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Vision improves with light-adjustable IOLs by inducing spherical aberration postop
Study finds that most patients achieved spectacle independence when corrected binocularly.
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Near vision improved significantly in patients who were implanted bilaterally with a light-adjustable IOL during cataract surgery and then 2 weeks later were noninvasively treated with spatial irradiance light profiles to induce controlled amounts of negative spherical aberration.
“The main benefit of light-adjusted lenses (LALs) is that the refractive outcome can be fully optimized after surgery,” co-author Pablo Artal, PhD, professor, founder and director of the Laboratory of Optics at the University of Murcia in Spain, said. “This can be especially important in cases of moderate astigmatism and when power calculations may fail.”
For several years, Artal and colleagues have been involved in the optical development of LALs at the laboratory.
“The initial good refractive results and the potential of LALs to induce optical shapes beyond defocus and astigmatism encouraged us to attempt to improve near vision with controlled amounts of asphericity,” he said.
Study, procedure
All patients underwent standard phacoemulsification, during which time they were implanted with an LAL manufactured by Calhoun Vision. Two weeks after surgery, patients were fully tested, and their lenses were irradiated to correct for refractive errors in one eye, optimizing distance vision, and to induce controlled asphericity in the fellow eye.
“Because the surgeries were not performed at the same time, one eye was treated first and around 1 month later the fellow eye was done,” Artal told Ocular Surgery News. “Once the optical condition of each adjustable lens was attained, they were locked in with a special irradiation profile.”
The prospective study, which appeared in the American Journal of Ophthalmology, of 17 patients found that by inducing a controlled amount of asphericity in the LAL, binocular near (30 cm) and intermediate (60 cm) decimal visual acuity was on average 0.75 and 1.07, respectively. Binocular distance decimal visual acuity was 1.19. These results corresponded to the case of larger induction of spherical aberration in the range of –0.2 µm.
“Binocularly, most patients achieved excellent distance visual acuity and good intermediate or near vision, depending of the amount of induced asphericity,” Artal said. In most cases, patients became completely spectacle independent.
No surprises
None of the study results surprised Artal.
“We knew from previous studies that achieving a particular value of special aberration would produce these types of visual results,” he said. “These lenses allow nice, fully optical customization after surgery.”
Artal said that a critical issue with this type of technology, however, is the need to use accurate methods to measure both refraction and spherical aberration in the eye of the patient before the light treatment.
“If these data are not correct, the final visual outcomes will not be adequate,” he said.
Artal said that LALs provide an advantage when there is evidence that refractive surprises may occur, such as in post-LASIK cataract patients. In addition, aspheric treatment should be used with LALs “when patients demand good near vision,” he said.
Artal and colleagues are conducting a subsequent study, whereby patients with LALs are being treated in an even more personalized fashion by using an adaptive optics vision analyzer developed in the Laboratory of Optics and now being commercialized by Voptica.
“The combination of these two technologies — LALs and adaptive optics instruments — will ensure even better visual outcomes in cataract patients,” Artal said. “The combination of these new approaches would offer doctors and cataract patients a real option for customization for the first time.” – by Bob Kronemyer