Retinal vascular disorders refer to a range of eye diseases that affect the blood vessels in the eye. These conditions are linked to existing vascular diseases, such as high blood pressure, high cholesterol and diabetes – conditions that cause atherosclerosis (thickening of the artery walls).
The most common retinal vascular disorders are:
Hypertensive RetinopathyHigh blood pressure (hypertension) causes the blood vessels in the eye to narrow, leak and harden over time as these vessels are subject to continued excessive blood pressure. In some cases, this can cause the optic nerve to swell and result in vision problems.
Retinal Vein Occlusion
Retinal vein occlusion (RVO) is a common vascular disorder where the vein becomes narrowed or obstructed (occluded). RVO is one of the most frequent causes of blindness after diabetic retinopathy. There are two main types of RVO. An RVO that happens in the retinal vein at the optic nerve is called a Central Retinal Vein Occlusion (CRVO).
About 90% of CRVO occurs in those aged 50 and above. An obstruction at a branch of the retinal vein is referred to as Branch Retinal Vein Occlusion (BRVO). BRVO accounts for some 30% of all vein blockages. Complications include swelling in the macula and proliferation of new vessels causing glaucoma. Central Retinal Artery Occlusion and Branch Retinal Artery Occlusion (BRAO)A central retinal artery occlusion (CRAO) is a blockage of the central retinal artery – the main blood vessel that brings blood and oxygen to the eye. This is a very serious condition that requires emergency treatment. When the main source of oxygen to the eye is blocked, permanent damage can occur. When the blockage occurs in one of the branches of the central retinal artery, it is called a branch retinal artery occlusion (BRAO).
Central Retinal Artery Occlusion
Hypertensive Retinopathy symptomsThere are few obvious symptoms of hypertensive retinopathy, but in some cases, there is vision loss or headaches.
Retinal Vein Occlusion (RVO) symptomsThe obstruction to the blood flow in the optic nerve by an RVO may cause blurring of vision or visual loss. These symptoms range from mild to severe and can either occur suddenly or gradually over time. In some cases, there might be pain and blindness in the affected eye.
Because of the threat to vision, regular eye examinations are important to pick up the problem early. An eye examination for RVO usually includes a range of vision tests to check vision accuracy and some investigations to study the eye itself and the presence of swelling or blockages.
Central Retinal Artery Occlusion (CRAO) symptomsCRAO presents as a sudden loss of vision in the affected eye.
Preventive measures include controlling systemic vascular diseases such as high blood pressure, high cholesterol and diabetes. Smoking should also be avoided.
What are the risk factors?Risk factors for Hypertensive Retinopathy
Risks of hypertensive retinopathy include chronic hypertension or high blood pressure which puts the blood vessels under a prolonged state of abnormal pressure.
Risk factors for Central Retinal Artery Occlusion (CRAO)Risks of CRAO include smoking, hypertension, high cholesterol, diabetes, coronary heart disease and a history of stroke. About 75% of CRAO cases occur in those with hypertension or blocked arteries in the heart.
The diagnosis is usually made with an eye examination by an ophthalmologist. Tests include optical coherence tomography (OCT) scanning to detect swelling of the macula. Occasionally, fluorescein angiography (where a dye is injected into the veins and the retinal vessels are visualised using a retinal camera) will be performed to assess the status of the blood flow in the retinal blood vessels.
Treatment for Hypertensive RetinopathyA major aim of treatment is to prevent and limit damage to the eye and target organs by addressing the root cause – hypertension – through medication and lifestyle changes. The eye is a prime target for complications due to high blood pressure and damage can be seen at very early stages. Regular eye examinations play an important role in preventing vision loss.
Treatments for Retinal Vein Occlusion (RVO)RVO is usually treated in two ways. The first is to identify and treat any underlying medical problems that cause the condition. Laser treatment is used to address complications associated with RVO. In some cases where there is a macula swelling, injection into the vitreous cavity can help to reduce the swelling.
Treatment for Central Retinal Artery Occlusion (CRAO)CRAO is treated in two stages. The first is the rapid diagnosis and treatment of the vision loss by lowering the eye pressure with ocular massage, anterior chamber paracentesis and medication. The second stage is to find out the root cause for the condition. Prompt treatment improves the chance of recovering vision, but outcomes remain poor, with only one in four patients able to retain useful vision. This means the management of risk factors and regular eye examinations are extremely important in preventing this condition from occurring.