Is there any evidence of energy drinks causing retinal damage and visual impairment?

(c) Ophthalmology Management

In a recent presentation at the virtual EURETINA meeting, a study from Turkey suggests consumption of energy drinks may lead to acute, reversible changes in retinal vascular density parameters.

The aim of the study, conducted at Health Sciences University School of Medicine in Afyonkarahisar, Turkey, was to use OCT angiography (OCTA) to analyze the retinal and choroidal morphological changes after energy drink consumption in healthy volunteers.

In 42 volunteers with a mean age of 20.5 years and no systemic or ocular disease, OCTA parameters were measured at various intervals up to 24 hours after consumption of 250 mL of Red Bull energy drink, containing caffeine, taurine and inositol as ingredients. The same measurements were taken 1 month later after drinking the same amount of water.

As per the study, vascular density measurements of the parafoveal and perifoveal deep capillary plexus obtained after energy drink consumption were significantly higher as compared with baseline. This increase seemed to start after half an hour and continued until measurement at 24th hour. 

In comparison, after just water consumption, there was a statistically significant increase in choroidal thickness at 30 minutes and 1 hour, but no significant difference was found in other parameters.

The authors of the study suggest that though caffeine has vasoconstrictive effects on retinal vessels, this study suggests that the effect of energy drinks is not only because of caffeine. The vasodilating effect due to inositol and taurine is predominant over the caffeine-induced vasoconstrictive effect, leading to increased vascularization of the deep capillary plexus in the parafoveal and perifoveal region. 

There have been other publications that have alluded to the effect of energy drinks on retina, including by the same group that presented this paper at the EURETINA meeting. In the paper published by this Turkish group, they found that the vascular density measurements of parafoveal and perifoveal deep capillary plexus after energy drink consumption were statistically significant. This increase in vascular density of the deep capillary plexus after energy drink consumption seemed to start after half an hour and continued until measurement at 24th hour.

In another paper published in 2017, a group from Costa Rica (authors include Dr. Lihteh Wu, who is on Retina Global Advisory Board) suggested high consumption of energy drinks may lead to intraretinal hemorrhages and acute visual loss.

In another paper published by a group in Canada in Investigative Ophthalmology and Visual Science, an ARVO Journal, the study in volunteers found that drinking an energy drink induces a vasoconstrictor effect on the optic nerve capillary structures in each participating subject. About 15 minutes after ingesting the drink, the blood oxygenation in the capillaries’ was found to be decreased, an average of 7,8%, and it continued to remain low 60 minutes later. They recommended that energy drinks should not be a recommendable drink for patients with a weak blood flow in the capillaries’ structures of the eye, like various types of glaucoma.

Another study from Ghana suggests that energy drinks may produce significant reduction

in intraocular pressure in the eye but have no effect on blood pressure. These findings may be interpreted as reflecting the effect of the combination of caffeine and taurine in the energy drink, and may result from the known hypotensive effect of taurine.

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Energy drinks have been found to have associated systemic effects as well, as alluded to in various publications referenced below. 

So what do we suggest? Our recommendation is to moderate the number of drinks, similar to the moderation for eating certain types of food, or alcohol, which health professionals advice people in general. If you have or are suspected to have any pre-existing condition that may likely cause impairment in your blood flow in the retina or the optic nerve, it may be best to seek the advice of your ophthalmologist or optometrist about it. 

Source: 1. More information in the following publications - 2 3 4 5

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