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Mohammad Ghoreishi , MD Isfahan University of Medical sciences Isfahan, Irann

Pentacam Topography. Mohammad Ghoreishi , MD Isfahan University of Medical sciences Isfahan, Irann info@persianeyeclinic.com. Topography systems. Placido disc (reflection) based Elevation based PAR Corneal Topography System (PAR CTS) Slit scanning (Orbscan)

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Mohammad Ghoreishi , MD Isfahan University of Medical sciences Isfahan, Irann

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  1. Pentacam Topography Mohammad Ghoreishi, MD Isfahan University of Medical sciences Isfahan, Irann info@persianeyeclinic.com

  2. Topography systems • Placido disc (reflection) based • Elevation based • PAR Corneal Topography System (PAR CTS) • Slit scanning (Orbscan) • Scheimpflug imaging (Pentacam, Galilei ,..)

  3. Problems with placidosystems • Assuming sphero-cylindrical optics on a smoothly reflective convex surface that falls within certain pre-determined parameters • Can not read if the cornea is badly distorted • Curvature is reference based • Elevations (shape) may not always be accurate

  4. Elevation Data • Elevation represents true shape of the cornea • It is independent of axis, orientation or positioning. • All subsequent maps (curvature …) can be derived from accurate elevation data • There is no reason for an elevation based topography system to incorporate Placido derived data unless their elevation data is unreliable Michael W. Belin, M.D., AAO Annual Meeting 2003, Anaheim, CA

  5. Elevation Based Systems • B & L OrbScan • Scanning Slit • Accuracy? • Relies on Placid augmentation • PAR CTS • Rasterphotogrammetry • Accurate but not commercially available • Oculus Pentacam • Rotating Scheimpflug images

  6. ضمن عرض پوزش بدلیل حجم بالای LECTUERادامه اسلایدها امکان پذیر نمیباشد در صورت نیاز به ادامه لطفا به واحد سمعی و بصری مرکز آموزشی درمانی فیض مراجعه و یا با شماره تلفن 03114476010 داخلی 392تماس حاصل نمائید با تشکر

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