Femtosecond Laser Assisted Deep Anterior Lamellar Keratoplasty (FS-DALK) Farid Karimian M.D. Department of Ophthalmology Labbafinejad Medical Center October 2012 www.iranophthalex.com

Overview Rational for DALK: DALK replaces anterior Corneal stromal Lamella Directly placed same thickness donor over Pre-Descemet and Endothelium Rational for DALK: Reduced risk of intraoperative complications Preserving recipient (Host) endothelium Transplantation of Epithelium and Stroma (only) Potentially clear interface with reducing Haze Reducing risk of immunologic Rejection Limitations of “Anwar Big-Bubble” Technique: Steep learning Curve Prolonged operation time ( in the beginning ) Risk of intraoperative corneal perforation

Indications FS-DALK indications similar to Manual DALK Optical and Tectonic indications: Pathologies involving anterior and deep corneal stroma in presence of Healthy Endothelium Reis-Buckler of Bowman’s layer Stromal dystrophies not-involving Endothelium Ectatic corneal disorders and Keratoconus Post-Refractive Surgery Keratectasia

Femtosecond Laser FS-Laser Abilities; Performs precise, pre-programmed Corneal incision Accurate “shape” and “Depth” Customized graft edges and lamella Stepped incisions increase surface area: improve apposition and alignment leading to faster wound healing Overall it is a “Laser knife”

Surgical Technique Anesthesia: Donor Cornea Preparation: Anterior LK: Topical DALK: General or Local FS-Laser Type: All types of New Generation machines Same laser parameters for both Donor and Recipient Donor Cornea Preparation: Preserved Corneoscleral donor over Artificial chamber Well pressurized whole globe

Different Side-Cuts and Configurations Zigzag shape Mushroom shape: Larger outer diameter Lower astigmatism Top-hat: Best wound stability Christmas tree shape Traditional Decagonal : More precise depth, No torque rotation Better suture placement

Recipient Preparation- Step 1 Recipient is prepared first Central cornea marking Side cut formation: Zigzag configuration 3 consecutive steps: Step 1: Anterior side cut: 30 deg. Angled, 25 deg. Arc length and 6.0 mm diameter Depth: 50 µ above thinnest point Pachymetry (According to Scheimpflug imaging) Energy: Maximum of energy minus 0.2 µJ Side-cut spot separation: 3 µm Side-cut layer separation: 3µm Depth in contact Glass: -200µm

Step 2 Recipient lamellar cut Diameter: 9.5 mm Depth in Cornea: 100µm above the thinnest corneal pachy point Lamellar cut intersects with (previous) channel created Diameter : anterior< posterior zigzag lamella 100µm

Step 3 Side-cut Zigzag lamella: Diameters: anterior: 8.1mm, Posterior: 9.0mm Target thickness: 100µm above thinnest corneal pachy Two constant values: 80µ ( stromal Thickness over DM ) + 20µ ( DM and Endothelium complex ) = 100µ( total stromal endothelial bed )

Donor Disc Preparation Postoperative increase of 120 µ is routinely planned T-factor = 20µ ( DM and Endothelial thickness complex)+ intended increase calculated to achieve an appropriate postop pachymetry ~ 140µ Donor Depth: Recipient lamellar cut depth + T-factor Laser Energy: 1.8 µJ Tangential spot separation: 5µm Radial spot separation: 5µm Again Zigzag lamella is prepared in Donor cornea

Air Bubble formation Air injection: Recipient Lamella removal Air injection cannula Fogla cannula ( B&L ) is flat needle with hole facing down at tip site Route of injection: previous created channel Channel may need dissection in thin keratoconic cornea Air injection: forceful to achieve big bubble over DM Procedure continues as Classic Big bubble technique

Advantages of FS-DALK Precision of Depth Configuration and customization of side-cuts Stronger wound strength and more stable Higher success for bubble formation ( 85% vs 65% ) Earlier wound stabilization: Earlier suture removal Reduction of surgeon learning curve

Advantages of FS-DALK 7- Easier air injection in deep stroma ( 50 µ over DM ): more smooth injection 8 - Faster visual recovery and less induced astigmatism

Disadvantages of FS-DALK High Expenses and instrument costs Space and facilities: needs 2 suite FS-Machine dependent Higher quality of Donor Donor lamella preparation: More Difficult More dependent on precise Pachymetry

Complications of FS-DALK Incomplete Lamellar Preparation: Donor Lamella: Corneal edema, haziness, Corneal arcus Recipient Lamella: Scar, opacities/ improper laser setting for deep cornea Inadvertent AC Penetration: Errors in Pachymetry Conversion to PKP: Due to DM rupture Other complications similar to Manual DALK

THANK YOU FOR YOUR KIND ATTENTION Summary FS-DALK is a new technique of Keratoplasty which applies the Precision and advantages of Femtosecond Laser to achieve higher success and better results with lower risks in performing DALK At present time high expenses and lower accessibility of Femtosecond machine limits its widespread application THANK YOU FOR YOUR KIND ATTENTION