Corneal transplantation: Corneal transplantation is the use of allogeneic normal clear corneal tissue to replace cloudy and diseased corneal tissue to restore sight or control corneal disease in the affected eye. It is a microsurgical procedure to improve vision or treat certain corneal disorders. Because the cornea itself does not contain blood vessels, it is in an “immune immune pardon” position, making it the most successful of other allogeneic transplants. It is one of the most important sight restoration procedures in ophthalmology. Most of the corneal material is taken from fresh donor donors, preferably no more than 6-12 hours after death, with intact corneal epithelium, transparent stroma and unchanged thickness (no edema), and if the fresh corneal material is specially treated with preservation solution or deep low temperature, it can be kept for several days or weeks before use. Generally, corneas between 6 and 60 years of age with healthy corneas are suitable, especially if they have died from acute illness or trauma, and between 25 and 35 years of age are best. If the donor cornea has been operated on, has glaucoma or has an eye tumor, it is certainly not suitable for corneal transplantation. Patients suffering from syphilis, hepatitis, leukemia, sepsis, AIDS, metastatic cancer or malignant disease are also not suitable for corneal transplantation. Whether a corneal transplant is viable and remains clear without rejection depends on a variety of factors. The compatibility of antibodies between allogeneic tissues plays an important role; the condition of the recipient and the surgical skill of the surgeon also largely influence the final outcome of the transplant. Corneal transplantation is divided into two categories: penetrating keratoplasty and lamellar keratoplasty. Penetrating keratoplasty: is a method of replacing a full layer of cloudy cornea with a full layer of clear cornea. The indications can be divided into optical, therapeutic, shaping and cosmetic according to their surgical purposes. 1, optical corneal transplantation common indications are: a, cone cornea (is the best and highest success rate of penetrating corneal transplantation indications, 8-year success rate of 90%.) b, corneal scarring due to various causes (common causes are keratitis due to bacterial, fungal, viral or echinococcal amoebic infections, corneal scarring due to corneal trauma, thermal burns, blast injuries and trachoma, etc., with a success rate of 60%); c, various corneal dystrophies, corneal endothelial cell failure due to various causes; d, various corneal degenerations (mainly referring to various corneal stromal dystrophies). 2, the indications for therapeutic corneal transplantation are septic corneal ulcer, ocular chemical injury, erosive corneal ulcer, corneal limbal degeneration, corneoscleral necrosis due to Wegener’s granuloma, recurrent pterygium, corneal dermatome, squamous epithelial carcinoma of the cornea, etc. Laminar corneal transplantation: It is a partial thickness corneal transplantation. The diseased tissue in front of the cornea is removed during surgery, leaving the underlying tissue as the graft bed. The graft bed is usually very thin, even leaving only the posterior elastic and endothelial layers. Therefore, all corneal lesions that do not invade the deep corneal stroma or the posterior elastic layer, and the endothelial physiological function is healthy or recoverable, are feasible for lamellar corneal transplantation. The indications are: 1, superficial corneal white spots; 2, various parenchymal superficial corneal dystrophy and corneal degeneration; 3, progressive keratitis or ulcers, corneal fistula, corneal tumors; 4, corneal fatigue scar although reaching the deep corneal layer, but there is hope to dissect to the implant bed transparent, and the systemic or local conditions are not suitable for penetrating corneal transplantation: such as psychiatric patients, nystagmus patients. In recent years, due to the low source of corneal donor materials, artificial corneal transplantation, which is in the experimental stage, is a special optical device made of transparent medical metal and polymer materials, which is surgically implanted into the cloudy corneal tissue. Therefore, it is not yet possible to use it widely. At this stage, artificial cornea is only suitable for those who suffer from serious corneal diseases, especially severe chemical burns that cause total corneal blepharoplasty and repeated corneal transplantation failure, and can no longer do other surgeries.