imaging as a source of biomarkers for diagnosis, characterization and prognosis of chronic illness or long-term conditions. Br J Radiol 2014;87:20130832.
REVIEW ARTICLERetinal imaging as a source of biomarkers for diagnosis, characterization and prognosis of chronic illness or long-term conditions 1,2 T J MACGILLIVRAY, MSc
ABSTRACTThe black void behind the pupil was optically impenetrable before the invention of the ophthalmoscope by von Helmholtz over 150 years ago. Advances in retinal imaging and image processing, especially over the past decade, have opened a route to another unexplored landscape, the retinal neurovascular architecture and the retinal ganglion pathways linking to the central nervous system beyond. Exploiting these research opportunities requires multidisciplinary teams to explore the interface sitting at the border between ophthalmology, neurology and computing science. It is from the detail and depth of retinal phenotyping that novel metrics and candidate biomarkers are likely to emerge. Confirmation that in vivo retinal neurovascular measures are predictive of microvascular change in the brain and other organs is likely to be a major area of research activity over the next decade. Unlocking this hidden potential within the retina requires integration of structural and functional data sets, that is, multimodal mapping and longitudinal studies spanning the natural history of the disease process. And with further advances in imaging, it is likely that this area of retinal research will remain active and clinically relevant for many years to come. Accordingly, this review looks at state-of-the-art retinal imaging and its application to diagnosis, characterization and prognosis of chronic illness or long-term conditions.Currently about 20 million people in the UK suffer from at least 1 long-term condition (a health problem that cannot be cured but can be controlled by medication or other therapies), and this is set to increase 3-fold over the next decade placing an enormous economic and humanresource strain on the National Health Service.1-3 The retina is unique in the body in allowing easy observation of blood vessels with simple, non-invasive instruments. It is also the only accessible site for studying the central nervous system (CNS) in vivo.4 This makes it a ripe environment for the study of systemic and neurological disease, in a patient-acceptable way. Changes to the retina can occur in some chronic diseases years before other signs become apparent. [5][6][7][8][9] Thus, studying the retina may provide an additional means for clinicians to stratify risk and help identify people who would benefit from early lifestyle changes and preventative therapies, as well as assessing the efficacy of new treatments. In addition, there is some early evidence that certain retinal measures may correlate with disease characterization and also prognosis, which not only provides clinicians with a useful assessment tool but also offers research scientists new avenues to explore in the understanding of the p...