The following article was just published in the June 2006 issue of
Medical Laser Report

Laser-induced bubbles help 'fix' presbyopia

A tool developed at the University of Michigan (Ann Arbor) allows for a
potentially noninvasive, painless fix to presbyopia using tiny bubbles
that help ophthalmologists reshape the eye's lens and restore its
flexibility and focusing ability. Matthew O'Donnell, professor and
chair of the U-M Department of Biomedical Research, along with Kyle
Hollman, assistant research scientist and adjunct lecturer, and
graduate student Todd Erpelding, developed the method.

Presbyopia-the inability to focus on close objects resulting in
blurred vision-affects 100% of people by age 50. The predominant
belief is that fibers created in the intraocular lens accumulate and
stiffen, thus making the lens less flexible. Laser correction of the
intraocular lens for presbyopia has been proposed, but it is risky
because there is no way to monitor the procedure.

The U-M tool uses bubbles, ultrafast laser pulses, and ultrasound to
measure the thickness and rigidity of the lens during laser surgery,
thus guiding the surgeon as they reshape the lens. It's a new
application for microscale bubbles, which scientists have experimented
with for years in the areas of drug delivery, tumor destruction and
other medical applications. For the treatment of presbyopia, the U-M
team used ultrafast laser pulses to create tiny gas bubbles within the
intraocular lens. Before the bubbles diffuse, researchers hit them with
high frequency sound waves, which push the bubbles against neighboring
lens fibers.

"Part of the sound is reflected, and from the characteristic of the
reflection, you know where the bubble is," O'Donnell said. "It
uses exactly the same technology as ultrasound imaging." In this way,
researchers measure how far the bubbles have moved based on the force
applied, and thus measure the pliability of the lens. "The bubbles
show you where the laser should cut," O'Donnell said. "If it's
still too hard, you cut some more. If it's soft enough, you stop."

Recently the process was tested successfully in pig eyes. The future
plan is to automate the procedure to quickly cover the entire lens with
bubbles, he said. The team, which will begin clinical testing this
year, is talking with several companies about commercial opportunities.