Extended Depth-of-Field Intraocular Lenses: An Update

Abstract

Extended depth-of-focus (EDOF) is a new intraocular lens (IOL) technology in the treatment of presbyopia. In contrast to multifocal (MF) IOLs, EDOF lenses create a single elongated focal point, rather than several foci, to enhance depth of focus. In this way, EDOF IOLs aim to reduce photic phenomena, glare, and halos, which have been reported in MF IOLs. A potential disadvantage is a decrease of retinal image quality if the amount of the aberrations is excessively increased. Frequently, EDOF IOLs are combined with MF optical designs; for this reason, EDOF IOLs are commonly a subject of confusion with optical multifocality concepts. The aim of this article is to clarify what an EDOF IOL is and to discuss the recently reported outcomes with these IOLs. We propose naming lenses that have combined optical designs as "hybrid IOLs."

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Extended Depth-of-Field Intraocular Lenses: An Update
Piotr Kanclerz, MD, PhD

, Francesca Toto, MDy, Andrzej Grzybowski, MD, PhD, MBAz§, and
Jorge L. Alio, MD, PhD, FEBOy
Abstract: Extended depth-of-focus (EDOF) is a new intraocular lens
(IOL) technology in the treatment of presbyopia. In contrast to
multifocal (MF) IOLs, EDOF lenses create a single elongated focal
point, rather than several foci, to enhance depth of focus. In this way,
EDOF IOLs aim to reduce photic phenomena, glare, and halos, which
have been reported in MF IOLs. A potential disadvantage is a decrease
of retinal image quality if the amount of the aberrations is excessively
increased. Frequently, EDOF IOLs are combined with MF optical
designs; for this reason, EDOF IOLs are commonly a subject of
confusion with optical multifocality concepts. The aim of this article
is to clarify what an EDOF IOL is and to discuss the recently reported
outcomes with these IOLs. We propose naming lenses that have
combined optical designs as “hybrid IOLs.”
Key Words: extended depth-of-focus, hybrid lenses, intraocular lenses,
presbyopia, retinal quality image
(Asia Pac J Ophthalmol (Phila) 2020;9:194–202)
Intraocular lenses (IOLs) are used in both refractive lens
exchange and cataract surgery to replace the natural human
lens and/or correct refractive errors. Over the recent years, a wide
spectrum of multifocal (MF) IOLs has been developed; these
IOLs have outweighed traditional monofocal IOLs. With the
increase of life expectancy and a change in lifestyle, an increasing
number of patients is requesting for spectacle-independent near
and intermediate vision for their daily activities, aside from
excellent distance vision.
1
Moreover, presbyopia-correcting IOLs
are a treatment option for presbyopic patients who are not
candidates for laser refractive surgery and do not want to rely
on reading glasses.
Presbyopia-correcting IOLs can be divided into 3 broad
categories: MF IOLs (including diffractive or refractive designs),
extended depth-of-focus (EDOF) IOLs, and accommodative IOLs
(intracapsular or sulcus placed).
2,3
The aim of this article is to give a brief overview of the
contemporary, frequently implanted EDOF IOLs. We decided to
focus on the physical aspects of the IOLs and discuss the principal
factors that could influence the neuroadaptation. Being a concise
overview, many issues can only be touched upon. IOLs that are
advertised as EDOF lenses but do not have true EDOF character-
istics are discussed below; however, they are not presented in the
Table 1.
DEFINITION OF AN EDOF
The EDOF IOL, or extended range of vision IOL, is a new
technology in the treatment of presbyopia-correcting lenses. The
basic optical principle is to create a single-elongated focal point to
enhance the depth-of-focus, on the contrary to monofocal IOLs (in
which light is focused on one single point) or MF IOLs (having 2
or 3 discrete points).
This elongated focus is introduced to eliminate the over-
lapping of near and far images caused by traditional MF IOLs,
thus eliminating the halo effect; ideally, these IOLs should
enhance intermediate and near visual performance, while
minimally affecting distance vision. EDOF IOLs provide a
continuous range of focus without a clearly asymmetric IOL
power distribution, avoiding the presence of secondary out-of-
focus images.
4,5
In this way, EDOF IOLs differ from the MF
IOLs which show at each of their foci secondary out-of-focus
images corresponding to the rest of the foci, which originate
halos and whose characteristics depend on the lens design
(especially the magnitude of the addiction) and pupil size.
3
Increasing depth of field might have a tradeoff, which is a
decrease visual quality. Particularly, if the aberration magni-
tude is too large it leads to a reduction in distance image
quality, overlapping of the percepted images, with dysphotop-
sia phenomena.
6
Several optical bench reports have shown that
the EDOF lenses provide better optical quality than MF and
monofocal lenses.
7–9
Nevertheless, in practice, EDOF lenses
provide excellent intermediate vision, but inadequate quality of
vision for near distance.
10,11
The idea of EDOF is not new. Nakazawa and Ohtsuki, in
1984, reported the effect of apparent 2.00 D accommodation in 39
eyes implanted with spherical IOLs.
12
The authors also measured
each patient’s pupillary diameter, anterior chamber depth, and
corneal refractive power to determine the factor that is account-
able for the increased depth of field. It was surmised that the
correlation between apparent accommodation and depth of
field was inversely proportional to the pupillary diameter.
12
From the

Hygeia Clinic, Gdan´sk, Poland; yVissum Corporation, Alicante, Spain;
zDepartment of Ophthalmology, University of Warmia and Mazury, Olsztyn,
Poland; and §Institute for Research in Ophthalmology, Foundation for Oph-
thalmology Development, Poznan, Poland.
Submitted February 28, 2020; accepted April 7, 2020.
There authors have no conflicts of interest to disclose.
Financial Disclosure: No author has a financial or proprietary interest in any
material or method mentioned.
Financial support This study has been supported in part by the Red Tema´ tica de
Investigacio´n Cooperativa en Salud (RETICS), reference number RD16/0008/
0012, financed by the Instituto Carlos III – General Subdirection of Networks
and Cooperative Investigation Centers (R&D&I National Plan 2008 –2011) and
the European Regional Development Fund (Fondo Europeo de Desarrollo
Regional FEDER)
Correspondence: Prof Jorge L. Alio, Vissum Instituto Oftalmologico de Alicante,
Avda de Denia S/N 03015, Alicante 03016, Spain. E-mail: jlalio@vissum.com.
Copyright ß2020 Asia-Pacific Academy of Ophthalmology. Published by Wolters
Kluwer Health, Inc. on behalf of the Asia-Pacific Academy of Ophthalmology.
This is an open access article distributed under the terms of the Creative
Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-
NC-ND), where it is permissible to download and share the work provided it is
properly cited. The work cannot be changed in any way or used commercially
without permission from the journal.
ISSN: 2162-0989
DOI: 10.1097/APO.0000000000000296
194 | https://journals.lww.com/apjoo ß2020 Asia-Pacific Academy of Ophthalmology.
REVIEW ARTICLE

Subsequently, during the past 2 decades, multiple strategies have
been used to extend the depth of focus at both the cornea and
lens plane.
In June 2014 the first EDOF IOL (Symfony, Johnson and
Johnson Vision, Jacksonville, FL) was introduced into the Euro-
pean market, having received the European Economic Area
certification mark. Consequently, the Symfony was also the
first EDOF-labeled IOL approved in the United States in
2016.
13
Since then, several EDOF-labeled IOLs have been
released in the market; these IOLs have been presented in the
following paragraphs.
INFLUENCE OF INDUCED ABERRATIONS ON THE
QUALITY OF THE RETINAL IMAGE
AND THE DEPTH OF FOCUS
Presbyopia correction is the balance of 3 interrelated factors:
visual quality, depth of field, and dysphotopsias. The most
important optical models employed in EDOF IOLs are presented
in the following paragraphs.
Spherical aberration (SA, Z
4,0
) is an aberration associated
with focal length difference between central and marginal ray
where the light enters in the lens (Fig. 1A). For any given eye, the
Zernike coefficients may vary widely, but a mean value of corneal
spherical aberration is þ0.31 0.135 mm for a 6.0-mm pupil
size.
14
It is possible to neutralize the corneal spherical aberration
within a limited degree by choosing a negative spherical aberra-
tion IOL. The benefit of an IOL correcting spherical aberrations is
to provide a sharper focus of light and therefore a better vision at a
particular distance. Although higher-order aberrations (HOAs)
degrade the quality of vision in most circumstances, there is
evidence that the presence of some HOAs (particularly spherical
aberration, coma, and secondary astigmatism) improves depth of
focus.
15
This is the principal mechanism than allows to increase
the depth-of-focus in pure EDOF IOLs.
Chromatic aberration (CA) is a consequence of focal
length difference between the visible spectrum of different colors
of light. The human cornea induces CAs, as blue light is diffracted
more than red light (Fig. 1B). Several factors affect CAs induced
by IOLs. First, the optical material dispersion, which is expressed
by the ABBE number, shows how much the refractive index
changes with the wavelength of light. The higher the disperision,
the smaller the ABBE number. The optical design also has an
impact: a refractive optic maintains CA induced by the cornea;
with this lens the final ocular CA will increase, with an increasing
of the dispersion of the wavelengths. On the contrary, the dif-
fractive IOLs can reverse CA: red blends more than blue. So, a
diffractive IOL can minimize the CA in every eye. Achromatiza-
tion does not bring an extended depth of field improvement but
rather an improvement in the contrast sensitivity function.
16
Consequently, a diffractive IOL can minimize CA in every
eye, and subsequently lead to an improvement of the contrast
sensitivity and the quality of vision.
17
The pinhole effect is another phenomenon which allows
obtaining greater depth of focus. From the equation presented
by Campbell over 50 years ago, it can be deduced that with
increasing pupil size, the depth of field decreases (and so does the
depth of focus).
18
Following this principle, the use of an opaque
pinhole mask in a monofocal IOL could enhance the depth of
focus. Moreover, the Stiles-Crawford should be taken into
accound; it is believed that when an equal intensity of light enters
the eye near the center of the pupil, it produces a greater
photoreceptor response compared with the light entering the
eye near the pupillary edge.
19,20
A review of the advantages of
presbyopia correction using the pinhole effect is described else-
where.
One might conclude that the EDOF effect is achieved just
with the increasing of the spherical aberration of the eye or by
employing the pinhole effect. To name a lens an EDOF IOL, the
optical profile has to be continuous, without a change in transition
TABLE 1. IOLs Having an EDOF Characteristic
Type IOL Material Design Optic Size Overall Size
Pure EDOF
IOLs
Spherical aberration-based
EDOF IOLs
SIFI Mini Well Ready Hydrophilic Acrylic with
Hydrophobic Surface
Closed loop 6.0 mm 10.75 mm
WIOL CF Hydrophilic Acrylic Without haptics 8.6–8.9 mm 8.0–8.6 mm
Tecnis Eyhance ICB00 Hydrophobic Acrylic C-Loop 6.0 mm 13.0 mm
EDOF IOLs utilizing the pinhole effect
IC-8 Hydrophilic acrylic C-loop 6.0 mm 12.5 mm
XtraFocus Pinhole Implant Hydrophobic acrylic C-loop (sulcus-placed) 6.0 mm 14.0 mm
Hybrid MF/
EDOF IOLs
Hybrid MF diffractive/EDOF IOLs
Tecnis Symfony ZXR00 Hydrophobic acrylic C-Loop 6.0 13.0 mm
Hybrid MF refractive/EDOF IOLs
Lentis Mplus Lentis Mplus X Hydrophilic acrylic Plate 6.0 mm 11.0 mm
Acunex Vario AN6V Hydrophobic acrylic C-Loop 6.0 mm 12.5 mm
Lucidis Hydrophilic acrylic Closed loop 6.0 mm 10.8 mm or 12.4 mm
Hybrid MF refractive-diffractive/EDOF IOLs
InFo Hydrophilic acrylic Closed loop 6.0 mm 10.8 mm or 12.4 mm
EDEN Hydrophobic acrylic Closed loop 6.0 mm 10.8 mm or 12.4 mm
Harmonis Hydrophilic acrylic Closed loop 6.0 mm 10.8 mm or 12.4 mm
Tecnis Synergy ZFR00 Hydrophobic acrylic C-Loop 6.0. mm 13.0 mm
CF indicates continuous focus; EDOF IOLs, extended depth-of-focus intraocular lenses; MF, multifocal; WIOL, Medicem Wichterle Intraocular Lens.
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equally refractive or diffractive. All the lenses that employ the CA
or have a diffractive diffractive-hybrid profile, or an additional
power to increase the near vision are not pure EDOF IOLs.
CLINICAL APPLICATION OF EDOF LENSES
Based on the IOL technologies we believe that 2 groups, pure
EDOF IOLs and hybrid MF-EDOF IOLs, should be differentiated.
Pure EDOF IOLs employ solely spherical aberration-based optics
or the pinhole effect. Hybrid MF-EDOF IOLs could be catego-
rized as diffractive-EDOF IOL, refractive-EDOF IOL, and dif-
fractive-refractive-EDOF IOL.
Pure EDOF IOLs
Spherical Aberration-Based EDOF IOLs
Inducing spherical aberrations in EDOF IOLs means that
incoming light waves are extended in a longitudinal plane. The
elongated focus eliminates the overlap of near and far images, and
theoretically eliminates the halo effect. The tradeoff is a decrease
in the quality of the retinal image, which limits their performance
as there is a degradation of the visual quality. This is why the near
vision capability is usually limited to about 1 D.
Mini Well Ready (SIFI, Catania, Italy) is a one-piece
EDOF IOL (Fig. 2A). The optic is purely aberration-based,
FIGURE 1. Spherical (A) vs chromatic (B) aberrations.
FIGURE 2. Spherical aberration-based EDOF IOLs: (A) Sifi Mini Well Ready, (B) medicem wichterle intraocular lens-continuous focus, (C) Tecnis
Eyhance ICB00. EDOF IOLs indicates extended depth-of-focus intraocular lenses.
Kanclerz et al Asia-Pacific Journal of Ophthalmology Volume 9, Number 3, May/June 2020
196 | https://journals.lww.com/apjoo ß2020 Asia-Pacific Academy of Ophthalmology.

and the IOL has a double aspherical optical design. Specifically,
the spherical aberrations are induced in certain areas of the optic
to increase depth of focus. The optical surface of this IOL is
divided into 3 different annular zones: the inner and middle zones
have different spherical aberrations with opposite signs, whereas
the outer one is a monofocal zone. The primary and secondary
spherical aberration, that are insignificant at the pupil center of a
real eye in normal conditions, are induced with this IOL in an
appropriate amount in some specific areas of the IOL optics,
providing an increase of the depth of focus and a control of the
level of HOAs. It has an overall diameter of 10.75 mm, an optical
surface diameter of 6 mm, and it includes an ultraviolet filter. The
lens is made of copolymer, and is also available in a toric version.
5
Theoretically, Mini Well Ready should have a spherical equiva-
lent addition of þ3.0 D.
21
Clinical studies reported different
results. In a study by Giers et al,
22
the defocus range (defined as
visual acuity better than 0.2 LogMAR) reached 4 D; however, still
the patients preferred a median intermediate reading distance of
62.8 cm. In another study, increased depth of focus was provided
through 2.0 D defocus, the best performance was reported at 1.0
and 1.5 D.
4
Although the lens manifests good optical quality at a
large defocus range, the modulation transfer function character-
istics are strongly affected by the pupil size.
8,9
Wichterle Intraocular Lens–Continuous Focus (Medi-
cem, Kamenne
´Zehrovice, Czech Republic) is categorized as
an EDOF lens bioanalogical lenses (Fig. 2B). It enables a contin-
uous range of focus due to a design with a hyperbolic optic. It has
a 1-piece polyfocal hyperbolic optic with no haptic elements, and
is made from a biocompatible 42% water hydrogel and mimics the
properties of a natural crystalline lens with a refractive index
1.43.
23
Although the lack of haptics was supposed to be benefi-
cial, single reports of IOL instability associated with this design
have been published
24– 26
; the IOL tilt and dislocation had a
characteristic pattern and was present despite the absence of
trauma.
24
As it is not an accommodative IOL the lens has several
zones that create different foci, and the refractive power is
maximal in the center and continuously decreases without steps
to the periphery. In a clinical study, patients achieved good far and
intermediate distance vision, whereas the near vision was rela-
tively good.
27
With that, the amount of HOAs was reasonable.
28
TECNIS Eyhance ICB00 (Johnson and Johnson Vision,
Jacksonville, FL). Although this IOL could be categorized as a
monofocal IOL, it offers a smooth and continuous progression of
its power from periphery to the center, with no demarcation line
(Fig. 2C). It aims to present the distance performance and mini-
mum photic effects of a monofocal (ZCB00) while providing
intermediate vision at 66 cm and compensating for spherical
aberrations in the cornea. It is a single-piece hydrophobic acrylic
IOL wit a 360 degree posterior square edge. The refractive index
is 1.47, and clinically it leads to an improvement in intermediate-
distance vision when compared to monofocal IOLs. Regarding
defocus, measurements indicate that the TECNIS Eyhance IOL
has a larger “landing zone” than the TECNIS Monofocal IOL, and
provides excellent (20/20) distance vision.
29
EDOF IOLs Utilizing the Pinhole Effect
IC-8 (AcuFocus Inc, CA) is a 1-piece small aperture
extended depth of focus IOL. The optic presents a small aperture
aspherical surface, 3.23 mm nondiffractive annular opaque mask
with 1.36 mm aperture, which blocks defocused paracentral light
rays, and allows entry of paraxial light rays giving an EDOF effect
(Fig. 3A). It is a hydrophilic acrylic IOL, and the total diameter is
12.50 mm, with a 6.0-mm optic. It is not pupil-dependent.
30
Clinical studies have shown that the IC-8 provides excellent
visual acuity at all distances, both after contralateral and after
bilateral implantation.
31– 33
The increase in depth-of-focus for the
IC-8 is particularly evident in photopic conditions.
33
Moreover,
the visual field with the pinhole design shows a small, but
clinically insignificant reduction in contrast sensitivity.
34
Another
study reported no influence on contrast sensitivity for mesopic
conditions with or without glare at all spatial frequencies.
31
XtraFocus Pinhole Implant (Morcher, Stuttgart,
Germany). It is intended for ciliary sulcus implantation as a
piggyback lens (Fig. 3B). Its overall diameter is 14 mm with a
central pinhole opening of 1.3 mm. The device is made of a black
hydrophobic acrylic which blocks visible light but is transparent
to infrared light >750 nm, to permit retinal examination through
the opaque material with optical coherence tomography and
scanning laser ophthalmoscope. Although large clinical studies
on the XtraFocus Pinhole Implant are not available, a single
FIGURE 3. EDOF IOLs utilizing the pinhole effect. (A) Acufocus IC-8, (B) XtraFocus Pinhole Implant. EDOF IOLs indicates extended depth-of-focus
intraocular lenses.
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investigation reported a disadvantage of this design in dim light
condition.
35
Hybrid MF-EDOF IOLs
We propose such a label for IOLs that combine multifocality
with low addition power and the EDOF technology.
Hybrid MF Diffractive/EDOF IOLs
New models of diffractive MF IOLs having reached a high
standard of clinical performance target the decrease in halos and
glare by decreasing the near optical power, substituting it by an
EDOF effect.
Tecnis Symfony ZXR00 (Johnson and Johnson Vision,
Jacksonville, FL) is a single-piece, hydrophobic acrylic EDOF
IOL, foldable lens with a biconvex, anterior aspheric surface, and
a posterior achromatic diffractive surface with echelette design
(Fig. 4). The asphericity is 0.27m. The performance of this IOL
is dependent of the pupil size. Available power spectrum ranges
from þ5.0 D to þ34.0 D, with an addition of þ1.75 D at the IOL
plane. The lens creates an achromatic diffractive pattern that
elongates a single focal point and compensates for the CA of the
cornea.
36
Symfony uses 2 complementary enabling technologies:
echelette design feature and achromatic technology. The echelette
technology is actually used in the Symfony lens and is based on a
design that forms a step structure whose modification of height,
spacing, and profile of the echelette extends the depth of focus.
These designs in combination with achromatic technology and
negative spherical aberration correction improve simulated retinal
image quality without compromising depth of field or tolerance to
decentration.
37
This lens is a low-power MF lens with some
EDOF characteristics.
10
At Lara 29 MP (Carl Zeiss Meditec, Jena, Germany) has a
continuous diffractive surface profile from intermediate to dis-
tance focal points. It is a hydrophilic acrylic IOL (25% water
content) with hydrophobic surface properties. The overall lens
diameter is 11 mm with an optical zone of 6mm.
38
Clinical results
confirm excellent visual acuity over a wide range of focus.
Binocular visual acuity was better than 0 logMAR (20/20 res.
1.0 decimal) at far and better than 0.1 logMAR (20/25 res. 0.8
decimal) at the intermediate distances of 90 cm and 60 cm.
38
Although the producer claims this is an EDOF IOL,
39
this lens
does not have EDOF characteristics.
Hybrid MF Refractive/EDOF IOLs
Lentis Mplus X (Oculentis GmbH, Berlin, Germany) is a
rotationally asymmetric refractive MF IOL with a reduced central
diameter designed with 2 distinct foci and 2 definite corrective
zones for far and for near vision (Fig. 5A). The smooth transition
between zones (surface design optimization technology) provides
EDOF, increasing near vision effectivity.
40
Additive paraxial
asphericity technology is a central modification of the IOL optic,
which broadens the 2 foci into far and near focus zones.
41
The
sectoral design makes this lens particularly suitable in patients
with a pupil diameter >3 mm.
42
Acunex Vario AN6 V is a foldable 1-piece posterior cham-
ber IOL for extended depth of focus and high-contrast sensitivity
with aspherical surface and blue light filter (Fig. 5B). The overall
IOL diameter is 12.5 mm, with C-loop haptics, and optical zone of
6 mm. The addition for intermediate vision is þ1.5 D. Both the
Acunex and Lentis IOLs share the same basic optical design with
a relatively low addition of 1.5 D; however, Acunex is a hydro-
phobic, whereas Lentis a hydrophilic acrylic lens.
Lucidis (Swiss Advanced Vision, SAV-IOL SA, Neucha
ˆ-
tel, Switzerland) is the new type of refractive/EDOF hybrid IOL
involving a central aspheric element surrounded by an outer
refractive ring (Fig. 5C). Lucidis is a single-piece foldable multi-
zone refractive/aspheric IOL, with a 3608square edge design and
closed loop haptics. The lens has a 6.0-mm optical diameter and a
total diameter of either 10.8 mm or 12.4 mm. It is made from
hydrophilic acrylic with a 26% water content. The IOL is
FIGURE 4. Hybrid MF Diffractive/EDOF IOLs: Tecnis Symfony. EDOF IOLs indicates extended depth-of-focus intraocular lenses; MF, multifocal.
Kanclerz et al Asia-Pacific Journal of Ophthalmology Volume 9, Number 3, May/June 2020
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designed for capsular bag implantation and is available in a power
range from þ5.0D to þ30.0D in 0.5 D steps with þ3.0 D
addiction/EDOF power.
43
Optically, the Lucidis IOL employs
both a refractive and an aspheric element. The 1-mm aspheric
zone occupies the center of the IOL and is surrounded by a 6-mm
refractive ring. According to the manufacturer’s documentation,
the main benefit of this particular design compared with classical
monofocal optics is to provide additional comfort in near and
intermediate vision, while still achieving the same optical quality
and visual acuity for distance vision. The lens is to be aberration-
neutral and minimize the rates of dysphotopsia.
44
Supraphob Infocus IOL (Appasamy Associates, Chennai,
India) is a proprietary newer-generation refractive EDOF IOL,
and is really a bifocal refractive lens with an EDOF profile. The
IOL is made of acrylic yellow chromophore material and has a
small central zone for near vision (3.50 D add), larger mid
peripheral zone for intermediate vision, and outer zone for
distance vision.
45
This is obviously not real EDOF but rather a
bifocal lens which offers a peripheral asphericity to increase the
effectivity for near as a support for the optical power of the lens.
10
Hybrid MF Refractive-Diffractive/EDOF IOLs
InFo–Instant Focus IOL (Swiss Advanced Vision, SAV-
IOL SA, Neucha
ˆtel, Switzerland) is an EDOF lens employing a
hybrid design. It employs 3 elements: a refractive (6-mm diame-
ter), diffractive element (3.5-mm diameter), and centrally a
spheric element (1-mm diameter).
46
The lens has a closed haptic
design and is available in 2 sizes: with a total diameter of 10.8 mm
and 12.4 mm.
EDEN (Swiss Advanced Vision, SAV-IOL SA, Neucha
ˆtel,
Switzerland) is a hybrid MF-EDOF lens, which is foldable1-
piece hydrophobic acrylic EDOF IOL (Fig. 6A). The optic
is aspheric, refractive-diffractive. The lens is pupil-dependent.
The total diameter is 10.8 or 12.4 mm, with an optic size of
6.0 mm.
47
Harmonis (Swiss Advanced Vision, SAV-IOL SA,
Neucha
ˆtel, Switzerland) is a foldable 1-piece hydrophilic acrylic
EDOF IOL (Fig. 6B). The optic is aspheric, refractive-diffractive.
The lens is pupil-dependent. The total diameter is 10.8 or
12.4 mm, with an optic size of 6.0 mm. The EDOF effect is
þ1.0 D to 2.0 D (0.5 D increments).
48
Synergy: ZFR00 (Johnson and Johnson Vision, Jackson-
ville, FL) is a bifocal combined with EDOF technology for
intermediate vision with potentially better visual continuity than
trifocal lenses (Fig. 6C). It features a wavefront-designed aspheric
surface and keeps the CAs corrections offered on the Symfony. Its
posterior surface is diffractive with 15 rings.
49
DISCUSSION
Laboratory Versus Clinical Outcomes
The introduction of reduced near add in MF IOLs has paved
the way to the development of EDOF IOLs, and they have become
a plausible alternative to traditional MF IOLs. Assessment of the
quality of vision and optical/refractive performance of EDOF
IOLs can be challenging due to the wide array of procedures
available for evaluation of these lenses. In some cases, even if the
FIGURE 5. Hybrid MF refractive/EDOF IOLs: (A) Lentis Mplus X, (B) Acunex Vario AN6 V, (C) Swiss Advanced Vision Lucidis. EDOF IOLs indicates
extended depth-of-focus intraocular lenses; MF, multifocal.
FIGURE 6. Hybrid MF Refractive-Diffractive/EDOF IOLs: (A) Swiss Advanced Vision Eden, (B) Swiss Advanced Vision Harmonis, (C) Tecnis Synergy:
ZFR00. EDOF IOLs indicates extended depth-of-focus intraocular lenses; MF, multifocal.
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optical laboratory benchmark study shows that an IOL has
supreme optical properties, these results are not always correlated
with patient satisfaction and spectacle independence in the sub-
sequent clinical trials. For example, the initial results of the
Wichterle Intraocular Lens–Continuous Focus performance were
presented in an observational study made by a Czech research
group; they indicated excellent visual acuity for far and interme-
diate vision and reasonably good near vision with minimal optical
phenomena.
27
Although the preliminary data were encouraging,
recent investigations revealed high rate of poor quality of vision
and a consistent pattern of spontaneous dislocation of the lens.
The lens was withdrawn from the market and the company ceased
commercial activities in October 2018.
28
For several IOL types, the currently available clinical evi-
dence is limited. In 2017, the American Academy of Ophthal-
mology Task Force Consensus Statement for EDOF IOLs was
published.
50
The report proposed criteria to evaluate clinical
performance of EDOF IOLs, and recommended a minimum of
100 patients in the EDOF IOL group (with a control group of
similar size). The depth of focus for an EDOF IOLs should be at
least 0.5 diopters greater than the depth of focus for a monofocal
IOL at logMAR 0.2 (20/32) Nevertheless, none of the currently
published studies fulfills all the aforementioned requirements. For
further information on visual performance, spectacle indepen-
dence, and patient satisfaction, we refer the reader to the previ-
ously mentioned reviews and references therein.
13
EDOF Versus MF IOLs
Breyer et al noted that with EDOF IOLs distance and
intermediate VA are good; however, near vision still falls short
for most of the EDOF lenses.
17
Although some studies reported
satisfactory quality of near vision with EDOF IOLs, this issue is
controversial.
51
One of the ways to compensate the insufficiency
in near visual acuity in patients with EDOF lenses is mini-
monovision, or mix-and-match strategies with diffractive low-
add lenses which should be considered; nevertheless, using the
mini-monovision may cause decrease in far vision and additional
halos from the low myopia in the contralateral eye.
36
These
studies indicate that mix and match and blended vision with
MF IOLs or EDOF IOLs are promising treatment options for
cataract or refractive surgery in patients who strongly desire
increased spectacle independence; blended vision with EDOF
IOLs particularly represents a viable treatment alternative to
trifocal IOL implantation.
We believe EDOF lenses should be used as monofocal lenses
with a minor improvement for near vision; they can be expected to
provide bad quality of near vision, whereas intermediate vision
can be adequate.
10
For MF hybrid IOLs, one can reduce the
quality of near vision but keeping intermediate vision the same
quality of retinal image but at the same time you decrease the
halos and glare. So, this is probably for conservative indications.
If a patient requires good near vision with an IOL, we believe that
he should receive an MF lens (a refractive and diffractive model)
making the choice depending on the patient profile and prefer-
ences. It is not an easy task to make the choice of lenses and this is
why objective information based on aberrometer internal compo-
nent information would be required. It would also be important to
develop a standardized objective means of measuring and report-
ing visual and refractive outcomes with these lenses, as a guide for
clinicians in the future.
Neuroadaptation is a major concern in MF or EDOF IOLs;
this process is time-consuming and dependent on individual
factors (of which some are unknown).
52
Pure EDOF lenses with
a relevant amount of aberrations to improve near vision may be
difficult to tolerate by the patient; although the brain is adapted to
a certain amount of aberrations over time, a sudden increase in
aberrations may not be accepted. Regarding photic phenomena
the evidence is scarce; however, some studies reported a lower
intensity of photic phenomena in EDOF IOLs when compared
with MF IOLs.
5
Particularly, Savini et al
5
reported smaller mean
size and lower mean intensity of photic phenomena in Mini Well
than in the ReSTOR SV25T. In the Concerto patients reported
minimal photic phenomena with the Symfony IOL; 4 to 6 months
after surgery 87.0% to 97.6% of individuals had no/mild intensity
of halos, glare, or starburst perception.
36
Confusion in Terminology
The pure EDOF lens is a lens that has spherical aberration
increased to elongate the focus but has no multifocality. In doing
that, certain amounts of ocular aberrations are increased on
purpose to create the minimal blur necessary to see different
distances, even though with a “blur.”
10
The cost of this might be
degraded quality of vision. We believe that an IOL should be
named an EDOF lens when it does not have either refractive or
diffractive added multifocality.
10
Importantly, the EDOF tech-
nology cannot provide more than a 1 D range of focus.
For example, the Symphony, Synchrony, At Lara tri are
hybrid IOLs, which combine an EDOF with multifocality. Those
lenses that have attempted to provide more are either out of the
market or the company has closed, or have very bad results and the
reason is that the quality of the retinal image for the first time we
are able to see the retina image quality with the pyramidal
aberrometry, and the results are very different.
Multifocality and EDOF characteristics are not exclusive of
each other. A bifocal IOL may exhibit EDOF characteristics,
likewise with an aspheric monofocal IOL or even a diffractive or
refractive trifocal IOL. Range of vision is partly limited compared
with modern MIOLs (trifocal)—limitation for near. Otherwise
EDOF IOLs could potentially induce less dysphotopic phenom-
ena compared with MF IOLs.
Future research will continue toward finding a balance
between quality of vision, EDOF, and dysphotopsias.
53
The
question still remains, however, as to how we can maximize
postoperative vision at all distances with these lenses? Could IOL
design be improved, or should more hybrid IOLs be introduced
into the market? Or maybe we should consider blended implan-
tation? Counseling and advice are needed to ensure satisfactory
outcomes—for both the patient and the surgeon.
CONCLUSIONS
There is a wide range of IOLs available in the market; a
careful and complete examination of the patient and the IOL
selection which is based on his lifestyle and visual needs would be
recommended. There is confusion in the terminology; some of the
so-called EDOF lenses available today are really MF lenses with
low near add power, in which part of the rest of the power has been
withdrawn to avoid the overlapping of images and the consequent
halos and glare, by a certain standard of focus caused by the
induction of spherical aberration to a certain level. We propose an
Kanclerz et al Asia-Pacific Journal of Ophthalmology Volume 9, Number 3, May/June 2020
200 | https://journals.lww.com/apjoo ß2020 Asia-Pacific Academy of Ophthalmology.

alternative terminology and naming lenses that have combined
optical designs as “hybrid IOLs.”
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