An introduction to corneal transplantation surgery
The human eye is an intricate structure with multiple layers, each of which plays a vital role in vision. Damage to any of these layers can lead to partial or complete vision loss. The cornea, located at the front of the eye, is responsible for transmitting light into the eye. When this delicate structure is compromised by trauma, injury, infection, or chemical burns, it can become opaque, hindering the transmission of light to the retina and causing visual impairment. Corneal transplantation surgery is a transformative solution that can restore vision layer by layer.
When the clarity of the cornea diminishes (cloudy or damaged), due to mentioned above, the prospect of a corneal transplant emerges as a hope for restoring vision. In our country, the Eye Bank of the Islamic Republic of Iran shoulders the responsibility of procuring corneas for transplantation in medical centers. To prepare the cornea for transplantation, the corneal tissue is carefully separated from the donor’s eye, and then tested and evaluated to ensure its safety and viability. Once approved, the cornea is transported to the hospital or medical center for transplantation.
Corneal transplant techniques
- FALK – Femtosecond Anterior Lamellar Keratoplasty:
FALK, as an transplant in vision restoration, emerges for individuals grappling with opacities in the anterior layer of the cornea. Whether triggered by infectious complications, strokes, degenerative diseases, or corneal dystrophy, this method employs the precision of a femtosecond device to delicately remove the affected anterior layer, up to a thickness of 200 microns. Post-excision, the tissue or collagen layer undergoes meticulous replacement, seamlessly performed without the need for stitches.
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LK – Lamellar Keratoplasty:
The technique of LK, stands as a transformative solution that addresses corneal damage that extends into the middle layers, reaching depths of approximately 300-350 microns. The procedure involves the meticulous removal of the impaired corneal layer, replaced with healthy human tissue utilizing a state-of-the-art femtosecond device. This technique, while highly effective, requires the precision of corneal sutures to ensure optimal results in vision restoration.
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DALK: DEEP Anterior Lamellar Keratoplasty:
DALK acts as an approach when a substantial 80-90% of the cornea succumbs to damage, leaving only the remaining 10% healthy. Employing techniques, the impaired layer is meticulously excised, making room for the integration of healthy human tissue. Whether executed through femto scan technology or traditional manual surgery, the final result involves replacing the human tissue and the cornea stitching together.
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DSEK: Decemet’s Stripping Epithelial Keratoplasty:
DSEK is a type of corneal transplant that replaces only the damaged posterior layer of the cornea, which contains the endothelium cells. The endothelium can be damaged by hereditary diseases or trauma caused by injuries or intraocular surgeries. In this technique, almost the entire thickness of the patient’s cornea is preserved, and only the posterior layer is replaced. The graft and the recipient cornea are connected by injecting air, which helps the graft adhere.
- DMEK: Decamet Membrane Epithelial Keratoplasty:
DMEK is a type of corneal transplant that is similar to DSEK, but the posterior layer separated from the human tissue is only 10-15 microns thick and is treated with a special technique to replace the Descemet’s membrane and the endothelium. In this method, the thin posterior tissue is glued to the back of the cornea with air.
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PKP: Full cornea transplant: Penetrating Keratoplasty:
PKP is a type of corneal transplant that replaces the entire cornea. It is the oldest and most common type of corneal transplant and is used when the posterior, middle, and anterior layers of the cornea are damaged. In this comprehensive transplant, the tissue of the complete human cornea is sutured to the patient’s cornea after cutting. The elevated risk of rejection of this type of transplant is higher than all the mentioned methods and requires specialized care.
Questions and Answers about Corneal Transplantation Surgery
Frequently asked questions regarding pre- and post-operative procedures for the Corneal transplantation surgery:
- It is advised to take a bath the night before the procedure.
- Please avoid using any perfumes and makeup around the eyes.
- Please refrain using soft contact lenses for a minimum 3 days, and hard lenses for 3 weeks, leading up to the operation.
- Please inform your doctor of any drug known sensitivities to medications.
It is important to note that these actions are not painful, and your cooperation greatly influences achieving the desired outcome. Therefore, maintain composure, keep calm and pay attention the surgeon’s instructions throughout the procedure.
- Fixate on the blinking green light and avoid moving your eyes or head during the operation.
- The laser exposure lasts less than 20 seconds, depending on the specific type of laser being used. Therefore, refrain from moving your eyes during the time you hear the sound of the laser.
- Rest assured about your eyelids during the operation; because they will be gently held open, minimizing any discomfort. Avoid squeezing or frowning to prevent discomfort and pain.
- Keep your hands clear of the surgical area to prevent any potential contamination.
- Avoid rubbing your eyes.
- Refrain from wearing sunglasses in direct sunlight.
- Avoid exposure to eye-watering situations in the initial day post-surgery.
- Abstain from swimming for at least one month.
- In case of mild discomfort and pain, consider using pain relievers.
- It is safe to resume driving after a few days, exercising caution.
- Avoid applying pressure to your eyes during the initial weeks.
Keratoconus, in its advanced stages, only requires a layered or full-thickness cornea transplant where the cornea is very thin and cloudy. However, in all other cases, crosslinking surgery or intrastromal corneal ring segments (ICRS) can be used, with high success rates.
In cases where genetics leaves its mark on patients, manifesting as corneal opacity due to hereditary diseases, this tailored layered or full-thickness graft can be used.
Patients with corneal diseases with blood vessels have a higher risk of corneal graft rejection, and full-thickness corneal transplants have a higher rate of rejection than anterior lamellar keratoplasty (ALK) transplants.
For those who have night blindness, the cornea transplant is not efficient for vision restoration. Night blindness is a condition of the retinal cells, and the cornea is usually clear and does not need to be transplanted.
