Oral intake of the caffeine metabolite 7-methylxanthine (7-MX), has been associated with reduced myopia progression and reduced axial elongation in a sample of myopic children from Denmark.
7-MX has been licensed in Denmark as a treatment to reduce the rate of childhood myopia progression since 2009. The only orally administered myopia management therapy available, the study aimed to assess the rate of myopia progression in the children prescribed.
Published in the British Journal of Ophthalmology, researchers collected longitudinal cycloplegic refraction and axial length data for 711 myopic children from Denmark, (median age at baseline 11.1 years, range 7.0 –15.0 years), who were treated with varying doses of oral 7-MX (0–1,200 mg per day). Data were analysed using linear mixed models.
After following the children for an average of 3.6 years (range 0.9–9.1 years) they determined the average myopia progression was 1.34D (range –6.50 to +0.75D). They reported that treatment with 7-MX was associated with a reduced rate of myopia progression (p<0.001) and axial elongation (p<0.002). Modelling suggested that, on average, an 11-year-old child taking 1,000mg 7-MX daily would develop –1.43D of myopia over the next six years, compared with –2.27D if untreated. Axial length in this child would increase by 0.84 mm over six years when taking a daily dose of 1,000mg of 7-MX, compared with 1.01mm if untreated. No adverse effects of 7-MX therapy were reported.
Randomised controlled trials are needed to determine whether the association is causal.
