One size (does not!) fit all
During the recent decade, all major contact lens manufacturers have changed their
portfolio from unplanned replacement soft contact lenses to frequent replacement and
disposables lenses. Whereas conventional lenses were often available in many different
diameters and radii of curvature, disposable lenses mostly have the “one size fits all”
philosophy. For some patients this does not work, and for them some good alternatives
are available, also in silicone hydrogel materials.
The first example is a 28-year-old female. She had been wearing soft contact lenses for a
few years, and since last year her lens comfort has been decreasing. She has worn all of
the “big brands,” but no lens provided good comfort until the end of the day. Her most
recent lenses felt as though the lens edge was not fitting well, and when she woke up her
eyes were full of mucine debris in the shape of threads. Her simulated keratometry
readings were OD 7.29 mm (46.3 D) OS 7.27 mm (46.4 D).
She preferred wearing monthly replacement lenses, so we made an agreement. We used
the steepest available monthly lens and gave it two weeks. If her cornea were to become
molded while wearing these lenses, she was going to wear “tailor made” lenses. That
lens did not work out, so currently she is wearing a quarterly replacement, custom-made
silicone hydrogel lens with a base curve radius of (BCR) of 7.80 mm. The comfort is good
and remains good during the day, and also the mucine threads are gone.
The second example is a 45-year-old male. His record shows that he has not been one of
the most compliant patients in our practice. He has been wearing lenses with a BCR
between 8.90 and 9.20 mm that he ordered via the Internet. He is complaining of
fluctuating vision. The topography map below was taken after removing his old lenses. As
you can see, the topography is distorted and has a very steep appearance. The simulated
keratometry readings are OD 7.07 mm (47.8 D) and OS 7.14 mm (47.3 D). We ordered a
pair of custom-made soft lenses with a BCR of 7.80 and took another topography after two
weeks. His vision at this moment is 20/20, which remains stable during the day.
When we are fitting RGPs, we always take a closer look at the topography. We want to
align the lens as closely as possible to prevent molding and spectacle blur. When looking
at soft contact lenses, we tend to look only at movement; maybe we need to change our
way of thinking in this regard.