April 2019

CATARACT

EDOF fundamentals
What they are, how and when to use them


by Chiles Aedam R. Samaniego EyeWorld Contributing Writer


EDOF IOL defocus curve; brown = Symfony ZXR00 (n=62); red = monofocal ZCB00 (n=73)
Source: Daniel Chang, MD

 

The U.S. FDA has defined an EDOF [extended depth of focus] IOL as a lens that provides at least an additional 0.5 D of 20/30 acuity range over the baseline lens model,” Daniel Chang, MD, told EyeWorld. “Additionally, the clinical defocus curve should decrease strictly monotonically (without an inflection upward).”
In other words, as the alternate nomenclature for this type of lens suggests, EDOF IOLs provide an extended range of vision as opposed to a number of peaks or focal points of acuity.
EyeWorld reached out to Dr. Chang as well as James Loden, MD, Shannon Wong, MD, and Elizabeth Yeu, MD, to get some clarity on a range of topics concerning this new generation of IOL.

Expanding the point
Currently, the Tecnis Symfony (Johnson & Johnson Vision) is the only FDA-approved EDOF IOL. This IOL uses a diffractive optic that employs a proprietary echelette design. In addition to extending the depth of focus, the design manipulates chromatic aberration, according to Dr. Loden.
Other technologies are being employed to achieve EDOF. The IC-8 (AcuFocus), approved for an investigational device exemption by the FDA in November 2018, uses pinhole optics, while others, Dr. Chang said, “attempt to leverage aberrations” to achieve the same effect.
The difference between EDOF and multifocals is pointed. Multifocals currently come in bifocal and trifocal designs, the latter only available outside the U.S. “These IOLs provide two to three areas of more focused light along the defocus curve,” Dr. Yeu said.
In other words, Dr. Wong said, EDOF IOLs provide continuous clear focus over an extended range while multifocals involve relatively defocused areas between focal points.
Thus, using multifocals involves nailing the refractive outcome to get two smaller focal points into usable ranges. In contrast, “EDOF IOLs have a single larger focal range with greater flexibility for refractive outcome,” Dr. Chang said.
To the patient, the difference should be clear. “The Symfony IOL allows for ~92% light transmission, which is greater than what is seen with domestically available multifocal IOLs,” Dr. Yeu said. “Clinically, this translates to greater contrast sensitivity.”
In addition, in Dr. Loden’s experience, EDOF IOLs have fewer halos and dysphotopsias than multifocals, albeit with the trade-off of less uncorrected fine near vision without spectacles.

EDOFs vs. multifocals in practice

EDOF IOLs have limitations, so a role for the traditional multifocal remains. “In my market the prime candidates for EDOF technology lenses are patients who are distance and intermediate dominant,” Dr. Loden said.
Prime candidates for EDOF IOLs in his practice include farmers who spend the day operating heavy equipment guided by GPS displays positioned about 3 feet away from their eyes or otherwise outdoor-oriented patients. In contrast, multifocal candidates say they love reading, love cooking, and hardly drive at night.
Meanwhile, Dr. Chang uses the Tecnis Symfony EDOF IOL as his go-to presbyopia-correcting IOL “because of its superior image quality, continuous range of vision, night vision symptom profile, and availability in a toric format,” he said. However, “if patients want better uncorrected near vision than I think I can provide with an EDOF IOL, I will offer a Tecnis multifocal IOL, in particular the +3.25 add (ZLB00) version, which provides an ideal reading distance for many patients.”
In Dr. Wong’s practice, while 95% of the presbyopia-correcting IOLs they implant are EDOF, they also go further to incorporate multifocals. In select cases, they implant a multifocal IOL in the second eye after implanting an EDOF IOL in the first. “By placing a multifocal lens in the second eye, we
can use the bimodal strength of the multifocal lens to give excellent far and near vision from the second eye while the Symfony lens placed in the first eye gives great far and mid-range vision,” he said.
Dr. Wong also finds EDOF IOLs useful when implanted bilaterally for monovision, with most patients tolerant of a 0.50 D myopic offset between the eyes. “The first eye is usually plano to –0.25 SEQ and the second eye is usually –0.25 to –0.75 D SEQ with the Symfony allowing great uncorrected far/mid and near vision,” he said.
Dr. Yeu also successfully uses the Symfony for monovision, but only offsets the non-dominant eye by –0.50 to –0.75, and only reserves this for patients who tolerated traditional monovision in soft contact lenses prior to cataracts forming. This micro-monovision “provides an excellent range of intermediate through near vision in the near eye, as compared to distance and either intermediate or near.” For the dominant eye, these patients may get another Symfony IOL but also do well with a monofocal IOL, which “often obviates any concerns for scotopic dysphotopsias.”
EDOF IOLs can expand a practice to include post-refractive cases. “Because the Symfony lens works well in eyes that have had prior LASIK and RK—which represents 35–40% of our surgical population—it has expanded the patient base of candidates who can optimize their vision with lens implant surgery,” Dr. Wong said. “We regularly implant EDOF lenses in patients with LASIK and up to 18 cut RK. The results have been fantastic to date.”
“Prior to the introduction of EDOF lenses, we used multifocal lenses extensively with great results,” Dr. Wong said. “The EDOF results have exceeded the results we could achieve with the multifocal lenses overall.”

About the doctors
Daniel Chang, MD
Cataract and refractive surgeon
Empire Eye & Laser Center
Bakersfield, California

James Loden, MD
Founder and president
Loden iVision Centers
Nashville, Tennessee

Shannon Wong, MD
Austin Eye
Austin, Texas

Elizabeth Yeu, MD
Assistant professor of ophthalmology
Eastern Virginia Medical School
Partner, Virginia Eye Consultants
Norfolk, Virginia

Financial interests
Chang: AcuFocus, Johnson & Johnson Vision
Loden: Johnson & Johnson Vision
Wong: Johnson & Johnson Vision
Yeu: Alcon, Carl Zeiss Meditec, Johnson & Johnson Vision

Contact information
Chang
dchang@empireeyeandlaser.com
Loden: lodenmd@lodenvision.com
Wong: shannon@austineye.com
Yeu: eyeulin@gmail.com

EDOF fundamentals What they are, how and when to use them EDOF fundamentals What they are, how and when to use them
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