The patient would need to be willing to take the risk while feeling that the alternatives were unacceptable. Other contraindications are relative and depend on the general condition of both eyes. A patient with glaucoma or ongoing eye inflammation should have these conditions controlled before considering transplant. The presence of an anterior chamber intraocular lens might necessitate removal of the lens before a corneal graft could survive. The surgery involves the partial or total replacement of the host cornea with a donor cornea.
Total replacement is much more common.
The operation can be done under general or local anesthesia and is increasingly being done as an outpatient without an overnight stay in the hospital, but most still require one to two days hospitalization. The operating time is approximately 60-90 minutes. First, donor tissue is obtained and the recipient prepared in the operating room. A round button of donor cornea is then cut to the desired size with an instrument called a trephine. A matching round button of host cornea is also cut, its precise depth being finely controlled.