OPTICAL Software Visualization Suite

The applications in our visualization suite are:

 * Videokeratograph Simulator
 * Optical Power Visualization
 * Fluorescein Simulator
 * Sphere/Cylinder Visualization
 * Computer Aided Contact Lens Design

Videokeratograph Simulator

This application allows us to simulate a videokeratograph, which is a device used to extract shape information from a patient's cornea. With this device, light rays (cyan lines in the image below) emanate from the rings of light (white mesh), bounce off the front of the cornea (here simulated by an ellipsoid on the right), pass through the lens, and fall on the image plane of the video camera on the far left. We simulate this process using a technique called backward ray-tracing, in which the rays of light start at the image, pass through the lens, and bounce off the cornea. This technique checks if the rays hit the rings of light. If they don't, this method adjusts the starting position of the rays and continues until all rays have hit the rings of light. The system has the capability to save this information into a file with exactly the same format as that created by the real videokeratograph.

Optical Power Visualization (in Diopters)

This is the flagship application in our visualization software suite. It reads in the files generated from a videokeratograph (or from our videokeratograph simulator) and then displays them using various techniques. It can display the optic power (measured in diopters) on a 2-D image (upper-left) or as a color-coding on top of the actual 3-D data (upper- and lower-right). It can shade the 3-D data using traditional computer graphics lighting methods, and has the ability to take a cross-section of the data (lower-left). It also has multiple-file capabilities, allowing many datasets to be viewed simultaneously, as well as extensive colormap editing features.

Fluorescein Simulator

This simulates the results of a traditional technique in which clinicians place a contact lens of known dimensions in the patient's eye, apply fluorescein dye and shine a light on the lens. The fluorescein forms a pattern in which brightness is related to the distance of the lens from the cornea. Our application allows a user to interactively choose parameters describing the simulated contact lens, and then it shades the dataset. The image below displays sclera of the eye (white surface), cornea (white mesh), and contact lens fluorescein pattern (green). The smaller sub-windows show a top-level view of the pattern, a 3-D mesh of the contact lens shape, and the specific contact lens parameters. Here is an image of a simulated fluorescein pattern with a more accurate colormap:

(small photo of fluorescein)
Simulated fluorescein pattern using a mathematical surface representation of a patient's cornea with a spherical contact lens, displayed with a photorealistic colormap

Sphere/Cylinder Visualization

This application is used to illustrate a new technique for visualizing shape information. One of the shortcomings of displaying corneal power is that there is an inherent singularity in the center of the data since the curvature is calculated radially. This application solves that problem by color-coding the data based on Sphere (the average of the maximum and minimum curvature, on the left) and Cylinder (the difference of the maximum and minimum curvatures, the image on the right). The advantage of this technique is that these quantities are continuous in the center and do not depend on an arbitrarily-chosen 'center' of the data about which to calculate curvature.

Computer Aided Contact Lens Design

This application allows the specification of various parameters for contact lenses and the interactive visualization of the results. This is a very useful tool for teaching student clinicians how the different parameters affect shape information as well as for specifying the shape of the lens to be simulated in the Fluorescein simulator.

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