Where the art meets the science: How do we balance refractive status to improve visual range and comfort? The Light Adjustable Lens™ (LAL®)—and LAL+® especially—is aspheric in design. It allows us to blend vision with one eye being set for distance, and the other to the patient’s preferred working distance, while preserving binocularity and visual comfort. It’s this unique design that separates the LAL from other monofocal IOLs—but let’s be real, calling the LAL just a monofocal is like calling the Mona Lisa just a painting.
More than 90% of my patients elect some level of blended vision. But just how much offset do we need? Light Delivery Device™ (LDD™) targeting isn’t like monovision contact lens fitting. With contact lenses, it’s not atypical to have 2.00 to 2.50 diopter anisometropia. This, understandably, isn’t well tolerated by everybody. I can’t tell you how many times I’ve heard, “Doc, I tried monovision and couldn’t stand it,” yet the patient ends up doing very well with LAL blended vision. The worst mistake you can make is pushing the non-dominant eye’s myopia too far. In our practice, I rarely push the non-dominant eye past -1.25. On average, our degree of anisometropia is 1.13 D with the LAL, and 1.05 D with the LAL+. With the LAL+, because of its more aspheric design, pushing past -1.25 D can have minimal and sometimes even counterproductive effects.
If our intent is blended vision, my first treatment is usually plano in the dominant eye and -0.75 in the non-dominant eye. The goal is to provide the patient with as little myopia as needed to meet their lifestyle demands, as to avoid compromising the distance or creating any anisometropia issues. Incremental movement in the myopic direction is optically advantageous and more predictable. Alternatively, trying to backtrack if you push too far can be difficult (although not impossible). If needed, I push a little more minus in the nondominant eye, targeting no further than -1.25. But never say never! There are a few occasions where I will push further, but it’s only for certain patients based on visual need and after proper education.
What about patients with extremely high near demand? Bilateral myopia is very doable, and can be quite comfortable. It is important, however, that the patient fully understands they may need a light spec Rx for distance tasks. Even in these scenarios, I still offset the two eyes slightly. Usually, my target will be -0.50 in the dominant eye, and -0.75 in the non-dominant eye. From there, I add 0.50-0.75 in the non-dominant eye, allowing 1-2 weeks in between treatments to allow neural adaptation. Patients are often surprised by how well they can still see at distance uncorrected, even with a bilateral myopic target. It’s not surprising when I have a -0.50-set eye still attain 20/20. Yes, it may be a “push” 20/20, but still 20/20 nonetheless!
Obviously, this isn’t your grandma’s monofocal IOL! The beauty of this process is we get three shots to get it right, and it’s completely customizable. LDD targeting is an art and open communication with your patient is crucial.
