Dysecdysis is an abnormal, incomplete shed — skin (or an eye cap, or toe/tail tips) that fails to come off — most often caused by humidity being too low.
Retained shed on toes or the tail tip can tighten like a tourniquet and cause the tip to be lost, and a retained eye cap can damage the eye. Fix the humidity, offer a humid hide, and never pull skin off dry — a warm soak helps, and a vet handles stubborn cases.