Abstract
Abstract: :
Purpose: To investigate whether progressive addition lenses( PALs) can slow down the progression of myopia. To develop the applicable principles of PALs correcting myopia. Methods: A randomized control trial(RCT) was conducted. 104 children aged between 6 and 15 years were selected in the outpatient department of E&ENT hospital from Apr.1999 to Apr.2000. Children were distributed into PALs group or control randomly. 27 male and 23 female were in PALs group. The mean age was 11.57±1.73 years. 24 male and 30 female were in SV group. The mean age was 11.63±1.69 years. Refractive error, axial length, anterior chamber depth, lens thickness, corneal curve (vertical and horizontal), heterophoria (vertical and horizontal) were examined at 6–month intervals. The factors may effect the progression of myopia were investigated such as Lens Wearing condition, near–work time and parental history of myopia. Subjects were followed–up for 18 months. Results: The rate of myopia progression was 1.21±0.58D and 0.82±0.36D in control group and PALs group respectively (P<0.001). Meantime, the axial elongation were 0.78±0.35mm and 0.57±0.30mm ,the change of horizontal corneal curve were 0.048±0.052mm and 0.079±0.048mm in control group and PALs group respectively (P<0.001). There is no significant difference in change of vertical corneal curve, anterior chamber, and lens thickness between two groups. The progression of myopia was reduced in that who were esophoric, orthoric, and mind exsphoric subjects, especial for the esophoric subjects. For the children who were moderate exophoric or intermittent exotropia, PALs could not slow down the progression of myopia. Lens wearing condition , near–work time and parental history of myopia could influence the progression of myopia. Conclusions: Progressive addition lenses could slow down the progression of myopia in esophoric, orthoric, and mind exophoric children. The rate of reduction was most significant in esophoric subjects, but no significant in moderate exophoric or intermittent exotropic subjects. Lens wearing condition may affect myopia control. The mechanism of PALs control myopia should be further studied in future.
Keywords: myopia • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled • visual development: infancy and childhood