Diurnal Variation in Accommodation, Binocular Vergence, and Pupil Size

Area of Science:

• Ophthalmology and Optometry
• Visual Science

Background:

• Diurnal variations in physiological functions are well-documented.
• Understanding daily fluctuations in visual parameters is crucial for accurate clinical assessments.

Purpose of the Study:

• To investigate diurnal variations in accommodation, binocular vergence, and pupil behavior.
• To assess how these visual functions change at different times of the day.

Main Methods:

• Twenty college students (22.8 ± 2.1 years) participated.
• Measurements of accommodation and binocular vergence were taken at three intervals: morning (9-11 am), afternoon (2-4 pm), and evening (7-9 pm).
• An autorefractometer (WAM-5500) was used to evaluate accommodative response and pupil function.

Main Results:

• Accommodative amplitude was significantly higher in the morning and afternoon compared to the evening.
• Participants exhibited greater esophoria in the morning and afternoon versus the evening.
• Accommodative response magnitude decreased throughout the day.

Conclusions:

• Significant diurnal variations exist in accommodative function and phoria magnitude.
• These findings highlight the importance of consistent timing for visual examinations.
• While modest, these diurnal variations may not impact routine orthoptic evaluations.