Psychosocial stress is linked to prolonged activation of the allostatic systems, with negative health outcomes, such as cardiovascular disease.(Danese and McEwen, 2012; McEwen, 2007) It is hypothesized that stress can contribute to cardiovascular diseases at different stages, including the long-term development of atherosclerosis and acute triggering of cardiac events.(Bairey Merz et al., 2002; Brotman et al., 2007; Steptoe and Kivimaki, 2012) In addition, the cardiovascular response to stress is different for acute and chronic stress.(Dimsdale, 2008; Steptoe and Kivimaki, 2012) Acute stress mainly triggers acute thrombotic and arrhythmic cardiovascular events, while chronic stress seems to affect cardiovascular risk by accelerating the atherosclerotic process.(Dimsdale, 2008; Steptoe and Kivimaki, 2012) Although stress has been associated with cardiovascular disease risk(Chida and Steptoe, 2010), few studies have examined the associations of stress with microvascular effects, such as changes in retinal vascular diameters, even though the microcirculation constitutes the majority of the circulatory system. The retinal microvasculature is seen as a good marker to assess the systemic microvasculature: it can be visualized non-invasively and it shares developmental and anatomical similarities with the microcirculation of the heart and brain.(Patton et al., 2005) Changes in the retinal microvasculature may thus reflect similar changes in the cardiovascular and cerebrovascular microvasculature, which might be important in determining an individual’s risk on cardiovascular, e.g. hypertension, myocardial infarcts and ischemic heart disease death, or cerebrovascular disease, e.g. vascular dementia and stroke.(Heringa et al., 2013; Liew and Wang, 2011; McClintic et al., 2010; Sun et al., 2009; Witt et al., 2006) Literature shows that cognitive functioning might also be associated with retinal microvascular changes (arteriolar narrowing).(Heringa et al., 2013; Shalev et al., 2013) Besides this, studies have also reported associations between retinal venular widening and schizophrenia.(Meier et al., 2015; Meier et al., 2013) It is therefore interesting to understand the determinants of the retinal microvasculature.