Ocular fundus changes in malignant or precocious stroke-prone spontaneously hypertensive rats after administration of antihypertensive drugs

Hypertensive Retinopathy and the Risk of Stroke Among Hypertensive Adults in China

Purpose

This study aimed to investigate the association between hypertensive retinopathy and the risk of first stroke, examine possible effect modifiers in hypertensive patients, and test the appropriateness of the Keith-Wagener-Barker (KWB) classification for predicting stroke risk.

Methods

In total, 9793 hypertensive participants (3727 males and 6066 females) without stroke history from the China Stroke Primary Prevention Trial were included in this study. The primary outcome was first stroke.

Results

Over a median follow-up of 4.4 years, 592 participants experienced their first stroke (509 ischemic, 77 hemorrhagic, and six unclassifiable strokes). In total, 5590 participants were diagnosed with grade 1 retinopathy (57.08%), 1466 with grade 2 retinopathy (14.97%), 231 with grade 3 retinopathy (2.36%), and three with grade 4 retinopathy (0.03%). Grades 1 and 2 were merged and classified as mild retinopathy, and grades 3 and 4 were merged and classified as severe retinopathy. There was a significant positive association between hypertensive retinopathy and the risk of first stroke and first ischemic stroke, and no effect modifiers were found. The hazard ratios (HRs) for first stroke were as follows: mild versus no retinopathy, 1.26 (95% confidence interval [CI], 1.01-1.58, P = 0.040), and severe versus no retinopathy, 2.40 (95% CI, 1.49-3.84, P < 0.001). The HRs for ischemic stroke were as follows: severe versus no retinopathy, 2.35 (95% CI, 1.41-3.90, P = 0.001), and nonsignificantly increased HRs for mild versus no retinopathy, 1.26 (95% CI, 0.99-1.60, P = 0.057).

Conclusions

There was a significant positive association between hypertensive retinopathy and the risk of first stroke in patients with hypertension, indicating that hypertensive retinopathy may be a predictor of the risk of stroke. A simplified two-grade classification system based on the KWB classification is recommended for predicting stroke risk.

Intravitreal administration of endothelin type A receptor or endothelin type B receptor antagonists attenuates hypertensive and diabetic retinopathy in rats

Hypertension is an independent risk factor for diabetic retinopathy, yet anti-hypertensive medications such as blockade of angiotensin II do not completely protect against vision-threatening vascular disease. We hypothesized that the potent vasoactive factor, endothelin (ET), is up-regulated in diabetic retinopathy and antagonism of the ET type A receptor (ETRA) or ET type B receptor (ETRB) ameliorates retinal vascular leakage independently of any blood pressure lowering effects. Spontaneously hypertensive rats (SHR) and their normotensive and genetic controls, Wistar Kyoto rats, were randomized to become diabetic or non-diabetic and studied for 8 weeks. Rats were further randomized to receive by intravitreal injection the ETRA antagonist, BQ123, the ETRB antagonist, BQ788, or vehicle, 5 days after the induction of streptozotocin diabetes and 4 weeks later. The treatments had no effect on systolic blood pressure which remained elevated in SHR. ET-1, ET-2, ETRA and ETRB were expressed in retina and retinal pigment epithelium (RPE)/choroid and increased by hypertension or diabetes. BQ123 reduced ET-1 and ET-2 expression in retina and RPE/choroid, while BQ788 had a similar effect but did not influence the mRNA levels of ET-1 in retina. Retinal vascular leakage and Müller cell stress as well as vascular endothelial growth factor (VEGF) expression in retina and RPE/choroid, were increased by hypertension or diabetes and there was an additive effect of these conditions. Treatment with BQ123 or BQ788 effectively reduced these events as well as the elevated levels of inflammatory factors in the retina. Our findings indicate that local ET systems exist in the retina and RPE/choroid that are up-regulated by hypertension and diabetes. The ability of locally delivered ET receptor antagonists to supress these overactive ET systems and reduce retinal vascular leakage and VEGF in the presence of hypertension indicate the potential of these approaches for the treatment of diabetic retinopathy.

Tremendous result of bevacizumab in malignant hypertensive retinopathy

Signs of hypertensive retinopathy are common and are correlated with elevated blood pressure. Patients who have swelling of both optic discs and very high blood pressure (i.e., malignant retinopathy) need urgent antihypertensive treatment. A patient was reported with malignant hypertensive retinopathy who recovered promptly following single intravitreal bevacizumab injection. Intravitreal bevacizumab (1.25 mg/0.05 mL) was injected in two eyes of a patient having malignant hypertensive retinopathy with optic disc edema, macular edema, and retinal exudates. A complete ophthalmic examination, including the best-corrected visual acuity (BCVA), central macular thickness on optical coherence tomography (OCT), and fluorescein angiography (FAG), was performed before and after the treatments. Two eyes in a patient received a single intravitreal injection of bevacizumab had improvement of macular edema on OCT at 1 month and decreased fluorescein leakage on FAG 3 months after the treatment, which led to improvements in the BCVA both eyes. The results suggest that intravitreal bevacizumab injections might be a useful and safe adjunctive treatment of malignant hypertensive retinopathy, in addition to proper medical management of malignant hypertension.

Hypertensive retinopathy signs as risk indicators of cardiovascular morbidity and mortality

Hypertensive retinopathy has long been regarded as a risk indicator for systemic morbidity and mortality. New population-based studies show that hypertensive retinopathy signs are strongly associated with blood pressure, but inconsistently associated with cholesterol and other risk factors of atherosclerosis. Mild hypertensive retinopathy signs, such as generalized and focal retinal arteriolar narrowing and arteriovenous nicking, are weakly associated with systemic vascular diseases. Moderate hypertensive retinopathy signs, such as isolated microaneurysms, haemorrhages and cotton-wool spots, are strongly associated with subclinical cerebrovascular disease and predict incident clinical stroke, congestive heart failure and cardiovascular mortality, independent of blood pressure and other traditional risk factors. These data support the concept that an assessment of retinal vascular changes may provide further information for vascular risk stratification in persons with hypertension.