Deep Anterior Lamellar Keratoplasty (DALK)
What Is Deep Anterior Lamellar Keratoplasty (DALK)
Deep anterior lamellar keratoplasty, commonly known as DALK, is a partial-thickness corneal transplant that replaces the damaged front layers of the cornea while preserving your own healthy inner layer. The cornea is made up of five distinct layers: the epithelium, Bowman's layer, the stroma (which makes up roughly 90 percent of corneal thickness), Descemet's membrane, and the endothelium. Many corneal diseases affect only the stroma and the layers in front of it, leaving the endothelium, the thin cell layer responsible for keeping the cornea clear by pumping fluid out, perfectly healthy.
During DALK, the surgeon carefully removes the epithelium, Bowman's layer, and most or all of the stroma while leaving your native Descemet's membrane and endothelium intact. A donor cornea, prepared with the endothelium removed, is then placed over your own inner layer and secured with fine sutures. Because your endothelial cells remain undisturbed, the risk of endothelial rejection, the most sight-threatening form of transplant rejection, is dramatically reduced. According to the EBAA 2024 Statistical Report, corneal transplant procedures remain one of the most successful forms of tissue transplantation, with partial-thickness techniques like DALK offering improved outcomes for appropriate candidates.
Our cornea specialists typically perform DALK using the big bubble technique, which involves injecting air into the corneal stroma to cleanly separate it from Descemet's membrane. This method creates a smooth, consistent dissection plane that helps maximize the amount of stroma removed while minimizing the chance of accidentally puncturing the deeper membrane. When a complete big bubble is achieved, visual outcomes are comparable to those of a full-thickness penetrating keratoplasty.
How DALK Differs from a Full-Thickness Corneal Transplant
In a full-thickness transplant, or PK, the surgeon removes all five layers of the cornea and replaces them with a complete donor cornea. DALK, by contrast, removes only the front layers and preserves your own Descemet's membrane and endothelium. This distinction is clinically significant because it eliminates the risk of endothelial graft rejection, which is the leading cause of transplant failure after PK. For a broader overview of all transplant options, visit our corneal transplant guide.
Endothelial rejection accounts for the majority of immune-mediated graft failures after corneal transplantation. Because DALK leaves your endothelium in place, this type of rejection cannot occur. Stromal and epithelial rejection can still happen after DALK, but these forms are far less common and typically respond well to topical steroid treatment without permanent damage to the graft.
Long-term studies show that endothelial cell loss after DALK is roughly half of what occurs after PK over a 10-year period. Preserving a higher endothelial cell count helps the cornea maintain its clarity for a longer time. This advantage is particularly important for younger patients who need their graft to last for decades.
Who Is a Good Candidate for DALK
The best candidates for DALK are patients with a normal endothelial cell count and corneal conditions that spare the inner layers. This includes many patients with keratoconus, anterior stromal dystrophies, and corneal scarring from prior infections or injuries. Younger patients often benefit especially from DALK because preserving their endothelium can extend the lifespan of the graft well beyond what a full-thickness transplant might achieve.
What Conditions Does DALK Treat
Keratoconus, a progressive thinning and bulging of the cornea, is the most common indication for DALK. Patients with advanced keratoconus who can no longer achieve adequate vision with contact lenses or who have significant corneal scarring may benefit from this procedure. Research with 20-year follow-up data has shown that DALK provides visual acuity comparable to PK in keratoconus while offering superior endothelial cell survival.
Scarring from prior corneal infections, trauma, or inherited stromal dystrophies can cloud the cornea and impair vision. When this scarring is limited to the front and middle layers of the cornea and does not extend to Descemet's membrane, DALK can effectively replace the damaged tissue. Stromal dystrophies such as lattice dystrophy and granular dystrophy are also treatable with DALK when they significantly affect vision.
Corneal scarring resulting from resolved infections, including herpes simplex keratitis and bacterial keratitis, can be addressed with DALK if the infection is fully inactive and the endothelium remains healthy. Our cornea specialists will evaluate whether the scarring involves only the anterior layers through detailed imaging and clinical examination.
Frequently Asked Questions
DALK eliminates the risk of endothelial graft rejection, preserves more of your own endothelial cells over time, and creates a stronger surgical wound that is more resistant to trauma. Patients who undergo DALK also have a lower risk of developing elevated eye pressure after surgery. These benefits make DALK a preferred technique when the endothelium is healthy.
Most patients can return to desk work and light indoor activities within one to two weeks after DALK. Vision begins improving within the first few weeks, though full visual stabilization typically takes 6 to 18 months as the cornea heals and sutures are gradually removed. You should avoid heavy lifting, swimming, contact sports, and rubbing your eye for at least 6 to 8 weeks.
The most notable intraoperative risk is perforation of Descemet's membrane, which may require conversion to a full-thickness transplant. Postoperative risks include infection, stromal rejection, suture-related complications, irregular astigmatism, and interface haze between the donor and recipient tissue. While these risks are real, they are less frequent and generally less severe than the complications associated with PK.
DALK grafts have excellent long-term survival. Studies report graft survival rates above 95 percent at both 10 and 20 years for keratoconus patients. Because the endothelium is preserved, the graft is less susceptible to the slow endothelial cell loss that can eventually cause a full-thickness graft to fail.
Most patients will need glasses or contact lenses after DALK to achieve their best corrected vision. Astigmatism is common following any corneal transplant because the shape of the new corneal surface is difficult to predict precisely. Your final eyeglass or contact lens prescription is typically determined after suture removal and corneal stabilization.
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