In this small study, wearers of multifocal contact lenses made fewer head movements than those wearing single-vision contact lenses or PALs. Photo: Getty Images.

A recent study sought to evaluate whether there are differences in gaze and behavioral metrics between common types of refractive correction for presbyopia. The authors randomly assigned 15 presbyopes to single-vision CLs (SVCLs), multifocal contact lenses (MFCLs) or progressive addition lenses (PALs) at five separate study visits. At each visit, they used a Pupil Core headset to record participants’ eye and head movements while they performed three visual tasks: reading, visual search and scene observation. The gaze parameters of interest were fixation duration and head movement, and behavioral metrics included reading speed, reading accuracy and visual search time.

After performing linear regression and post hoc analysis on the data, the authors reported the following observations:

• Reading speed was significantly faster in SVCLs than in MFCLs and PAL spectacles.
• There were no significant differences in visual search times based on the type of refractive correction worn or the viewing distance.
• Fixation duration varied across different visual tasks (reading, visual search, hazard perception), with significantly longer fixation durations observed during distance vision tasks.
• During visual search tasks, PAL spectacles exhibited significantly more horizontal and vertical head movements vs. SVCLs and MFCLs.
• Participants rated SVCLs higher than MFCLs in distance vision, near vision and overall impression.
• Comfort scores were higher for contact lenses (SVCLs and MFCLs) than PAL spectacles.
• SVCLs and PAL spectacles demonstrated statistically significantly better visual acuity scores vs. MFCLs.

Looking at these findings, the only behavioral metric affected by the type of refractive correction was reading speed, while reading accuracy and search time were not different between correction types. On the other hand, both studied metrics of gaze behavior—fixation duration and head movement—were affected by the correction modality worn.

Regarding the last two findings in the bulleted list above, the authors pointed out that given the evidence that contact lens comfort is associated with vision, this may have influenced the superior visual acuity and coinciding favorable comfort scores observed in SVCLs.

“The findings of this study suggest that under certain conditions, wearers of MFCLs make fewer head movements compared to PAL spectacles,” the authors concluded. “Gaze behavior metrics offer a new approach to compare and understand contact lens and spectacle performance, with potential applications including peripheral optical designs for myopia management,” they wrote.