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

2. 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

3. 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

4. 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”

5. 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

6. 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

7. 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

8. 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

9. 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 )

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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