If proven effective in clinical trials, 7-MX could be a valuable future treatment.
A metabolite of caffeine known as 7-MX can slow the progression of myopia, also known as myopia, in children. This is according to observational study published on August 22, 2022 in the British Journal of Ophthalmology.
According to the researchers, 7-MX could become a valuable treatment for a condition for which current options are somewhat limited if it has been shown to be safe and effective in large clinical trials.
Nearsightedness occurs when the eye grows too long, stretches and becomes thinner. This often begins at age 6-7 and continues through age 16-20.
In addition to causing myopia, myopia is associated with an increased risk of several conditions that affect vision and eye health, including macular degeneration, glaucoma, cataracts, and retinal detachment.
Preliminary research indicates that the caffeine metabolite 7-methylxanthine, or 7-MX for short, inhibits excessive elongation of the eye (axial elongation).
7-MX has been used in Denmark since 2009 to treat myopia in children. But so far, it hasn’t been fully evaluated in long-term studies, and the researchers wanted to know how quickly myopia progresses in children taking 7-MX.
The scientists reviewed the medical records of 711 children (356 girls and 355 boys) who were treated for myopia between June 2000 and January 2021 at an eye clinic in Denmark.
Extensive eye tests were performed on the children, including measurement of axial length. 624 (88%) of the children took 7-MX tablets up to 1200 mg per day (average 470 mg), while 87 did not for various reasons.
Their mean age was 11 (range 7-15) when they started treatment, and their eye length and degree of myopia were followed for a mean of 3½ years (range 11 months-9 years).
Diopters (D) are the units of measurement used to assess the degree of eye function: the mean refractive error (nearsightedness) was initially -2.43 D, which increased by an average of 1.34 D during the monitoring period. -3.00 D is considered moderate myopia; -6 D or more is considered severe nearsightedness.
The mean axial length was initially 24.4 mm and increased at a mean of 0.21 mm/year.
Treatment with 7-MX was associated with a slower worsening of myopia and axial elongation, with higher doses apparently being more effective.
Based on this data, the scientists estimated that for a typical 7-year-old with a refractive error of -2.53 D to begin with, that child’s myopia would increase by 3.49 D over the next 6 years without treatment.
But with a daily dose of 1000 mg of 7-MX, that same child’s myopia would increase by -2.65 D over the next 6 years.
Similarly, without treatment, axial length would increase by 1.80 mm in the coming years, while at a daily dose of 1000 mg it would only increase by 1.63 mm.
According to the researchers’ calculations, an 11-year-old taking 1000 mg of 7-MX daily would increase that child’s myopia by -1.43 D over the next 6 years, compared to -2.27 D without treatment.. And the axial length would increase by 0.84 mm without treatment, compared to 1.01 mm.
None of the children taking 7-MX reported side effects during the control period.
According to the scientists, the findings are in line with those of experimental studies. However, they acknowledge that their study is observational and they failed to take into account potentially influential factors, such as genetic factors, ethnicity, time away from home and time spent near work. Their findings therefore cannot demonstrate causality.
“The question of causality and the magnitude of a potential treatment effect can only be determined through a randomized trial,” they write.
But they conclude, “Existing intervention methods for myopia are not fully effective in preventing children from progressing to high myopia, and 7-MX could become a valuable addition if causality and efficacy can be confirmed in future randomized controlled trials.”
Reference: “Oral administration of caffeine metabolite 7-methylxanthine is associated with delayed myopia progression in Danish children” by Klaus Trier, Dongmei Cui, Søren Ribel-Madsen, and Jeremy Guggenheim, Aug. 22, 2022, British Journal of Ophthalmology.