Acute effects of caffeine and glucose intake on retinal vessel calibres in healthy volunteers

Int Ophthalmol. 2023 Jan;43(1):207-214. doi: 10.1007/s10792-022-02417-z. Epub 2022 Jul 25.


Purpose: To evaluate the acute effects of caffeine and glucose intake on retinal vascular calibre of healthy adults.

Methods: This prospective crossover study was conducted at the Centre for Eye Research Australia (Melbourne, Australia). Standardized doses of 300 mg caffeine (approximately 3 cups coffee), 30 g glucose or 300 ml of water, were each given to 19 healthy subjects on separate days. Retinal photographs and blood pressure measurements were taken at baseline, 30-, 60- and 120-min after ingestion of each solution. Central retinal artery and vein equivalents (CRAE, CRVE) and the arterio-venule ratio were measured using computer-assisted software. The mean retinal vascular calibre measurements were compared between pre- and post-ingestion images.

Results: After caffeine intake, significant reductions were observed in mean CRAE of - 9.3 μm, - 10.4 μm and - 8.5 μm and CRVE of - 16.9 μm, - 18.7 μm and - 16.1 μm at 30-, 60- and 120-min after intake when compared with baseline (p ≤ 0.002 for all; paired t test). No significant changes were observed in mean retinal vascular calibre measurements after intake of either glucose or water when compared to baseline (p ≥ 0.072 for all). When controlling for baseline characteristics and blood pressure measurements, only caffeine intake had a significant effect on reducing both CRAE and CRVE at all time points post ingestion (p ≤ 0.003 for all, multiple linear regression model).

Conclusion: Caffeine is associated with an acute vasoconstrictive effect on retinal arterioles and venules in healthy subjects. Factors other than blood pressure-induced autoregulation play a significant role in caffeine-associated retinal vasoconstriction.

Keywords: Caffeine; Glucose; Optical imaging; Retinal artery; Retinal vein; Retinal vessels.

MeSH terms

  • Adult
  • Blood Pressure / physiology
  • Caffeine* / pharmacology
  • Cross-Over Studies
  • Healthy Volunteers
  • Humans
  • Prospective Studies
  • Retinal Vein*
  • Retinal Vessels


  • Caffeine