To develop a flexible model of the average eye that incorporates changes with age and accommodation in all optical parameters, including entrance pupil diameter, under photopic, natural, environmental conditions. We collated retrospective in vivo measurements of all optical parameters, including entrance pupil diameter. Ray-tracing was used to calculate the wavefront aberrations of the eye model as a function of age, stimulus vergence and pupil diameter. These aberrations were used to calculate objective refraction using paraxial curvature matching. This was also done for several stimulus positions to calculate the accommodation response/stimulus curve. The model predicts a hyperopic change in distance refraction as the eye ages (+0.22D every 10 years) between 20 and 65 years. The slope of the accommodation response/stimulus curve was 0.72 for a 25 years-old subject, with little change between 20 and 45 years. A trend to a more negative value of primary spherical aberration as the eye accommodates is predicted for all ages (20-50 years). When accommodation is relaxed, a slight increase in primary spherical aberration (0.008μm every 10 years) between 20 and 65 years is predicted, for an age-dependent entrance pupil diameter ranging between 3.58mm (20 years) and 3.05mm (65 years). Results match reasonably well with studies performed in real eyes, except that spherical aberration is systematically slightly negative as compared with the practical data. The proposed eye model is able to predict changes in objective refraction and accommodation response. It has the potential to be a useful design and testing tool for devices (e.g. intraocular lenses or contact lenses) designed to correct the eye's optical errors.

PURPOSE: To compare the in vitro optical performance of five premium multifocal intraocular lenses (IOLs), including a single-valued metric that shows the total range of distances where a multifocal IOL generates an acceptable image quality. METHODS: Through-focus modulation transfer function (MTF) and the image of a United States Air Force target were obtained for a 3-mm pupil and a wavelength of 546 nm in five multifocal IOLs (Tecnis Symfony [Johnson & Johnson], FineVision Micro F [PhysIOL], Acrysof IQ PanOptix [Novartis], and Artis Symbiose Mid and Plus [Cristalens Industrie] multifocal IOLs). Total depth of focus (TDOF) is computed by adding the vergence intervals where the through-focus MTF at 50 cycles/mm is 0.15 or greater. RESULTS: Due to their different optical designs (bifocal, trifocal, or extended depth of focus), energy is distributed differently between far, intermediate, and near focus for each multifocal IOL. The light distribution of the Symbiose Mid and Plus multifocal IOLs was similar, concentrating the energy into far focus and the intermediate into near focus, but extending the intermediate focus more (Plus) or less (Mid) toward the near focus. TDOFs were: 1.58 diopters [D] (FineVision); 1.71 D (Tecnis Symfony); 1.73 D (Artis Symbiose Plus); 1.74 D (Artis Symbiose Mid); and 1.90 D (Acrysof IQ PanOptix). CONCLUSIONS: TDOFs were similar between multifocal IOLs with a maximum difference of 0.32 D and mean value of 1.73 D. The combination of the Symbiose Mid and Plus IOLs can theoretically provide a TDOF of 2.90 D in case one is implanted in one eye and the other in the fellow eye. [ J Refract Surg . 2020;36(9):578–584.]

The key determinants of the range of clear focus in pre-presbyopes and their relative contributions to the difference between subjective range of focus and objective accommodation assessments have not been previously quantified. Fifty participants (aged 33.0 ± 6.4 years) underwent simultaneous monocular subjective (visual acuity measured with an electronic test-chart) and objective (dynamic accommodation measured with an Aston open-field aberrometer) defocus curve testing for lenses between +2.00 to −10.00 DS in +0.50 DS steps in a randomized order. Pupil diameter and ocular aberrations (converted to visual metrics normalized for pupil size) at each level of blur were measured. The difference between objective range over which the power of the crystalline lens changes and the subjective range of clear focus was quantified and the results modelled using pupil size, refractive error, tolerance to blur, and ocular aberrations. The subjective range of clear focus was principally accounted for by age (46.4%) and pupil size (19.3%). The objectively assessed accommodative range was also principally accounted for by age (27.6%) and pupil size (15.4%). Over one-quarter (26.0%) of the difference between objective accommodation and subjective range of clear focus was accounted for by age (14.0%) and spherical aberration at maximum accommodation (12.0%). There was no significant change in the objective accommodative response (F = 1.426, p = 0.229) or pupil size (F = 0.799, p = 0.554) of participants for levels of defocus above their amplitude of accommodation. Pre-presbyopes benefit from an increased subjective range of clear vision beyond their objective accommodation due in part to neural factors, resulting in a measured depth-of-focus of, on average, 1.0 D.