Subclinical variability in visual function modulates visual dependence - independent of age.

Area of Science:

• Vision science
• Gerontology
• Human factors

Background:

• Visual dependence, a factor in falls risk, paradoxically increases with age despite typical visual function decline.
• Understanding the relationship between aging, visual function, and visual dependence is crucial for fall prevention strategies.

Purpose of the Study:

• To investigate the association between age, objective and subjective visual function measures, and visual dependence in healthy young and older adults.
• To determine if age-related visual decline influences visual dependence and spatial orientation accuracy.

Main Methods:

• Assessed 44 healthy adults (young and older) on objective visual functions (visual acuity, contrast sensitivity, depth perception, peripheral vision) and subjective visual function (VFQ-25).
• Measured visual dependence using Subjective Visual Vertical (SVV) tilt errors and motion sickness susceptibility via the Rod and Disc Test (RDT).
• Employed Mann-Whitney U tests for group comparisons and Multiple regression modelling to identify determinants of SVV variability.

Main Results:

• Older adults exhibited lower visual acuity and contrast sensitivity compared to younger adults.
• Visual dependence, measured by SVV tilt errors, was not significantly associated with age.
• Visual acuity and contrast sensitivity significantly, though modestly, predicted SVV tilt error variability in both age groups.

Conclusions:

• Subclinical variations in visual acuity and contrast sensitivity, not age itself, contribute to spatial orientation variability (SVV tilt errors).
• These findings highlight the importance of visual acuity and contrast sensitivity in maintaining spatial stability across the adult lifespan.
• Further research is needed to explore the interplay of visual, vestibular, somatosensory, cognitive, and behavioral factors in visual dependence and falls risk.