The good news is that with proper treatment an ulcer can heal up to 1mm per day. So if a horse has a 1/2 cm ulcer, the horse could potentially be ulcer free in 5 days if complications are prevented. Problems arise when the ulcer goes undetected and untreated for even brief periods of time. It can rapidly become large and deep, making treatment more difficult. If an infection becomes established deep in the stroma, it is possible to develop into a stromal abscess. This complication becomes very difficult to treat and often results in the loss of the eye.