San Francisco-In a study that quantified the anterior movement of an accommodative IOL (HumanOptics 1CU lens), the investigators reported an anterior shift of less than 0.5 D of accommodation, which was disappointing in that patients were not spectacle-independent, according to Eduardo Marques, MD, who spoke here at the American Society of Cataract and Refractive Surgery annual meeting.
The IOL evaluated in this study has four flexible haptics that allow, in theory, he explained, forward movement of the IOL in response to contraction of the ciliary body.
"This should provide some capacity of pseudophakic accommodation," said Dr. Marques, consultant at the Centro Oftalmológico de Lisboa, Lisbon, Portugal.
Anterior segment measured
"The Pentacam allows precise and reproducible measurements of several parameters in the anterior segment," Dr. Marques said. "We wanted to determine the distance between the corneal endothelium and the anterior surface of the IOL, the anterior chamber depth, before and after contraction of the ciliary muscle. We used pilocarpine to stimulate the ciliary muscle because it is thought to be the most powerful stimulus to achieve that end in the pseudophakic eye."
Six eyes of three patients were included in the study. All patients underwent phaco and had the HumanOptics 1CU accommodative IOL implanted. The mean patient age was 71 years, and the mean study follow-up was 3 years.
Dr. Marques demonstrated with a Scheimpflug photograph that in one patient before the instillation of pilocarpine the anterior chamber depth was slightly greater than 4.2 mm and after pilocarpine the distance was less than 4 mm.
In all patients in the study, the mean anterior chamber depth varied between 3,775 ± 159.4 μm before instillation of pilocarpine and 3,431 ± 208.03 μm after pilocarpine instillation. This represented a mean movement of the optics of 344 μm after the ciliary muscle was stimulated by pilocarpine. This decrease in the anterior chamber depth was consistent in all eyes studied, Dr. Marques reported.
"The results seem to confirm that there is a forward shifting of the IOL, but this raises the question of why our patients did not have good near visual acuity," Dr. Marques said. "The reason is that 344 μm corresponds to less than 0.5 D of pseudophakic accommodation, and therefore poor near vision, which was disappointing.
"We think that with this type of implant there is limited accommodative amplitude and in the future we will need to develop new technologies to provide our patients with more significant spectacle independence," he concluded.