ROTATING SCHEIMPFLUG TOPOGRAPHIC PARAMETERS IMPORTANT IN DISTINGUISHING NORMAL FROM KERATOCONIC CORNEAL MORPHOLOGICAL FEATURES Clayton Falknor, MD, Orkun Muftuoglu, MD, Steven Verity, MD, James P. McCulley, MD Some of the authors have received consultant reimbursement from Alcon Labs, Inc. None of the authors have financial interest in the subject matter of this poster.
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ROTATING SCHEIMPFLUG TOPOGRAPHIC PARAMETERS IMPORTANT IN DISTINGUISHING NORMAL FROM KERATOCONIC CORNEAL MORPHOLOGICAL FEATURES Clayton Falknor, MD, Orkun.
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ROTATING SCHEIMPFLUG TOPOGRAPHIC PARAMETERS IMPORTANT IN DISTINGUISHING NORMAL FROM KERATOCONIC CORNEAL MORPHOLOGICAL FEATURES
Clayton Falknor, MD, Orkun Muftuoglu, MD, Steven Verity, MD, James P. McCulley, MD
Some of the authors have received consultant reimbursement from Alcon Labs, Inc.
None of the authors have financial interest in the subject matter of this poster.
Keratoconus
Essential to identify keratoconus prior to keratorefractive surgery
Keratoconus is characterized by: Non-inflammatory, progressive corneal disease Stromal thinning and anterior bulging of cornea Irregular astigmatism and myopia Potentially severe corneal scarring
Keratoconus is identified by: Fleisher ring (corneal iron line at base of cone) Vogt striae (stromal stress lines within cone) Scissoring of retinoscopic reflex Apical scarring and/or subepithelial fibrosis Central or paracentral steepening on topography
Subclinical (forme fruste) keratoconus is difficult to identify
Identification of keratoconus Traditional method to identify subclinical
keratoconus is corneal topography Placido disk-based Measures slopes of anterior corneal surface only Axial curvature method subject to misalignment of
corneal apex and corneal sighting point May lead to misleading maps, eg normal eyes may show
asymmetric bow-tie or inferior steepening Contribution of posterior corneal surface important
Orbscan (Bausch and Lomb, Salt Lake City, Utah, USA) Slit-scanning beam combined with Placido ring technology Posterior surface recreated with triangulation algorithms Not all images include central cornea
Pentacam (Oculus Optikgeraete GmbH, Germany)
Pentacam Comprehensive Eye Scanner Rotating Scheimpflug camera Monochromatic slit light source rotates with
camera 25-50 slit images per acquisition Eye movement monitoring by 2nd camera
Less than 0.6mm decentration Rotates 180º in 2 seconds All images include central cornea Corneal elevation data independent of visual axis
and corneal apexhttp://www.oculus.de/chi/downloads/dyn/sonstige/sonstige/pentacam_aao_2006.pdf
Purpose
Evaluate parameters obtained by Pentacam important in distinguishing keratoconus from normal