Sometimes a vein in the retina (at the back of the eye) can become blocked. This can either be a central retinal vein occlusion, or a branch vein occlusion. There is a loss of perfusion of the retina, similar to the loss of perfusion of the tissues of the heart after a heart attack. The result is that areas of the retina cease to function and there is loss of visual function. The degree of loss and long-term recovery depends on the severity and location of the blockage.
These photos show a central vein occlusion and an inferior branch vein occlusion.
Symptoms
There is a sudden onset of painless blurring of vision, which may involve the whole of the field of vision (generally central retinal vein) or an area above or below and possibly including the central vision (most likely branch vein occlusion). There may be some distortion and associated field defect (patchy area of visual loss).
This is a condition that generally occurs from the 60’s onwards.
Risk Factors
- Age
- Raised blood pressure
- Diabetes
- Blood clotting anomalies
- Raised intraocular pressure/glaucoma
- Abnormal blood proteins/hyperviscosity states
Investigation
- Blood tests (glucose/viscosity/clotting)
- Fundus photos (back of the eye pics)
- Fluorescein angiogram
- OCT scan
Treatment
This may involve watching and waiting, particularly if the visual acuity is relatively unaffected.
Laser may be offered in order to seal off vessels that are leaking and also to reduce swelling of the retinal tissues. Sometimes a more general application of laser is required to prevent further new vessels and haemorrhage at the back of the eye.
New treatments involving injections of an antibody against new vessel growth (Avastin or Lucentis) that prevents new haemorrhage from occurring, as well as reducing tissue swelling, are now used in many cases.
For central retinal vein occlusions a laser shunt procedure is available. This addresses the underlying cause of the problem. Professor Ian McAllister at the Lions Eye Institute pioneered the procedure. He is running a clinical trial involving the use of this kind of laser in combination with the Avastin or Lucentis injections. You may wish to be included in this study.
Outcome
This really depends upon the severity of the tissue damage in the first instance. Generally branch vein occlusions fare better than central retinal vein occlusions; this is because there is a lesser area of retina damaged in the former.
The individual outlook will be discussed on a case-by-case basis.
