The Relationship Between Axial Length And Optic Disc Morphology And Mean Retinal Nerve Fiber Layer Thickness In Young Adults

Objective: To analyze the relationship between axial length of the eye and the shape of optic disc and the average retinal nerve fiber layer thickness in young adults,and to study the correlation between age,gender,outdoor activity time,body mass index and axial length of the eye,to explore the risk factors for the occurrence and development of myopia from various aspects.Methods: The research method adopted in this paper is a cross-sectional study.The study patients were selected from 76 healthy people with 79 eyes(53 females,accounting for 67.10%),aged 18-45 years old,-9-0D with equivalent spherical lens,who were admitted to the ophthalmic Department of Qingdao Municipal Hospital from November 2021 to October 2022 for physical examination.They were divided into 3groups according to the axial length of eyes: Group A AL≤24mm(25 eyes),group B24 mm < AL≤26.5mm(28 eyes),and group C AL > 26.5mm(26 eyes).Basic information was collected for each patient in the three groups,including BMI,outdoor activity time,etc.IOL-Master was used to measure the axial length of the eye.Fundus photos were collected by fundus camera,and the longest axis(MA)and shortest axis(MI)of optic disc were marked with Image J software,and the ratio of MA to MI(inclination of optic disc)was recorded.Optical Coherence Tomography was used to perform optical disc OCT examination and record the area of optic disc,the area along the disc,the average cup-to-disc ratio,the vertical cup-to-disc ratio,and the average retinal nerve fiber layer thickness.Image J software analyzed and processed OCT Enface images of optic disc,traced the scope of atrophic area beside optic disc and calculated the area,namely the atrophic area around optic disc.The area and thickness parameters of optic disc in OCT were amplified and corrected using Littmann’s formula,and the corrected data were used for statistical analysis.SPSS 26.0 statistical software was used for analysis.Pearson correlation analysis,Spearman correlation analysis,Chi-square test,single and multiple linear regression analysis methods,One-way ANOVA between groups and least significant method(LSD)were applied to evaluate the correlation of axial length and optic disc parameters,m RNFLt,gender,time spent outdoors,and body mass index.Results: 1.The correlation coefficients between the axial length and corrected by optical amplification of the optic disc,the area along the disc,the area of peripapillary atrophy,the inclination of the optic disc and |SE| were r=0.326,r=0.324,r=0.802,r=0.728,r=0.886,respectively.The correlation coefficients were all greater than 0,and were significant at the level of 0.01.p < 0.01,indicating that the axial length was positively correlated with the area of the optic disc,the area along the disc,the area of peripapillary atrophy,the inclination of the optic disc and|SE|.2.There was no significant correlation between axial length and m RNFLt corrected by optical amplification(p > 0.01).The correlation coefficient with m RNFLt(before correction)was r=-0.529,and both were significant at the level of 0.01,p < 0.01,indicating that axial length was negatively correlated with m RNFLt(before correction).3.The correlation coefficients between |SE| and PPA,m RNFLt(before correction),optic disc inclination,AL and BMI were r=0.836,r=-0.586,r=0.736,r=0.887,r=-0.291,and all were significant at the level of 0.01,p < 0.01.The results showed that |SE| was positively correlated with PPA,optic disc inclination and AL,and negatively correlated with m RNFLt(before correction)and BMI.4.The correlation coefficients between optic disc area and ACDR,VCDR,the area along the disc,PPA and m RNFLt were r=0.539,r=0.538,r=0.532,r=0.292,r=0.253,respectively.The correlation coefficients were all greater than 0,and were significant at the level of 0.01,p < 0.01.The results showed that the area of optic disc was significantly positively correlated with ACDR,VCDR,the area along the disc,PPA and m RNFLt.5.The average area of optic disc in group A,B and C was 1.86±0.39mm~2,1.78±0.37mm~2 and 2.09±0.49mm~2,respectively.The average area of optic disc in group A and B was close to that in group C.One-way ANOVA results showed that the differences in optic disc area were statistically significant among different eye axis groups(F = 4.02,P < 0.05).6.The mean retinal nerve fiber layer thickness of groups A,B and C before correction was 104.6±6.30μm,96.64±7.62μm and 92±7.86μm,respectively.The mean retinal nerve fiber layer thickness of groups A,B and C before correction was significantly different.One-way ANOVA results showed that the difference in mean retinal nerve fiber layer thickness before correction was statistically significant between the different eye axis groups(F = 19.325,P < 0.05).7.The average axial length was 24.82±1.50 mm in males and 25.64±0.98 mm in females.The chi-square test results showed that the significance P value was 0.000,indicating that there was a significant difference between gender and axial length(P < 0.05).Conclusion: 1.The longer the axial length of the eye,the higher the myopia diopter,the thinner the average retinal nerve fiber layer thickness before correction of optical magnification effect;The area of optic disc,the area along the disc and the atrophic area around the optic disc after correction of optical magnification effect increased,and the inclination of optic disc became more serious,but the correlation between m RNFLt and axial length of the eye disappeared.2.The lower the BMI,the more severe the myopia.3.In young people,the average axial length of female eyes is longer than that of male eyes.