How the retina works
The retina is the layer that lines the inside of your eye. In fact, the retina has many different layers, all of which are involved in different functions. One important layer in the retina contains cells known as rods and cones. These are the photoreceptor cells, and they are the only cells in the retina that are sensitive to light.
There are about 125 million rods, which allow us to see in low light – at dusk, or just before it becomes really dark. The cones carry out a different function. There are about six to seven million cones in a human eye, and they make it possible for us to see accurate images, with clear outlines. These cells also allow us to see different colours.
How high blood pressure affects the retina
As with most cases of high blood pressure, this health problem often goes unnoticed, because it doesn’t cause many symptoms. High blood pressure is also known as hypertension. A blood pressure reading of 140/90mm Hg (or above) is regarded as high blood pressure. If your blood pressure is even higher – 180/110mm Hg – this is classed as malignant or accelerated hypertension, which tends to develop rapidly. This condition is regarded as a medical emergency, as it is life threatening, and can damage vital organs – in particular your kidneys or eyes.
Fortunately, malignant hypertension is quite unusual. Of all the people who have, or have had high blood pressure, this condition only develops in about 1% of them.
What are the symptoms of hypertensive retinopathy?
If you have chronic (long term) high blood pressure, it can cause serious health problems, including heart attacks, heart failure, kidney disease and stroke, as well as hypertensive retinopathy. Often the only symptoms of this condition are that you may notice that your vision isn’t as clear as usual.
Although you may not be aware of what’s happening in your eye(s), hypertensive retinopathy can make the walls of the tiny blood vessels in your retina thicker. This means that less blood reaches your retina. And this drop in the blood supply can result in damage to areas of your retina, and can affect how clearly you can see.
As the condition progresses, it can cause more damage, with blood eventually leaking across parts of the retina. You may not be aware of the change in your vision, as this happens gradually. Even if your blood pressure isn’t very high, unless you have treatment to bring it down, it can slowly cause damage to your retina over time. And if your blood pressure is high, it will cause greater damage. The longer this goes on for, the worse the damage is likely to be.
How is hypertensive retinopathy diagnosed?
One of the problems with hypertensive retinopathy is that you may not display any symptoms of this condition. In some cases you may have symptoms, but you may not be aware of their importance. These are three symptoms that you should watch out for:
1. Having double vision, or vision that seems as though it has had the brightness turned down
2. Having headaches (especially if you don’t normally have these)
3. Having visual disturbances (cotton wool spots for instance), or vision loss that happens out of the blue.
If you have these symptoms it’s really important that you see an optician or eye specialist as soon as possible.
If you have malignant hypertension, you may have slightly different symptoms, such as chest pain, trouble breathing, very bad headache, and feelings of numbness in your face, arms and legs.
Your optician or eye specialist will examine your eye with an ophthalmoscope, This piece of equipment allows them to look at the interior of your eye (and the surface of the back of your eye), and check to see if the blood vessels there are narrower than they should be, and whether any fluid is leaked from these tiny blood vessels.
Is it time for an eye check?
Both of these are signs of hypertensive retinopathy. This is usually classed in one of four grades, with the last, Grade 4, being the worst. The symptoms can vary from almost nothing, to some loss of sight.
If you have signs of hypertensive retinopathy in your eye(s), it means that high blood pressure is affecting your whole body, and is likely to be damaging blood vessels elsewhere in your body. So hypertension could be affecting your heart, your kidneys and your brain. It is extremely important to make an appointment to see your GP, to have your blood pressure readings taken, and to get urgent treatment for high blood pressure.
How to monitor your blood pressure
Your GP will probably want to see you again, soon, to see if your blood pressure has come down. As a precaution, they may also suggest that you be referred on to see specialists if they are concerned about the effect high blood pressure may have had on your vital organs.
How is hypertensive retinopathy treated?
Because hypertensive retinopathy is caused by high blood pressure, the aim of your treatment will be to lower your blood pressure, and to keep it at a safe level long term. Generally, as long as your blood pressure is controlled, and kept at a safe, low level, your retina should heal.
Controlling your blood pressure is probably the most important aspect of treating hypertensive retinopathy, so your doctor will prescribe the medication they feel will be most helpful in bringing your blood pressure down. They will monitor your response to the medication, and may change it for another, if they feel it isn’t the best choice.
To help keep your blood pressure down, you will probably also need to make changes to how you live.
How to bring down your blood pressure
Can hypertensive retinopathy be prevented?
Hypertensive retinopathy is caused by high blood pressure that isn’t being controlled. So the way to prevent hypertensive retinopathy is to make sure that your blood pressure is at a healthy level, and to make sure that it stays that way.
A healthy blood pressure is under 120 over 80, or 120/80. This is the blood pressure that will contribute to being healthy, and reducing your risk of having a heart attack or stroke. The common blood adult pressure measurements in the UK tend to be 120/80 to 140/90. If your blood pressure falls between these figures – or above – you must take steps to bring it down to a safer level.
Systolic vs diastolic: what do the numbers mean?
Diet plays an important part in maintaining a healthy blood pressure.
Salt raises your blood pressure, so reduce the amount of salt in your diet as much as possible. There can be quite a lot of salt in foods that you buy that are ready to eat, such as cereals, bread, sauces and ready meals that you heat in the oven or the microwave. Make sure you read the labels on the packaging, and choose low salt foods where possible. When you’re cooking at home, don’t add salt.
10 signs you’re eating too much salt
- Make sure you include plenty of fruit and vegetables in your diet. Try to add at least two portions to your lunch and evening meal every day, and eat a couple of portions of fruit as a snack every day.
- Get moving. Being active is really good for your heart, and plays a part in reducing your risk of heart disease. If you haven’t been exercising, or being very active recently, start small, and build up from there. The British Heart Foundation has a 10-minute workout video that you can do at home, to get you started. You’ll find the video at www.bhf.org.uk/heart-health/preventing-heart-disease/staying-active.
- If you smoke, do everything you can to quit. Smoking is a serious health hazard, and giving up will make a huge difference to your risk of having heart disease, a stroke, and a range of cancers. Ask your doctor or pharmacist for advice and help on how to quit smoking. Visit Smokefree NHS, which provides free support to help you give up. Keeping yourself occupied can help you quit smoking, as can enlisting the support of family and friends. Having the support of those around you can really help.
- Watch how much you drink. Alcohol contains a lot of calories, which means that you can easily put on weight, which can increase your blood pressure. Drinking more than a safe amount can also damage your heart, and can cause abnormal heart rhythms. Try to keep to the recommended amount of alcohol. This is no more than 14 units of alcohol a week, with at least two days a week when you don’t drink alcohol.
- Watch your weight, to help keep your blood pressure down. Being overweight will push up your blood pressure, so it’s important to reach and maintain a healthy weight for your height. Your Body Mass Index (BMI) is calculated by dividing your weight in kilograms, by how tall you are in metres. You then divide that number by your height in metres. A BMI between 18.5 to 24.9 shows that you are in the healthy weight range. If your BMI is higher than this it means that you are overweight, and need to lose some weight. Blood Pressure UK have a Healthy lifestyle and blood pressure booklet that you can order online.
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