Summary: The caffeine metabolite 7-methylxanthine (7-MX) is associated with a slower progression of myopia (short-sightedness) in children, according to observational data from Denmark.
Source: BMJ
Background: Myopia develops when the eyeball grows too long, causing images to focus in front of the retina rather than on it. This axial elongation typically begins in early childhood (around ages 6–7) and often progresses through adolescence. Higher degrees of myopia increase the lifetime risk of sight-threatening conditions such as retinal detachment, glaucoma, cataracts and macular degeneration.
New observational findings: Researchers publishing in the British Journal of Ophthalmology report that oral treatment with 7-methylxanthine (7-MX), a metabolite of caffeine, was associated with a reduced rate of myopia progression and slower axial elongation in a large clinic cohort of Danish children. If confirmed by randomized trials, 7-MX could become a valuable oral option for myopia management alongside existing approaches.
7-MX has been available in Denmark for childhood myopia treatment since 2009, but long-term data have been limited. To evaluate its association with disease progression, investigators reviewed medical records from one ophthalmology clinic covering the period June 2000 to January 2021.
The analysis included 711 myopic children (356 girls and 355 boys). Comprehensive eye examinations with cycloplegic refraction and axial length measurements were performed regularly. Of these patients, 624 received oral 7-MX in doses ranging up to 1,200 mg per day (mean dose about 470 mg), while 87 did not take 7-MX for various reasons. The average age at the start of follow-up was 11 years (range 7–15), and patients were monitored for a mean of 3.6 years (range 11 months–9 years).
At baseline the average refractive error was −2.43 diopters (D). Over the monitoring period the average refractive change across the cohort was an increase in myopia of 1.34 D. Mean axial length at baseline was 24.4 mm and increased on average by 0.21 mm per year.
Effect estimates and clinical implications: Using linear mixed models to account for repeated measures, the researchers found that treatment with 7-MX was associated with a statistically significant reduction in both refractive progression and axial elongation. Higher doses of 7-MX tended to show larger associations with slower progression.
Modeling from the data gives practical examples: a typical 7-year-old starting with −2.53 D of myopia would be expected to worsen by −3.49 D over six years without treatment. With a daily 1,000 mg dose of 7-MX, progression in the same child was estimated at −2.65 D over six years. Over the same period axial length would increase by 1.80 mm without treatment versus 1.63 mm with 1,000 mg daily. For an 11-year-old, the model estimated a 6-year progression of −2.27 D without treatment compared with −1.43 D on 1,000 mg 7-MX, and axial length increases of 1.01 mm versus 0.84 mm, respectively.
Safety and limitations: No adverse effects were reported among the children taking 7-MX during the follow-up period in this clinic cohort. However, the authors emphasize important limitations: this was an observational study and not a randomized trial. Key confounding factors that influence myopia progression—such as family history and genetic predisposition, ethnicity, time spent outdoors, and near-work activities—were not fully accounted for. Because of these limitations, the observed associations cannot establish causality.
The investigators conclude that randomized controlled trials are required to determine whether 7-MX causally reduces myopia progression and to establish optimal dosing and long-term safety. They note that current myopia control methods are only partially effective for preventing progression to high myopia, and that 7-MX could become a useful oral supplement if efficacy and safety are confirmed.
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Author: Press Office, BMJ
Source: BMJ
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Original research (open access): “Oral administration of caffeine metabolite 7-methylxanthine is associated with slowed myopia progression in Danish children” by Klaus Trier et al., British Journal of Ophthalmology.
Abstract (condensed)
Purpose: To assess the rate of myopia progression and axial elongation in children treated with oral 7-methylxanthine (7-MX), an orally administered therapy licensed in Denmark since 2009.
Methods: Longitudinal cycloplegic refraction and axial length measures from 711 myopic Danish children receiving variable daily doses of 7-MX (0–1,200 mg) were analyzed with linear mixed models.
Results: Median baseline age was 11.1 years. Mean follow-up was 3.6 years. Treatment with 7-MX was associated with a reduced rate of myopia progression (p < 0.001) and axial elongation (p < 0.002). Modeling suggested clinically meaningful differences in predicted refractive progression and axial growth for children taking 1,000 mg daily versus no treatment. No adverse effects were reported in this cohort.
Conclusions: In this observational sample, oral 7-MX use correlated with slower myopia progression and reduced axial elongation. Randomized controlled trials are necessary to determine whether the association is causal and to evaluate long-term safety and optimal dosing.