The effect of caffeine on the accommodative response/accommodative stimulus function and on the response AC/A ratio

Area of Science:

• Ophthalmology
• Neuroscience
• Pharmacology

Background:

• Caffeine is a widely consumed stimulant with known effects on the central nervous system.
• Visual functions like accommodation and convergence are complex neuromuscular processes.
• Understanding how common substances affect visual parameters is crucial for eye health and performance.

Purpose of the Study:

• To investigate the effects of caffeine on human accommodation and convergence responses.
• To quantify changes in the accommodative response/accommodative stimulus (Ar/As) slope and the accommodative convergence/accommodative convergence (AC/A) ratio.
• To determine if caffeine impacts the relationship between accommodative and convergence eye movements.

Main Methods:

• A phoro-accommodometer was used to measure accommodation and convergence.
• 17 experimental subjects ingested 200 mg of caffeine.
• 16 control subjects underwent measurements at two separate sessions without caffeine intervention.

Main Results:

• The Ar/As slope increased by 0.05 D/D in the caffeine group (p<0.05).
• The response AC/A ratio decreased by 3.05 delta/D in the caffeine group (p<0.05).
• The y-intercept of the convergence response/accommodative response increased by 3.7 delta in the caffeine group (p<0.05).

Conclusions:

• Caffeine ingestion significantly alters visual vergence and accommodation control.
• These findings suggest caffeine impacts the neural pathways regulating eye movements.
• Further research is warranted to explore the clinical implications of caffeine on visual function.