Hypertension and the eye
Hypertension is defined as having a sustained blood pressure of 140/90mmHg or higher. It is usually asymptomatic but can be a major risk factor for other cardiovascular disease. It is one of the most common diseases in the western world, affecting around 60% of people over the age of 60.
Hypertension can be classified into two groups, essential or secondary to other diseases. Essential hypertension can be considered a multifactorial disease with interactions of many different abnormalities. These include abnormalities in the cell membrane affecting movement of electrolytes, abnormalities in calcium and sodium metabolism, affecting smooth muscle contraction and kidney function respectively. Also abnormalities in the renin-angiotensin –aldosterone system and the central nervous system including the abnormal release of humoral factors and increased sympathetic outflow. There may also be genetic interactions in the development of hypertension. Obesity, alcohol and salt intake can also contribute to essential hypertension. Renal or endocrine diseases can cause secondary hypertension. Drugs and pregnancy can also increase blood pressure resulting in secondary hypertension.
Ocular manifestations of Hypertension:
Main complications:
Hypertension can be classified into two groups, essential or secondary to other diseases. Essential hypertension can be considered a multifactorial disease with interactions of many different abnormalities. These include abnormalities in the cell membrane affecting movement of electrolytes, abnormalities in calcium and sodium metabolism, affecting smooth muscle contraction and kidney function respectively. Also abnormalities in the renin-angiotensin –aldosterone system and the central nervous system including the abnormal release of humoral factors and increased sympathetic outflow. There may also be genetic interactions in the development of hypertension. Obesity, alcohol and salt intake can also contribute to essential hypertension. Renal or endocrine diseases can cause secondary hypertension. Drugs and pregnancy can also increase blood pressure resulting in secondary hypertension.
Ocular manifestations of Hypertension:
Main complications:
- Silver wiring – narrowing and sclerosis of the arteries.
- Arteriovenous nipping – The arteries are thickened and push on the nearby veins and give them a nipped appearance as they cross the arteries.
- Arteriolar narrowing – most reliable fundal sign, seen in retinal and more severely in choroidal arteries.
- Papilloedema - Swelling of the head of the optic nerve – with accelerated (malignant) hypertension, this is blood pressure ≥180 mmHg systolic and ≥110 mmHg diastolic.
- Hard exudates, cotton wool spots, haemorrhages – These signs lead to a grave prognosis
- Retinal detachment can also occur.
- Retinal vein occlusion is also more common in patients with hypertension.
Grading of retinopathy
Mild retinopathy – This consists of retinal-arteriolar signs (generalised and focal narrowing of the arteries), opacification of the arteriolar wall, arteriovenous nipping
Moderate retinopathy – flame – shaped or blot-shaped haemorrages, cotton wool spots, hard exudates, microaneurysms, could be a combination of all of these.
Severe retinopathy – some or all of these signs are present alongside swelling of the optic disc. This is poorly understood but could be due to increased intracranial pressure. There can also be a macular star, which is a ring of hard exudate formed around the macular region. Visual acuity can be impaired
Mild retinopathy – This consists of retinal-arteriolar signs (generalised and focal narrowing of the arteries), opacification of the arteriolar wall, arteriovenous nipping
Moderate retinopathy – flame – shaped or blot-shaped haemorrages, cotton wool spots, hard exudates, microaneurysms, could be a combination of all of these.
Severe retinopathy – some or all of these signs are present alongside swelling of the optic disc. This is poorly understood but could be due to increased intracranial pressure. There can also be a macular star, which is a ring of hard exudate formed around the macular region. Visual acuity can be impaired
Hypertensive Retinopathy
Hypertensive Choroidopathy
Hypertensive optic neuropathy
Other ocular complications of hypertension
Other forms of hypertensive retinopathy – In advanced renal disease, with patients with Phaochromocytoma and also in patients with preeclampsia-eclampsia, severe hypertensive retinopathy can be seen.
The risk of stroke increases with hypertensive retinopathy. This has been supported by many anatomical, physiological and pathological studies.
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- Focal intraretinal periarteriolar transudates (FIPTs) - These are small, white lesions deep to the retina, which are associated with the major arteries in the retina. This is one of the earliest signs seen with malignant hypertension.
- Cotton-wool spots
- Retinal arteriolar changes – These include Arteriolar pseudo-narrowing, arteriosclerosis, Arteriolar sheathing, macroaneurysms, Central/ branch retinal artery occlusion.
- Retinal capillary changes – These include focal capillary obliteration, microaneurysms, intraretinal microvascular abnormalities (IRMA).
- Retinal venous changes – These include venous nipping at arteriovenous crossings, central/ branch retinal vein occlusion and increased permeability of the retinal vascular bed.
- Amaurosis Fugax – temporary monocular blindness due to lack of blood supply to retina.
- Haemorrhages in the retina
- Retinal oedema and macular oedema
- Lipid deposits in the retina – These form hard exudates
- Loss of nerve fibres in the retina
Hypertensive Choroidopathy
- Choroid vascular bed abnormalities – The arterial circulation of the choroid can be impaired. There can be sclerosis and occlusion of the choroidal arteries, arterioles and choriocapillaries.
- Focal infarcts (Elsching’s spots) or linear infarcts (Siegrist’s streaks)
- Retinal pigment epithelium lesions – These can be acute and focal or there can be degenerative lesions that are focal or diffuse.
- Serous retinal detachment – This is a separation of the inner retina from the retinal pigment epithelium
Hypertensive optic neuropathy
- Oedema at the optic disk
- Pallor at the optic disk - consequence of microvascular occlusion
Other ocular complications of hypertension
- Cranial nerve palsies - impairment of the function of cranial nerves. This can cause paralysis of muscles and loss of sensation.
- Diplopia can also occur due to infarction of cranial nerves III and VI.
- Subconjunctival haemorrhage
Other forms of hypertensive retinopathy – In advanced renal disease, with patients with Phaochromocytoma and also in patients with preeclampsia-eclampsia, severe hypertensive retinopathy can be seen.
The risk of stroke increases with hypertensive retinopathy. This has been supported by many anatomical, physiological and pathological studies.
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