Adaptive optics optical coherence tomography in glaucoma

Abstract

Since the introduction of commercial optical coherence tomography (OCT) systems, the ophthalmic imaging modality has rapidly expanded and it has since changed the paradigm of visualization of the retina and revolutionized the management and diagnosis of neuro-retinal diseases, including glaucoma. OCT remains a dynamic and evolving imaging modality, growing from time-domain OCT to the improved spectral-domain OCT, adapting novel image analysis and processing methods, and onto the newer swept-source OCT and the implementation of adaptive optics (AO) into OCT. The incorporation of AO into ophthalmic imaging modalities has enhanced OCT by improving image resolution and quality, particularly in the posterior segment of the eye. Although OCT previously captured in-vivo cross-sectional images with unparalleled high resolution in the axial direction, monochromatic aberrations of the eye limit transverse or lateral resolution to about 15-20 μm and reduce overall image quality. In pairing AO technology with OCT, it is now possible to obtain diffraction-limited resolution images of the optic nerve head and retina in three-dimensions, increasing resolution down to a theoretical 3 μm3. It is now possible to visualize discrete structures within the posterior eye, such as photoreceptors, retinal nerve fiber layer bundles, the lamina cribrosa, and other structures relevant to glaucoma. Despite its limitations and barriers to widespread commercialization, the expanding role of AO in OCT is propelling this technology into clinical trials and onto becoming an invaluable modality in the clinician's arsenal.

Review of adaptive optics OCT (AO-OCT): principles and applications for retinal imaging [Invited]

“…Changes in the geometry of pores may be an indicator for glaucoma [141]. The pores are a three dimensional structure and changes with depth can be observed using AO-OCT [142][143][144].…”

Redefining clinical outcomes and endpoints in glaucoma

“…Adaptive optics (AO) is a technology that can improve the real-time resolution of optical systems by using a deformable mirror to reduce optical aberrations [132]. Previously incorporated into fundus cameras and cSLO, AO in OCT combines the superior axial resolution of OCT with the ability of AO technology to improve lateral resolution, increasing threedimensional resolution of optic nerve head and retinal imaging to a theoretical 3 μm 3 / voxel [59]. In glaucoma this can enable visualisation of RNFL axon bundles [118], with initial studies demonstrating double the light reflectivity from these fibres when compared to surrounding tissue [117].…”

The Future of Imaging in Detecting Glaucoma Progression

“…The incorporation of adaptive optics (AO) systems into ophthalmic imaging has further improved achievable image quality (48). AO corrects for the monochromatic optical aberrations of the eye, thus improving the resolution of ocular imaging technologies (49).…”

“…Others have allowed detection of damage down to individual retinal fiber layer bundles and the inner and outer retinal layers in glaucoma (55) (56). This technology, however, still presents some barriers to its widespread adoption, namely high cost, limited field of view, narrow depth of focus, and extended acquisition time (48). …”