The prevalence of simple anisocoria

Area of Science:

• Ophthalmology
• Physiology

Background:

• Anisocoria, or unequal pupil size, is a common clinical finding.
• Understanding the prevalence and variability of anisocoria in normal subjects is crucial for accurate diagnosis.

Purpose of the Study:

• To investigate the prevalence and variability of anisocoria in a cohort of normal subjects.
• To determine if factors such as time of day, day of the week, sex, age, or iris color influence anisocoria prevalence.

Main Methods:

• Pupil size was photographed in 128 normal subjects under dim light conditions.
• Data were collected over five consecutive days, with morning and afternoon sessions.
• Anisocoria was defined as a pupillary inequality of 0.4 mm or more.

Main Results:

• 41% of subjects exhibited anisocoria (≥0.4 mm) at some point during the five-day observation period.
• Only 3% of subjects consistently showed anisocoria across all ten photography sessions.
• At any single examination, approximately 19% of subjects displayed anisocoria (≥0.4 mm).
• Prevalence was not significantly affected by time of day, day of the week, sex, age, or iris color.

Conclusions:

• Pupillary inequality is common but often transient in normal individuals.
• The observed prevalence of anisocoria is highly dependent on the definition used.
• Anisocoria in normal subjects is not influenced by circadian rhythms, weekly variations, or demographic/physical characteristics.