Purpose To investigate the safety and therapeutic effect of a modified posterior scleral reinforcement (PSR) in treating high myopia. Methods A total of 85 highly myopic eyes in 47 children (6.3±3.6 years of age, range from 3 years to 15 years) who underwent this modified PSR were included in this study. Axial length, refractive error, best-corrected visual acuity (BCVA), macular scans, and adverse events were recorded before the operation (as a baseline) and in postoperative reviews taken yearly for 5 years. Results This was a 5-year research: 50% of the children (20 children, 40 eyes) participated in the 6-month review, 41% of the children (17 children, 33 eyes) participated in the 1-year review, 26% of the children (11 children, 21 eyes) participated in the 2-year review, 16% of the children (7 children, 13 eyes) participated in the 3-year review, 13% of the children (5.3 children, 11 eyes) participated in the 4-year review, and 8% of the children (3.3 children, 7 eyes) participated in the 5-year review. Compared with the baseline, axial elongation was significantly changed (P<0.05) over the 5-year period in all of the children: 6-month (P=0.003), 1-year (P=0), 2-year (P=0), 3-year (P=0), 4-year (P=0), and 5-year (P=0). The axial length was extended. No significant difference was found in refractive error between measurements taken at baseline and at the 5-year postoperative visit in all of the children: 6-month (P=0.51), 1-year (P=0.50), 2-year (P=0.46), 3-year (P=0.56), 4-year (P=0.30), and 5-year (P=0.16). There were significant differences in BCVA between measurements taken at baseline and at the postoperative 5-year visit in all the children: 6-month (P=0), 1-year (P=0), 2-year (P=0), 3-year (P=0), 4-year (P=0), and 5-year (P=0). BCVA improved in 71 eyes (83.52%), remained stable in 14 eyes (16.47%), and declined in none of the children. No serious adverse events occurred before the operation and during the 5-year follow-up period. Conclusion This modified PSR could be a therapeutic treatment for high myopia.