[Age and photopic and mesopic visual acuity]

Area of Science:

• Ophthalmology
• Neuroscience
• Human Physiology

Background:

• Visual acuity is crucial for daily tasks and occupational safety.
• Age-related changes in vision can impact performance, especially in low-light environments.
• Previous theories suggested night myopia or presbyopia as causes for reduced low-light vision.

Purpose of the Study:

• To investigate the effect of age on visual acuity at both high and low luminance levels.
• To determine the underlying physiological system responsible for age-related changes in low-light visual acuity.

Main Methods:

• Visual acuity was measured in normal subjects (20-50 years) under high (100 cd/m²) and low (0.8 cd/m²) luminance conditions.
• Interference fringes generated directly on the retina bypassed optical eye effects.
• Statistical analysis confirmed the observed trends.

Main Results:

• High luminance visual acuity remained stable at 20/20 across all age groups.
• Low luminance visual acuity showed a significant decrease with age, averaging 20/30 at 30 years and 20/40 at 40 years.
• The retina-brain system was identified as the primary cause of reduced mesopic visual acuity.

Conclusions:

• Age-related decline in mesopic visual acuity is a significant finding.
• The retina-brain system, not ocular conditions like night myopia or presbyopia, is responsible for this decline.
• These findings have implications for individuals working in low-light conditions, such as pilots and drivers.