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Original Investigation
June 11, 2020

Association of Weight-Adjusted Caffeine and β-Blocker Use With Ophthalmology Fellow Performance During Simulated Vitreoretinal Microsurgery

Author Affiliations
  • 1Department of Ophthalmology, Universidade Federal de São Paulo, São Paulo, Brazil
  • 2Vision Institute, Universidade Federal de São Paulo, São Paulo, Brazil
  • 3Johns Hopkins University School of Medicine, The Wilmer Eye Institute, Baltimore, Maryland
  • 4Department of Neurology and Neurosurgery, Neuroengineering and Neurocognition Laboratory, Universidade Federal de São Paulo, São Paulo, Brazil
JAMA Ophthalmol. Published online June 11, 2020. doi:10.1001/jamaophthalmol.2020.1971
Key Points

Question  Is there an association of weight-adjusted doses of caffeine alone, a β-blocker (propranolol) alone, or a β-blocker and caffeine combination with surgical performance by novice vitreoretinal surgeons?

Findings  In this cross-sectional study of 15 vitreoretinal surgical fellows, propranolol alone was associated with improved surgical performance compared with caffeine alone and the combination of caffeine and propranolol.

Meaning  The findings suggest that caffeine is negatively associated with surgical performance among novice vitreoretinal surgeons but that addition of propranolol is associated with improved performance.


Importance  Vitreoretinal surgery can be technically challenging and is limited by physiologic characteristics of the surgeon. Factors that improve accuracy and precision of the vitreoretinal surgeon are invaluable to surgical performance.

Objectives  To establish weight-adjusted cutoffs for caffeine and β-blocker (propranolol) intake and to determine their interactions in association with the performance of novice vitreoretinal microsurgeons.

Design, Settings, and Participants  This single-blind cross-sectional study of 15 vitreoretinal surgeons who had less than 2 years of surgical experience was conducted from September 19, 2018, to September 25, 2019, at a dry-laboratory setting. Five simulations were performed daily for 2 days. On day 1, performance was assessed after sequential exposure to placebo, low-dose caffeine (2.5 mg/kg), high-dose caffeine (5.0 mg/kg), and high-dose propranolol (0.6 mg/kg). On day 2, performance was assessed after sequential exposure to placebo, low-dose propranolol (0.2 mg/kg), high-dose propranolol (0.6 mg/kg), and high-dose caffeine (5.0 mg/kg).

Interventions  Surgical simulation tasks were repeated 30 minutes after masked ingestion of placebo, caffeine, or propranolol pills during the 2 days.

Main Outcomes and Measures  An Eyesi surgical simulator was used to assess surgical performance, which included surgical score (range, 0 [worst] to 700 [best]), task completion time, intraocular trajectory, and tremor rate (range, 0 [worst] to 100 [best]). The nonparametric Friedman test followed by Dunn-Bonferroni post hoc test was applied for multiple comparisons.

Results  Of 15 vitreoretinal surgeons, 9 (60%) were male, with a mean (SD) age of 29.6 (1.4) years and mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) of 23.15 (2.9). Compared with low-dose propranolol, low-dose caffeine was associated with a worse total surgical score (557.0 vs 617.0; difference, –53.0; 95% CI, –99.3 to –6.7; P = .009), a lower antitremor maneuver score (55.0 vs 75.0; difference, –12.0; 95% CI, –21.2 to –2.8; P = .009), longer intraocular trajectory (2298.6 vs 2080.7 mm; difference, 179.3 mm; 95% CI, 1.2-357.3 mm; P = .048), and increased task completion time (14.9 minutes vs 12.7 minutes; difference, 2.3 minutes; 95% CI, 0.8-3.8 minutes; P = .048). Postcaffeine treatment with propranolol was associated with performance improvement; however, surgical performance remained inferior compared with low-dose propranolol alone for total surgical score (570.0 vs 617.0; difference, –51.0; 95% CI, –77.6 to –24.4; P = .01), tremor-specific score (50.0 vs 75.0; difference, –16.0; 95% CI, –31.8 to –0.2; P = .03), and intraocular trajectory (2265.9 mm vs 2080.7 mm; difference, 166.8 mm; 95% CI, 64.1-269.6 mm; P = .03).

Conclusions and Relevance  The findings suggest that performance of novice vitreoretinal surgeons was worse after receiving low-dose caffeine alone but improved after receiving low-dose propranolol alone. Their performance after receiving propranolol alone was better than after the combination of propranolol and caffeine. These results may be helpful for novice vitreoretinal surgeons to improve microsurgical performance.

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    2 Comments for this article
    Caution Please
    Jeffrey Hammersley, MD, ABIM - IM, PulmonaRy | Pulmonary/Critical Care and Sleep Div., University of Toledo Medical Center
    If this paper is taken as support to justify routine beta-blocker use, I have a precautionary tale. During my training and subsequent time on the faculty of the University of Michigan the bulk of currently available beta-blockers were released. As our medical residents began using such blockade prior to stressful presentations we began having status asthmaticus episodes in residents with undiagnosed asthma. Some of these even required intubation and ventilatory support. May I respectfully request that the routine use of beta-blockers in young residents to reduce tremor be approached with an abundance of caution. If you contemplate beta-blocker use, it may worthwhile to consider screening spirometry in residents, of any specialty, that have undiagnosed throat clearing, cough or shortness of breath with exercise. Thanks.
    Reply to Hammersley
    Marina Roizenblatt, MD | Department of Ophthalmology, Universidade Federal de São Paulo, São Paulo, Brazil
    Our research team thanks you sincerely for raising these cautionary points and the constructive format of your comment. We do intend that our paper recognizes potential adverse effects of beta-blocker use, specifically referring to a prior diagnosis of asthma and heart illness as exclusion criteria and getting screening ECGs prior to enrollment. In future work we may consider your good suggestion of spirometry. It is worth considering that propranolol-related adverse effects are usually dose-dependent and that the weight-adjusted propranolol dose used in this study was intentionally “low” as compared to its dose in other clinical disease settings, such as benign essential tremor or systemic hypertension where beta-blocker use is common.

    Most notable however, is that this paper provides data (in an area where data is sparse) that may be useful to surgeons in making their own medical decisions. The prevalence of the practice of beta-blocker use in microsurgery does give merit to informing surgeons, and to the documentation of a quantifiable effect, as noted here. Thank you for the opportunity to emphasize in this forum, that no specific recommendation is offered to surgeons seeking to potentially improve their own surgical performance. We do remain positive that the results of this study are scientifically relevant and also recognize that some physicians may choose to incorporate them, in concert with other available information, into their own clinical practice.

    Thank you for the opportunity to clarify these important points.

    Kind regards. Authors