Metodologia para projeto de lente intraocular trifocal difrativa modulada por função cossenoidal

Abstract

This paper presents the proposal and development of an innovative diffractive trifocal intraocular lens (IOL) based on the modulation of the diffractive steps height using a periodic function given by the modulus of a shifted cosine function. By means of the proposed modulation function it is also intended to establish a correlation between the analytical parameters of the modulation function (amplitude, frequency and phase) and the figures of merit that characterize the optical quality of the lens and thus to be able to propose a lens design with optical features that are equal or superior to those of lenses present on the market. The multifocal IOL developed in this paper is dictated by: the description of the mathematical formulation of the refractive and diffractive behavior of the lens; the lens optical modelling in the OpticStudio software to evaluate the optical performance of the IOL based on the current standards (ISO standard parts 2 and 9); the optimization of the IOL by the use of a deterministic optimization algorithm (DLS – Damped Least Square algorithm) and a stochastic algorithm (NSGA-II – Non-dominated Sorting Genetic Algorithm II); the optical performance evaluation considering quantitative evaluation parameters (efficiency and MTF – Modulation Transfer Function); and, finally, the tolerance analysis due to the deviations of the manufacturing process. The simulation results presented for the proposed IOL show that it was possible to achieve an innovative IOL design with competitive performance in relation to the diffractive trifocal IOLs present on the market. The tolerance analysis shows that is possible to manufacture, on average, the proposed design with the accuracy required to guarantee the optical performance shown in the simulation results. The optical performance results of the prototype are compared with the main trifocal IOLs on the market. Although this work is focused on the IOL development, the methodology presented can also be applied to the development of multifocal lenses in a broader spectrum of applications.