Deep Anterior Lamellar Keratoplasty (DALK)

A variety of corneal conditions can affect the clarity or shape of the cornea.

Deep anterior lamellar keratoplasty (DALK), is a newer method of corneal surgical procedure that selectively removes the diseased anterior layers of the cornea and retains the healthy innermost layer (endothelium). As the inner layer is retained the body does not recognize the donor tissue, hence there is no risk of rejection, and steroid medications need not be continued for a long duration.

Indications

DALK can be an effective treatment for any pathology of the anterior cornea (epithelium, Bowman’s layer and stroma) as long as the patient has an intact, functioning endothelium. Common indications for DALK include keratoconus and corneal scars. Patients with keratoconus are good candidates for DALK because they are typically young and have healthy endothelium. Less common indications for DALK include vernal keratoconjunctivitis, corneal dystrophies and ocular surface diseases with limbal stem cell deficiency, including Stevens-Johnson syndrome, ocular cicatricial pemphigoid and chemical/thermal burns.

Partial Thickness Corneal Transplantation

Deep Anterior Lamellar Keratoplasty (DALK) is a specialist surgical procedure which is a partial thickness graft that aims to preserve the two inner most layers of the cornea: Descemet’s membrane and the endothelium. Traditionally, penetrating keratoplasty (PK), which involves a full-thickness corneal graft, has been the treatment of choice for corneal stromal diseases.

Deep Anterior Lamellar Keratoplasty (DALK) is the most useful for the treatment of corneal disease in the setting of a normally functioning endothelium. The primary function of the procedure is to retain the endothelial layer of the host, if this layer is normal, then it is worth preserving and keeping. This layer keeps the cornea clear by removing fluid from the bulk of the cornea. Retaining this layer avoids the risk of potentially blinding Graft Rejection that can occur with Penetrating Keratoplasty (PK).

The procedure is technically skilled and involves dissecting the cornea to almost 95% thickness, and removing the top layer. A donor corneal button is prepared by removing Descemet’s membrane and donor endothelium. The donor graft is then sutured to the host. The cornea typically clears earlier than would occur with full thickness transplants and with newer techniques visual results can be similar to those of a penetrating keratoplasty.

Deep Anterior Lamellar Keratoplasty (DALK) can be an effective treatment for any pathology of the anterior cornea (epithelium, Bowman’s layer and stroma) as long as the patient has an intact, functioning endothelium. Although DALK has the reputation of being a challenging and time-consuming operation, recent improvements and advances in techniques have cut the surgical time and improved outcomes.

In patients with anterior corneal opacification or structural corneal defects with a healthy endothelium, DALK can be considered as the first line treatment due to its preservation of host endothelium and Descemet’s Membrane.

Advantages

  • Closed eye surgery
  • No chance of blinding Endothelial rejection (by retaining the recipient’s own endothelial layer)
  • Can always perform a Penetrating Keratoplasty (PK) if visual results are not satisfactory

Disadvantages

  • Technically challenging
  • Potential for interface scarring (and reduced visual clarity)