Eyeworld

EW CORNEA 30 April 2015 uniquely beneficial for patients with anterior stromal pathologies," Dr. Hersh said. While Dr. Price prefers to use the femtosecond laser in big bubble surgeries, he said its true advantage is not in its ability to dissect, but in its ability to cut the most precise of edges. Manual trephination is limited in the complexity of the cuts, whereas the femto can produce for deep anterior lamellar keratoplas- ty (DALK) surgery, and it is useful for anterior lamellar keratoplasty (ALK)," he said. For ALK, Dr. Hersh prefers the laser in patients with superficial corneal pathology and superficial corneal scars but that involve the anterior stroma. "With femto ALK you want to keep the depth of your lamellar cut less than 250–200 µm if you can because that ensures a smoother bed afterward," he said. Too deep of a cut risks the surgeon creating ridges on the stromal bed. "We can remove an anterior lamellar 'pancake' of tissue con- taining the pathology and replace it with tissue from the eye bank of the same dimensions. In my mind, that makes the femtosecond laser a zig-zag, mushroom, or top hat configuration at a variety of depths. Of these, Dr. Price tends to use the zig-zag pattern, since "the last part of the incision angles toward the center of the cornea and down," he said, so if surgeons need to convert to a hand dissection, they're at "the perfect angle." Because the femtosecond cuts are so much cleaner and de- fined than manual cuts, both the zig-zag and mushroom configuration make it easier to define the plane of dissection to determine where to insert the needle for the big bubble, making dissection easier and giving these techniques better structural advantages, Dr. Hersh said. Dr. Price thinks zig-zag has been a "huge" improvement for DALK or deep anterior lamellar cases because the resulting wound alignment of anterior surface of the donor/ graft is very smooth as compared to trephined wounds where the donor and graft bed have differing thick- ness, often causing irregular topogra- phies at the wound margins. "That's a huge advantage for vision," he said. "There seems to be a stronger wound healing with the zig-zag due to the stacked incisions that diago- nally cut across the corneal lamellae. The scarring is much stronger than with a manual trephine," he said. But thin corneas (under 300 µm) are better served with top-hat con- figurations, he said. Both the donor and recipi- ent are "cut so meticulously" that "patients recover quite quickly," Dr. Hersh said. But manual dissections have advantages over femto, too, Dr. Hersh said, especially in deep lamel- lar transplants where the femto has a more difficult time retaining a smooth stromal bed beyond about 200 µm. "As you go deeper into the cornea, the micro architecture of the cornea is much more planar, that is the corneal lamellae act more like pancakes that are easily separated with dissection spatulas because they are less interwoven," he said. EW Editors' note: Drs. Hersh and Price have no financial interests related to their comments. Contact information Hersh: phersh@vision-institute.com Price: fprice@pricevisiongroup.net Endothelial Glide This unique instrument is used to atraumatically insert endothelial tissue. Its open design features a platform for tissue placement (endothelial side facing up) and a funnel-shape tapered tip which allows the surgeon to gently slide the tissue into position for the "pull-through" technique. Once the tissue is correctly seated, the instrument is inverted (endothelial side facing down) and the tip is placed at the edge of the primary incision. A special forceps is inserted through an opposing paracentesis incision and is used to grasp and pull the tissue into the anterior chamber. This retinal-style forceps has been specifically designed for use with the Busin Glide during Endothelial Keratoplasty procedures. The slightly curved 23-gauge shaft allows the instrument to be used through a paracentesis incision while its delicate end gripping platforms gently grasp the edge of the endothelial tissue to facilitate the "pull-through" technique. Endothelial Grasping Forceps K5-7550 K3-4270 Tissue on platform (endothelial side up) Gentle positioning toward tip Forceps grasps edge of tissue Tissue is "pulled through" into A/C Tissue in place (endothelial side down) Pull Through Technique ™ Endothelial Endothelial Inser tion Instruments 973-989-1600•800-225-1195•www.katena.com Shifting preferences continued from page 28

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