Energy efficiency of a new trifocal intraocular lens

Abstract

The light distribution among the far, intermediate and near foci of a new trifocal intraocular lens (IOL) is experimentally determined, as a function of the pupil size, from image analysis. The concept of focus energy efficiency is introduced because, in addition to the theoretical diffraction efficiency of the focus, it accounts for other factors that are naturally presented in the human eye such as the level of spherical aberration (SA) upon the IOL, light scattering at the diffractive steps or the depth of focus. The trifocal IOL is tested in-vitro in two eye models: the aberration-free ISO model, and a so called modified-ISO one that uses an artificial cornea with positive spherical SA in instead. The SA upon the IOL is measured with a Hartmann-Shack sensor and compared to the values of theoretical eye models. The results show, for large pupils, a notorious reduction of the energy efficiency of the far and near foci of the trifocal IOL due to two facts: the level of SA upon the IOL is larger than the value the lens is able to compensate for and there is significant light scattering at the diffractive steps. On the other hand, the energy efficiency of the intermediate focus for small pupils is enhanced by the contribution of the extended depth of focus of the near and far foci. Thus, while IOLs manufacturers tend to provide just the theoretical diffraction efficiency of the foci to show which would be the performance of the lens in terms of light distribution among the foci, our results put into evidence that this is better described by using the energy efficiency of the foci.

Visible Versus Near-Infrared Optical Performance of Diffractive Multifocal Intraocular Lenses

“…Assessment of the optical imaging quality of the IOLs was made using an optical test bench with a model eye (artificial cornea plus wet cell) that has been described in detail elsewhere. 15,22,23 Supplementary Figure S1 shows a sketch of the setup, which was in agreement with International Standard Organization (ISO) 11979-2 and 11979-9 recommendations, 24,25 except for the artificial cornea that was not an aberration-free doublet because this was not representative of the average human cornea, which has intrinsic positive SA. 26,27 Instead, we used a double convex lens that provided a level of SA at the IOL plane of þ0.27 lm for a 6.0-mm pupil, 28 similar to the one induced by the human cornea on average.…”

Polychromatic Image Performance of Diffractive Bifocal Intraocular Lenses: Longitudinal Chromatic Aberration and Energy Efficiency

“…By doing so, all the refractive and diffractive power was exclusively due to the IOL. The optical setup was similar to that used by the authors in related works and described in detail elsewhere, 4,5 except for the artificial cornea, which was removed from the setup in this experiment. Once the TF-EE and LCA measurements were taken, we additionally set the IOL virtually in a pseudophakic schematic eye (Le Grand eye), 6 which provided the average refractive characteristics of other ocular media (cornea, aqueous and vitreous humors) and computed closer estimates for the LCA in the human eye.…”

Optical Characterization of Intraocular Lenses

“…En la tesis se pueden encontrar resultados con diferentes modelos de MIOLs [6][7][8]. La eficiencia energética de los focos de las MIOLs difractivas depende significativamente de la longitud de onda.…”

“…La calificación obtenida fue de "Sobresaliente -Cum Laude" (Junio de 2014). Las aportaciones y los resultados de la tesis, de los resultados derivados de la misma y de algunas aplicaciones al ámbito clínico están recogidas en las referencias [1][2][3][4][5][6][7][8][9][10][11]. El manuscrito completo se puede consultar en la referencia [12].…”