Deep Anterior Lamellar Keratoplasty (DALK)
What are the differences between Penetrating Keratoplasty (PK) and Deep Anterior Lamellar Keratoplasty (DALK)?
Penetrating keratoplasty (PK) involves the transplantation of the full cornea’s thickness. A circular cutting instrument called a trephine is used to cut through the entire thickness of the damaged cornea. Then a new donor corneal button will be placed and sutured with tiny stitches around it edges.
Deep Anterior Lamellar Keratoplasty (DALK) is a partial thickness corneal transplantation, which involves the transplantation of only the front portion of the cornea. This method involves the removal of the outer and middle layers (stroma) of the cornea and replacement with a donor graft.
Depends on which part of the cornea needs to be replaced, your ophthalmologist will choose one of the above procedures, and it will be performed under general or local anaesthesia.
In both of these procedures, the donor cornea is fixed in place with stitches.
DALK offers the following advantages:
- Rapid healing and recovery
- Reduced rejection
- Improved safety
Who are the best candidates for DALK?
DALK is used in corneal diseases that exclusively affect the middle stromal layer:
- Advanced corneal ectasias such as Keratoconus
- Corneal stromal dystrophies
- Corneal scars
- Ocular surface disease
- Corneal clouding
In all of the above conditions, the inner layers of the cornea (Descemet’s membrane and endothelium) are healthy and do not require to be replaced.
How is DALK performed?
A circular cutting instrument (trephine) is used to cut the central 8 to 9 mm portion of the cornea. The depth of the cut is approximately two-third of the entire corneal thickness. Next, a tiny blunt needle is inserted into the centre of the cornea and air is then injected forcefully into the tissue. This “Big-bubble Technique” helps to separate the middle layer (stroma) of the cornea from the inner layers. All the remaining stromal tissue is removed, and the donor corneal graft is sutured in place.
This procedure is very delicate as the endothelial layer is thinner than a piece of paper. If the endothelium develops a break, the surgeon may have to remove it and replace it with a full-thickness graft. If the endothelial preservation is successful, a donor graft without endothelium is then sewn into place with 16 carefully placed micro-sutures.
What should I expect after DALK?
- Following DALK, your eye will be patched and your ophthalmologist will check it on the following day after surgery
- It usually takes 2 to 4 weeks for the surface layer (epithelium) to heal
- You will need to use eye drops frequently for the first few months, which will be slowly tapered down to once daily
- Once the epithelium is healed, patients will be examined monthly
- DALK is usually fully healed within 6 to 8 months, when it is safe to remove some of the sutures
- Visual recovery is gradual and may only be apparent when some sutures are removed
- Patients will need to see their ophthalmologist at least yearly and more often if taking corticosteroid eye drops
- Any new symptoms such as redness, sensitivity to light, vision changes, or pain need to be seen by your ophthalmologist immediately since any of these could be a sign of rejection or other complications