Benefits and barriers of accommodating intraocular lenses :

Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. Assuming no refractive error, presbyopes have clear vision of distant objects; they require reading glasses for viewing near objects. Area-divided bifocal lenses are one example of a treatment for this problem. However, the field of view is limited in such eyeglasses, requiring the user to gaze down to accomplish near-vision tasks and in some cases causing dizziness and discomfort. Here, we report on previously undescribed switchable, flat, liquid-crystal diffractive lenses that can adaptively change their focusing power. The operation of these spectacle lenses is based on electrical control of the refractive index of a 5-mum-thick layer of nematic liquid crystal using a circular array of photolithographically defined transparent electrodes. It operates with high transmission, low voltage ( 90%, small aberrations, and a power-failure-safe configuration. These results represent significant advance in state-of-the-art liquid-crystal diffractive lenses for vision care and other applications. They have the potential of revolutionizing the field of presbyopia correction when combined with automatic adjustable focusing power.

To evaluate the 12-month U.S. phase II clinical trial results of the Crystalens AT-45 (eyeonics, Inc.) intraocular lens (IOL) used to provide uncorrected distance, intermediate, and near visual acuities in patients having cataract extraction and to compare in a substudy the contrast sensitivity and near visual acuity in patients with the Crystalens AT-45 IOL and those receiving a standard IOL. Fourteen clinical sites throughout the U.S. for efficacy and 3 non-U.S. sites for safety and efficacy. Patients 50 years or older had small-incision cataract extraction with implantation of the Crystalens AT-45 IOL. Unilateral implantation was followed by fellow-eye implantation. Postoperatively, uncorrected distance, near, and intermediate visual acuities were determined. Near and intermediate visual acuities were tested through a distance correction to eliminate potential pseudoaccommodative effects of residual myopia and corneal cylinder. A substudy tested contrast sensitivity under mesopic conditions with and without glare, as well as visual acuity in a subset of Crystalens AT-45 patients and a control group receiving a standard IOL. A total of 263 patients participated in the U.S. clinical trial and had 1 year of follow-up. Near visual acuities through the distance correction of 20/40 (J3) or better, monocularly and bilaterally, respectively, were seen in 90.1% and 100%; intermediate near visual acuities were seen in 99.6% and 100%. More than half the bilaterally implanted Crystalens AT-45 patients achieved uncorrected near acuity of 20/25 (J1) or better through the distance correction, and 84% achieved 20/32 (J2) or better. In the substudy, monocular near vision through the distance correction of 20/25 (J1) or better was seen in 50.4% with the Crystalens AT-45 IOL and in 4.7% with the standard IOLs. Mesopic contrast sensitivity results with and without glare for the Crystalens AT-45 were similar to those with standard monofocal IOLs. Nearly all patients (74 patients; 97.3%) who bilaterally were within 0.50 diopter of plano postoperatively achieved 20/32 (J2) or better uncorrected near, intermediate, and distance visual acuities. The Crystalens AT-45 accommodating IOL provided good uncorrected near, intermediate, and distance vision in pseudophakic patients. Contrast sensitivity with the Crystalens AT-45 was not diminished relative to standard monofocal IOLs, and near and intermediate visual performance was significantly better than with standard IOLs.