The cornea is a clear tissue that covers the front of each eye. Light entering the eye first passes through the cornea, then the pupil (the dark spot at the centre of the coloured iris), and then the lens.
A corneal transplant is the process of removing all (Penetrating keratoplasty), or part of (DSAEK/DMEK, DALK), a cloudy or abnormally shaped cornea and replacing it with a healthy donor’s cornea.
Common indications for DSAEK/DMEK
- Fuchs’ endothelial dystrophy
- Corneal decompensation after cataract, glaucoma or retinal surgery or trauma
- Endothelial failure of a full-thickness transplant
- Congenital and other dystrophies such as CHED, ICE
Common indications for DALK
- Advanced keratoconus
- Stromal corneal dystrophies such as granular dystrophy
- Partial thickness corneal scarring
Common indications for PK
- Corneal scarring of all layers of the cornea due to trauma and corneal infections
- Significantly advanced keratoconus
Treatment
Descemet’s Stripping Automated Endothelial Keratoplasty/Descemet Membrane Endothelial Keratoplasty (DSAEK/DMEK)
DSAEK/DMEK is a partial-thickness corneal transplant used to treat diseases where only the endothelium (the back layer of the cornea) is affected, such as, Fuchs’ dystrophy. The principle behind partial-thickness transplantation is to only replace the necessary affected tissue instead of the entire cornea.
Advantages of DSAEK/DMEK compared to standard corneal transplantation:
a. The eye surface is kept intact, thus remaining more resistant to injury and infection
b. There is minimal change in refraction because only the endothelial layer (approximately 5% of the cornea) is replaced
c. Suture-related problems are significantly reduced/can be eliminated
d. Visual recovery is significantly faster and better
e. There is significant reduction in risk of graft rejection
Deep Anterior Lamellar Keratoplasty (DALK)
DALK is a partial thickness corneal transplant used to treat diseases, which affect the stroma (the front layers of the cornea), such as keratoconus or dystrophies such as granular dystrophy. It is most useful for the treatment of corneal disease in the setting of a normally functioning endothelium (cells lining the interior surface of the cornea). The diseased stromal layer is removed in its entirety and the healthy endothelium is left intact. This results in excellent optical clarity whilst reducing risk of graft rejection and failure.
Penetrating Keratoplasty (PK)
PK is a full-thickness corneal transplant used to treat diseases that affect the full thickness of the cornea. The host cornea is replaced with a donor cornea. It is used with success in patients with decreased visual acuity secondary to full-thickness corneal opacity or scarring.
Femtosecond Laser-Enabled Keratoplasty (FLEK)
This technique of penetrating keratoplasty (PK) utilizes a femtosecond laser to create customized donor and host edge patterns. A variety of complex patterns of laser cuts can be used including “top-hat,” “mushroom,” “zig-zag,” and “Christmas tree” patterns. This allows for quicker healing, improve tissue alignment, quicker stitch removal and the cornea has superior biomechanical strength as compared with the traditional manual blade trephination keratoplasty. In addition, studies of femtosecond laser-enabled keratoplasty (FLEK) have shown rapid visual recovery and astigmatism comparable with or often better than traditional PK.
How is the surgery performed
Dr. Gupta currently performs all corneal transplant surgery at Memorial Hospital. On treatment day, the patient will be instructed to arrive at the hospital about 1.5 hours in advance.
The surgery usually takes about an hour and can be done using local anaesthesia. Medication is used to numb the eye and stop it from moving. The patient stays sedated during the surgery. General anaesthesia is also an option and will need to be discussed with Dr. Gupta and the anaesthetist. Most patients go home on the day of the surgery, though some may require an overnight stay.