Ocular biomarkers for neurodegenerative and systemic disease

The eye is a readily accessible window to the brain and the retina has been proven to reveal presymptomatic evidence of brain disorders and systemic diseases, including Alzheimer disease, stroke and diabetes. Here we describe three approaches we are taking to examine the utility of retinal imaging for age-onset diseases.

Alzheimer disease develops slowly, with “plaques” of amyloid-β building up in the brain 15–20 years before memory symptoms and clinical diagnosis. With United States biotech company NeuroVision Imaging, we have been investigating whether similar plaques deposit in the retina. Researchers in the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing (aibl.csiro.au) are running a trial that involves highlighting amyloid plaques in the retina using oral dosing of curcumin, a natural ingredient which gives the spice turmeric its fluorescent yellow colour. The study builds on previous work that found changes to vision and to the retinal blood vessels in Alzheimer disease.1 We believe that retinal imaging may hold a key to early screening for disease and to monitoring interventions aimed at preclinical disease before irreversible brain damage occurs.

Vascular risk factors appear years before stroke and may also influence the likelihood of recurrent stroke. Another CSIRO study is embedding retinal vascular photography in a hospital stroke ward setting. The aims are to investigate the feasibility and utility of ward-based retinal photography as a tool to screen for retinal signs of disease, which may improve diagnosis of the aetiology of acute ischaemic and haemorrhagic stroke. The study may also facilitate appropriate preventive treatments, and improve the prediction of risk of recurrent stroke and other major vascular events.

CSIRO is also a partner in the Remote-I telemedicine project, which supports remote reporting, through a web-based, fully automated disease grading and clinical decision support system for eye diseases, such as diabetic retinopathy and age-related macular degeneration. It is now widely used in Australia and in China.