Computer Aided Cornea Modeling, Reconstruction, and Visualization

Brian A. Barsky

Distinguished Visitor at the School of Computing, NUS

Professor of Computer Science and Affiliate Professor of Optometry and Vision Science

University of California, Berkeley, California 94720-1776

Organized by

Time: 6-7pm, January 4, 2000

Venue: LT34, Level 3, S17, School of Computing, Lower Kent Ridge Road, NUS

Chair: Associate Professor Loe Kia Fock

E-mail address:

Personal home page:

OPTICAL home page:

Seminar of School of Computing:



The cornea is the clear fibrous tissue forming the front surface of the eye. It performs 3/4 of the refraction, or bending, of light in the eye and thus its shape is critical in determining visual acuity. Recently, there has been tremendous interest in refractive surgeries (such as PRK and LASIK) for reshaping the cornea to eliminate the need for spectacles and contact lenses; this has provided an impetus for the accurate measurement of the shape of patient's corneas, called corneal topography. This talk will discuss three aspects of our research: computer-aided modeling, reconstruction, and visualization of the shape of the human cornea.

First, we have developed several surface models for the cornea, by defining surfaces derived from semi-regular tensor product B-spline surfaces over a polar coordinate domain. The representations are fit to sampled data from a range of shapes and compared in terms of overall fit and fidelity at the origin.

Second, we have assimilated ideas from a variety of fields, including ray-tracing (computer graphics and optics), smooth B-spline surfaces (computer modeling) and simulation, to develop a new reconstruction algorithm. It has several advantages compared to current approaches: it is more accurate, it directly recovers position of the cornea, and it produces a continuous map over the entire surface.

Third, our new visualization methods enable the prediction of a patient's visual acuity using several techniques based on fundamentals of geometric optics and wave optics. These displays are intended to reveal how well the cornea focuses parallel light onto the fovea of the eye by pseudo-coloring the cornea with various error metrics. Several error metrics will be illustrated using both real and simulated data.


Brian A. Barsky is Professor of Computer Science and Affiliate Professor of Optometry and Vision Science at the University of California at Berkeley. He is a member of the Bioengineering Graduate Group, an interdisciplinary and inter-campus program, between UC Berkeley and UC San Francisco.

He has been a Distinguished Visitor at the School of Computing at the National University of Singapore in Singapore, and a Visiting Professor of Computer Science at The Hong Kong University of Science and Technology in Hong Kong, at the University of Otago in Dunedin, New Zealand, in the Modélisation Géométrique et Infographie Interactive group at l'Institut de Recherche en Informatique de Nantes and l'Ecole Centrale de Nantes, at the University of Toronto, an Attaché de Recherche Invité at the Laboratoire Image of l'Ecole Nationale Supérieure des Télécommunications in Paris, and a visiting researcher with the Computer Aided Design and Manufacturing Group at the Sentralinsitutt for Industriell Forskning (Central Institute for Industrial Research) in Oslo.

He attended McGill University where he received a D.C.S. in engineeringand a B.Sc. in mathematics and computer science. He studied computer graphics and computer science at Cornell University where he earned an M.S. degree. His Ph.D. degree is in computer science from the University of Utah. He is a Fellow of the American Academy of Optometry.

He is a co-author of the book An Introduction to Splines for Use in Computer Graphics and Geometric Modeling, co-editor of Making Them Move: Mechanics, Control, and Animation of Articulated Figures, and author of the book Computer Graphics and Geometric Modeling Using Beta-splines. He has published 100 technical articles in this field and has been a speaker at many international meetings.

Dr. Barsky was a recipient of an IBM Faculty Development Award and a National Science Foundation Presidential Young Investigator Award. He is an area editor for the journal CVGIP: Graphical Models and Image Processing and the editor of the Computer Graphics and Geometric Modeling series of Morgan Kaufmann Publishers, Inc. He was the Technical Program Committee Chair for the Association for Computing Machinery / SIGGRAPH '85 conference.

His research interests include computer aided geometric design and modeling, interactive three-dimensional computer graphics, visualization in scientific computing, computer aided cornea modeling and visualization, medical imaging, and virtual environments for surgical simulation.

He has been working in spline curve/surface representation and their applications in computer graphics and geometric modeling for many years. He is applying his knowledge of curve/surface representations as well as his computer graphics experience to improving videokeratography and corneal topographic mapping, forming a mathematical model of the cornea, providing computer visualization of patients' corneas to clinicians, and developing new techniques for contact lens design and fabrication. This research forms the OPTICAL (OPtics and Topography Involving Cornea and Lens) project.