THURSDAY, June 8 (HealthDay News) -- U.S. researchers say they've developed a noninvasive procedure that helps correct presbyopia -- blurred vision that occurs when focusing on close objects.

The procedure, which was successfully tested on lenses in pigs, involves using tiny bubbles to reshape and improve the flexibility of the eye's lens. This improves its ability to focus, particularly on near objects.

Right now, "there are no noninvasive or minimally invasive procedures for presbyopia," Matthew O'Donnell, professor and chairman of the University of Michigan Department of Biomedical Research, noted in a prepared statement. O'Donnell developed the procedure with Kyle Hollman, assistant research scientist and adjunct lecturer, and Todd Erpelding, a graduate student.

The procedure, a laser surgery, uses ultrasound and ultra-fast optics technology, in addition to the gas bubbles, to measure the lens. This tool allows the surgeon to safely reshape the lens by measuring its thickness and flexibility.

"The bubbles show you where the laser should cut," O'Donnell explained. "If it's still too hard, you cut some more. If it's soft enough, you stop."

The gas bubbles, infused with high-frequency sound waves, push against the fibers of the intraocular lens.

"Part of the sound is reflected, and from the characteristic of the reflection, you know where the bubble is," said O'Donnell. "It uses exactly the same technology as ultrasound imaging."

Presbyopia causes many people to need reading glasses, beginning as early as age 40. Around that age, fibers in the intraocular lens begin to stiffen, and the lens loses some flexibility. As the lens loses flexibility, the eye loses its ability to change its shape and focus on close objects.

More information

The Mayo Clinic has more information on presbyopia .

-- Diana Kohnle

SOURCES: University of Michigan, news release, May 23, 2006

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