Long-term observation of the endothelium morphology and corneal thickness in myopic adolescents treated with orthokeratology: a 10-year retrospective study

AIM: To assess the long-term safety of orthokeratology (ortho-k) in myopic children by evaluating changes in corneal endothelial morphology and central corneal thickness (CCT) after prolonged ortho-k lens wear. METHODS: This study included 65 myopic children (130 eyes). The ortho-k group comprised 39 children who had worn ortho-k lenses for more than 10y. The control group included 26 children who wore single-vision spectacles for myopia correction. Clinical data and adverse events were documented throughout the follow-up period. Endothelial cell density (ECD), coefficient of variation (CV) of cell area, percentage of hexagonal cells (%SIX), and CCT were measured at baseline and at the final follow-up visit. RESULTS: The 39 participants (18 males, 21 females) enrolled in the ortho-k group completed the 10-year follow-up examinations successfully. The ages ranged from 7 to 12 (9.24±1.26)y. In the control group, 26 participants (13 males, 13 females) were successfully recalled and completed their 10th year examinations. The ages ranged from 7 to 12 (9.62±1.68)y. In the ortho-k group, ECD was 3119.86±202.07 cells/mm² at baseline and 3057.42±264.52 cells/mm² at the 10-year follow-up (P=0.058). CV was 30.78%±6.70% and 32.45%±7.87% (P=0.053). %SIX was 62.23%±13.07% and 60.31%±11.59% (P=0.234). CCT decreased by 8±4 μm at the 6-month visit and remained stable thereafter (538.85±43.61 μm at 6mo vs 540.78±41.44 μm at 10y, P=0.528). At the 10-year follow-up, no significant between-group differences were observed in ECD, CV, %SIX, or CCT (all P>0.05). CONCLUSION: This 10-year retrospective study demonstrates that long-term ortho-k lens wear has no significant adverse effects on corneal endothelial morphology or CCT compared with spectacle wear. Ortho-k shows excellent long-term safety with regard to corneal endothelial parameters and CCT, comparable to that of conventional spectacle correction in myopic children.