-source (SS)-OCT, is able to image the LC and the choroid in vivo. SS-OCT employs a longer wavelength compared with the conventional OCT, generally set at 1050 nm (instead of 840 nm). We review current knowledge of the LC, findings from trials that use SD-OCT and EDI-OCT, and our experience with a prototype SS-OCT to quantify choroid changes and visualize the LC in its entirety.

Keywords::

• choroid
• glaucoma
• lamina cribrosa
• swept-source optical coherence tomography

Financial & competing interests disclosure

This study was supported by an unrestricted grant from Research to Prevent Blindness (New York, NY, USA), and Velux Foundation (Zurich, Switzerland). K Mansouri has acted as a consultant for Sensimed AG. RN Weinreb has received funding from and acted as a consultant to Carl Zeiss Meditec, and has received funding from Heidelberg Engineering GmbH, Nidek, Optovue and Topcon Medical Systems. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • The pathogenesis of glaucoma is insufficiently understood.

• • The lamina cribrosa is considered a key structure in glaucomatous damage.

• • Current imaging technologies provide some degree of visualization of deep ocular structures, such as the lamina cribrosa and choroid.

• • A new generation of optical coherence devices, called swept source-optical coherence tomography, promises to enhance the evaluation of these deep structures.

• • Resulting improvements in the diagnosis and management of glaucoma and other retinal conditions would have an important impact on the societal burden of chronic eye disease.