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

Abstract

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 (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.

Main outcome measures: Postoperative ΔM values.

Results: 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.

Conclusions: The anterior-chamber angle-supported PIOL changes its position during accommodation only marginally. The PIOL does not affect postoperative accommodation.