LONGITUDINAL EVALUATION OF AXIAL LENGTH CHANGES FOLLOWING ORTHOKERATOLOGY IN MYOPIC CHILDREN

Abstract

Background:Orthokeratology  is  widely  used  for  myopia  management  in  children.  Although  axial  elongation may continue during orthokeratology treatment, the magnitude of elongation varies among individuals and may be influenced by demographic, clinical, and behavioral factors.Objective:To  longitudinally  evaluate  changes  in  axial  length  over  12  months  in  myopic  children  undergoing orthokeratology treatment and to identify factors associated with greater axial elongation.Methods:This prospective longitudinal observational study was conducted from July 2024 to June 2026 at Shifa Eye Care Clinic, Mardan, Pakistan. A total of 120 myopic children aged 8–14 years were enrolled and fitted with overnight  orthokeratology  lenses.  Participants  were  followed  for  12  months,  with  axial  length  measured  in  the right  eye  at  baseline  and  at  3,  6,  and  12  months  using  the  same  optical  biometer  and  measurement  protocol. Longitudinal  changes  in  axial  length  were  evaluated,  and  demographic,  clinical,  and  behavioral  factors associated with 12-month axial elongation were assessed using univariable and multivariable analyses.Results:The mean age was 10.8±1.9 years, mean baseline spherical equivalent was −3.21±1.24 D, and mean baseline right-eye axial length was 24.63±0.82 mm. Mean axial length increased to 24.66±0.82 mm at 3 months, 24.70±0.83  mm  at  6  months,  and  24.82±0.85  mm  at  12  months,  corresponding  to  a  mean  12-month  axial elongation of 0.19±0.13 mm (p<0.001). Greater axial elongation was observed among children aged 8–10 years than among those aged 11–14 years (0.24±0.14 vs. 0.16±0.11 mm, p=0.004), those with a positive family history of  myopia  than  those  without  (0.22±0.13  vs.  0.15±0.11  mm,  p=0.017),  and  those  with  poor  than  good  lens compliance (0.33±0.14 vs. 0.16±0.11 mm, p<0.001). Children reporting ≥2 hours/day of outdoor activity had lower   axial   elongation   than   those   reporting   <2   hours/day   (0.14±0.10   vs.   0.21±0.13   mm,   p=0.012).   In multivariable  analysis,  younger  age,  lower  baseline  myopia,  positive  family  history,  and  poor  lens  compliance were  independently  associated  with  greater  axial  elongation,  whereas  ≥2  hours/day  of  outdoor  activity  was associated with lower elongation.Conclusion:Axial  length  increased  progressively  over twelvemonths  in  children  undergoing  orthokeratology treatment,  with  greater  elongation  observed  in  younger  children  and  those  with  a  positive  family  history  of myopia,  lower  baseline  myopia,  and  poorer  lens  compliance.  Greater  outdoor  activity  was  associated  with  less axial  elongation.  As  this  study  had  no  untreated  or  conventional-correction  control  group,  the  observed  axial elongation  should  be  interpreted  as  change  occurring  during  orthokeratology  treatment  and  should  not  be  used alone to infer the efficacy of orthokeratology in controlling axial elongation