What is a corneal transplant?
The cornea is the colorless, transparent surface in front of the eye. It is the main component of the human eye, and it is as easily damaged as the windshield of a car. The cornea can be severely damaged by knives, pencils and other sharp objects in our lives. Fireworks, exploding batteries and toxic chemicals, especially alkaline substances, can cause severe damage to the cornea. If the cornea becomes cloudy due to disease, trauma, infection or other causes, vision can be abruptly reduced.
Corneal transplantation is the surgical procedure of replacing the damaged cornea with a similar healthy formed cornea. Among whole body organ and tissue transplants, corneal transplants are in a relatively immune immune immune state due to the absence of blood vessels, and the procedure has the highest success rate among allogeneic organ transplants, with a success rate of 80-90%.
Who needs a corneal transplant?
Patients with corneal clouding caused by recurrent viral keratitis, who are completely cured and do not have further attacks within six months, can be considered for corneal transplantation; patients with corneal clouding caused by acid or alkaline chemical burns, one year after the injury is cured, corneal transplantation is feasible; patients with corneal ulcers of large extent, deeper invasion, untreated for a long time, at risk of perforation or central invasion of erosive corneal ulcers should undergo corneal transplantation immediately. Patients with congenital corneal degeneration, cone cornea, etc.; corneal scarring caused by ocular trauma.
Corneal Transplantation
The most critical thing for corneal transplantation is to have healthy corneal material, and the allogeneic (human) corneal material (donated by others) must be available within 48 hours Our hospital is the first to carry out corneal transplantation, ocular surface reconstruction, anterior segment reconstruction and corneal limbal stem cell transplantation in Fujian Province, and is one of the first medical units to carry out ocular surface reconstruction in China. With the only eye bank in Fujian Province, we have brought sight to thousands of corneal blind patients.
There are several types of corneal transplantation procedures
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, lamellar corneal transplantation is feasible for all corneal lesions that do not invade the deep corneal stroma or the posterior elastic layer, and where the endothelium is healthy or recoverable. It is commonly used in eyes with superficial corneal opacity or corneal dystrophy, progressive keratitis or ulceration, corneal fistula, corneal tumor, and some eyes with poor conditions that cannot undergo penetrating corneal transplantation, in order to improve corneal conditions first for lamellar transplantation.
Penetrating corneal transplantation: It is a method of replacing a full layer of cloudy cornea with a full layer of clear cornea. Indications can be classified as optical, therapeutic, shaping, and cosmetic according to their surgical purpose. The common indications for optical keratoplasty are conical cornea, corneal scarring due to various causes, various corneal dystrophies, and corneal endothelial cell failure due to various causes. Indications for therapeutic corneal transplantation are septic corneal ulcers, ocular chemical injuries, erosive corneal ulcers, corneal limbal degeneration, corneoscleral necrosis due to Wegener’s granuloma, recurrent pterygium, corneal dermatomes, and squamous epithelial carcinoma of the cornea.
Artificial cornea transplantation: It is a surgical method to restore vision by surgically implanting a special optical device made of transparent medical polymer material into the corneal tissue to replace part of the corneal scar tissue. Since the problems such as rejection of synthetic materials by corneal tissues have not been finally solved, the long-term effect is not good, often causing atrial water leakage at the transplantation site and the detachment of the transplantation piece, so it is not possible to be widely used yet. At this stage, artificial cornea is only suitable for those who suffer from double vision after various serious corneal diseases, especially for those who suffer from severe chemical burns causing total corneal leukoplakia and repeated corneal transplantation failures and cannot undergo other surgeries.
A new breakthrough in corneal transplantation treatment
Compared with traditional penetrating corneal transplantation, the advantages are: significantly shorter operation time, faster recovery of vision, less astigmatism, and less postoperative rejection rate than traditional penetrating corneal transplantation. The figure below shows the preoperative and 2-year postoperative photos of the sutureless deep lamellar endothelial graft.
The advantages over traditional lamellar keratoplasty are: significantly shorter operative time, improved postoperative suture-induced discomfort, and a simple, safe, and effective surgical approach. Below is a pre- and post-operative photograph of a biogel-assisted lamellar corneal graft for the treatment of keratoconjunctival melanoma.
Pre-operative precautions
Due to the difficulty in sourcing fresh material, the surgery is mostly performed at night or on weekends, resulting in you coming to the hospital in a hurry. Please do not be nervous and anxious, relax and actively cooperate with the doctor to understand the surgical procedure, which is conducive to intraoperative cooperation and can shorten the operation time.
Pre-operative antimicrobial eye drops should be prescribed to clean the conjunctival sac to prevent post-operative infection. The purpose of preoperative pupil reduction medication for penetrating corneal transplant patients is to protect the lens from damage during surgery. The purpose of preoperative IOP-lowering medication is to keep the IOP within the appropriate range for surgery. To ensure that you are comfortable, please empty your bowels, remove your dentures, watch and jewelry, and braid your long hair at your sides before surgery.
Intraoperative Precautions
All surgeries are performed under a microscope and are sterile to ensure accuracy. During the surgery, please keep your hands at your side, lie flat on the surgical bed and do not touch the cleaned eyes. With your cooperation, the surgery usually takes 30-90 minutes.
During the operation, your whistle, pulse and blood pressure will be closely monitored by central electro-monitoring. Do not stop taking antihypertensive medication before the operation if your blood pressure is high. If you have to cough, tell the surgeon in advance to protect the incision and cough with your tongue against your palate.
Post-operative precautions
①Regular review: Please follow the doctor’s instructions for regular review and review at any time in case of emergency.
Emergencies include
a. Sudden onset of blurred vision and loss of vision.
b. Sudden onset of eye pain, eye grinding, eye redness, tearing and photophobia.
c. External trauma to the operated eye.
d. Sudden onset of other eye discomfort.
②If you cannot go to our hospital in time, you should immediately go to the local hospital for consultation and treatment, and it is better to return to our hospital for follow-up if possible. The general treatment is: Bactrim eye drops, every 2 hours; 2% cyclosporine eye drops, 4 times a day; Dexamethasone eye ointment, once a day at bedtime; methylprednisolone intravenous drip, which can be changed to oral hormone after about 3 days according to the restoration of transparency of the transplantation piece, gradually reducing the dose, and the eye continues to be dripped, but gradually decreasing the number of times.
Medication change
After the operation, we will visit the hospital daily to change the medication and observe the growth of the implant under the slit lamp and the healing of the corneal wound. Our hospital uses imported 10-0 nylon sutures, which need to be removed at any time when the sutures are loose. Adults usually start to adjust the sutures 6 months after surgery to improve their vision. In principle, all sutures are removed in 1 year. The time of suture removal differs for each patient’s specific situation (such as age and recovery of the disease).
Proper eye drops
Wash your hands carefully before the eye drops, do not press the eyeball or touch the corneal implant when using the drops, shake well when using the suspension, use two or more eye drops at the same time with an interval of more than 15 minutes, use the less irritating one first, do not touch the eyelids and eyelashes with the eye drops, put 1-2 drops into the conjunctival sac, and order the drops strictly according to the doctor’s prescription.
Wearing protective glasses
It is indispensable to wear anti-collision and anti-UV glasses when going out, which can be worn after discharge from the hospital.
Postoperative living and mental adjustment.
There is no special contraindication to diet, avoid spicy and stimulating food, avoid smoking and alcohol; preferably light, eat more soft food and easy to digest food, eat more fruits and vegetables to promote wound repair, can appropriately enhance protein intake; keep bowel movement and sleep well, if insomnia or constipation, please inform the doctor in time, in order to cooperate with the use of relevant drugs to facilitate recovery. Keep your mind as optimistic and relaxed as possible.