Theoretical and Measured Pseudophakic Accommodation after Implantation of a New Accommodative Posterior Chamber Intraocular Lens

Abstract

Objective: To analyze different techniques of measuring accommodation after implantation of a new accommodative posterior chamber intraocular lens (PCIOL). Methods: In this comparative, nonrandomized interventional study, we analyzed 15 eyes of 15 patients (aged 44-84 years) at 6 months after cataract surgery and PCIOL implantation (Akkommodative 1CU; Human Optics AG, Erlangen, Germany) and compared these results with those of an age-matched control group (n = 15). We used the following methods to measure accommodation: dynamic measurement with objective (videorefractometry [PowerRefractor; PlusOptix, Erlangen] and streak retinoscopy) and subjective (subjective near point [push-up test and accommodometer] and defocusing) techniques, as well as static measurement of the change in anterior chamber depth (ACD) using the IOL Master (Zeiss, Jena, Germany) after pharmacological stimulation using 2% pilocarpine eye drops. Main Outcome Measures: Theoretical accommodation calculated from the forward shift of the lens optics (decrease of ACD) using paraxial geometrical optics and measured accommodation amplitude. Results: Accommodation amplitude (mean ± SD; range; median) results after 6 months in the study and control groups were as follows: 1.00±0.44; 0.75-2.13; 1 diopter (D); and 0.35±0.26; 0.10-0.65; 0.25 D, respectively, using the PowerRefractor; 0.99±0.48; 0.13-2.00; 0.88 D; and 0.24±0.21; -0.13-0.75; 0.25 D, respectively, using retinoscopy; 1.6±0.55; 0.50-2.56; 1.7 D; and 0.42±0.25; 0.00-0.75; 0.50 D, respectively, using subjective near point; and 1.46±0.53; 1.00-2.50; 1.75 D; and 0.55±0.33; 0.25-0.87; 0.50 D, respectively, using defocusing. Anterior chamber depth decreased in the study and control groups as follows: 0.78±0.12; 0.49-1.91; 0.65 mm; and 0.16±0.09; 0.00-0.34; 0.18 mm, respectively, after applying 2% pilocarpine eyedrops, indicating an accommodation of 1.16±0.22; 0.72-1.88; 1.05 Dvs 022±0.13; 0.00-0.47; 0.23 D (P=.001). Conclusions: Accommodation after implantation of a presumably accommodative PCIOL can be measured with clinical methods or derived from the biometric data of the eye and the measured ACD decrease using geometrical optics. For clinical purposes, pseudophakic accommodation should be assessed with a variety of different techniques, including subjective and objective measurements. The theoretical approach using geometrical optics may be an additional indicator for the accommodative response in patients with pseudophakic eyes and may allow a subdivision of the measured accommodation into true pseudophakic accommodation and pseudoaccommodation.