Dynamic Positional Change and Defocus Curve of a Phakic Foldable Anterior-Chamber Angle-Supported Intraocular Lens during Accommodation

Objective: To evaluate movements of an anterior-chamber angle-supported phakic intraocular lens (PIOL) Cachet (Alcon, Fort Worth, Texas) and their influence on visual acuity during accommodation. Design: Prospective case series. Participants: We included 54 eyes of 27 patients (15 female, 12 male; age, 38 +/- 7.61 years; preoperative manifest spherical equivalent -8.7 +/- 2.5 diopters [D]). Methods: Evaluation of the PIOL's positional stability (distance to the corneal endothelium [M1] and the natural lens [M2]) as well as the pre- and postoperative anterior chamber depth (ACD) and pupil diameter (PD). Measurements were performed for accommodation stimuli ranging from -7 to +1 D in 1-D increments using optical coherence tomography (Visante OCT, Carl Zeiss Meditec, Jena, Germany). The respective defocus curve was evaluated using Early Treatment Diabetic Retinopathy Study charts. Statistical analysis included a Kolmogoroff-Smirnov test for parametric distribution, a Friedman-and consecutive Conover-Iman-Bonferroni test for detection of PD, ACD, and defocus curve differences from before to after the operation, a 1-sided t test for analysis of positional changes (Delta PD, Delta ACD, and Delta M values compared with a zero stimulus position), and a regression analysis for the evaluation of influence of age, IOL diameter, and power on Delta-values. Significance was set at P = 0.05. Main Outcome Measures: Postoperative Delta M values. Results: The PD, Delta PD, ACD, and Delta ACD did not differ significantly between pre-and postoperative values. The Delta M1 and Delta M2 differed significantly from the zero-stimulus position for defocus stimuli of >=-3 D and -2D, respectively; mean Delta M1(max) was -0.09 +/- 0.06 mm for -7-D stimulus; mean Delta M2(max) was -0.09 +/- 0.10 mm for -5-/-6-D stimulus. Apart from Delta PD, all Delta-values decreased with age. Visual acuity was significantly better postoperatively for defocus stimuli between 0 and -3 D. Conclusions: The anterior-chamber angle-supported PIOL changes its position during accommodation only marginally. The PIOL does not affect postoperative accommodation.