Article

Multifocal lens glasses (MfLs) negatively affect vision, increase falling risk
and contribute to gait changes during stepping. Previous studies on the effects
of MfLs on gait have focused on experienced wearers. Thus, the initial response
of first-time wearers, who may face significant challenges in adapting to these
glasses, is not well understood. This study aimed to quantify the effects of MfLs
on novice wearers during stepping up and down. Additionally, young adults were
compared against a middle-aged adults to determine the validity of convenience
sampling in testing novice response to MfLs. Fifteen young adults (18-34 y.o.)
and seven middle-aged adults (46-56 y.o.) were recruited to perform stepping
trials while wearing progressive MfLs and blank single lens glasses. Participants
stepped up and down from a 75 mm and 150 mm step in randomized order. Step
placement, minimum toe clearance, lower body kinematics and stepping time were
measured during step up. Step placement, minimum heel clearance, vertical forces
and stepping time were measured during step down. MfLs significantly increased
toe clearance in the lead and trailing legs, hip flexion, knee flexion and
stepping time during step up and increased vertical forces and stepping time
during step down. Step placement and hip angle explained 17% of the toe clearance
variability. Changes during step up suggest a more conservative adaptation while
increased forces during step down suggest a reduced level of control. No age
group effects were observed, which supports the use of convenience sampling for
evaluating the novice response to MfLs.
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