You may be too young to remember (and we are included in this group), but you used to have to fit soft lenses on patients. Can you believe it? Really, you would take measurements of people’s eyes, do some calculations, and then order a lens to be made for your patients based upon their eye shape. Nowadays, most practitioners have their favorite lens material and choose the lens based on what has been working best for their patients. From our point of view (and personal experience), little has been done to “fit” the lenses. With new data coming out, we ask: Is fitting soft lenses going to become the new normal?

About a year and a half ago, Eef van der Worp, BSc, PhD, shared with me (Kading) some preliminary research on soft lens sagittal depth. We have learned that soft lenses can be fit and that much of what we need to know is based on sagittal depth.

The research team has measured sagittal depth on most of the soft lenses available, and several things stand out about their research. It appears that base curves and diameters as they relate to sagittal depths are not universal across companies. Lenses from different companies that all have an 8.4mm base curve may have little relation to each other. We assumed that if lenses had the same diameter and base curve, then their sagittal depths would be nearly the same, but that is not always the case.

We took their preliminary data home to our practice and displayed the sagittal depth graphs in our contact lens fitting rooms. Over the past year, we have referenced the graphs to help solve many of our contact lens comfort challenges.

When a patient is in a shallow-sagittal-depth lens but is not happy, we try a large-sagittal-depth lens and see what happens. Some patients have smaller corneas (lower sagittal depth) or larger corneas (higher sagittal depth), and this guide has really helped. We may look to the graphs to decide on a starting lens; if that one doesn’t work, we go to a custom lens.

The Verdict

The data from this research (van der Worp et al, 2021) is now widely available (see figure). It has become a normal part of our contact lens “fitting” process. We have our go-to low-, medium-, and high-sagittal-depth lenses, and we are now “fitting” lenses again. Thanks to Dr. van der Worp and his colleagues for making fitting contact lenses the new normal for everyone. CLS

For references, please visit www.clspectrum.com/references and click on document #306.