Potential applications of spectral-domain optical coherence tomography (SD-OCT) in the study of Alzheimer's disease

Alzheimer's Disease (AD) is the most common subtype of dementia. As the prevalence of dementia is projected to increase, the burden of the disease on society is expected to become increasingly significant. The link between eye pathology and neurodegenerative diseases has been established in multiple studies. In particular, optic nerve parameters associated with neuronal loss in AD include retinal ganglion cells (RGC). Retinal ganglion cells are similar to neurons in the cerebral cortex, and have been correlated to neurodegeneration in AD. Ocular imaging techniques such as optical coherence tomography (OCT) have provided a rapid and non-invasive method for quantifying optic nerve parameters in vivo. Spectral domain (SD)-OCT has shown good potential in the study of the optic nerve in AD as it enables more comprehensive assessment of RGCs. Earlier generation OCT techniques only assess the retinal nerve fibre layer, which consists of RGC axons. Spectral domain-OCT offers ultra-high scan speed and image resolution, enabling improved sampling of retinal layers. Retinal layers such as the ganglion cell-inner plexiform layer (GC-IPL), which contain the dendrites and nuclei of RGCs, can be assessed with SDOCT. This article presents a review of literature associating eye pathology with AD, and explores the potential of SD-OCT in future AD studies. Spectral domain-OCT has the potential to draw more links between optic nerve pathology and neurodegeneration.