Extended Depth of Focus IOLs
Extended Depth of Focus (EDOF or EDF), or Extended Range of Vision, is a new technology that has recently emerged in the treatment of Presbyopia-correcting IOLs. In contrast to multifocal intraocular lenses (IOLs) used in treatment of presbyopia, EDOF lenses work by creating a single elongated focal point to enhance “range of vision” or “depth of focus”.
American Academy of Ophthalmology released consensus guidelines on defining and testing for extended depth of focus (EDF) IOLs. The key principle defining an extended depth of focus IOL is a single, contiguous, elongated focal point that enhances depth of focus. An ideal EDOF IOL would provide a sharp focus over a wide range, from Plano to -1.5D, thus giving patient excellent distance and intermediate vision. However, such a lens remains theoretical.
As of February 2023, there are three major types of EDOF lenses available in the United States.
- Small aperture EDOF lenses (True EDoF): the small aperture increases depth of focus and depth of field due to its pinhole effect. However, because less light gets into the eye, it makes vision difficult in low light conditions. The IC-8 AptheraTM (AcuFocus) is a hydrophobic acrylic single-piece IOL that uses small aperture optics to provide good intermediate and near vision. The Xtrafocus IOL (Morcher GmbH, Germany) is a small-aperture hydrophobic acrylic sulcus IOL with no power designed for implantation as a piggy back lens for patients with a lens already implanted in the capsular bag.
- EDOF-effect lenses: This diffractive multifocal-EDoF lens uses an aspheric anterior surface and a posterior diffractive surface with a echelette design that creates a diffractive pattern that also elongates a single focal point. While still a diffractive optic, the extended foci allows for nearly all light to be transmitted through the IOL, with the reduction of chromatic aberrations. The TECNIS Symfony and Synergy IOL (Abbott Medical Optics/AMO, Inc. of Santa Ana, California, Now Johnson-Johnson Vision) are lenses available in the United States that fall into this category. The Acrysof IQ and Clareon Vivity uses Alcon’s proprietary X-WAVE technology that stretches and shifts light without splitting it and has a discrete change in radial curvature of about 2mm. Studies have shown the Vivity IOL meets ANSI criteria for an EDOF lens.
- Enhanced monofocal IOLs: Also called beam-shaping extended depth-of-focus (EDOF) lenses, these lenses change the geometry of the central optical area, causing a change in the power from center to periphery, either increasing the central power of the lens or elongation of the focus by a wavefront modulation effect. At least two main IOLs fall into this category and are available in the United States - EyHance ICBOO Tecnis lens (J&J) and Rayone EMV (Rayner Intraocular Lens Limited). EyHance ICBOO lens offers a smooth and continuous progression of power from periphery to center, without a demarcation line, theoretically offering the distance performance and minimal photic effects of a monodical lens, while providing intermediate vision. RayOne EMV uses increased positive spherical aberrations to enhance the depth of focus, while the lens periphery behaves aberration neutral. When used for bilateral emmetropia, it allows for ~1.25D of extended visual range.
A thorough review of extended depth of focus IOLs includes IOL models not available in the United States.  Both multifocal and EDOF lenses have been shown to increase levels of spectacle independence, however both lens types may be associated with unwanted photic phenomena such as glare, halos, and photic phenomenon.
IOL implantation after cataract extraction, or as part of refractive lens exchange, is a relatively safe procedure. However, risks that come with invasive eye surgery are still significant and may include, but are not limited to infection, increased IOP, corneal edema, posterior capsular opacification (PCO), IOL decentration, macular edema, and retinal detachment. Severe, vision threatening infections (e.g. endophthalmitis) are rare, but possible, adverse events associated with any intraocular surgery.
High levels of patient satisfaction were achieved in at least one initial study. One hundred two patients (91.1%) and 283 patients(94.6%) in the monovision and non-monovision groups, respectively, said they would recommend the same procedure to their friends and family. In the entire cohort of 411 patients, 385 (93.7%) would recommend the surgery and 388 (94.4%) would choose the same IOL again.
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