Foot clearance and variability in mono- and multifocal intraocular lens users during stair navigation

Abstract

Abstract-Intraocular lenses (IOLs) provide distance and near refraction and are becoming the standard for cataract surgery. Multifocal glasses increase the variability of toe clearance in older adults navigating stairs and increase fall risk; however, little is known about the biomechanics of stair navigation in individuals with multifocal IOLs. This study compared clearance while ascending and descending stairs in individuals with monofocal versus multifocal IOLs. Eight participants with multifocal IOLs (4 men, 4 women; mean age = 66.5 yr, standard deviation [SD] = 6.26) and fifteen male participants with monofocal IOLs (mean age = 69.9 yr, SD = 6.9) underwent vision and mobility testing. Motion analysis recorded kinematic and custom software-calculated clearances in threedimensional space. No significant differences were found between groups on minimum clearance or variability. Clearance differed for ascending versus descending stairs: the first step onto the stair had the greatest toe clearance during ascent, whereas the final step to the floor had the greatest heel clearance during descent. This preliminary study indicates that multifocal IOLs have similar biomechanic characteristics to monofocal IOLs. Given that step characteristics are related to fall risk, we can speculate that multifocal IOLs carry no additional fall risk.

Vestibular Rehabilitation and Factors That Can Affect Outcome

“…61 Stair climbing has been analyzed in older patients with multifocal lenses. 72 There was no difference in stair climbing clearance or descent in either group; however, the sample was small. 72 Bifocals and progressive lenses make adaptation exercises difficult for patients to perform, as they have difficulty keeping the target in focus with the two different focal lenses.…”

“…72 There was no difference in stair climbing clearance or descent in either group; however, the sample was small. 72 Bifocals and progressive lenses make adaptation exercises difficult for patients to perform, as they have difficulty keeping the target in focus with the two different focal lenses. In addition, after cataract surgery, there is an increased incidence of reported falls when wearing progressive lenses.…”

Decomposing sensorimotor variability changes in ageing and their connection to falls in older people

“… Trip probability per-step prediction: We built a model predicting the trip-over probability per step taken on negotiating structured obstacles, specifically ascending stairs with 150 mm risers. We fitted the sensorimotor variability data of the 150 mm condition of the FOHEPO task to a linear model which predicted the variability as a function of age We assumed foot clearance data during stair climbing distribute normally based on literature 47 and our own data (Supplementary Material Fig. 4 ).…”

“…We assumed foot clearance data during stair climbing distribute normally based on literature 47 and our own data (Supplementary Material Fig. 4 ).…”

The role of sensorimotor variability and computation in elderly’s falls

“…We assumed foot clearance data during stair climbing distribute normally based on literature 74 and our own data (supplementary material figure 4). We used published foot clearance to low-rise staircases (as our 150 mm example case) from a study by Riener and colleagues 75 as the mean µ and sigma 150 of our model the standard deviation of foot distributions.…”