Following the New Generation

Modern refractive extended depth of focus (EDOF) intraocular lenses (IOLs) induce fewer dysphotopsias than older diffractive IOLs and appear highly suitable for mini-monovision approaches to presbyopia treatment, said Francesco Carones MD.

The EDOF IOLs currently available include diffractive and refractive varieties: Diffractive options include the AT LARA (Zeiss) and the Symfony (Tecnis), which use echelette technology based on Fresnel principles. Refractive options such as the Clareon^® Vivity^® (Alcon) and the PureSee (Johnson & Johnson) use wavefront stretching and other power manipulation strategies to expand defocus. And the Mini WELL^® (Sifi) provides an extended depth of focus, introducing different and controlled amounts of spherical aberrations (SAs) within 3-mm diameter in the central part of the IOL optic. The newer non-diffractive models provide around 1.75 D of defocus, Dr Carones said.

“The first generation of refractive EDOF IOLs provided more spectacle independence than monofocal with slight dysphotopsia,” Dr Carones said. “The new generation of refractive EDOF lenses provides more in the way of spectacle independence without increasing dysphotopsia.”

Optical bench testing shows the PureSee has a flatter defocus curve from distance to near compared to the Tecnis Eyhance enhanced monofocal or the Tecnis monofocal IOL. Clinical studies confirm those results and show a similar dysphotopsia profile with the Eyhance and PureSee IOLs, with more than 90% either not noticing or only slightly bothered by halos, starbursts, and glare. The two lenses also perform similarly regarding contrast sensitivity.

Because of the low degree of dysphotopsia induced and good contrast sensitivity, non-diffractive EDOF IOLs offer the potential to provide a high degree of spectacle independence to some patients for whom multifocal IOLs would normally be contraindicated. Such patients would include those for whom night-time dysphotopsia could be a major problem and those with mild ocular comorbidities such as ocular surface abnormalities and early macular changes.

Another potential application of EDOF IOLs is in a mini-monovision strategy, Dr Carones said. He presented the results of a study he and his associates recently conducted involving three groups of 25 patients comparing two mini-monovision strategies—one with an enhanced monofocal and the other with a multifocal IOL. One group underwent bilateral implantation of the Vivity IOL, with one eye targeted to plano and -0.5 D in the other eye. Another group underwent bilateral implantation of the Impress (Hoya) enhanced monofocal IOL with one eye targeted to plano and the other eye to -0.5 D to -0.75 D. The third group underwent implantation of the diffractive hybrid Synergy (Johnson & Johnson) multifocal IOL targeted to plano in both eyes.

The study found 80% of the Vivity and Impress groups said they rarely or never needed reading glasses at 40 to 45 cm, and 100% of both groups said they never needed glasses for reading at intermediate distances (60 to 65 cm). In the multifocal group, 100% said they rarely or never needed spectacles for near, intermediate, or distance vision. Regarding dysphotopsias, the proportion reporting never or rarely seeing halos, light rings, or starbursts in night-time conditions was 80% in the Vivity group, 100% in the Impress group, and 24% in the Synergy group.

Dr Carones presented his paper at the ESCRS eConnect Webinar, “Evidence-based overview of current premium IOL technologies.”

Francesco Carones MD is the medical director and physician CEO of Advalia Vision, Milan, Italy. fcarones@carones.com