Hypertension is a common but detrimental cardiovascular disease in modern society. It is defined by having systolic blood pressure of 140 mmHg or more and diastolic blood pressure of 90 mmHg or more. According to studies, hypertension is responsible for 57% of all stroke deaths in East Asians. Hypertension affects multiple organs and tissues’ integrity and eyes, particularly the retina, are one of them.
Hypertensive retinopathy serves as a complication of hypertension but on the other hand it has valuable diagnostic and indicative values in managing hypertension and even predict stroke risk. It means by having comprehensive eye examination and examining the retina, practitioners can even get vital information that can save lives of hypertension patients. Now let’s learn more about the connections between hypertension and eyes.
High blood pressure affects the health and integrity of the blood vessels and the circulatory system. In retina, there are numerous blood vessels to support the normal functions of retinal cells which makes retina prone to hypertensive damage, forming hypertensive retinopathy. The prevalence of hypertensive retinopathy ranges from 3 to 14% at people of 40 years or older. For people with hypertension, on average it takes 6 years for hypertension patients to get hypertensive retinopathy. However, the level of current blood pressure does not always correlate with the severity of hypertensive retinopathy as retinopathy reflects blood vessels health cannot be represented by blood pressure only. People can also show some of the retinal changes before being diagnosed hypertension. Everybody should not look down the importance of checking retinal health.
Hypertensive retinopathy can be divided into 4 Grades according to the retinal signs. For Grade 1 hypertensive retinopathy, the retinal small arteries are generally narrowed. In Grade 2 hypertensive retinopathy, some small retinal arteries are found compressing retinal veins, called AV nipping, in addition to the arteriolar narrowing. In Grade 3 stage, the retinal vessels start to leak blood and fluid to the retina. Signs of retinal infarction may also be found. Grade 4 hypertensive retinopathy is found usually in patients with severely surged blood pressure, namely malignant hypertension. In Grade 4 hypertensive retinopathy, the optic disc and macula are also swollen in the retina besides all other signs found in Grade 3. Grade 4 hypertensive retinopathy requires emergency referral to control blood pressure as malignant hypertension is fatal. All these retinal signs are unable to be observed unless through comprehensive eye examination. For the symptoms, Grade 1 and Grade 2 hypertensive retinopathy usually yield no symptoms. Vision will only be affected when there are blood or swelling close to the macula in more advanced stages.
Complications of Hypertension in the Eye
Hypertensive retinopathy is the condition that the retina shows changes and signs due to hypertension. But on the other hand hypertension predispose factors of more severe sight-threatening complications in the eye, including ischemic optic neuropathy, retinal vein occlusion and retinal arteriolar emboli, all of these can be grouped as ‘stroke in the eye’ as they are similar to the stroke happening in the brain. Patients may experience sudden or progressive painless vision loss which can be permanent. Hypertension can also increase the risk of nerve palsies, causing sudden onset squint and double vision.
Values of Comprehensive Eye Examination to Hypertension-related Diseases
Retina serves as a window for practitioners to look at the blood vessels’ health easily and non invasively. Observation of retinal vessels gives many valuable information about the patient’s general health. Studies show that non-hypertensive individuals having generalised retinal vessel narrowing have 60% higher chance of diagnosing high blood pressure in the coming 3 years, independent of their weight and current blood pressure. Also, retinal arteriolar narrowing and AV nipping reflects the hypertensive damage 6-8 years ago which provide information about the patient’s previous blood pressure status. And most importantly, having comprehensive eye examination does not only save the eyes of hypertension patients but also their lives. It is because the structure and physiology of retinal blood vessel circulation is very similar to that of the brain. Patients found Grade 3 hypertensive retinopathy are 2-4 times more likely to develop stroke in the coming 3 years, the risk can even reach 18 times higher if there is associated brain lesion scanned by MRI. Grade 3 hypertensive retinopathy patients are also found having 2-3 times higher risk of developing heart failure. Therefore, by picking up moderate hypertensive retinopathy patients, they can be potentially benefited by referring for cardiovascular and stroke risk workups.
Comprehensive eye examination is crucial for the eyes and general well-being. It is recommended that everybody should attend it at least once per year. To care about your eyes and health more, it’s time to contact your optometrist for a comprehensive eye examination!
By Jeff Tang, Registered (Part I) Optometrist
Eyecare information by Swisscoat Vision Centre
Address : G/F Yuen Yick Building, 27-29 Wellington Street, Central, Hong Kong
Appointment :+852 3579 4763
Website : www.swisscoat.com