Power Profiles: A Scleral Multifocal Analysis

Background: Scleral contact lenses have gained great popularity in the contact lens
community. As more practitioners are using them, their uses are being expanded to
include multifocal scleral lenses. Are these lenses reaching the full add power? How
quickly from optical center does the power transition from the near to distance optics?
What is the maximum positive power and where is this located from optical center? The
purpose of this study is to analyze various scleral multifocal contact lens designs in two
different distance powers, and to determine what the anterior surface power profiles of
the lenses look like. Methods: Thirteen (13) different scleral multifocal contact lens
designs (26 lenses total) were evaluated. Lens 19 was excluded due to breakage. Power
measurements with varying distances from optical center were generated using the NIMO
TR1504. Power profiles were obtained for all lenses as well as maximum plus power.
Results: Due to the small number of lenses, no measurement results were significant.
There were trends showing differences in the center to full distance power between
myopic and hyperopic lenses. Other notable differences included: difference in zone
sizes between lenses, power graduation from near to distance zone, and positioning of
near optics. Conclusion: Depending on the lens design and distance power ordered,
scleral multifocal lenses need to transition from near to distance power quickly enough so
that proper optics can be presented in front of the pupil for clear visual acuity. This
reinforces the importance of contact lens practitioners working in concert with their
manufacturing laboratory to understand the lens design being worked with, as each
design is different and may require different adjustments. A larger sample size is needed
along with further investigation to ensure the accuracy of this type of analysis.