1. Effect of CXL on FS laser Channel Creation for ICR in KC Tamer M. El-Raggal, MD, PhD, FRCSEd Associate Professor of Ophthalmology Ain Shams University, Cairo - Egypt No Financial Interest

2. 1.Studies demonstrated efficacy of ICRS → improvement of KC. 2.CXL ↑ mechanical stiffness → stabilization of KC 3.FS laser photodisruption → separate tissue at molecular level without impact on surrounding tissue. Combination of 3 modalities provide better results as they complement each other. Introduction El-Raggal, T

3. Aim of the Study To evaluate efficacy of FS laser for channel creation after CXL in KC eyes. Inclusion criteria CL intolerance. Clear cornea. Maximum K < 60 D. Minimum thickness > 450 µm. CXL done 6 m before. El-Raggal, T

4. Patients & Methods (Amsler- Krumeich)A prospective non-randomized study included 15 eyes of 11 patients with II-III KC (Amsler- Krumeich) treated by CXL → 6 m later channel creation using Intralase FS 60. Group 1 5 eyes → 1.50 mJGroup 1 5 eyes → 1.50 mJ Group 2 5 eyes → 1.60 mJGroup 2 5 eyes → 1.60 mJ Group 3 5 eyes → 1.70 mJGroup 3 5 eyes → 1.70 mJ Control 5 virgin KC eyes → 1.50 mJControl 5 virgin KC eyes → 1.50 mJ El-Raggal, T

5. →Axis → steep topography. 80% depth. Inner diameter 5.0 & outer 5.8 mm. Entry cut thickness 1 µm. Incision length 1.40 mm. Ring energy 1.50 – 1.70 mJ. Spot separation Default. Implantation immediately before bubbles disappear using forceps. Corneal Channels Creation El-Raggal, T

6. Keraring Insertion ICR insertion graded subjectively 0 = Easy, no resistance 1+ = Slight resistance 2+ = Moderate resistance, some manual separation 3+ = Difficult, severe resistance, all manual dissection Corneal haze quantified subjectively on slit lampCorneal haze quantified subjectively on slit lamp 0 = No haze, totally transparent 1+ = Slight corneal haze, slight loss of transparency 2+ = Moderate haze. iris details seen 3+ = Exaggerated haze, iris details hardly seen El-Raggal, T

7. Results Difficulty El-Raggal, T

8. Results Haze El-Raggal, T

9. Incomplete tunnel creation is most common difficulty of FS laser Tissue bridges in tunnel may resist ICRS implantation. Although channel creation & segment implantation can be done without changing FS parameters, it is better to ↑ energy. Resultant ↑ corneal reaction postoperatively. El-Raggal, T

10. CXL causes compactness of stromal lamellae in superficial 300 µm but deeper stroma also affected to some extent Also CXL cornea less clear than normal → FS laser penetration less effective. Conclusion El-Raggal, T

11. Conclusion FS channel creation can be performed safely after CXL. Better to perform channel dissection before or concurrent to CXL → More improvement in corneal shape by ICR. Limitations: Non-randomized, small sample, subjective grading of difficulty & haze. Further studies with larger samples & studying effect of spot separation recommended. El-Raggal, T