Spectacle independence is a central aim in modern cataract surgery. Although bilateral
monofocal IOL implantation, aiming for emmetropia or low myopia, leads to high levels of
patient satisfaction in distance vision, spectacle dependence for reading and other near
vision tasks is the usual result.
The option commonly used to achieve spectacle independence are multifocal intraocular lenses
(IOLs). Multifocal IOLs either use a refractive or diffractive design or a combination of
both or segmented asymmetric optics. The principal of the refractive design is based on
changing the route of light rays by thickness, curvature and optical density of the lens. The
principal of diffractive design is based on scattering of light rays when passing an edge in
the material of the lens. Usually, the characteristic diffractive ring patterns are
incorporated on the posterior surface of an IOL, whereas the anterior lens surface remains
purely refractive. One potentially negative aspect of multifocal refractive IOLs is pupil
size dependence, another is loss of light energy to higher order diffraction which is not
useful for the patient. In clinical studies, diffractive lenses resulted in a better outcome
in terms of optical quality, better contrast sensitivity, and less photic phenomena
(dysphotopsia such as halos and glare) compared to refractive lenses.
Until recently multifocal lenses were typically bifocal with a focus assigned to near and a
focus assigned to far vision. However, the intermediate working distance is poorly covered by
the bifocal design. Since objects commonly viewed in this distance include computer displays
and tablets, the intermediate distance has become a crucial part in daily life. Variations in
the addition of power chosen for near vision provided some intermediate visual acuity, but
still suboptimal. Therefore, a new concept of multifocality has been introduced, the trifocal
lens. Trifocal IOLs provide three focal distances: far, intermediate, and near. This ideally
results in even less spectacle dependence, including for computer work. However, one
potential disadvantage of trifocal IOLs is slightly poorer near vision compared to bifocal
IOLs with need for reading glasses for prolonged fine near work and loss of contrast
sensitivity in the intermediate distance.
A better intermediate performance concerning contrast vision compared to trifocal IOLs can be
reached using enhanced depth of focus (EDOF) lenses. These IOLs have an extended far focus
area which reaches to the intermediate distance, providing high-quality vision over a
continuous range of focus, rather than distinct foci with blur in between.
To provide similar outcomes to trifocal IOLs, mix-and-match of additions ("blended vision")
is another option, in which additions of multifocal IOLs between both eyes differ. The idea
behind it is to improve the contrast in the intermediate distance compared to trifocal IOLs.
The combination of +1.75D/ +4D10 and +1.5D/ +3D11 successfully achieved a regular defocus
curve, but patient's subjective binocular comfort was not determined. To preserve the
binocular balance between the eyes, a difference in addition of 0.5D was proposed and the
combination of +2.5D/ +3D showed similar results as trifocal IOLs, except in the intermediate
range of -1D and -1.5D.
Therefore, it would be necessary to provide an IOL with a continuum of good visual acuity
from distance to 40 cm using binocularity to preserve binocular balance between the eyes.
Hence, the primary objective of this study is to compare a new designed twinset of EDOF IOLs,
ARTIS ACTIVE (Artis Active Mid and Artis Active Plus), with the standard EDOF IOL AT Lara in
binocular visual acuity at 40 cm. Secondary objective is to compare binocular contrast
sensitivity (with and without glare), binocular defocus curves with distance correction,
monocular and binocular halos, and reading speed between the two IOLs.