Choose the extended depth of focus IOL that will have best results with fewest compromises. The three main EDOF IOL designs available in the U.S. are small aperture, diffractive optics and beam shaping.
Our goal in cataract surgery is to restore vision to our patients and also to tailor the results to their needs.
While some patients would be very happy with a monofocal IOL and a target of great distance vision while using reading glasses for near work, some patients have a strong desire to lessen their dependence on spectacles. The two primary designs for giving patients a wider range of vision without glasses are multifocal IOLs and extended depth of focus (EDOF) IOLs, each having their own benefits and compromises.
Multifocal IOL designs, typically trifocal or bifocal in nature, split the incoming light using diffractive optics, thereby providing a wide range of vision with a near addition of up to 3.5 D. This allows vision from far distance to as close as 30 cm (12 inches) without glasses, provided that there is sufficient illumination. The compromise is that this splitting of light into multiple zones decreases contrast and induces glare/halos, particularly at night.
EDOF IOLs aim to lessen the compromises of these multifocal IOL designs but, as a result, produce less range without glasses, typically about 1.5 D. This allows vision from far distance to as close as 67 cm (26 inches) without glasses. If used in a mild monovision approach with one eye at emmetropia and the other eye at -1 D, this can be extended to a binocular range of 2.5 D, which brings the near point closer to about 40 cm (16 inches). Because residual astigmatism can also increase the depth of field, we compare these EDOF models in eyes with emmetropia and no residual cylinder (Figure 1). The three main EDOF IOL designs available in the U.S. are small aperture, diffractive optics and beam shaping.