Adaptive optics imaging of the retinal microvasculature

Abstract

The eye has long been recognised as the window to pathological processes occurring in the brain and other organs. By imaging the vasculature of the retina we have improved the scientific understanding and clinical best practice for a diverse range of conditions, ranging from diabetes, to stroke, to dementia. Mounting evidence suggests that damage to the smallest and most delicate vessels in the body, the capillaries, is the first sign in many vasculopathies. These are the most critical vessels involved in the exchange of metabolites with tissue. Accurate assessment of retinal capillary structure and function would therefore be of great benefit across a broad range of disciplines in medical science; however, their small size does not make this an easy task. This has led to the development of high‐resolution adaptive optics imaging methods to non‐invasively explore retinal microvascular networks in living human eyes. This review describes the present state of the art in the field, the scientific breakthroughs that have been made possible in the understanding of vessel structure and function in health and disease, and future directions for this emerging technology.

Spatial frequency-based image reconstruction to improve image contrast in multi-offset adaptive optics ophthalmoscopy

“…Through the use of the SMART method, all capillaries, independently on their orientation, present an optimal contrast [see Fig. 4(b)], which could be extremely helpful when measuring the wall-to-lumen ratio and other important vessel-based biomarkers [16]. Although not shown here, the SMART method might also improve contrast of generated perfusion maps using off-axis detection methods [4].…”

Adaptive optics: principles and applications in ophthalmology

“…Several AO systems and imaging modalities allowed for exquisite visualization of blood vessel wall, lumen and blood cells, enabling the assessment of vascular morphology and perfusion (51). Arteriolar wall thickness and lumen diameter can be measured reliably from AO images (Figure 4) (52).…”

Trans-ocular hypertension assessment

“…The largest retinal vessels can be accessed non-invasively at a high resolution with optical imaging technology. Retinal blood vessels share structure and function with the heart and cerebral vasculature, making them an interesting non-invasive proxy for coronary artery disease and stroke 3,14 . Previous studies indicated that microstructural alterations in retinal arteries (manifested as vessel wall rigidity, an increase in their stiffness and loss of smooth muscle layer) may be linked to hypertension 15 .…”