The security evaluation of corneal endothelium in the children wearing orthokeratology contact lens for longterm

Background Wearing of orthokeratology contact lens can slow down the development of myopia,especially in childhood.However,if wearing orthokeratology contact lens for long-term affect the corneal health is worthy of consideration.Objective This study was to evaluate the security of wearing orthokeratology contact lens in children.Methods A retrospective case-observational study was adopted.One hundred and fifty eyes of 76 myopic children aged 8-15 years were enrolled in Shanghai Tenth People's Hospital during December,2009 to December,2011.Orthokeratology contact lens were worn at night for 8-10 hours daily.Area of corneal endothelial cells,density of corneal endothelial cells,coefficient of variation of corneal endothelial cells and percentage of hexagonal cells were measured before wearing and 3,6,12,24 months after wearing.Repeated measurement of single factor analysis of variance was used to evaluate the changes of corneal endothelial cells after wearing of orthokeratology contact lens.Results No significant differences were found in the area of corneal endothelial cells and density of corneal endothelial cells among the different time points (F =11.34,P＞0.05 ; F =7.16,P＞0.05).A significant difference was seen in the coefficient of variation of corneal endothelial cells at various time points in the children(F=12.70,P=0.02),and the coefficient of variation of corneal endothelial cells was 0.36±0.02 24 months after wearing lens,which was higher than 0.28 ±0.05 before wearing lens (P＜0.05).In addition,the percentage of hexagonal cells in different time points was significantly different (F=13.40,P =0.04),and the percentages of hexagonal cells at 12 hours and 24 months after wearing lens were (62±12)％ and (60±14)％ respectively,which was significantly lower than (69±12)％ before wearing lens (P＜0.05).Conclusions Wearing of orthokeratology contact lens for over one year leads to the decrease of percentage of hexagonal cells and increase of coefficient of variation of corneal endothelial cells. Key words: Ametropy/myopia ;  Childhood ;  Orthokeratology contact lens ;  Corneal endothelial cells ;  Security