Purpose:
In sclera from myopic eyes, collagen content is reduced. The adenosine antagonist 7-methylxanthine (7-mx), a theobromine metabolite, increases collagen in rabbit sclera and may therefore hypothetically reduce eye elongation in childhood myopia. In a 12-months clinical trial, 68 myopic children (mean age 11.3 years) with a minimum base-line axial growth rate of 0.075 mm per six months received either placebo tablets or 7-mx, 400 mg per day. Participants from both groups subsequently received 7-mx for another 12 months. At 24 months, a significantly lower axial growth was found among children treated with 7-mx for 24 months compared with those only treated for 12 months. Treatment with 7-mx was then stopped in both groups.
Methods:
Axial length was measured with Zeiss IOL-Master at -6, 0, 12, 24, and 36 months.
Results:
33 children completed 36-months follow-up (interim data). In the group treated with 7-mx 0-24 months (n=16), axial growth rate in the first as well as the second year of treatment was significantly lower compared with the precedent period (p<0.0001 and p=0.004). In the group treated with 7-mx 12-24 months (n=17), a significant drop in axial growth rate was only seen during treatment with 7-mx (p=0.01). Axial growth rate 24-36 months was in neither group significantly different from the precedent period (p=0.090 and p=0.363).
Conclusions:
During treatmentwith 7-mx, axial growth continuously decreases, but when treatment is stopped, the effect disappears. These results confirm that 7-mx reduces eye elongation in myopia. The treatment is safe and without side-effects and may be continued until 18-20 years of age when age-related cross-linking of collagen prevents further elongation of the eye.
Clinical Trial:
www.clinicaltrials.gov NCT00263471
Keywords: myopia • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials