Embed Size (px)
Citation preview
MOHAMMAD GHOREISHI, MDISFAHAN UNIVERSITY OF MEDICAL SCIENCES
ISFAHAN, [email protected]
Pentacam Topography
Placido disc (reflection) based Elevation based
PAR Corneal Topography System (PAR CTS) Slit scanning (Orbscan) Scheimpflug imaging (Pentacam, Galilei ,..)
Topography systems
Problems with placido systems
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 distortedCurvature is reference basedElevations (shape) may not always be accurate
Elevation DataElevation represents true shape of the cornea It is independent of axis, orientation or
positioning.All subsequent maps (curvature …) can be
derived from accurate elevation dataThere 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
Elevation Based SystemsB & L OrbScan
Scanning Slit Accuracy? Relies on Placid augmentation
PAR CTS Rasterphotogrammetry Accurate but not commercially
available
Oculus Pentacam Rotating Scheimpflug images
پوزش عرض ضمنباالی حجم بدلیل
LECTUER ادامهپذیر امکان اسالیدها
نیاز صورت در نمیباشدواحد به لطفا ادامه بهمرکز بصری و سمعیفیض درمانی آموزشیشماره با یا و مراجعه
تلفن 03114476010
تماس 392داخلی نمائید حاصل
تشکر با
