REVIEW How does hypertension affect your eyes? M Bhargava 1 , MK Ikram 1,2 and TY Wong 1,3 1 Singapore Eye Research Institute, National University of Singapore, Singapore; 2 Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands and 3 Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia Hypertension has profound effects on various parts of the eye. Classically, elevated blood pressure results in a series of retinal microvascular changes called hypertensive retinopathy, comprising of generalized and focal retinal arteriolar narrowing, arteriovenous nicking, retinal hemorrhages, microaneurysms and, in severe cases, optic disc and macular edema. Studies have shown that mild hypertensive retinopathy signs are common and seen in nearly 10% of the general adult non-diabetic population. Hypertensive retinopathy signs are associated with other indicators of end-organ damage (for example, left ventricular hypertrophy, renal impairment) and may be a risk marker of future clinical events, such as stroke, congestive heart failure and cardiovascular mortality. Furthermore, hypertension is one of the major risk factors for development and progression of diabetic retinopathy, and control of blood pressure has been shown in large clinical trials to prevent visual loss from diabetic retinopathy. In addition, several retinal diseases such as retinal vas- cular occlusion (artery and vein occlusion), retinal arteriolar emboli, macroaneurysm, ischemic optic neu- ropathy and age-related macular degeneration may also be related to hypertension; however, there is as yet no evidence that treatment of hypertension prevents vision loss from these conditions. In management of patients with hypertension, physicians should be aware of the full spectrum of the relationship of blood pressure and the eye. Journal of Human Hypertension (2012) 26, 71–83; doi:10.1038/jhh.2011.37; published online 21 April 2011 Keywords: blood pressure; retinopathy; cardiovascular disease; retinal vascular conditions Foreword Hypertension is associated with profound, often asymptomatic, multisystemic effects. The eye is not spared the effects of elevated blood pressure. However, the eye is distinctive in that it allows the direct sequelae of elevated blood pressure to be visualized early, particularly changes in the retinal microvasculature. The most well-known effect of the hypertension on the eye is therefore the condi- tion called hypertensive retinopathy, in which the retinal circulation undergoes a series of changes in response to high blood pressure. Hypertensive retinopathy has long been regarded as a risk indi- cator for systemic morbidity and mortality. How- ever, besides hypertensive retinopathy, elevated blood pressure has a key role in the pathogenesis of diabetic retinopathy, a major cause of vision loss in working adults. In fact, control of blood pressure has been shown in large clinical trials to prevent progression of diabetic retinopathy and prevent blindness, an effect that is almost equivalent to control of hyperglycemia. Finally, several retinal diseases such as retinal vascular occlusion (artery and vein occlusion), retinal arteriolar emboli, macroaneurysm, ischemic optic neuropathy and age-related macular degeneration may also be related to hypertension, but these relationships are not as well known to physicians. This review will summarize the broad ocular effects of hypertension, concentrating on literature published in the last decade (2000 onwards). Hypertensive retinopathy Pathophysiology and clinical features Hypertensive retinopathy refers to a spectrum of retinal microvascular signs that typically include retinal arteriolar narrowing, arteriovenous nicking (AVN), retinal hemorrhages, microaneurysms and, in severe cases, optic disc and macular edema. These signs develop due to acute and chronic elevations in blood pressure. 1 The initial response is diffuse and localized vasospasm of the retinal arterioles with consequent narrowing (generalized arteriolar narrowing and focal arteriolar narrowing (FAN), respectively). Arteriolar narrowing is a defining sign of hypertensive retinopathy and reflects vasoconstriction as an autoregulatory re- sponse in an attempt to control the volume of blood received by the retinal capillary bed (Figure 1). It is most commonly seen in the early phase of hyper- tensive retinopathy before the onset of sclerosis and Received and accepted 10 March 2011; published online 21 April 2011 Correspondence: Dr TY Wong, Singapore Eye Research Institute, Singapore National Eye Centre, 11 Third Hospital Avenue 168751, Singapore. Email: ophwty@nus.edu.sg Journal of Human Hypertension (2012) 26, 71–83 & 2012 Macmillan Publishers Limited All rights reserved 0950-9240/12 www.nature.com/jhh