Visual acuity of pseudophakic patients predicted from in-vitro measurements of intraocular lenses with different design

Abstract

The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtained with an asymptotic limit found to be the best VA achievable by the patients. Two mathematical fitting functions between clinical VA and MTFa were derived with high correlation coefficients (R 2 ≥0.85). They were applied to the MTFa obtained from a different set of IOLs with advanced designs (trial set: one extended range of vision-ERV-, one trifocal ERV and one trifocal apodized) to predict VA versus defocus of patients implanted with these IOLs. Differences between the calculated VA and the clinical VA for both fitting models were within the standard deviation of the clinical measurements in the range of-3.00 D to 0.00 D defocus, thus proving the suitability of the MTFa metric to predict clinical VA performance of new IOL designs.

Equivalence of two optical quality metrics to predict the visual acuity of multifocal pseudophakic patients

“…Our study is limited to diffractive IOLs with either a single [18,19] or two combined [20,21] parabolic phase profiles of three different designs (trifocal ERV, trifocal apodized, and ERV) and two pupil sizes. Since MTFa has been proved to serve as preclinical metric for average visual performance [3][4][5]22], the results of this study will clarify whether EE metric can be used in a similar way.…”

“…To calculate the MTFa for a given image vergence within the TF range, we computed first the MTF from the images of the four-slit test produced by the model eye with the IOL under study as reported elsewhere [4]. We averaged the four MTF curves in the horizontal and vertical directions and integrated the average MTF curve in the spatial frequency range from 0 to 50 cycles/mm, which turned out to be the MTFa value.…”

“…The optical image quality of an intraocular lens (IOL) and its variation with defocus provides an essential knowledge to interpret the pseudophakic visual performance in a distance range [1][2][3][4][5]. Marsack et al [6] investigate the ability of 31 scalar metrics derived from wavefront aberration maps to predict changes in the high-contrast visual acuity (VA).…”

“…Recently, more efforts have been made to obtain optical image quality metrics computed from either on-bench measurements [1,3,4] or from optical simulations [5] that may correlate well with average visual outcomes tested in clinical assessments such as VA or contrast sensitivity (CS). When a high correlation is found, such metrics becomes a preclinical metrics, meaning that it is possible to predict the relative change in the clinical average defocus VA curves from the in-vitro on-bench measurements of the IOL.…”

“…Nonlinear fits of through-focus values of such three MTF-based metrics versus clinical VA assessed in patients implanted with six different IOL designs reached high correlation coefficients (R 2 > 0.93). Vega et al [4] considered one of these metrics, the MTFa in the frequency integration range from 0 to 50 cycles/mm, under green light (530 nm), and hypothesize an asymptotic limit in the VA achievable with IOL implants of exceedingly large MTFa. With these assumptions and after refining the non-linear function that fits optical bench MTFa values with clinical VA data for a modeling IOL set (consisting of one monofocal and two bifocals), they were able to predict clinical VA at different defocus levels of patients implanted with trial IOLs of different design (two trifocals and one extended range of vision).…”