Objective  To investigate the effects of overnight orthokeratology lens on corneal endothelium and corneal thickness after one year of treatment.

  Methods  Totally 40 patients(79 eyes)aged 8-14 years received orthokeratology lens treatment in our hospital from August 2008 to February 2009 were observed.Corneal endothelium and corneal thickness were assessed before the treatment, 6 months and 1 year after the treatment.Uncorrected visual acuity, diopter, and corneal topography were documented at the same time points as well.

  Results  Corneal endothelial cell density showed no significant reduction 6 months and 1 year after the treatment when compared with the baseline level(P > 0.05).Cell Variant Index and percentage of hexagonal cells showed no significant change 6 months after the treatment but the former slightly increased and the later decreased after 1 year of the treatment(both P < 0.05).Corneal thickness showed no significant change after 6 months or 1 year of treatment(both P > 0.05).Uncorrected visual acuity, diopter, and corneal topography significant changed after 1 year of treatment(P < 0.01).

  Conclusion  Orthokeratology lens can correct refractive error and control the development of myopia.However, its long-term wear may have slight deformative effect on corneal endothelium.Strictly monitoring and follow-up are required to ensure long-term effectiveness and safety.