SUBJECTIVE AND OBJECTIVE COMPARISON OF TWO ADVANCED MONOFOCAL INTRAOCULAR LENSES

To compare the subjective depth-of-field, objective optical quality, and refractive power profile of two advanced monofocal intraocular lenses (IOLs) designed to improve the intermediate vision of pseudophakic patients.

This prospective study evaluated forty-six eyes of twenty-three patients, aged 54-86 years, of whom 12 were implanted binocularly with IOL IsoPure 123 (PhysioI, Belgium) and 11 with IOL Tecnis Eyhance (Johnson&Johnson, NL). All patients presented a monocular uncorrected visual acuity at distance of at least 0.1 logMAR, posterior capsule transparency and an average pupillary diameter of 3.60±0.60mm (mean±sd). Subjective through-focus visual acuity curves were obtained by overlapping trial lenses to the best spherical-cylindrical correction for distance, in steps of -0.50D, between +0.50D and - 2.00D. The objective optical quality was defined as the area under the modulation transfer function (MTFa), integrated between 0 and 50 cycles/mm, calculated using Fourier optics methods directly from the wavefront values obtained with the Osiris-T high resolution aberrometer (CSO, Italy). The optical characterization of both lenses was made based on their refractive power profile measured with the NIMO TR1504 Interferometer (Lambda-X, Belgium), with the lenses immersed in saline solution.

The power profiles of both lenses show an IOL design with a progressive center-near aspherical geometry, in which the sagittal power decreases rapidly from the center of the optical zone to reach the nominal power at about 0.87 mm from the center (IsoPure +23.14D to +20.00D; Eyhance from +22.50D to +20.00D, from 0 to 0.87 mm). Comparison between mean monocular through-focus curves show a best corrected distance visual acuity of 0.0 logMAR (+1 letter) with both lenses. Through-focus visual acuity was marginally higher for the Eyhance, with a difference of only 1 letter at the defocus position of -0.50D (2m) and of about 3 letters at the defocus positions between -1.00D and -2.00D (1m to 0.5m). These differences were not statistically significant for a 95% confidence level. Objective assessment of optical quality based on wavefront measurements revealed only a clinically and statistically insignificant marginal difference in best corrected distance optical quality, with a higher value in MTFa obtained with the IsoPure (36.28±1.62 vs.35.01±1.97, mean±IC95%) and almost undifferentiated through-focus image quality from -0.50D to -2.00D defocus positions.

Both IOLs use a similar approach to enhance the depth-of-focus and improve intermediate vision. The small differences observed in the optical design of these special IOLs do not produce a functional difference, since both lenses present similar subjective and objective through-focus curves.