When simultaneous-design multifocal contact lenses are fit on presbyopic patients, the assumption is that their optical center aligns with a wearer’s visual axis. However, we understand that these two points of interest are rarely coincident when such a lens is placed on eye.

A randomized, single-masked, IRB-approved study evaluated the effects of offset multifocal optics in relation to subjects’ visual axes on overall success of soft multifocal contact lens wear (Ramdass et al, 2018). During the initial visit, topography was performed over SpecialEyes 54 Multifocal (SpecialEyes, LLC) trial lenses. The distance from the visual axis to the approximate center of near optics was measured using the instrument’s built-in software to determine the misalignment between the two points. Two pairs of lenses were ordered, one with geometrically centered optics and the other with optics displaced nasally 1.0mm.

At follow-up, logMAR visual acuity at both distance and near were recorded for both the centered and offset lens pairs. Additionally, all subjects rated their binocular distance and near visual acuity as well as their ability to view the following specific targets held at set distances:

1. Article in a magazine
2. Email on a cell phone
3. Usage instructions on an eye drop bottle

Difference topography maps were utilized to compare no lens wear at baseline with the zero-offset (Figure 1) and 1.0mm-offset (Figure 2) optics at study visit #2. All (100%) of the measured misalignments were located temporal to the visual axis for the zero-offset lenses compared to 61% in the 1.0mm-offset lenses. The average binocular distance visual acuity (DVA) while wearing the 1.0mm-offset lenses and the zero-offset lenses was 0.08 (± 0.07) and 0.11 (± 0.12), respectively. The average binocular near visual acuity (NVA) while wearing the 1.0mm-offset lenses and the zero-offset lenses was 0.03 (± 0.09) and 0.09 (± 0.10), respectively. There was no statistically significant difference (SSD; α = 0.05) in objective measurement of distance visual acuity with either lens pair (p = 0.43). However, a SSD exists at near viewing distances (p = 0.04) and in subjective responses when viewing various targets, with 19 out of 20 subjects who completed the study favoring the lens pair with offset near optics.

The Results Are Clear

This evaluation determined that a 1.0mm nasal offset of multifocal optics provided both a statistically and a clinically significant difference for subject performance and preference when viewing various types of near targets. Distance viewing was similar regardless of lens pair worn.

Following are examples of feedback directly from subjects while wearing multifocal lenses with offset near optics as compared to the pair with zero-offset optics:

• No letters are overlapping.
• I have less of a three-dimensional effect.
• The double letters are gone.
• I don’t see a halo around the letters anymore.

Quality of vision can be improved by nasally decentering the optics in near-center multifocal lenses. CLS

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