Visual Acuity Prediction In Eyes Implanted With Pupil-Dependent Intraocular Lenses

New refractive extended depth of focus intraocular lenses (EDoF IOLs) intend to overcome the drawbacks associated with both monofocal and multifocal designs. However, optical bench studies have shown that refractive EDoF IOLs may deal with a significant dependence of their optical performance on pupil size. The American National Standards Institute (ANSI Z80.35-2018) requires with EDoF IOLs, to provide the expected visual acuity (VA) from preclinical on-bench measurements. The purpose of this study is to improve the pre-clinical prediction of the monocular VA in pseudophakic eyes implanted with a representative pupil-dependent EDoF IOL, by incorporating the pupil size into the prediction model.

Group of Applied Optics and Image Processing, Faculty of Optics and Optometry, Universitat Politècnica de Catalunya, Barcelona Tech, Spain.

The through-focus area under the modulation transfer function (TF-MTFa) of the refractive EDoF AcrySof IQ Vivity (Alcon Laboratories, Inc) was obtained in a model eye with 2-, 3-, and 4.5-mm pupils ([MTFa_2mm], [MTFa_3mm], [MTFa_4.5mm] respectively. The TF-MTFa curve with a 3-mm pupil was correlated with the clinical VA defocus curve (R² = 0.95) of a large sample of pseudophakic patients (n = 107). This group also was split into three cohorts according to pupil size: small (< 3 mm; n = 6), medium (3 to 4 mm; n = 52), and large (> 4 mm; n = 49). Each pupil group showed a differentiated clinical VA defocus curve that was respectively highly correlated with the TF-[MTFa_2mm] (R² =0.97), TF-[MTFa_3mm] (R² = 0.97), and TF-[MTFa_4.5mm] (R² = 0.96).

The formula proposed by the American National Standards Institute (VA [logMAR] = a [MTFa_pupil]^-1 + c), was used to derive for each pupil a new set of fitting coefficients (a and c) to transform MTFa into expected VA accordingly. Four new predictive functions of the expected VA were obtained for the pupil-dependent refractive EDOF IOL: one for the whole sample of patients (VA [logMAR] = 0.092 [MTFa_3mm] ^-1 – 0.15), which averages out pupillary differences between patients, and three functions that incorporate the influence of the pupil size: Small Pupil (VA [logMAR] = 0.123 [MTFa_2mm] ^-1 – 0.21), Medium Pupil (VA [logMAR] = 0.086 [MTFa_3mm] ^-1 – 0.16) and Large Pupil (VA [logMAR] = 0.072 [MTFa_4.5mm] ^-1 – 0.14).

The correlation between on-bench MTFa and clinical VA has been evaluated for a representative refractive EDoF IOL (AcrySof IQ Vivity) incorporating the effect of pupil size. Three new predictive functions of the expected monocular VA defocus curve of pseudophakic patients according to their pupil size: small (< 3 mm), medium (3 to 4 mm), and large (> 4 mm) have been obtained with high correlation values. This segregation allows for a more accurate determination of the scenarios in which the EDoF IOL will offer its best and worst performance (small and large pupil groups, respectively).