PCL 3 - The High Life

DEFINITION

HYPERTENSION: chronically elevated blood pressure. In current usage, the word hypertension without a qualifier normally refers to systemic, arterial hypertension
Normal blood pressure: generally less than 120/80 mmHg (i.e. systolic blood
pressure less than 120 and diastolic blood pressure less than 80 mmHg).
Normal to high blood pressure: between 120/80 and 140/90 mmHg.
High blood pressure: 140/90 mmHg or higher. If your blood pressure is
180/110 mmHg or higher, you have very high blood pressure.

Essential/Primary Hypertension: no specific medical cause can be found to explain the rasied pressure.
Secondary Hypertension: the high blood pressure is a result of (i.e., secondary to) another condition.

INCIDENCE

Worldwide: estimated 600 million people affected worldwide (Cardiovascular Diseases – Prevention and Control, WHO, 2001-2002)
Australia: hypertension reported by 11% (2.1 million) (National Heart Foundation)
Indigenous Australia: unknown

How hypertension affects the eyes:
Hypertension leads to many changes in the blood vessels of the body, which affect the eyes in many ways. It can cause the following problems in the eye:
• Hypertensive retinopathy
• Macroaneurysms
• Branch retinal vein occlusion (BRVO) and vitreous hemorrhage
• Optic nerve involvement (Optic neuropathy)
• Involvement of the nerves supplying the eye muscles, leading to temporary paralysis or weakness of these muscles
Symptoms of these conditions
Many of these conditions may not have any symptoms in the initial stages. Therefore it is important to have a periodic eye checkup to detect these.

Hypertensive Retinopathy
The retina has delicate blood vessels that can be affected by many medical conditions and eye diseases. With high blood pressure that is not well controlled, changes can occur in the retinal blood vessels. These changes are called hypertensive retinopathy.
There are 4 grades of hypertensive retinopathy:
• Grade 1: slight narrowing of the retinal arteries (blood vessels)
• Grade 2: narrowing and irregularity of the retinal arteries
• Grade 3: Grade 2 changes plus bleeding in the retina
• Grade 4: Grade 3 changes plus optic nerve swelling
Grade 4 hypertensive retinopathy is a medical emergency that requires hospitalization for careful lowering of the blood pressure.
• Hypertensive retinopathy can occur when high blood pressure has not been well controlled for a long time, or if blood pressure suddenly increases. The retinal arteries respond to high blood pressure by narrowing.
• Over time, the vessels become stiff and they can push on nearby retinal veins.
• Damage to the blood vessels can cause them to change shape over time. They may also leak, leading to retinal bleeding and swelling of the retina. Swelling of surrounding nerves called cotton wool spots can also occur.
malignant hypertension - When blood pressure suddenly increases, severe leakage can occur from the retinal arteries, causing bleeding within the retina and swelling of the retina and optic disc.
Symptoms:
None noticed symptoms during early stages of hypertensive retinopathy. Symptoms of hypertensive retinopathy that occur later include:
• blurred vision
• headache (if your blood pressure is very high)
If blood pressure is not treated, permanent changes in the retinal arteries may develop. This can cause a loss of vision from poor blood flow, swelling in the retina and blockage of the retinal veins. Some of these effects may be permanent.

Branch retinal vein occlusion (BRVO) is a condition that is commonly associated with high blood pressure and changes of hypertensive retinopathy.

Arterial compression of the vein is believed to be the main cause of BRVO. The artery and the vein share a common adventitial sheath. Increased arterial stiffness may be a mechanical factor in the pathogenesis of BRVO. Compression of the vein may lead to turbulent flow in the vein. The turbulent flow in combination with the preexisting endothelial vascular damage from the different conditions creates a local environment favorable to intravascular thrombus formation.

BRVO may lead to a blurring of vision especially for fine work. This condition may lead to loss of vision by two mechanisms:

• Macular edema (swelling of the region of macula): Macula is the central region of the retina and is important for seeing fine details. A swelling in this region leads to a decrease in vision. This condition can be treated by doing laser therapy
.
• Vitreous hemorrhage: A vitreous hemorrhage may lead to a more severe loss of vision associated with a shower of red floaters. Sometimes the BRVO may lead to formation of new vessels in the retina. These vessels are abnormal and are very fragile. These may bleed and may cause vitreous hemorrhage and thus loss of vision. A timely detection of these new vessels can be treated by doing laser therapy and thus causing these new vessels to disappear.
Macroaneurysm: This is an uncommon manifestation of hypertension. An idiopathic weakening of the vessel wall leads to focal outpouching and aneurysm formation. The aneurysms are sites of leakage of exudates and hemorrhage in the macula. Over time or after acute hemorrhage, spontaneous thrombosis and closure of the aneurysm may occur; in some cases, the artery may return to normal. Untreated, this may cause bleeding into vitreous and thus loss of vision. This condition can be treated by laser therapy

Optic neuropathy may also lead to a loss of vision, which is painless and not associated with any floaters. Paralysis or weakness of the muscles of the eye leads to restriction of movement of the eye and double vision.

Sharanya

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