Summary: Several studies have shown that the caffeine metabolite 7‐methylxanthine (7‐mx) prevents myopia and eye elongation in animals subjected to form deprivation. A randomized, placebo‐controlled clinical trial with up to 8 years of follow‐up including a total of 750 myopic children aged 7–18 years has demonstrated that 7‐mx is safe and without side effects. In the age‐group 8–15 years the myopia progression and the corresponding eye elongation is reduced by around 60% with one tablet of 400 mg 7‐mx twice per day. The efficacy would probably improve if the serum concentration of 7‐mx could be kept more constant by means of a sustained release formulation. 7‐mx appears to work by blocking adenosine receptors in the posterior part of the eye and increasing the concentration of scleral collagen. The accelerated myopia progression found in periods with low ambient lighting may be related to increased accumulation of adenosine in the retina or retinal pigment epithelium. Thus, hypothetically, 7‐mx offsets the myopia‐enhancing effects of low ambient lighting.