Femtosecond Laser-Assisted DALK

Using advanced femtosecond lasers to help dissect donor and recipient corneas in deep anterior lamellar keratoplasty (DALK) can improve outcomes compared with manual trephination, according to Mayte Ariño-Gutierrez MD.

Laser incisions can produce complex graft shapes that better match the donor and recipient tissue interface, improving fit and alignment, she explained. This may contribute to reduced risk of endothelial cell loss, rejection, and perforation and faster visual recovery in many cases.^1–6

Modern femtosecond laser systems also integrate high-resolution swept-source optical coherence tomography (OCT) imaging, which allows for intraoperative procedure monitoring. Surgical planning software enables customised treatments according to specific patient parameters, and a curved interface allows large treatment zones to accommodate all treatment designs, Dr Ariño-Gutierrez said.

“The curved [interface] requires less pressure and avoids oval cuts when working with ectasias.”

Useful shapes

Laser assistance supports a variety of graft cut shapes, from cylindrical side cuts to shapes with differently sized anterior and posterior surfaces joined by top hat, zigzag, anvil, or ‘Christmas tree’ shapes to hold the graft in place. Dr Ariño-Gutierrez typically uses a mushroom-shaped graft with a larger epithelial surface—up to 9.0 mm—stepped down to a smaller-diameter of 6.0 mm on the endothelial side.

“This allows us to treat larger superficial zones and is very convenient when working with ectasias,” she said.

The smaller posterior dissection zone also lowers the risk of perforation, she added. Creating an intrastromal tunnel at a depth of 50 to 80 microns from the endothelium enables air or gas to be injected to safely separate the layers. In addition to corneal ectasias (including keratoconus and post-LASIK), the procedure is useful for corneal scarring, corneal dystrophies, and previous penetrating keratoplasties where the endothelium is functional and intact.

For the donor, Dr Ariño-Gutierrez pressurises the anterior chamber with BSS and manually ensures the laser is centred before cutting. Similarly, she marks the centre of the recipient cornea before docking to ensure proper placement.

“It’s easier to be more accurate on the centration when you make your marks under the surgical microscope,” Dr Ariño-Gutierrez observed.

She also manually adjusts the depth of the posterior cut to make sure it is deep enough for a successful graft but not deep enough to penetrate, leaving about 50 to 60 microns of tissue anterior to the endothelium. Dr Ariño-Gutierrez then removes the superficial stroma to get a better view of the deeper layers before manually completing the dissection. OCT helps give a better view to ensure cuts are complete and non-penetrating.

For advanced keratoconus cases, Dr Ariño-Gutierrez uses 16 sutures to close, but generally 8 with more superficial wounds. She is currently conducting a study on how different stitching approaches affect outcomes.

Drawbacks

While laser-assisted DALK offers significant advantages, it also comes with some downsides, Dr Ariño-Gutierrez said. Extra time and resources are required.

In addition to the laser, preparing the donor cornea requires an artificial anterior chamber and a scleral-corneal rim of 3.0 mm. Donor and recipient preparation both take more time, Dr Ariño-Gutierrez noted.

Transparent tissues also are necessary. The procedure also entails suction, which may worsen glaucoma, and a laser with a flat interface risks oval cuts in ectasias.

Laser cuts also can lead to less regular surfaces in deep planes, Dr Ariño-Gutierrez said. The compression of docking systems can induce posterior deformation, with reduced collagen fibre compaction, potentially decreasing quality.

In general, however, laser assistance speeds recovery and reduces endothelial cell loss, rejection, and perforation risk, Dr Ariño-Gutierrez said.

Dr Ariño-Gutierrez made her comments at the 2025 ESCRS Annual Congress in Copenhagen.

Mayte Ariño-Gutierrez MD is an ophthalmologist at Hospital Clinico San Carlos and at Oftalvist Madrid, both in Madrid, Spain. arinomayte@gmail.com

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