Why Deep Anterior Lamellar Keratoplasty (DALK)?

Lamellar transplantation is the preferred method for most patients with keratoconus or post-LASIK corneal ectasia, as it offers greater safety and precision. Among the various techniques, DALK is favored over penetrating keratoplasty (PK) and Descemet’s stripping endothelial keratoplasty (DSEK) due to its ability to preserve the corneal endothelium, reducing the risk of graft rejection and intraocular pressure (IOP) spikes associated with corticosteroid use.

Advantages of DALK Over PK

✅ Preserves corneal endothelium – Lowers the risk of graft rejection.
✅ Reduces IOP complications – Avoids steroid-related pressure spikes.
✅ Improves graft survival – PK has a higher failure rate, even in keratoconus cases.
✅ Faster and safer healing – Avoids full-thickness corneal replacement.

While DALK is an invasive treatment for ectasia, less invasive treatments such as rigid gas-permeable contact lenses, intracorneal rings, and corneal cross-linking should be considered first. However, DALK is recommended if the patient:

• Cannot tolerate contact lenses.

• Has central corneal thickness < 300 µm.

• Has significant corneal scarring.

The Role of Femtosecond Laser in DALK

Femtosecond lasers provide high precision in performing side cuts for lamellar transplantation. A zigzag incision, created using femtosecond laser technology, enhances safety and accuracy when working with thin corneas.

Advantages of Zigzag Incision

🔹 Improves wound stability – The interlocking tongue-and-groove configuration strengthens the interface between the lamellar graft and the recipient cornea.
🔹 Minimizes air escape – When using the big bubble technique, a zigzag incision placed within 70 µm of Descemet’s membrane helps maintain air pressure and improves dissection depth control.
🔹 More accurate depth control – Compared to manual incisions, femtosecond laser cuts ensure precise wound shape and depth, leading to better graft-host matching.
🔹 Facilitates deep dissection – Reduces the need for a big bubble while enhancing precision.

Lamellar Dissection Techniques

Three primary techniques for lamellar dissection include:

1. Hand dissection – Standard but challenging due to difficulties in achieving a 90° incision angle.

2. Big bubble technique – Uses air to separate corneal layers, but can lead to complications if air escapes into the periphery.

3. Peeling technique – Gradual removal of layers for a smoother transition.

The Role of Optical Coherence Tomography (OCT)

Optical Coherence Tomography (OCT) is a noninvasive imaging technology that provides high-resolution cross-sectional images of the retina, allowing for:

• Early detection of retinal diseases.

• Monitoring disease progression.

• Assessing treatment effectiveness.

OCT uses light instead of sound waves to achieve sharper and clearer resolution than ultrasound. The test is painless and does not involve radiation or X-rays. It is commonly used for:

• Evaluating retinal swelling.

• Comparing OCT results with other diagnostic tools.

• Ensuring the effectiveness of medication regimens.