Corneal Transplantation (眼角膜移植)
What is corneal transplantation?
Corneal transplantation, also known as keratoplasty or corneal graft, is a surgical procedure to replace a damaged or diseased cornea with healthy donor tissue. It is primarily performed to restore vision but may also be used to improve the structural integrity of the eye or to treat severe corneal infections that do not respond to medical treatment.
Common indications for corneal transplantation
- Keratoconus – A progressive thinning and bulging of the cornea that distorts vision.
- Corneal scarring – Results from infections or trauma.
- Fuchs' endothelial corneal dystrophy (FECD) – A condition that causes damage to the corneal endothelial cells resulting in corneal swelling. The corneal endothelium is the innermost layer of the cornea, composed of a thin single layer of cells that are responsible for pumping water out from the cornea.
- Bullous keratopathy – Persistent corneal swelling / oedema due to endothelial cell failure, often following cataract surgery or trauma.
- Corneal dystrophies – Hereditary conditions causing deposits or clouding in the cornea. Depending on the condition, it may affect any layer of the cornea.
- Corneal ulcers – Severe or non-healing ulcers or infections that threaten the integrity of the eye.
- Chemical or thermal burns – Damage to the cornea from hazardous chemical substances or extreme heat.
Types of corneal transplantation
(A) Normal corneal anatomy consisting of 6 layers; (B) Penetrating keratoplasty (PKP); (C) Deep anterior lamellar keratoplasty (DALK); (D) Descemet stripping automated endothelial keratoplasty (DSAEK); and (E) Descemet membrane endothelial keratoplasty (DMEK). The red shaded areas refer to the areas of replacement by the corneal transplantation. This figure is adapted from a published article (Ting DSJ, et al. Tissue Eng Part B Rev 2022;28(1):52-62).
Several types of corneal transplantation procedures are available, depending on the extent and location of the corneal damage.
1. Penetrating Keratoplasty (PKP)
- Full-thickness corneal transplant where the entire central cornea (usually around 8-9mm in diameter) is replaced.
- Performed in cases where all layers of the cornea are affected.
- Longer recovery time as the entire corneal structure needs to heal.
- The surgery usually takes around 1-2 hours and is performed under general anaesthesia.
2. Deep Anterior Lamellar Keratoplasty (DALK)
- Partial-thickness transplant where only the diseased anterior layers of the cornea (epithelium, Bowman's layer and stroma) are replaced, preserving the endothelium, Descemet membrane, and/or pre-Descemet layer.
- Performed for advanced keratoconus and corneal scars that do not involve the endothelium.
- Sometimes, the surgery may be converted to PKP if there is a tear in Descemet membrane during the operation. However, studies have shown that the outcomes of PKP and DALK are comparable, except that DALK has no risk of endothelial rejection.
- Lower risk of graft rejection as the patient's/recipient's own endothelium is retained.
- The surgery usually takes around 1-2 hours and is performed under general anaesthesia.
3. Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK)
- Replaces the damaged endothelial layer with a thin layer of donor tissue, including a portion of the donor stroma, pre-Descemet layer, Descemet membrane and endothelium.
- Performed for endothelial disorders such as Fuchs' endothelial corneal dystrophy and pseudophakic bullous keratopathy (irreversible corneal swelling after cataract surgery).
- Faster recovery and better visual outcomes compared to full-thickness PK.
- The surgery usually takes around 1-2 hour and is performed under local or general anaesthesia.
4. Descemet Membrane Endothelial Keratoplasty (DMEK)
- The most advanced form of endothelial transplant, replacing only the Descemet membrane and endothelium.
- Provides better visual outcomes and lower rejection rates compared to DSAEK.
- Requires precise surgical technique but offers faster recovery and minimal graft thickness.
- The surgery usually takes around 1-2 hour and is performed under local or general anaesthesia.
Potential risks and considerations
- Potential complications include graft detachment (in DSAEK / DMEK), graft rejection, failure infection, and increased intraocular pressure.
- Success rates are high, but long-term monitoring is necessary to ensure graft health. Risk of graft rejection increases with the number of corneal transplantation performed in the same patient.
Recovery and aftercare
- The speed of recovery and vision improvement varies, depending on the type of corneal transplant, with endothelial procedures (DMEK/DSAEK) typically having faster recovery (as only the affected Descemet membrane and endothelium of the patient are removed during the procedure).
- Patients will need to use eye drops such as antibiotic drops (for short term to reduce risk of infection) and steroid drops (for long-term to reduce the risk of graft rejection).
- Regular follow-up visits are essential to monitor healing and detect complications early.
- Sutures (usually 16 of them) are required in PK and DALK and are typically removed in stages over several months to years.
© Copyright. All rights reserved.
We need your consent to load the translations
We use a third-party service to translate the website content that may collect data about your activity. Please review the details in the privacy policy and accept the service to view the translations.