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Light adjustable lens shows promise for improved vision for cataract patients |
| Theallineed/NC&T/UCSF |
Based on technology developed by researchers at the University of California, San Francisco and California Institute of Technology, the lens is made of photosensitive silicone that can be precisely and non-invasively adjusted after cataract surgery, reducing the refractive errors that are common after the surgical procedure.
"The technology allows us to make adjustments after the lens is in place and healing has occurred," said Daniel Schwartz, MD, associate professor of ophthalmology and director of the retinal service at UCSF. "This allows us to achieve optimal distance vision after surgery without the need for eye glasses."
Schwartz, who is co-inventor of the lens, presented the clinical findings on Sunday, March 19, in San Francisco at the meeting of the American Society of Cataract and Refractive Surgery.
During conventional cataract surgery, the cataract is removed and replaced with an intraocular lens (IOL) designed to focus images on the retina and provide clear post-operative vision. While the IOL improves vision, a majority of patients experience residual refractive errors due to unpredictable wound healing, inaccuracies in pre-operative measurements, or preexisting corneal astigmatism, according to Schwartz.
More than three million cataract surgeries are performed each year throughout the United States, and a majority of these patients require prescription glasses following surgery to have 20/20 vision, he said.
The lens developed by the UCSF-Cal Tech team is named the light adjustable lens, or LAL, and is implanted using the same standard surgical techniques used in conventional cataract surgery. After the eye has healed, the surgeon adjusts the lens power to the patient's specific visual needs by directing a low intensity beam of light onto the lens from outside the eye.
 | | Daniel Schwartz, MD. (Photo: UCSF) |
"The lens material is photosensitive and designed to respond in a predictable manner according to the duration and intensity of light delivered, and by customizing LAL power, patients can achieve optimal vision," Schwartz said.
Initial results from a clinical trial of LAL conducted in Europe are promising. Following light adjustment, 87 percent of patients (21 out of 24) were within 0.25 diopters (the measurement of the power of a lens) of the intended refractive result. After two years, no patients have lost any visual acuity. For the study, lenses were adjusted over a range of -1.75 to +2.25 diopters of the intended refractive result.
"This clinical experience with the LAL is very encouraging," he added. "The refractive corrections are precise and have been stable for more than two years following implantation. Clinical trials are ongoing and commercialization of the LAL is anticipated in Europe this year."
In the United States, it is hoped that clinical trials will begin by the end of the year.
Schwartz said he thinks LAL has potential beyond cataract surgery, including use as an alternative to LASIK surgery for severe myopia (nearsightedness) and for the loss of reading vision that occurs with aging (presbyopia).
The LAL is produced by Calhoun Vision, Inc., of Pasadena, Calif. Schwartz is founder and chairman of Calhoun and has a proprietary interest in the company. He joined with Robert Grubbs, who was recently awarded the Nobel Prize in Chemistry, and Julia Kornfield of Cal Tech and Calhoun scientists in 2000 to create the lens and the laser equipment necessary to adjust it. Funding for the initial research was provided by That Man May See, Inc.
UCSF is a leading university that consistently defines health care worldwide by conducting advanced biomedical research, educating graduate students in the life sciences and providing complex patient care.
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