Keratoplasty - Definition, Types, Complications, Procedure, Pictures
Keratoplasty is a surgical procedure also known as corneal transplantation where the procedure is described as replacement of abnormal host tissue with a healthy corneal tissue from a donor. The replacement of the cornea can either be partial or full depending on the severity of damage in the cornea.
Keratoplasty is performed to restore the function and shape of the cornea while eradicating the damages and deformations subjected directly to the cornea due to any form of injuries and diseases. The corneal transplant procedure is among the most common and most successful transplant procedure which has been done for over a hundred years and is usually done on an out-patient basis.
The cornea is a component of the eye that is dome shaped and transparent and functions to cover the front of the eye. It is a refracting surface of the eye that serves as a clear window to be able to view the external environment. The cornea generally contains no blood vessels thus its characteristics of transparency and rather a shiny surface.
The cornea is an integral part of the eye to allow visual and any injuries subjected to it either through direct damage or any disease involving the cornea will greatly affect the visual acuity thereby resulting in visual distortion. Keratoplasty on the other hand has different types which are classified according to the purpose of the procedure and such are:
- Therapeutic keratoplasty is aimed at restoring the damages in the cornea and is also recommended in inhibiting the progression of the disorder affecting the cornea either partly or fully.
- Optical keratoplasty is focused on restoring and improving the visual acuity and is also aimed at improving the transparent characteristic of the cornea which is significant to a clear visual.
- Cosmetic keratoplasty is performed to improve or correct the distortions and any defects subjected to the cornea which may be brought by either congenital diseases and deformations or acquired diseases and traumas.
Penetrating keratoplasty or also known as traditional corneal transplant surgery is performed on outpatient basis and generally takes about one to two hours to perform. It is the traditional method of corneal transplantation indicated for a cornea that has an abnormality in both the front and back layers. The procedure involves removal of the diseased host tissue subsequently replacement of the cornea that came from a donor.
Penetrating keratoplasty is performed using a cutting instrument called trephine which is utilized to cut the cornea of the host. The cornea from the donor is then sutured into place using either an interrupted suture or a continuous non-absorbable suture. The procedure is concluded by filling the eye with a viscoelastic fluid. The eye is then covered with a plastic shield to protect the eye during the process of healing.
Endothelial keratoplasty is a new procedure indicated for the treatment diseases and disorders affecting the innermost layer of the cornea. It is now the preferred method of restoring vision as opposed to traditional corneal transplant surgery.
The procedure involves only the diseased layer of the cornea and is usually concluded with only one suture or no suture at all. Visual function in this procedure is usually recovered within a few days or a few weeks against the traditional corneal transplant surgery that usually takes a year to fully recover.
Endothelial keratoplasty involves no suture as it uses an air bubble to hold the tissue of the donor in place as it usually self adhere after a short period of time and when the air bubble is fully absorbed by the surrounding tissues.
Anterior Lamellar Keratoplasty
Anterior lamellar keratoplasty is a method of corneal transplant indicated for corneal damage limited to the anterior portion of the cornea. The procedure only involves the diseased portion while the healthy portion of the cornea is left intact.
The procedure utilizes a cutting instrument or a trephine in removing the diseased portion of the anterior layer of the cornea. After the diseased layer has been removed, the donor tissue is then sutured in place. This method is generally indicated for keratoconus and corneal scarring and is performed on an out-patient basis with the patient under the local anesthesia. As opposed to traditional corneal transplant surgery, anterior lamellar keratoplasty has fewer post-operative complications and with a diminished risk of damage or infection of the other part of the eye including less risk of graft rejection. The procedure also entails similar visual result with a short period of recovery as opposed to traditional corneal transplant surgery. It is however, a technically precise procedure that Descemet’s membrane perforation is potential which may call for a full thickness or Penetrating keratoplasty.
The local eye bank is an establishment where corneas from donors are usually kept. The recipient has to enlist their name in the local eye bank to wait for the availability of suitable tissue from the donor. This is usually done after the patient and the doctor has both agreed to corneal transplant as the best option for treatment.
The donor cornea is basically checked for any disease and damage and carefully screened for clarity prior to its release for transplant surgery. Strict guidelines and regulations are to be met before the donor cornea is released for transplant to ensure the safety and health of the recipient. The donor cornea is usually harvested within 24 hours following the death of the donor although cornea is generally not accepted in cases where the cause of death is unknown. The age of the donor is also another factor to consider prior to harvesting the cornea. Donors who are very young are not indicated for transplant owing to the characteristic of their cornea which is rather floppy and may only give poor refractive results post-operatively. Donors who are also above the age of 70 years are also contraindicated owing to the low endothelial cell counts.
The patient is brought and prepared in the clinic or in the operating room and placed under the anesthesia depending on the method of keratoplasty, overall health condition of the patient and the disease or damages in the cornea.
A speculum is placed over the eyelid to keep it open as soon as the anesthesia has taken an effect. Local anesthesia is usually injected into the surrounding skin of the eye to relax the muscle and keep the eye from blinking. The patient under the local anesthesia is basically awake during the entire procedure. General anesthesia will have the patient asleep during the entire procedure and is put in the recovery room right after the procedure and sends off home as soon as the effect of anesthesia wears off or if the patient is totally awake.
The recovery period following the procedure depends on the type or method of keratoplasty including the overall health condition and the underlying cause of the disease that affected the cornea. Blurry vision is common right after surgery and during the initial stage of recovery. The necessary precautions are instructed to prevent the eye from becoming infected including other problems that can affect the transplant and jeopardize the success of the surgery and full recovery.
Corneal transplant is regarded as the most common and successful transplant surgery although the procedure still entails small risk of serious complication despite its being a safe procedure.
The complications of keratoplasty may include the following:
- Cornea graft rejection
- Eye infection
- Irritation from protrusion of surgical sutures
- Elevation of the intraocular pressure
- Endophthalmitis which is rare but is life-threatening and requires an emergency medical attention
- Wound leakage
Graft rejection is the most serious complication of corneal transplant that significant signs and symptoms of rejection should be recognized to prompt the patient to seek immediate medical attention.
Signs and symptoms of graft rejection include the following:
- Redness of the eye
- Increased sensitivity to the light
- Decreased vision or loss of vision