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Peripheral optimized CXL and high power . Theo Seiler. I nstitut für R efraktive und O phthalmo- C hirurgie (IROC ) and University of Zürich. PMD . thinnest point. steepest point. PMD vs KC . PMD. thinnest pachymetry / μ m. KC. 700. 500. 300. 0.5. 1.5. 0. 1. 2.
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Peripheraloptimized CXL and high power Theo Seiler Institut für Refraktive und Ophthalmo-Chirurgie (IROC ) and University of Zürich
PMD thinnest point steepest point
PMD vs KC PMD thinnest pachymetry / μm KC 700 500 300 0.5 1.5 0 1 2 radial distance to apex / mm
CXL In themajorityofthekeratectasiacases theweakestpointofthecornea thatneeds CXL most is1 to 3 mm awayfromthecenter
study OCT 1 monthpost CXL, 10 eyes, inhomogeneityofthe beam in curve th1 100 th 90 th1 80 relative depth in % 70 mav 60 50 0 0 1 2 3 radial distance / mm
proposal In ordertocreate a homogeneous CXL-effect also in theperipheryofthecornea irradiationwith a top hat-profile is not goodenough. 3 mm awayfromthecenterthe light intensityneeds tobeincreasedbyat least 25%
profile UV-X2000 Avedro I0 UV-X1000 8mm 4mm 4mm 8mm 0
profile Crosslinkingprofileofthe UV-X2000
CXL-types 30 min 3.00 mW/cm² 9min 10.00 mW/cm² volume-type surface-type 0μm 100μm 200μm 300μm 400μm 500μm 600μm 0.1% 30 min 0.5% 2 min
CXL-types Pseudo-Bowmans
CXL-types volume-type CXL-depth 250 to 330 μm
CXL-types • Applicationsvolume-type (homogeneousriboflavin, low power) • infectiouskeratitis • meltingdiseases • keratoconus ? • Applicationssurface-type (high riboflavingradient, high power) • refractivelasersurgery • customizedCXL
conclusion • In themajorityofthecases a peripheral CXL ismandatory • Second generation CXL lightsourcesneed an optimized beam profile • The surface-type CXL worksonlyifthecentralirradianceguarantees an illumination time of 10 min andless