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Science and Technology
Scientists Model Defective Corneas
Professor’s Own Condition Is Inspiration for ‘Eye-Opening’ Vision Research

Contributing Writer
Wednesday, October 23, 2002

Brian Barsky is not like most people who suffer from vision problems—stuck living with what their doctor prescribes or picking from a narrow set of options.

As a professor of computer science, optometry and vision science at UC Berkeley, he has taken matters into his own hands when it comes to treating an eye disorder from which he suffers.

Called keratoconus, the condition is characterized by bulges in the eye that occur where the cornea is too thin.

To illustrate how a thin area causes a bulge rather than a dent, Barsky used the analogy of a balloon bulging out from pressure in an area where its skin is thinner.

The effects of keratoconus are somewhat like those of nearsightedness, but with a faint double image.

"One of the problems I've observed is that if I look at the edge of an object, I might see two edges," Barsky said.

Glasses and standard contact lenses, which rely on a spherical eye surface, do not deal well with keratoconus, and it is often difficult and time consuming for doctors to find lenses for a patient with the condition.

To alleviate these problems, Barsky created computer simulations of vision, both with normal and defective eyes, using measurements from real patients.

"We're successful the vast majority of the time, but when someone's keratoconus becomes more advanced, it becomes more difficult to find a contact lens that fits them," said clinical optometry professor Michael Harris. "Barsky's custom lenses help solve that problem."

These artificial images Barsky has created can help doctors see what their patients see, and better treat them.

They can also be used to visualize the results of a successful surgical operation ahead of time.

Barsky applied his background in computer science to the design of contact lenses to help his own keratoconus.

By using a type of mathematical curve called a spline, he distilled the irregularity in a karatoconus-afflicted eyes down to a few equations.

"The salient feature of splines is that, rather than trying to find a single equation to describe the entire curve or surface, they break it into smaller pieces and define an equation to describe each of the pieces," Barsky said.

In order to measure the cornea so that he could fit contacts to it though, the measurement tools needed to be refined.

Physicians typically use a machine called a corneal topography device to measure the cornea and determine its shape.

Unsatisfied with the inadequacies of existing devices, Barsky and his collaborators took the raw data from the device, before it had done its own calculations, and manipulated the data themselves, so the direction in which the eye was looking would not matter.

With this precise data, doctors can create contact lenses custom-fit to a patient's eyes.

Since keratoconus involves a thinning of the cornea, procedures like Lasik surgery, which correct vision by carving away pieces of the cornea with a laser, may be inadvisable.

"One of the applications of the measurement is to detect if a person has keratoconus, to suggest that they should not get Lasik surgery," Barsky said.

These techniques may also show up in Holllywood—they could be used for making computer-generated scenes closer to those captured by real cameras and eyes, Barsky said.

"I think it's a very interesting and innovative approach to solving a problem that affect the vision of a significant number of people," Harris said.

(c) 2002
Berkeley, California