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Factors affecting light-adapted pupil size in normal human subjects
B Winn1, D Whitaker, D B Elliott
1Department of Vision Sciences, Glasgow Caledonian University, United Kingdom.
Investigative Ophthalmology & Visual Science
|March 1, 1994
Summary
As people age, their light-adapted pupil size decreases significantly, a phenomenon known as senile miosis. This age-related change in pupil diameter occurs across various light conditions and is independent of gender or eye characteristics.
Area of Science:
- Ophthalmology
- Human Physiology
Background:
- Pupil size regulation is crucial for visual function.
- Understanding factors influencing pupil size is important for clinical assessments.
Purpose of the Study:
- To determine the impact of age, gender, refractive error, and iris color on light-adapted pupil size.
- To investigate age-related changes in pupil diameter across different illuminance levels.
Main Methods:
- Objective infrared-based continuous recording of pupil diameters in 91 healthy subjects (17-83 years).
- Measurements were taken at five photopic ocular illuminance levels (2.15–1050 lm/m²).
- Accommodative status was precisely controlled during measurements.
Main Results:
- Pupil size demonstrated a linear decrease with increasing age across all tested illuminance levels.
- The rate of pupil diameter change per year decreased at higher illuminance levels.
- Pupil size was not significantly affected by gender, refractive error, or iris color (P > 0.1).
- Inter-subject variability in pupil size decreased with increasing luminance.
Conclusions:
- Chronologic age is the primary factor influencing light-adapted pupil size among those investigated.
- Senile miosis, the age-related reduction in pupil size, is evident across a broad spectrum of ocular illuminance levels.