Abstract
Purpose: :
Many practicing microsurgeons forego their morning coffee prior to operating for fear that caffeine-induced tremor might impact their surgical outcomes. This study aims to objectively measure the effect of caffeine and caffeine withdrawal on hand tremor and on microsurgical skill.
Methods: :
This was a prospective controlled interventional study. Nineteen healthy ophthalmology residents and medical students were recruited. Subjects were categorized as habitual or non-habitual caffeine consumers. Subjects performed four different modules on the EYEsi VRmagic Simulator for Anterior Segment, Mannheim, Germany. Modules included a basic and advanced anti-tremor skill and a basic and advanced capsulorhexis task. All of these tasks required entry into the simulated eye with an instrument and completion of a dynamic task. Non-habitual caffeine consumers performed the modules at baseline (no caffeine consumed for at least three hours) and 50-75 minutes after a caffeine load of 200 mg. Habitual caffeine consumers performed the modules at baseline, after a caffeine load and following abstinence of caffeine for 24 to 48 hours when withdrawal symptoms are at their peak. An objective score between 0 and 100 was assigned by the simulator based on target achievement, efficiency, instrument handling, and tissue treatment. Subjects were also asked to subjectively rate their level of tremor prior to performing each task.
Results: :
Statistical analysis was performed using two factor ANOVA with replication. There was no statistically significant difference in tremor score for any subgroup after caffeine or with caffeine withdrawal. (p=0.662 for the basic and p=0.271 for the advanced anti-tremor module). Caffeine had a detrimental effect on the performance of both simple and advanced capsulorhexis for the inexperienced surgeons (p=0.025 and p=0.014 respectively). Caffeine had a detrimental effect on only the advanced capsulorhexis for the experienced surgeons (p=0.032). Habitual caffeine consumers at all experience levels also showed score reduction on the advanced capsulorhexis only (p=0.001).
Conclusions: :
Caffeine did not have an appreciable effect on tremor, however it did degrade the performance of the capsulorhexis particularly in the novice surgeon and non-habitual caffeine consumer. This could lead us to conclude that caffeine may degrade performance in ways other than by inducing hand tremor. Although caffeine withdrawal is described in the DSM-IV and can often mimic amphetamine or cocaine withdrawal, it did not have a significant impact on either hand tremor or capsulorhexis performance.
Keywords: cataract • training/teaching cataract surgery