Overview

This record will give you an outline of vasculopathies affecting the retina. Go to our dedicated records for more information on:

Diabetic Retinopathy and Diabetic Eye Problems
The Eye in Systemic Disease
Retinopathy of Prematurity (Retrolental Fibroplasia)

Retinal anatomy

The retina has two main components. The outer pigmented layer of the retina consists of a single layer of cells known as the retinal pigment epithelium (RPE). This lies adjacent to the richly vascular choroid. The inner neural retina is made up of multiple layers of neural cells, starting with the photoreceptors which sit on the RPE and overlaid by ganglion cells with associated neuronal and supporting connective tissue. These overlying layers vary in thickness around the retina, generally getting thinner towards the fovea and disappearing altogether at the fovea centralis (the point where vision is maximal), leaving a small area of uncovered photoreceptors.

Retinal blood supply

There are two sources of blood supply to the retina:

• The outer RPE, the photoreceptors and a few of the overlying tissue layers are supplied by the choroid, itself supplied by the various ciliary arteries (branches of the ophthalmic artery - itself a branch of the internal carotid artery). There is a blood-retina barrier between the RPE and the photoreceptors such that this portion of the neural retina is protected from large toxic molecules and the molecular environment is tightly controlled.
• The inner neural retina is supplied by the central retinal artery and vein - directly derived from the ophthalmic artery and the associated veins respectively. The artery divides into two equal superior and inferior branches nasally (medially) and temporally (laterally) which supply all the inner layers of the neural retina. There is corresponding venous drainage. There are no arteriovenous anastomoses.

Clinical significance of the two blood supplies

Depending on the problem and at what level it occurs, different layers of the retina can be affected or spared. Thus, an embolus occurring in the ophthalmic artery will have a devastating effect as all layers of the entire retina lose their blood supply, whereas a small embolus lodged in a distal end branch of the artery will only affect the inner neural retina of that part of the retina, sparing the photoreceptors and limiting any symptoms.

Retinal artery occlusions

See Central Retinal Arterial Occlusion article.

Retinal vein occlusions

See Central Retinal Vein Occlusion article.

Problems specifically associated with systemic disease¹

Hypertensive retinopathy²

• Description - this can occur over time when there is a persistently raised blood pressure. Initially, there is arterial narrowing (copper wiring) which is followed by vascular leakage and subsequent arteriosclerosis, graded 1-4. This has a characteristic appearance on fundoscopy (described below). Rarely, choroidal changes may occur: this tends to be in a context of an acute hypertensive crisis (accelerated hypertension) in young adults. These patients are at risk of developing the retinal vein occlusions described above, particularly when there are concurrent risk factors (such as smoking and hyperlipidaemia).²
• Presentation
  • Chronic hypertension - usually asymptomatic or may have slightly decreased vision. Fundoscopy reveals bilateral attenuation of arterial vessels ('copper or silver wiring'), arteriovenous nipping (where the arteries cross the veins) and, eventually, haemorrhage and exudates.
  • Malignant (accelerated) hypertension - may have decreased vision and headaches. On fundoscopy, you may see hard exudates appear as a 'macular star' (thin white streaks radiating around the macula), disc swelling, cotton wool spots, flame haemorrhages and arterial or venous occlusions.
• Management - this should be aimed at controlling the hypertension. Accelerated hypertension is a medical emergency.
• Outcome - this depends on the blood pressure control.

Ocular ischaemic syndrome³

• Description - this uncommon condition arises as a result of chronic ocular hypoperfusion secondary to severe ipsilateral atherosclerotic carotid stenosis.
• Presentation - it usually presents in the 7th decade of life (range 50-80 years), often in association with diabetes, hypertension, ischaemic heart disease or cerebrovascular disease. It may also occur in the context of giant cell arteritis.⁴ Male:female is 2:1. Symptoms are unilateral and include a gradually decreasing vision (over weeks or months; rarely, this can be sudden), periorbital pain, prolonged recovery of images after exposure to bright light and there may be a history of amaurosis fugax. Signs include a red eye, corneal oedema, a mid-dilated poorly reacting pupil and there may be rubeosis iridis. Fundoscopy will show venous dilatation, micro-aneurysms, neovascularisation and disc oedema.
• Management - refer. These patients will be variously treated with topical steroids and mydriatics and laser to any new vessel growth. Any associated raised intra-ocular pressure will also be treated. The underlying carotid disease needs addressing; > 60% carotid stenosis needs discussing with a vascular surgeon.⁴
• Outcome - both visual recovery and systemic outcome are poor. There is a ~40% 5-year mortality rate, usually from cardiac disease.¹

Sickle cell retinopathy

• Description - the most severe forms of retinopathy are associated with sickle-cell C disease and sickle-cell thalassaemia but all types of sickle cell disease can give rise to retinopathy. The impacted sickle-cells occlude arteries (stage 1), giving rise to peripheral arteriovenous anastomoses (stage 2) and then sprouting of new vessels from these anastomoses (stage 3). Trivial ocular trauma may precipitate vitreous haemorrhage (stage 4) resulting in subsequent fibrovascular proliferation and tractional retinal detachment (stage 5).
• Presentation - there may be comma-shaped vessels, particularly in the inferior conjunctiva and there may be iris atrophy.⁴ Usually there are no intra-ocular symptoms until stage 4 when there may be floaters and stage 5, which presents with flashes and floaters ± loss of vision (in advanced disease). Signs will depend on the stage of the disease as described above. Haemoglobinopathies can also give rise to non-proliferative retinopathies characterised by arteriosclerosis, venous tortuosity, equatorial 'salmon patches' (superficial retinal haemorrhages), 'black sunbursts' (intraretinal haemorrhages), macular oedema, micro-aneurysms and cotton wool spots.⁵
• Management - there are no well-established treatment options for the early stages. Later on (stages 3-5), patients may benefit from laser treatment to abnormal vessels and surgery to address tractional fibrosis and detachment.
• Outcome - this depends on the stage and to what degree neovascularisation can be controlled. This ultimately depends on the underlying systemic illness.

Purtscher's retinopathy⁶

• Description - this is the retinopathy resulting from microvascular damage and occlusion occurring as a result of severe head trauma, chest compression injury or other crush injuries involving broken bones, fat embolisms or a number of systemic diseases (e.g. pancreatic disease, connective tissue diseases, lymphomas, thrombocytic thrombocytopenic purpura and following bone marrow transplantation). It can also occur during pregnancy or delivery.
• Presentation - there is sudden, severe, bilateral (unusually, unilateral) visual loss. Fundoscopy reveals multiple white retinal patches and haemorrhages around the disc.
• Management - there is no established ocular treatment (management of the underlying cause is the mainstay of treatment).
• Outcome - although the fundus changes often resolve within a few weeks, there is variable visual recovery, particularly where macular or optic nerve damage has occurred.

Non-infectious retinal microvascular retinopathy ('HIV retinopathy')³

• Description - HIV patients can suffer from a variety of ocular complications, many of these infectious in nature. However, 50-70% develop HIV retinopathy which may even be the first sign of AIDS.
• Presentation - this tends to be asymptomatic but, in 3% of patients, there is severe visual loss. Fundoscopy reveals a diabetic-type of appearance (cotton wool spots and micro-aneurysms) ± ischaemic maculopathy.
• Management - there is no specific treatment and management lies in concentrating on anti-retroviral therapy.
• Outcome - opportunistic infections and the systemic disease often overtake any visual impairment developing from HIV retinopathy.

Retinopathy in blood dyscrasias

• Anaemia - the various anaemias can cause retinal changes including flame haemorrhages with pale centres (Roth's spots), cotton wool spots and venous tortuosity. Optic neuropathies are also described - particularly in pernicious anaemia. However, these changes are often innocuous and rarely of diagnostic importance. Management lies in treating the underlying cause of anaemia.
• Leukaemia - retinopathy is relatively common in the leukaemias and is characterised by similar findings to those described for anaemia. The cotton wool spots may represent leukaemic infiltrates. There may also be orbital involvement (particularly in children), spontaneous subconjunctival haemorrhage and optic neuropathy.
• Hyperviscosity states - retinopathy is characterised by venous dilatation, tortuosity and retinal haemorrhages. There may also be cotton wool spots and disc swelling.⁵ Management is of the underlying condition.

Other retinal vascular problems^1,2

Retinal artery macro-aneurysm

• Description - this localised dilatation of a retinal arteriole tends to occur in older (60-80 year-old), hypertensive women.² It is distinct from the micro-aneurysms of diabetic retinopathy in that macro-aneurysms are larger in size, they tend to occur singly and form in much the same manner as aneurysms found elsewhere in the body (i.e. they are an idiopathic weakening of the vessel wall which leads to focal outpouching and aneurysm formation).
• Presentation - this is usually unilateral (90% of cases) and may be an incidental finding or may present with sudden painless visual loss from haemorrhage. However, more commonly there is gradual visual impairment due to insidious macular oedema and hard exudate formation (seen around the aneurysm on fundoscopy).
• Management - a rupture leads to haemorrhage which is observed until this involutes (as laser treatment cannot be carried out through the haemorrhage) and laser treatment is then performed to the lesion.
• Outcome - involution of the haemorrhage is very common but, occasionally, there is a chronic leak resulting in permanent loss of central vision.

Primary retinal telangiectasia

• Description - this describes a group of rare, idiopathic disorders which may be congenital or acquired. There is a variety of vessels' abnormalities (tortuosities, leakages, aneurysms and deposition of hard exudates) which often progress over time.
• Presentation - they may be asymptomatic until later on in life when they have progressed and then manifest themselves with (usually unilateral) painless, blurring of vision. Coats' disease is the most severe of this group of disorders and often presents early (typically affecting boys, presenting in the first decade of life, often by 5 years of age). There may be a retinal detachment associated with this form of disease (often seen as leucocoria).
• Management - this depends on the subtype and severity of the condition. Management ranges from observation to photocoagulation laser therapy, cryotherapy and vitreoretinal surgery.
• Outcome - this is generally poor.

Radiation retinopathy

• Description - this may develop following treatment of intra-ocular tumours with radiation therapy. It can also occur following treatment of sinus, orbital or nasopharyngeal tumours. The risk of retinopathy increases with radiation dose.⁵
• Presentation - patients usually present 6 months to 3 years post-therapy with a (usually) painless gradual loss of vision. Fundoscopy will reveal micro-aneurysms, macular oedema, hard exudates and flame-shaped retinal haemorrhages. There may be associated disc oedema ± proliferative retinopathy and tractional retinal detachment. A variant is the acute response to high-dose radiation: the retina then shows evidence of necrosis with widespread vascular occlusion, cotton wool spots and widespread haemorrhages.⁵
• Management - it depends on the exact findings but this may include topical steroids, laser treatment or surgery.
• Outcome - this depends on the degree of retinopathy. Poor prognostic features include optic nerve involvement and neovascularisation.