Relation Between Axial Length And Ocular Parameters

Objective To investigate the relation between axial length and ocular parameters.Methods A total of374patients (374right eyes) with emmetropia or myopia wererecruited. Refraction, center corneal thickness (CCT), axial length (AL), intraocular pressure(IOP), corneal curvature (CC) and anterior chamber depth (ACD), retinal nerve fibre layerthickness (RNFLT) were measured by CANON RK-F1automatic-refractor, Pachymeter SP3000, A-mode ultrasound (OPTIKON2000), CANON TX-F non-contact tonometer, Orbscan II(BAUSCH＆LOMB), Three dimensional frequency domain coherent optical tomography(TOPCON3D-OCT), respectively. Shapiro-Wilk test (W test) was used to analyze AL normaldistribution. The Spearman correlation coefficient (r) and multiple regression analysis wereapplied to evaluate the relationship between axial length and ocular parameters. Then,69subjects with an axial length ranging from22millimeters（mm） to24mm,69subjects with anAL from24mm to26mm and69subjects with an AL greater than26mm were selectedrandomly. They were named group1,2,3, separately. The ocular parameters among the threegroups were tested by one-way ANOVA and the Least-significant difference (LSD) methods.Results The average AL was24.49±1.49mm. The AL values showed non-normaldistribution in Shapiro-Wilk test (P <0.001). Then the Spearman correlation analysis was usedto do the further test. We found that with elongation of the AL, Spherical equivalent (SE)(r=-0.712，P<0.001), CC (r=-0.351，P<0.001) and RNFLT (r=-0.385，P<0.001) all decreased,while the mean ACD (r=0.361，P<0.001) increased. Multiple regression analysis showed thatthe AL and SE (t=-26.240，P<0.001), CC (t=-15.757，P<0.001), ACD (t=5.927，P<0.001),RNFLT (t=-2.118，P=0.035) has significance correlation. Further more the one-way ANOVAwas used among the three groups we have classified. CCT (F=0.333，P=0.717), WWD (F=2.341，P=0.099) were not statistically different, while SE (F=202.000，P<0.001), ACD(F=17.077，P<0.001), CC (F=9.338，P<0.001) and RNFLT (F=21.729，P<0.001) showedstatistically significant differences among the three groups. Then using LSD for further analysis,we found that with the increasing AL, SE, CC and RNFLT were all decreased; in contrast, theACD was increased and CCT, WWD had no significant change between group1and2. Andso did the statistic between group1and3. As the AL increased, the SE and RNFLT weredecreased and the other parameters remained constant between group2and3.Conclusion While the AL is less than26mm, there was a trend toward myopia, a flattercornea, a deeper ACD and a thinner RNFLT with the increasing AL. However, when the ALwas greater than26mm, except for the SE and RNFLT were decreased with the longer AL,other ocular biological parameters tend to be stability.