1. ADVANCED SURFACE ABLATIONS Postoperative pain Late visual recovery Risk of Haze Risk of corneal ectasia Unpredictable flap induced aberrations Epithelial injury Intrastromal incision In a deep plane in the stroma PRK FDA approval:1995 LASIK FDA approval:1999 Evolution of surface treatments for the correction of ametropias

2. Advanced Surface Ablations The term “advanced surface ablations”:  was coined as a way to explain the evolution in surface ablation techniques from the earlier PRK days  covers several techniques such as:  PRK with the intraoperative use of mitomycin-C (MMC) (PRK-MMC)  epipolis LASIK (Epi-LASIK)  laser epithelial keratomileusis (LASEK)

3. Advanced Surface Ablations Advanced surface ablation techniques offer several advantages over conventional PRK such as:  increased quality of vision  reduced postoperative pain  minimized corneal haze

4. Advanced Surface Ablations Reasons for selecting a surface treatment:  Thin corneas for attempted correction (residual bed thickness < 300μm)  Preoperative Dry Eye  Epithelial basement membrane dystrophies  Flat or steep corneas  No risk of flap-related complications  No risk of flap-induced aberrations

5. Epithelial Removal The epithelium can be removed with several ways:  Mechanical removal of the epithelium with a blade or newly a rotating brush  Epithelial removal with the use of alcohol (LASEK)  Epi-LASIK  Epithelial removal with the laser (transepithelial)

6. Evolution of Advanced Surface Ablations (I)  Introduction of MMC for the control of corneal haze:  Therapeutic use globally accepted (selected complicated cases)  Intraoperative prophylactic use after PRK (PRK-MMC)

7. Evolution of Advanced Surface Ablations (II)  Introduction to the retained epithelial flaps (LASEK, Epi-LASIK):  Allow for decreased incidence of haze  Offer with better tolerance of patients  Mechanical epithelial separation provides with the benefit of avoiding alcohol toxicity

8. PRK-MMC  0.02% for up to 1.5 min depending on the attempted correction (delay in epithelial healing at 2 min)  Reduction of myofibroblast activity / haze (compared to corticosteroids)  Faster visual recovery and confocal microscopic normalization  Safety up to about 10 yrs max experience

9. LASEK  A dilute solution (20%) is used on the eye in a holding cup (8.5mm diameter) for approximately 30 seconds in order to loosen the epithelium and creates a complete epithelial flap  After the loosened epithelium is slid to the side and the stromal surface is treated with the laser  The epithelium is replaced or can be directly removed

10. Epi-LASIK  Surface ablation (epi-polis  superficial)  Epithelium is separated as a sheet and replaced on the ablated stroma  Special device (Epikeratome) - automated procedure  No use of alcohol  Dealing with drawbacks of PRK (postoperative pain/ discomfort, late visual recovery, haze) and avoiding risks of LASIK  Suitable for thin corneas