7‐methylxanthine for myopia control in Denmark – Clinical results 2003–2023

Abstract

In 2009, the Danish Medicines Agency authorized the use of pharmacy‐compounded 7‐methylxanthine (7‐MX) tablets for treatment of progressive myopia in children. 7‐MX has since been prescribed to more than 1200 individuals with no reports of adverse effects. A high compliance rate has demonstrated that the concept of using an oral pharmaceutical to control myopia progression is feasible. Analysis with the use of linear mixed models of longitudinal data from 711 children aged 7–14 years and with less than 10 diopters (D) of myopia at baseline has shown that myopia progression and axial eye growth is linearly associated with the average daily dose of 7‐MX taken during the observation period. Linear regression of data from 350 children aged 7–10 years at baseline who completed 3 years of follow‐up suggest that the absolute reduction of myopia progression and axial growth over 3 years associated with taking 400 mg three times daily is approximately 1.2 D and 0.35 mm, regardless of baseline myopia. Linear regression of data from 157 children aged 7–10 years at baseline who completed 5 years of follow‐up suggest that the absolute reduction of myopia progression and axial growth over 5 years associated with taking 400 mg three times daily is approximately 1.8 D and 0.62 mm.Thus, the efficacy of 7‐MX does not seem to decrease with duration of treatment. Negative eye growth (eye shortening) of 0.05 mm or more in children taking an average daily dose of 640 mg or more occurs in 1% of children aged 6–9, 3% of children aged 10–13, and 8% of children aged 14–15 at baseline. The largest eye shortening found was in a 6‐year‐old child with an initial myopia of −7.125/−7.75 diopters (D) and axial length of 26.07/26.29 mm who took an average dose of 1152 mg 7‐MX per day. After 1 year, the myopia was reduced to −5.5/−5.75 D and the axial length reduced to 25.77/25.94 mm. 7‐MX does not seem to induce thickening of the choroid and may therefore work by another mechanism than other myopia control interventions. Preliminary data suggest that the effects of 7‐MX and other myopia control methods are additive. In conclusion, based on 20 years of clinical experience in Denmark, 7‐MX shows promise as a non‐toxic, side‐effect free, oral myopia control pharmaceutical, suitable for use as a supplement when myopia progression cannot be completely arrested by monotherapy with low‐dose atropine or an optical device.