It depends on the stage and severity of ROP. The less scar tissue present at the time of treatment, the greater the potential for visual development. Eyes treated at stage 2 or 3 may see as well as 20/40 or better. Eyes at early stage 4 often see as well as 20/80 – 20/200. About half of eyes at more severe stages of stage 4 see better than 20/2000 (ambulatory vision). Ambulatory vision is defined as being able to see objects and move around a room without stumbling or bumping into obstacles. Surgery for stage 5 ROP is often done to preserve vision in the range of ambulatory vision to light perception.