Dynamic positional change and defocus curve of a phakic foldable anterior-chamber angle-supported intraocular lens during accommodation.

Abstract

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. Prospective case series. 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]). 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 (ΔPD, ΔACD, and ΔM values compared with a zero stimulus position), and a regression analysis for the evaluation of influence of age, IOL diameter, and power on Δ-values. Significance was set at P = 0.05. Postoperative ΔM values. The PD, ΔPD, ACD, and ΔACD did not differ significantly between pre- and postoperative values. The ΔM1 and ΔM2 differed significantly from the zero-stimulus position for defocus stimuli of ≥-3 D and ≥-2D, respectively; mean ΔM1max was -0.09 ± 0.06 mm for -7-D stimulus; mean ΔM2max was -0.09±0.10 mm for -5-/-6-D stimulus. Apart from ΔPD, all Δ-values decreased with age. Visual acuity was significantly better postoperatively for defocus stimuli between 0 and -3 D. The anterior-chamber angle-supported PIOL changes its position during accommodation only marginally. The PIOL does not affect postoperative accommodation.