![]() 16– 20 Advancing the lateral image resolution on clinical subjects by at least one order of magnitude (from 20-μm to 2-μm), AOSLO brought vascular wall components, microaneurysms, and single capillary segment details into focus. 15 A significant advancement in retinal microvascular imaging, adaptive optics scanning light ophthalmoscopy (AOSLO), was the first technology to reveal the delicate structure of capillaries at a much higher resolution than conventional fluorescein angiography (FA) in a variety of modalities, including confocal and non-confocal techniques. Novel preclinical biomarkers could also shed additional light on to the pathophysiology of diabetic microvascular disease and retinopathy.Īdvances in retinal imaging and image processing techniques have allowed researchers to detect earlier signs of disease preceding classic NPDR, including structural markers such as arteriolar and venular caliber changes, tortuosity progression, and foveal avascular zone (FAZ) size and shape alterations, as well as functional markers such as vasodilatory response, blood flow and oxygen saturation variances. 14 These markers would potentially allow clinicians to monitor tissue response to current and emerging systemic and ocular treatment modalities in a more sensitive and individualized manner. This is important since earlier treatment is associated with better outcomes. The hope is that these markers will allow clinicians to diagnose disease and stratify patients according to their risk for end-organ complications earlier. 12 The relative success achieved with current retinal screening and treatment protocols 13 has encouraged further research to identify earlier preclinical biomarkers of microvascular abnormality in the diabetic retina. 10, 11 This approach may be more sensitive than the reverse since in some patients structural changes occur despite apparent good metabolic control. The ability to monitor tissue response to treatment through serial examinations of the retina has been used to guide management goals of hyperglycemia with systemic medicines such as oral hypoglycemics and insulin in attempts to lower the risk of diabetic damage to the eye as well as other micro- and macro-vascular end organ complications. 8 The earliest clinically observable signs of NPDR include microaneurysms, capillary non-perfusion and dot-and-blot intraretinal hemorrhages. 7 Non-proliferative diabetic retinopathy (NPDR) has been used as an umbrella term for the clinically identifiable biomarkers of diabetic microvascular disease in the retina prior to the development of more vision-threatening proliferative changes. 6 The visualization of retinal vascular lesions has helped scientists and clinicians better understand the natural course of the disease. Many insights into the microvascular changes that occur from long-term exposure to hyperglycemia have been gained from taking advantage of the transparency of ocular structures and examining the living retina. 2 Additionally, diabetes is a major cause of life-threatening complications such as end-stage renal disease, 3 myocardial infarction, stroke and peripheral vascular disease. ![]() 1 Diabetic retinopathy is the most common complication of diabetic microvascular disease, and is the leading cause of vision loss in adulthood. The global prevalence of diabetes mellitus has reached epidemic proportions, estimated to have affected 415 million people in 2015, and is expected to affect 642 million by 2040.
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