Association Between Axial Length To Corneal Curvature Radius Ratio And Myopia In Myopic People And People Wearing Orthokeratology Lenses

Objective: Aims: To analyse the distribution characteristics of ocular biometric parameters such as axial length to radius of corneal curvature ratio(AL/CR)and their relationship with myopia in adults,adolescents and myopic patients with keratomileusis.Methods:Patients with no eye disease other than refractive error attending the optometry clinic of the First Hospital of Hainan Medical College from January 2022 to June 2022 were studied.A total of 322 patients aged 8-43 years with myopia were selected by random sampling: including: 187 eyes(right eye)of 187 adults aged18-43 years with myopia;and 135 adolescents aged 8-18 years with myopia(135eyes),including 96 mild to moderate adolescents aged 8-16 years with night-wear keratomileusis(96 eyes).Based on the equivalent spherical refraction(SE)from the dilated eye examination,all subjects were first divided into adults,adolescents and then separately according to the population: the adult group was divided into three groups: mild myopia(≤-0.50 D and >-3.00 D,42 eyes),moderate myopia(≤-3.00 D and >-6.00 D,80 eyes)and high myopia(≤-6.00 D,65 eyes);The adolescent population was divided into: mild myopia(≤-0.50 D and >-3.00 D,52 eyes),moderate myopia(≤-3.00 D and >-6.00 D,44 eyes)and high myopia(≤-6.00 D,39 eyes),with non-highly myopic adolescents wearing keratoplasty lenses divided into: mild myopia(≤-0.50 D and >-3.00 D,52 eyes),moderate myopia(≤-3.00 D and >-6.00 D,44 eyes).(≤-3.00 D and >-6.00 D,44 eyes).The observation period was 6 months and the longitudinal study was divided into pre-wear,post-wear 1month,3 months and 6 months for statistical study.Axial length(AL),radius of corneal curvature(CR)and AL/CR were measured and compared in the three groups of patients.correlations between ocular AL,AL/CR and SE were analysed using multiple linear regression methods.ROC curves were used to study the predictive ability of AL/CR for high myopia.Results:1.There were no statistically significant differences between the three groups in terms of age,gender and IOP.In the adult group: the mean values of AL/CR in the mild,moderate and high myopia groups were 3.17±0.06,3.31±0.08 and 3.43±0.10 respectively,with statistically significant differences between both groups(P<0.001).Linear regression analysis showed that both AL and AL/CR were strongly negatively correlated with SE(P<0.05),while CR was weakly positively correlated with SE and the differences were not statistically significant(P > 0.05).After adjusting for confounders(sex,age,IOP),the linear regression equation showed that for every 0.1unit increase in AL/CR,SE increased by 1.54 D.The area under the ROC curve for AL was 0.830(95% confidence interval: 0.769 to 0.900)compared to 0.896(95%confidence interval: 0.851 to 0.941),indicating that AL/CR had a higher diagnostic value than AL for high myopia(p< 0.01).When the Jorden index reached its maximum value(0.626),the AL/CR threshold was 3.309,with sensitivities and specificities of 0.954 and 0.672 respectively.2.Adolescent population: The differences in baseline age and IOP between the three groups were statistically significant(P< 0.05).135 adolescent myopic patients had a median age of 13 years(10,16 years)and a mean non-contact IOP: 16.10 ±1.75 mm Hg.In terms of ocular biological parameters,the differences between the three groups of SE,AL,AL/CR,CCT,and LT(P< 0.05)were statistically significant,while the differences between the three groups of gender,CR and ACD were not statistically significant(p>0.05).The median AL/CR in the adolescent mild,moderate and high myopia groups conformed to a normal distribution of 3.11((3.05,3.14),3.11(3.05,3.14)and 3.42(3.35,3.48)respectively,with statistically significant differences between the two groups(P<0.001).According to linear regression analysis,there was a negative linear correlation between AL and SE(r=-0.835,r2=69.7%,p<0.001).Adjusting for confounders(gender,age,IOP),SE decreased by1.14 D when AL increased by 1 mm,i.e.myopia increased by 1.14 D.Similarly,there was a negative linear correlation between AL/CR and SE(r=-0.888,r2 =78.8%,P<0.001).for every 0.1 unit increase in AL/CR,SE decreased by 1.18 D.While CR,CCT,the linear regression model between ACD and SE was not statistically significant(P>0.05).the area under the ROC curve for AL and AL/CR was 0.963(95% CI 0.931-0.995)and 0.984(95% CI 0.967-1.00)respectively,indicating that the diagnostic value of AL/CR was higher than that of AL(P<0.01).In the ROC curve for AL/CR,the threshold for the maximum Jorden index(0.955)was 3.32,with a sensitivity of 0.923 and specificity of 0.968.3.The results of the statistical analysis of non-highly myopic adolescents before wearing keratoplasty lenses showed that the differences in AL/CR and CR were statistically significant at each time point(p<0.05),and that AL/CR gradually decreased with time until it was stable and almost unchanged,i.e.the change was greatest at the first month of wear and almost unchanged at 6 months after wear compared to 3 months before wear;while CR The length of the AL tends to get shorter at 3 months after wear,and then gradually starts to lengthen again at 6 months,but this difference is not statistically significant,and the differences in the other secondary indicators CCT,LT and ACD are not statistically significant at each time point(p>0.05).Therefore,the relationship between the main ocular biometric parameters(AL,CR,AL/CR)and SE was further explored.The results showed that there was a negative linear correlation between AL and SE(r=-0.491,t=3.830,P<0.001).According to the linear regression model,when AL increased by 1mm,SE decreased by 8.518D;there was a negative linear correlation between CR and SE(r=-0.192,t=-3.998,P<0.001),and for every 1 unit increase in CR,SE decreased by27.34;there was a negative correlation between AL/CR and SE(r=-0.354,t=-3.934,P< The ROC curve was used to analyze the predictive ability of AL/CR,CR,and AL for moderate myopia,and the sensitivity and specificity of each index for the diagnosis of moderate myopia.The results showed that the areas under the ROC curves for AL/CR,CR,and AL were 0.738(95% CI 0.689-0.787),0.605(95% CI0.550-0.660),and 0.662(95% CI 0.608-0.716),respectively.Comparison of the AUC between the three indices showed that AL/CR was the most predictive and that AL/CR(all p<0.05)had the best critical value of 3.076 for predicting moderate myopia,with a sensitivity of 77.8% and specificity of 65.6%,and could be used as a monitoring point for moderate myopia.Conclusion:1.AL,AL/CR and SE in adults and adolescent myopic patients showed significant negative correlation,and the correlation between AL/CR and SE was greater than that of AL.Therefore,AL/CR can be used to analyze the dynamic changes of SE during the development of myopia in adolescents and adults on a certain basis independently of optometry,which is especially applicable to the diagnosis of high myopia;2.The correlation between AL/CR,AL,CR and SE in adolescent and child myopia patients with keratoplasty is significantly negative,and the correlation between AL/CR and SE is greater than that between AL and CR,and AL/CR can be used on a certain basis independently of optometry to analyse the changes in SE during the development of myopia in adolescent and child myopia with keratoplasty,which is particularly applicable to the prevention and control of moderate myopia in adolescent and child myopia It is particularly suitable for the prevention and control of moderate myopia in young children.