The cornea is the transparent window at the front of the eye, that can become cloudy due to disease. Just like looking through a dirty window, this causes blurry vision. A corneal transplant (also called a corneal graft or keratoplasty), is an operation to replace this cloudy cornea with a clear one. The cornea is divided into a front half and back half. The cloudy cornea can be the result of disease in the front half, back half or both halves. Modern corneal transplant surgery aims to replace only the layer of the cornea that is abnormal, thereby minimising the risk of rejection. Corneas for transplant are provided by eye banks. Eye banks receive corneas from tissue donors when they pass away. A cornea should therefore always be treated with respect, as it is a living organ that has been donated for the gift of sight. All corneas undergo testing to ensure that they are of good quality and are safe to use. As a cornea is a type of organ transplant, there remains a lifelong risk of rejection and follow-up with your doctor after surgery is essential.