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Retinal Vascular Diseases – Having A Clearer Understanding of The Problem
By: Dr Yeoh Phee Liang


The wonder of our eyes. Do our eyes play tricks on us?

The structure of our eye is similar to the built up of a camera. The image which we visualize is projected to the retinal quite like the image being directed on the film. This layer of retinal then relays information to our brain for the perception of what we view. A wide range of pathology can initiate within the retinal. Similar to any organ in our body, the retinal receive oxygen and nutrients from the arterial supply and toxic waste products are being removed via the venous supply.


Retinal Arterial Disease

Central retinal arterial occlusion (CRAO) or stroke to the eye has been reported to occur in 1 in 10,000 outpatient visits. Be it stroke to the eye or any part of the brain, narrowing of the great vessels at the neck accounts for 50% and diseases of the heart, of which atrial fibrillation (irregular heart beat) is the commonest, accounts for much of the remainder. It involves men and women >60 years of age with an equal frequency. Unilateral involvement is the rule in 98%of patients.

When narrowing takes place at the major blood vessels called carotid vessels at the neck, it will either cause low flow of nutrient or in turn cause turbulent flow at the narrowing, resulting in small particles called emboli being thrown off and block off smaller vessels. These emboli are made up of cholesterol, calcific particles and fibrin platelet aggregation.

Clinical features:

  1. Transient ishaemic (lack of nutrient supply, causing damage to the respective organ) attack refers to temporary loss of function to the brain, resulting in contralateral weakness involving the face and arm or leg and either a language disorder or other brain defects depending on the site. Major disabling stroke has symptoms persisting more than seven days.

  2. If the insult involves the eye, it can present as transient monocular blindness (amaurosis fugax) which may be described as like a shutter falling, a curtain being drawn or vision dimming. Episodes usually last only a few minutes. Persisting visual loss refers to occlusion to the central or smaller retinal arteriolar occlusion.

Patients with threatened stroke (i.e. transient attack) may be at high risk of second, more devastating events. The warning sign has set in and active intervention to find out the origin of the disease is called for.

Major risk factors for inflammatory and embolic disease should be defined including: diabetes mellitus, smoking, cholesterol, hypertension, heart disease, valve disease, irregular heart beat or peripheral vascular disease. Investigations should include blood test, chest x-ray, ECG and ultrasound or MRI of carotid vessels. Brain imaging should be undertaken in all those with focal neurological symptoms or signs to define the distribution of the lesion.


All patients should be advised about lifestyle issues and risk factor modification to reduce the risk of all forms of vascular disease including: cessation of smoking, control of diabetes and blood pressure and cholesterol lowering. Patients should be told not to drive for one month after their event. A risk reduction of about 20% can be achieved using anti clotting agent such as aspirin. Patients with high-grade narrowing are at high risk of stroke. They should be operated to remove such narrowing. Risk reduction and operative intervention therefore carries very different benefits in each of these groups and should be tailored to their individual needs.

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Retinal Vein Occlusion

Retinal vein occlusion can occur in all ages: 51% occur in patients aged 65 years or older, but 10-15% occurs in patients under the age of 45 although it is very rare in childhood. The visual prognosis is dependent on the type of retinal vein occlusion, either central or branch, the severity of initial result, underlying medical and ocular conditions, ocular squeal and recurrence.

There is no standardized ocular or medical intervention that can reverse retinal vein occlusion once it has occurred. Therefore ocular management is aimed at identifying underlying medical risk factors to possibly prevent a recurrence and also to prevent the possible complications associated.

It is now recognized that an important primary event is damage of the wall of the venous vasculature. This will in turn cause a clot formation leading to the final occlusion of the retinal vein. The predisposing conditions leading to this event include hypertension, high lipid in the body, diabetes mellitus, smoking, glaucoma (increased pressure in the eye), trauma and rarer conditions such as chronic renal failure, oral contraceptive pills, clotting disorders and inflammatory diseases.

Clinical Features

Patients usually present with sudden onset of painless decrease in vision associated with a visual field defect. The mechanisms can be either the

  1. Ischemic (lack of nutrient causing death to the tissue) type or the from the complications such as new vessels formation at the retinal causing glaucoma, retinal detachment and bleeding that follow or
  2. Oxidative (leaking) type causing swelling at the macular.


Once again, life style adjustment and respective treatment directed to prevent Recurrence. With the ischaemic type, careful evaluation to ascertain new unhealthy vessels do not occur and thus hindering further complications as mentioned. This can be achieved by applying laser to the retinal to improve the perfusion of nutrients to the retinal. As with the exudative type, gentle laser is applied to prevent leakage of excess fluid and lipid.

There is an increase in vascular causes of death (heart and brain) in patients with retinal vein occlusion. The recurrence of retinal vein occlusion may also occur up to 15% of patients over a 5-year period. Management of cardiovascular risk factors and recurrence should include antihypertensive therapy with aspirin.

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For further information please contact:
Dr Yeoh Phee Liang, Advance Vision Eye Specialist Centre, Tel: +603 - 7724 1392
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