Each time the retina is detached there is some permanent damage to the cells that sense light. That said, it is still possible for vision to improve for up to two years after successful retinal detachment surgery. There are several possible causes for the decreased vision such as swelling of the retina or scar tissue formation. Your surgeon should be able to determine if there is a treatable problem. Unfortunately, in some people vision never completely recovers after a retinal detachment.