Impact Of Overnight Wear Of Orthokeratology Lens On Thickness Of Tear Film Lipid Layer In Children With Myopia

Objective: To analyze the situation of tear lipid layer(LLT)and refractive state in children with and without refractive error corrected by wearing an Overnight wear of orthokeratology(OOK)at night,and to explore the impact of wearing OOK on children’s LLT.To provide important reference for the diagnosis and treatment of children with ametropia.Methods: We conducted a retrospective cross-sectional study on ametropic children who visited the First Affiliated Hospital of USTC from July 2021 to September 2021.LLT and partial blinks ratio were evaluated using Lipi View ocular surface interferometer.All children with refractive error corrected by OOK were taken as the observation group,and those without refractive error corrected by OOK were taken as the control group.All children obtained equivalent spherical equivalent(SE)through cycloplegia optometry,and recorded various data of corneal topography.All data were analyzed using Graph Pad Prism 7.02 statistical software.The measurement samples are expressed by the mean ±standard deviation.Two groups of measurement samples that conform to the normal distribution and have the same variance use the independent-sample t test.Three or more groups of measurement samples use the analysis of variance.Mann Whitney U nonparametric analysis was used to compare the two groups of measurement samples that do not conform to the normal distribution.Counting samples using chi square test.The test standard was P < 0.05,and the difference was statistically significant.Results:The number of children enrolled in this program was 402(804 eyes).One hundred and seventy-one children(342 eyes,79 males and 92 females)aged 4～17 years(10.59 ± 2.54 years)who never wore OOK were included in the control group,while 231children(462 eyes,121 males and 110 females)aged 7～18 years(11.09 ± 2.24 years)who wore OOK for more than 1 week were included in the observation group.Compared to the control group with an LLT of 58.5 ± 18.19 nm,the OOK group exhibited a significant decrease in the LLT value to 54.42 ± 17.60 nm.In addition,the LLT in females was significantly thicker than that in males in both the control(male 54.78 ± 16.56 nm,female61.70 ± 18.95 nm)and observation groups(male 51.88 ± 16.68 nm,female 57.21 ± 18.18nm).It is worth noting that the influence of wearing OOK on the LLT value was only detected up to 18 months.Eighteen months later,there was almost no difference in LLT between the control and observation groups.We also noted that there was no change in LLT correlated to the surface regularity index.Conclusion: Wearing OOK can affect the LLT of tear film in the first 18 months after wear.The effect of wearing OOK on tear film LLT in men was greater than that in women.To sum up,more attention should be given to children wearing OOK for less than 18 months,especially males.