The very small blood vessels at the back of the eye may also be affected by diseases such as high blood pressure, high cholesterol, diabetes and even high pressure changes within the eye itself.
Smoking or certain illnesses with thickened blood states may also contribute to vein occlusions – we may wish to investigate you intensively (with blood test and/or scans/cardiac investigations) if you have few other risk factors to explain your condition.
Often the veins and arteries lie in close proximity – so close in fact that the hardening of the arteries may negatively affect the veins where the two touch each other. If there is a slowing of the blood flow or the vein becomes compressed for too long, a blockage results in the vein. This effectively leads to much fluid build up and back pressure – much like a blocked drain pipe. Eventually the fluid (blood) spills over in to tissues adjacent to the blood vessel – usually the nerve fibres of the retina – and this leads to loss of vision.
This condition may progress to cause swelling in the centre of the eye (the very sacred central high clarity macula area) which is very disturbing to the vision. This may need treatment with special medications we deliver into the back of the eye in the form of intravitreal injections – these are very effective in ‘drying up’ the swollen tissue. Eventually the eye stops needing as many of these injections and many patients will be able to stop their treatment after a certain period of time. There is always a risk of this condition returning in the same or in the fellow eye.
Importantly, Dr de Wit will liaise with your GP and any other physicians to control your risk factors as best we can to prevent further episodes of vein occlusions occurring in you.