Correlation Between Diopters And Refractive Parameters Among5to12Years Old School-age Children Of Lanzhou City

Objectives:To investigate the epidemiological status of refractive state among school-age children of5to12years in chengguan district of Lanzhou city, measure axial length (AL), horizontal and vertical corneal refractive power (K1, K2), anterior chamber depth (ACD) and corneal diameter (W-W) by IOL-Master (Zeiss) and analyze the correlation between refractive state and all above refractive parameters, and establish the archive of refractive changes, in order to provide evidence for prevention and treatment of refractive error in children.Methods:Axial length (AL), horizontal and vertical corneal refractive power (K1, K2), anterior chamber depth (ACD) and corneal diameter (W-W) of813school-age children (1626eyes) aged8.46+2.30year old (5-12years old) were measured by IOL-Master, refractive error was measured by computer refractor. The eyes were divided into5groups according to different mean spherical equivalent diopter:high myopia, moderate myopia, low myopia, emmetropia and hyperopia. The correlation between diopter and different refractive parameters of different ages and different diopter groups were analyzed respectively, the SPSS19.0was used for the statistical analysis.Results:1. There was a statistically significant difference (P<0.05) in uncorrected visual acuity among the different groups of5to12years old school-age children, the uncorrected visual acuity average of5year old children was0.79±0.24, increased to0.89±0.43of9year old, then decreased to0.60±0.47of12year old. There was a statistically significant difference (P<0.05) in refractive state among the different groups of5to12years old school-age children, the prevalence of myopia tended to increase with the age.2. There were statistically significant difference (P<0.05) in axial length (AL) and anterior chamber depth (ACD) among the different age groups, AL and ACD growed with the increase of age. There were statistically significant difference (P<0.05) in axial length (AL) among three myopic groups. There were statistically significant difference (P<0.05) in anterior chamber depth (ACD) between low myopia and moderate myopia or low myopia and high myopia. There were statistically significant difference (P<0.05) in corneal refractive power between low myopia and high myopia or moderate myopia and high myopia. There were statistically significant difference (P<0.05) in corneal diameter (W-W) between low myopia and high myopia or moderate myopia and high myopia.3. SE was negatively correlated with axial length(r=-0.764, P<0.01) and anterior chamber depth (r=-0.498, P<0.01), but had week correlation with corneal refractive power or corneal diameter.4.Anterior chamber depth was positively correlated with axial length(0.40<|r|<0.69), vertical, horizontal and mean corneal refractive power were insignificantly negatively correlated with axial length(0.20<|r|<0.39), and corneal diameter was insignificantly positively correlated with axial length(0.20<|r|<0.39).5. Corneal diameter was insignificantly negatively correlated with corneal refractive power(0.20<|r|<0.39), corneal diameter was insignificantly positively correlated with anterior chamber depth(0.20<|r|<0.39), corneal refractive power had no correlation with anterior chamber depth, horizontal corneal refractive power had positive correlation with vertical corneal refractive power(r=0.866, P=0.000).6. There were statistically significant difference (P<0.05) in AL/CR ratio among the different age groups and different refractive state groups of5to12years old school-age children, AL/CR ratio increased with the increase of age, AL/CR ratio had negative correlation with spherical equivalent diopter(r=-0.842,P=0.000).7. Multiple linear regression using AL, K1, K2, ACD and W-W as independent variable and SE as dependent variable was applied to analyze the relationship of these variables, and the equation was:SE=61.416-1.714*AL-0.543*K1-0.136*K2+0.651*ACD+0.381*W-W.Conclusions:The increase of axial length plays an important role in the changes of refractive among school-age children of5to12years old, AL is the main morphological variable related to myopia. Meanwhile, refractive changes may be affected by corneal refractive power (K1, K2), anterior chamber depth (ACD) and corneal diameter (W-W).7to8years old could be regarded as the main phase from emmetropization to myopization of school-age children.