The risks are similar to other intraocular procedures, but additionally include graft rejection (lifelong), detachment or displacement of lamellar transplants and primary graft failure. Use of immunosuppressants including cyclosporine A, tacrolimus, mycophenolate mofetil, sirolimus, and leflunomidprevent to prevent graft rejection is increasing but there is insufficient evidence to ascertain which immunosuppressant is better. In a Cochrane review which included low to moderate quality evidence, adverse effects were found to be common with systemic mycophenolate mofetil, but less common with topical treatments cyclosporine A and tacrolimus. There is also a risk of infection. Since the<unk> has no blood vessels (it takes its nutrients from the aqueous humor) it heals much more slowly than a cut on the skin. While the wound is healing, it is possible that it might become infected by various microorganisms. This risk is minimized by antibiotic prophylaxis (using antibiotic eyedrops, even when no infection exists). There is a risk of<unk> rejection, which occurs in about 10% of cases. Graft failure can occur at any time after the<unk> has been transplanted, even years or decades later. The causes can vary, though it is usually due to new injury or illness. Treatment can be either medical or surgical, depending on the individual case. An early, technical cause of failure may be an excessively tight stitch cheesewiring through the sclera. Infectious disease transmission through<unk>  is exceedingly rare. All<unk>  grafts are screened for the presence of viruses such as HIV or hepatitis through antibody or nucleic acid testing, and there has never been a reported case of HIV transmission through<unk>  transplant surgery. Prior to the development of reliable HIV testing, many countries instituted bans on<unk>  donation by gay men. For example, on May 20, 1994, the United States banned<unk>  donation by any man who has had sex with another man in the preceding 5 years, even if all HIV testing is negative (a policy which continues to be enforced today).
Corneal transplantation
Conductive keratoplasty
Laser thermal keratoplasty
Phototherapeutic keratectomy
Excimer laser trabeculostomy
Boston keratoprosthesis
Descemet membrane endothelial keratoplasty
Photorefractive keratectomy