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BLOG: An evidence-based approach to choosing presbyopia-correcting implants
Without question, extended depth of focus lenses have heightened interest in presbyopia-correcting lenses for surgeons and patients. As our cover story relates, these implants provide an elongated focal range rather than two distinct focal points as in a multifocal lens. Although optically it uses a distinct mechanism, functionally the Tecnis Symfony from Johnson & Johnson Vision works similarly to a low add multifocal in giving patients distance and intermediate vision.
But like any lens that extends beyond a single focal point, the EDOF Symfony does have its limitations. Even with a perfect emmetropic result, a few patients complain about “spiderweb” glare, especially while driving at night. These complaints become much more common when there is residual refractive error. These implants are indeed more forgiving of residual refractive error than traditional high add multifocals, but I’ve learned to avoid doing mini-monovision with them because of these unwanted visual phenomena.
About 60% of my cataract patients choose presbyopia-correcting lenses, and here’s an approach I have found to be very rational based on data from several studies we have performed on patient satisfaction.
First, let’s assume that we’ll only talk about patients who are good candidates for a multifocal or EDOF lens. They have healthy maculas, controllable dry eye and fairly aberration-free corneas.
For patients who desire distance and intermediate (but not near), if they have low astigmatism, the Symfony lens is a perfect choice. It has high refractive accuracy and only rare issues with unwanted visual phenomena. Other reasonable choices for this patient are bilateral ReSTOR ActiveFocus 2.5 lens (Alcon) or Crystalens (Bausch + Lomb), targeting emmetropia with all of the above.
If a patient has astigmatism greater than 0.5 D and desires distance and intermediate vision, the Symfony toric (as well as other Tecnis monofocal and multifocal lenses) lacks rotational stability for me to be completely confident in it. Instead, I will choose a ReSTOR ActiveFocus 2.5 toric or Trulign (the toric version of Crystalens) for both eyes, again targeting emmetropia. The ActiveFocus lens yields the lowest complaints of glare and halos of any multifocal I have worked with and has excellent rotational stability in its toric form.
For patients who desire distance, intermediate and near, I do not recommend targeting a mini-monovision with an EDOF Symfony lens. Too many of these patients do not tolerate the spiderwebs in the nondominant, near eye. Instead, these patients will do well with a ReSTOR ActiveFocus 2.5 in the dominant and a +3.0 ReSTOR in the nondominant eye. (With low astigmatism, it also makes sense to do this with a Tecnis multifocal 2.5/3.25 as well, again for patients with low astigmatism.)
Another approach for patients wanting distance, intermediate and near is to do mini-monovision with either the ReSTOR ActiveFocus 2.5 (targeting plano and –0.5 for the dominant and nondominant eyes, respectively) or the Crystalens (targeting plano and –0.7 D). When more than 0.5 D of astigmatism is present, the toric versions of each these lenses provide excellent rotational stability, with the Trulign having the best rotational stability of any presbyopia-correcting lens, according to FDA study data.
We have studied patient satisfaction extensively in our practice using MDbackline, our software that encourages every postop patient to report his or her perceptions in an orderly way. A recent study we performed looked at the combination of a ReSTOR ActiveFocus 2.5 mixed with a ReSTOR 3.0 in the dominant and nondominant eyes. Comparing these patients to similar eyes that received bilateral 3.0 add ReSTOR lenses, we found some important differences: Spectacle independence is almost identical, except that patients with a 2.5/3.0 combination have significantly better computer vision than 3.0/3.0. Also, glare and halo complaints were significantly less prevalent in patients implanted with the 2.5/3.0 combination. I suspect this is because the ActiveFocus lens has a distance-focused central optic, yielding similar low contrast vision to a monofocal implant.
We are also beginning to collect data on patients with mini-monovision using the ActiveFocus platform in both eyes. This approach too seems promising now, as we maintain spectacle independence without significantly conceding glare and halos.
Just a few years ago, it was unrealistic to hope that we could give patients distance, intermediate and near with multifocal lenses. Both EDOF and low add multifocal lenses now offer promise for patients to have natural, uncompromised vision after cataract surgery. The new lenses have truly converted me, a surgeon committed to almost exclusively using accommodating implants, to one who is fully comfortable recommending multifocal and EDOF technology as a first choice to well-selected patients.
Disclosure: Hovanesian reports he is a consultant for Alcon, Bausch + Lomb and Johnson & Johnson Vision, and is the founder of MDbackline.