Summary
Using a wearable eye tracker and spectroradiometer in real-world conditions, this study found that melanopic illuminance better predicts light-adapted pupil size than photopic illuminance, and that pupil size declines with age—particularly at lower light levels. These findings argue for adopting melanopic metrics in lighting standards and accounting for age when designing personalized lighting solutions, especially in environments serving older adults.
Key Findings
- Pupil size ranged approximately 2–8 mm across bright to dark illumination conditions in natural viewing.
- Melanopic illuminance provided a better model fit for predicting pupil size than photopic illuminance under real-world conditions.
- Pupil size decreased with increasing age (N=83, ages 18–87), with steeper age-related slopes observed at lower light levels.
- No significant effects of sex, iris colour, or caffeine consumption on pupil size were detected.
- Results suggest photoreceptor integration (beyond a single channel) plays a role in steady-state pupil control.
Categories
The Science of Light: Demonstrates that melanopic units provide better model fit than photopic units for predicting pupil size, supporting melanopsin-based metrics in lighting standards.
Eye Health & Vision: Characterizes pupillary light reflex across the human lifespan under natural viewing conditions, with direct implications for age-related vision and lighting design.
Author(s)
R Lazar, J Degen, AS Fiechter, A Monticelli
Publication Year
2023
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