AIM: To evaluate the changes of amplitude of accommodation(AA)and axial length(AL)undergoing overnight orthokeratology treatment. And to explore the mechanism of orthokeratology on controlling the development of myopia in pre-adolescent.

METHODS: Prospective study, 215 pre-adolescent myopia aged 7-14 years old were enrolled in the study from May 2018 to August 2019. Every subject was measured for comprehensive eye examination. And according to the above measurements and the compliance of children and their parents, 113 patients who matched the inclusion criteria accepted treatment of orthokeratology(ortho-k group)and the other 102 subjects were selected to wear spectacle(spectacle group). During regular follow-up visits, AA was measured respectively at pre-wear, 1, 3, 6mo and 1a after orthokeratology. AL was measured at baseline and after 1a. The changes were evaluated and compared between the orthokeratology and spectacle group.

RESULTS: After 1a follow-up, 100 eyes of 100 subjects in the ortho-k group completed the follow-up, and 13 eyes of 13 subjects were withdrawn from the study. In the spectacle group, 77 eyes of 77 subjects completed the study, and 25 eyes of 25 subjects were withdrawn. At baseline, the AA of myopia was 13.57±2.47D, the AA after 1, 3 and 6mo, 1a was significantly higher than before(all P<0.005). It reached its peak after 6mo treatment(15.74±2.32 D), and it slightly decreased at 1a treatment(15.44±2.35 D), compared with 6mo treatment. The axial elongation in orthokeratology group was significant smaller than in spectacle group during the 1a study period(0.13±0.15mm vs 0.50±0.28mm, P<0.001).

CONCLUSION: AA was improved after orthokeratology in pre-adolescents. Orthokeratology suppressed axial elongation in myopic, suggesting that it is one of the effective treatments in slowing the progression of myopia in pre-adolescents.