Caffeine intake may reduce vessel length density (VD) and perfusion area density (PD) in patients with high myopia, according to a study published in the Journal of Optometry.
Researchers conducted a crossover, self-control randomized trial of 18 participants (mean age: 24.3 years, 12 women) with high myopia. They randomly assigned patients to a 200 mg caffeine capsule or placebo capsule in 2 visits separated by at least 1 week. The team captured and monitored superficial retinal vasculature including VD and PD using spectral domain optical coherence tomography angiography (OCTA). Following baseline measurements, they monitored blood pressure (BP), intraocular pressure (IOP), and subfoveal choroidal thickness (ChT) at 30‐minute intervals until study completion at 3 hours.
The researchers found a significant increase in BP (P <.01), a decrease in ChT (P <.01), and no change in IOP (P =.36) in patients who took the caffeine capsule. VD showed a trend toward reduction at the central 1‐mm circle, and 1‐3 mm annulus (P <.01) using the Early Treatment of Diabetic Retinopathy Study (ETDRS) grid. The team also noted a PD reduction trend at the central 1‐mm circle, 1‐3 mm annulus, and the entire 3‐mm circle (P <.01). Compared with baseline, significant VD and PD reductions emerged 3 hours following caffeine capsule intake at the central 1‐mm circle; however, the reduction was small (VD: by 1mm-1; PD: by 1%). Researchers reported no significant changes in other regions.
“The current study found significant reduction in VD and PD after taking 200 mg of caffeine capsule,” according to the researchers. However, they added, “Such a small amount of alteration may be clinically irrelevant.”
Study limitations include a limited sample size, failure to differentiate between low and high caffeine consumers, short study duration, and a relatively small caffeine intake based on participants’ body weight.
Law VKM, Lam AKC. Effect of caffeine on superficial retinal vasculature of the macula in high myopes using optical coherence tomography angiography – A pilot study. J Optom. Published online May 28, 2022. doi:10.1016/j.optom.2021.06.005