Читать книгу High Blood Pressure: Natural Self-help for Hypertension, including 60 recipes - Michelle Berriedale-Johnson - Страница 24

High blood pressure damages small arteries throughout your body. Those in the back of the eye have the advantage of being visible using an ophthalmoscope and they show the state of arterioles throughout your system, including your brain. Early changes due to hypertension include thickening of retinal blood vessel walls. If hypertension becomes long-standing or severe, the blood vessels leak and little haemorrhages form. Other changes are probably due to obstruction of vessels and reduced blood circulation.

Your doctor will regularly check the back of your eyes for signs of damage if your blood pressure has been high. This is performed in a darkened room using an ophthalmoscope, which contains a number of lenses and a light source. Sometimes you may have one eye dilated first with drops to make the task easier. The doctor is looking for various abnormalities known as Keith-Wagener retinal changes. These are divided into four stages of severity:

Grade 1 – retinal arteries are more tortuous i.e. less straight. Because they are thickened and bulging under pressure, they also reflect light from the ophthalmoscope more than usual. This gives them an appearance known as silver wiring.

Grade 2 – as in grade 1, plus evidence that the thickened, bulging arteries are compressing the veins where they cross over them (arterio-venous nipping).

Grade 3 – as in grade 2, plus signs that the arteries have started leaking. Leakage of protein-rich fluid produces white, soft, ‘cotton wool’ – like blobs while leakage of blood produces flame-shaped haemorrhages.

Grade 4 – as in grade 3, plus swelling, bulging and blurring of the head of the optic nerve (papilloedema).

If haemorrhages, exudates or papilloedema are visible in the back of the eye, it shows that malignant hypertension (see page 5) has developed. These are the same sort of processes that are occurring in the brain and which are thought to lead to a stroke. It is very important that your hypertension is brought under control quickly and safely. You may be admitted to hospital for complete bed rest while your drug treatment is adjusted.