Fig. 6. Canthotomy and cantholysis for repair of full-thickness eyelid avulsion defects. Lateral portion of skin incision has been carried out as a small myocutaneous sliding semicircular flap A. Canthotomy. B. Cantholysis. C. Closure of eyelid margin. D. Skin closure. Semicircular flap can also be used to close a partial-thickness defect due to avulsion of eyelid skin and muscle. The semicircular flap can also be reversed to close an upper eyelid defect.