Environmental variables and mobility performance in adults with low vision

Area of Science:

• Ophthalmology
• Mobility Science
• Human Factors Engineering

Background:

• Object avoidance during ambulation for visually impaired (VI) individuals is influenced by vision loss type, light, contrast, and object characteristics.
• Previous research indicates a complex interplay of factors affecting mobility in VI populations.

Purpose of the Study:

• To investigate how different types of vision loss, illumination levels, and object properties affect obstacle avoidance in visually impaired adults.
• To quantify the impact of mesopic lighting on mobility performance compared to photopic conditions.

Main Methods:

• Assessed mobility performance in 88 visually impaired adults on an indoor obstacle course.
• Evaluated performance under both photopic (bright) and mesopic (dim) lighting conditions.
• Categorized participants based on primary vision loss: acuity loss, peripheral field restriction, or a combination.

Main Results:

• Mobility performance significantly worsened in mesopic lighting, doubling the time and object contacts.
• Acuity loss individuals performed better in photopic conditions, but showed relative improvement in mesopic conditions compared to other groups.
• Low contrast obstacles and head/step-level objects were more frequently contacted than high contrast or floor-level obstacles.

Conclusions:

• Mesopic illumination severely impairs obstacle avoidance abilities in visually impaired individuals.
• Object contrast and placement (e.g., floor vs. head level) are critical determinants of successful obstacle negotiation for VI persons.