Why does retinal vein occlusion cause decreased vision? What is the likely visual outcome?
When the vein is blocked, the circulation is greatly slowed. When this happens, the retina (the part of the eye which sees, like the film in a camera) does not work as well as it should. In addition, tiny blood vessels called capillaries leak excessive fluid into the retina, causing it to swell. This is called macular edema. The ultimate visual outcome for patients with retinal vein occlusion cannot be predicted. About one-quarter of these patients have spontaneous improvement in vision, but in others, the vision remains decreased or even worsens. The only known way to improve vision for patients with retinal vein occlusion is to treat the swollen retina with laser. With laser treatment, most patients have a small improvement in vision. A small minority have improvement to near normal. In many the vision is not helped at all. However, physicians normally wait a few months to see if there is a spontaneous improvement before considering laser treatment.
