Design of double-zone aspheric diffractive intraocular
lens with extended depth of focus
Yayan Bian (边亚燕), Yongji Liu (刘永基)*, and Lai Jiang (姜 来)
Institute of Modern Optics, Nankai University, Tianjin 300350, China
*Corresponding author: yjliu@nankai.edu.cn
Received May 21, 2018; accepted July 25, 2018; posted online August 29, 2018
A double-zone aspheric diffractive intraocular lens (IOL) was designed and manufactured aiming to regain a
continuous range of clear vision for pseudophakic presbyopia. After obtaining the IOL structure parameters
through optimization based on an aphakic model eye, its imaging performances were analyzed in the model
eye. The modulation transfer function at 50 cycles∕mm remained above 0.29 within 5° field of view for object
distance ranging from 6 to 0.66 m. In addition, the imaging qualities are robust for pupil changes, polychromatic
light, and different corneal asphericities. The manufactured IOL exhibits the ability to extend depth of focus.
OCIS codes: 330.4460, 220.2740, 330.7323, 050.1965.
doi: 10.3788/COL201816.093301.
The accommodation amplitude of the human eye de-
creases almost linearly with age at a rate of about 0.2 di-
opter (D) per year
[1]
. It usually decreases to less than 1 D
after 50 years old, resulting in an inability to focus near
objects accurately. This dysfunction is called presbyopia,
which makes it impossible for human eyes to obtain clear
vision over a continuous object range from distance to
near. In addition, the crystalline lens may become cloudy,
resulting in cataract, which is the most common cause of
blindness and visual impairment
[2]
. The implantation of an
intraocular lens (IOL) to replace the crystalline lens is a
mature method in clinical practice
[3]
. Using the specially
designed IOLs
[4]
to regain continuous clear vision is the ul-
timate goal for pseudophakic presbyopia. Many attempts
have been made in this research area.
Bifocal IOLs
[5]
attempt to provide distance and near
vision. Multifocal IOLs
[6–8]
attempt to allow distance,
near, and intermediate vision to be corrected simultane-
ously, yet they fails to provide continuous clear vision.
Accommodative IOLs
[9–12]
overcome the defects of bifocal
and multifocal IOLs, making the axial movements
possible by the special design or the use of special mate-
rials, but the provided adjustment is currently very
limited. Therefore, the extended depth of focus (EDOF)
IOL is proposed, aiming to provide clear images in a con-
tinuous vision range from distance to near. The TECNIS
Symfony
®
IOL using diffractive techn ology by Johnson &
Johnson Vision Care, Inc. (JJVCI) now is commercially
available, claiming that a 1.5 D defocus vision range can
be provided, but its technical details have not yet been
announced
[13]
.
There are also some other EDOF IOLs in research for
vision correction. Light sword lenses
[14,15]
are proposed as
an IOL, exhibiting great potential to extend the depth
of focus (DOF) for the human eye, though it causes a loss
of distance visual acuity. A multifocal IOL designed by
Fernández
[16]
demonstrates theoretically that the modula-
tion transfer function (MTF) at 50 cycles∕mm (c∕mm)
remained above 0.47 for object distance ranging from
5 m to 0.4 m. The aspheric diffractive IOL proposed by
Jiang et al.
[17]
provides continuous vision for object dis-
tance ranging from 0.4 to 8 m. One limit of this design
is a relatively small optical zone, which is 4.5 mm in
diameter.
For commercial application, an optical zone of 6 mm is
generally required. Furthermore, the human eyes work in
white light conditions and under different illumination,
which causes pupil diameter changes. These factors re-
quire the IOLs to provide robust imaging performance
under polychromatic light with different pupil sizes. Be-
sides, the IOLs are also required to provide robust imaging
for different corneal asphericites due to the individual dif-
ference of corneal asphericity.
This Letter is aimed to design an IOL, which can not
only provide a 1.5 D DOF, but also meet the above re-
quirements. A double-zone aspheric diffractive IOL with
EDOF was obtained by the optimization in Zemax . Sub-
sequently, this IOL was manufactured. The experimental
result shows that the manufactured IOL exhibits the abil-
ity to extend the DOF.
An aphakic model eye with an axial length of 23.471 mm
was used for IOL optimization. The parameters of the
aphakic model eye are shown in Table
1.
The material of the IOL is chosen to be the polymethyl
methacrylate (PMMA) material with a refractive index of
1.494 and an Abbe number of 57.5. The IOL with a 6 mm
optical zone was placed 3.5 mm behind the cornea’s pos-
terior surface. The wavelength was set to be 550 nm be-
cause the human eye is the most sensitive to this
wavelength. The field of view (FOV) is set to be 0°.
The optical design Zemax software (Zemax OpticStudio
16.5 SP5, Premium Edition) was used to build the model
eye and perform the optimization and analyses of the IOL.
The IOL surfaces are described by aspheric surfaces
with two concentric optical zones. The two concentric
zones are divided by two radial coordinates A
1
and A
2
COL 16(9), 093301(2018) CHINESE OPTICS LETTERS September 10, 2018
1671-7694/2018/093301(8) 093301-1 © 2018 Chinese Optics Letters