Two lenses may be better than one. In a prospective trial of 30 eyes, a dual-accommodating IOL, with a high-diopter anterior optic and a minus-power posterior optic, provided good distance visual acuity, depth of focus, and a good safety profile.
Dr. Dick discussed 2-year data related to his experience of implanting 30 of the silicone lenses, which have a high-diopter anterior optic and a minus-power posterior optic, in a prospective trial of otherwise healthy eyes.
"Two lenses are better than one," he said. "The hypothesis is that the anterior lens is moving." He added that an important element in the trial has been preoperative counseling and biometrics, including lens thickness evaluation.
"We tried to measure lens movement, using [a partial coherence interferometer (AC-Master, Carl Zeiss Meditec)]," he said. "This device allows measurement of any changes of distances in the eye with micrometer precision. Using this device, we were not able to measure any movement because of too many lens optic spikes overlapping, so we were strongly dependent on subjective means to measure the potential accommodation postoperatively."
Patient assessments were very positive. "All of the patients were very satisfied with the lens, and in terms of functionality, it was quite satisfying," Dr. Dick said. "Also, reading speed was very sufficient."
In addition, he said no Nd:YAG capsulotomies have been required in any of the 30 eyes in which the dual accommodating lens has been implanted.
According to Dr. Dick, because of the relatively large size of the IOL, it requires a relatively large incision for implantation.
"My standard incision size for this IOL is about 3.5 mm," he said. "The thickness of the lens implant leads to an even distribution and extension of the capsular bag. The homogenous tension on the capsular bag along with the fluid channels might lead to an interaction of aqueous humor and epithelial cells. Interlenticular opacification did not develop in any case."
The lens has earned a CE Mark in Europe; it conforms to the legal requirements of the European Union directives, which Dr. Dick said will lead to trials at more centers in Europe and could pave the way for FDA trials in the United States.
"The dual-optic lens principle provides some type of depth of focus, but, honestly, I do not know the exact reason," he said. "It may be because of movement, or it may be an optical phenomenon of the lens, because of its four surfaces and different curvatures. Moreover, it may also provide some true accommodation.
"Whatever the case, this lens is easy to implant, it centers well, and [it] provides good distance visual acuity along with the depth of focus," Dr. Dick said (Figure 2). "Most importantly, it also offers good safety in terms of posterior capsular opacification development."