2024-03-29T06:42:31Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/85612018-09-25T14:49:21Zcom_10261_93com_10261_4col_10261_346
Pentacam Scheimpflug Quantative Imaging of the crystalline lens and intraocular lens
Rosales, Patricia
Marcos, Susana
Scheimpflug
Crystalline lens
Intraocular lens (IOL)
Radii of curvature
8 pages, 5 figures.-- Article in press.
[Purpose] To implement geometrical and optical distortion correction methods for anterior segment Scheimpflug images obtained with a commercially available system (Pentacam, OCULUS Optikgeräte GmbH).
[Methods] Ray tracing algorithms were implemented to obtain corrected ocular surface geometry from the original
images captured by the Pentacam’s CCD camera. As details of the optical layout were not fully provided by the manufacturer, an iterative procedure (based on imaging of calibrated spheres) was developed to estimate the camera lens specifications. The correction procedure was tested on Scheimpflug images of a physical water cell model eye (with polymethylmethacrylate cornea and a commercial IOL of known dimensions) and of a normal human eye previously measured with
a corrected optical and geometrical distortion Scheimpflug camera (Topcon SL-45 [Topcon Medical Systems Inc] from the Vrije University, Amsterdam, Holland).
[Results] Uncorrected Scheimpflug images show flatter surfaces and thinner lenses than in reality. The application of geometrical and optical distortion correction algorithms improves the accuracy of the estimated anterior lens radii of curvature by 30% to 40% and of the
estimated posterior lens by 50% to 100%. The average error in the retrieved radii was 0.37 and 0.46 mm for the anterior and posterior lens radii of curvature, respectively, and 0.048 mm for lens thickness.
[Conclusions] The Pentacam Scheimpflug system can be used to obtain quantitative information on the geometry of the crystalline lens, provided that geometrical
and optical distortion correction algorithms are applied, within the accuracy of state-of-the art phakometry and biometry. The techniques could improve with exact knowledge of the technical specifications of the instrument, improved edge detection algorithms, consideration
of aspheric and non-rotationally symmetrical surfaces, and introduction of a crystalline gradient index.
2008-11-14T10:11:39Z
2008-11-14T10:11:39Z
2008-10-15
artículo
Journal of Refractive Surgery 2008 (in press)
1081-597X
http://hdl.handle.net/10261/8561
eng
http://www.journalofrefractivesurgery.com/showAbst.asp?thing=58
openAccess
International Society of Refractive Surgery