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Oral intake of 7-methylxanthine (7-MX) was associated with reduced myopia progression and axial elongation in children, according to a retrospective study from Denmark, where the caffeine metabolite is authorized for myopia control.

Across an average of 3.6 years, nearsighted children at one ophthalmology center who started with a mean refractive error at baseline of -2.43 diopters (D) had an average myopia progression of 1.34 D with varying doses of 7-MX, according to findings in the .

Treatment with 7-MX was associated with significant reductions in myopia progression and axial elongation, reported Klaus Trier, MD, of Trier Research Laboratories in Hellerup, Denmark, and colleagues.

Their modeling suggested that an 11-year-old child taking 1,000 mg of 7-MX daily would develop -1.43 D of myopia on average over 6 years compared with the -2.27 D experienced by an untreated peer. Axial lengths would increase by 0.84 mm versus 1.01 mm, respectively.

In Denmark, 7-MX has been licensed since 2009 as a treatment to reduce the rate of childhood myopia progression and is the only orally administered therapy available there, according to the researchers. 7-MX is not available in the U.S.

The caffeine metabolite is thought to work by increasing scleral collagen content, the diameter of collagen fibrils, and the thickness of the posterior sclera, which may result in the white outer shell of the eye being more resistant to the irreversible deformation of myopia.

Myopia is a refractive error associated with excessive stretching and thinning of the retina, retinal pigment epithelium, and choroid. Possible complications include retinal detachment, myopic macular degeneration, and glaucoma -- and an increased risk of permanent vision loss.

According to the NIH's , nearsightedness normally starts around age 6-14 years and worsens until one's early 20s. However, the risk of myopia doesn't simply disappear then: a recent study found that of patients who did not have myopia by age 18 to 22 years, 14% went on to develop myopia within the next 8 years.

Glasses and contacts are the most common ways to correct refractive errors. LASIK and small incision lenticule extraction are the surgical alternatives available.

Trier and colleagues noted that the current treatments for myopia are not fully effective and suggested that 7-MX may be a valuable supplemental treatment if it passes randomized clinical trials.

For this retrospective study, the investigators followed the myopia progression of 711 children taking 7-MX at doses up to 1,200 mg per day. Data were collected from myopic children being treated at one ophthalmology unit in Denmark from June 2000 to January 2021. Children using other myopia control methods were excluded.

Participants were split between the sexes and had a mean age at baseline of 10.9 years.

No adverse effects of 7-MX were reported in the study.

However, the length of the follow-up varied widely and there was no control group, study authors acknowledged. Furthermore, as an observational study, there is the possibility of unknown confounding factors and causality could not be established. Finally, the authors noted that the results may not be generalizable to populations outside of Denmark.

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