Caffeine is an ingredient found in beverages such as coffee, tea, hot chocolate and cola drinks. It could be considered the stimulating substance of greater consumption and the most socially accepted worldwide.
Caffeine acts as stimulant of the Central Nervous System, facilitating memorization, the association of ideas and the perception of the senses. It is also a myocardial stimulant; its administration causes an increase of blood pressure and has a positive chronotropic and inotropic effect by inhibition of the cardiac adenosine receptors, resulting in an increase in the heart rate.
Caffeine improves physical performance because it produces vasodilation at the muscular level, the contractile response increases to nervous stimulation and decreases fatigue.
Caffeine is used alongside with analgesics to potentiate antalgic and antimigraine efficacy.
It has a diuretic action due to an increased glomerular filtration and decreased tubular reabsorption. At the same time, they have digestive activity since they increase gastrointestinal secretions and exercise gastrointestinal prokinetic action, and lipolytic movement, activating lipolysis and the displacement of fats.
The consumption of high doses produces excitement, anxiety and insomnia, tremor, hyperesthesia (exaggerated increase in sensitivity in general), hyporeflexia (diminution of reflexes), manic alterations and seizures. Also, they can lead to appearance of dependence: headache, irritability and pathological drowsiness.
Is Coffee Bad For Glaucoma Patients?
A team of researchers from Brigham Hospital and Women in Boston surveyed more than 120,000 people of the United Kingdom and the United States, who had not been diagnosed glaucoma, and it turned out that those who drank more than three cups of coffee a day had a higher risk of developing glaucoma than those who did not.
Even small amounts of coffee threaten to develop this devastating eye disease, which is characterized by the progressive loss of nerve fibers in the retina. The study, published in the journal ‘Science Investigative Ophthalmology & Visual’, recommends consuming less coffee per day to reduce the chances of developing this disease. The researchers found no correlation between the disease and other products with caffeine such as tea, soft drinks or chocolate. One of the main factors that can influence the appearance of glaucoma is the high intraocular pressure. The intraocular pressure is the pressure exerted by eye fluids against the wall of the eye, which is necessary for this organ to remain distended.
When the liquid cannot drain properly, the pressure builds up and can damage the optic nerve. This negative side of coffee contrasts with its benefits. A research published earlier this year in the ‘New England Journal of Medicine’ showed that drinking four to five cups of coffee a day can reduce the risk of heart disease or diabetes.
In Israel, a study is conducted to assess the effect of coffee intake on intraocular pressure. A cross-over study was designed comparing the effect of coffee consumption (180 mg of caffeine in 200 ml of beverage) versus decaffeinated coffee (3.6 mg of caffeine in 200 ml of beverage) on intraocular pressure in patients with normotensive glaucoma or with ocular hypertension. The results show that after 7-10 days of controlled intake of caffeine patients with normotensive glaucoma when they drink caffeinated coffee there is an increase in intraocular pressure (mean: 3.6 mm Hg at 60 minutes) higher than when they drink decaffeinated coffee (average: 0.7 mm Hg at 60 minutes). The results are similar in the group of patients with ocular hypertension. Patients who drink coffee with caffeine show an increase in intraocular pressure that can be clinically significant. The authors concluded that the consumption of caffeinated beverages (<180 mg of caffeine) may not be recommended for patients with normotensive glaucoma or patients with ocular hypertension.
According to the researches, coffee´s effect on intraocular pressure is controversial, because it is a substance that brings multiple benefits, but also constitutes a factor of risk for certain pathologies.
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