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Published byMelody Whiteman Modified over 9 years ago
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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
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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)
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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
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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
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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)
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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)
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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
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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
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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
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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
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