In this incredible macro photograph of a human eye, we see the stitches that resulted from a recent corneal transplant. The surgery was used to treat a patient suffering from Keratocnus, a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve. [Source]

In a corneal transplant, a damaged or diseased cornea is replaced by donated corneal tissue (the graft) in its entirety (penetrating keratoplasty) or in part (lamellar keratoplasty). The graft is taken from a recently deceased individual with no known diseases or other factors that may affect the viability of the donated tissue or the health of the recipient. The cornea is the transparent front part of the eye that covers the iris, pupil and anterior chamber. [Source]

According to the Encyclopedia of Surgery, corneal transplant is the most common type of human transplant surgery and has the highest success rate. To learn more about the actual procedure check out this link.