Research On Correlation Between Ametropia And Refractive Factors Of Children Aged From5to13Years Old

Research background:Myopia is the main type of ametropia. The juvenile myopia prevention is a public health problem to both China and the world. The effective control of the myopia incidence, which is expected to decrease year by year, is a difficult and important task to the medical profession and education sector. In China, the myopia pathogenesis has been researched for years. But until now the myopia pathogenesis and risk factors is unclear. In the other hand, the mss prevention and treatment of myopia has a history of several decades in China, but the juvenile myopia incidence does not reduce. In order to study the mechanism of myopia and find the effective prevention methods, the foundation work of the prevention and treatment of myopia must be carried out.Objective:To understand the refractive growth curve of children and the probable influence made by the refractive factors of children, then to analyze the correlation between the refractive state and factors of children, and to predict the refractive state of children according to the refractive factors.Methods:Fifty-one children (102eyes), aged from5to13years old, were selected from outpatients who went to our hospital ophthalmology clinic in winter vacation of2011. The static diopter was measured by the optometry with the continuous mydriasis of five days using the ophthalmic gel of1%atropine. And the biological measured values of refractive factors were obtained by the A type ultrasonic and keratometer. On the other hand, the parameters including the height, weight and the dominant eye were recorded to analyze the refractive growth curve of children and the correlation between the refractive state and factors, and find out the possible influence of the refractive factors on the myopia of children. After that, the equation between the diopter and the correlative factors including the biological measured values of refractive factors and growth factors was established by the stepwise multiple regression analysis.Results:(1) The ocular axial length of the right eye was longer than the left, and the right eye corneal curvature of the level diameter was larger than the left. The myopia degree of the right eye static diopter was deeper than the left (p<0.05). In the group in which the right eye was dominant, the difference of the left eye and right eye was not statistically significant. And in the group in which the left eye was dominant, the difference of the left eye and right eye was not statistically significant either.(2) In the period of5to13years old, the myopia developing trend of girls was earlier than boys.(3) The curve, which showed the refractive development of children, was obtained. The characteristic of the curve was as follows. In the period of5to13years old, the refractive state showed the myopic trend with the change of age. The ocular axis length extended gradually with the change of age. The intraocular pressure increased gradually with the change of age, but the pressure was lower than16mmHg. Around11years old, the corneal curvature showed an upward trend after the first drop, and the main type of the corneal astigmatism was the astigmatism with the rule. The central anterior chamber depth and crystal thickness did not change much. The vitreous chamber depth increased gradually with the change of age. The ocular axis length and height development had a close relationship.(4) The relationship between the refractive state and refractive factors was described as follows. Around llyears old, the correlation between the intraocular pressure and ocular axis length growth was transformed from the positive to the negative. And the correlation between the corneal curvature and ocular axis length growth was transformed from the negative to the positive. With the increase of age, there was a common "inflection point" in the consistency and inconsistency of the intraocular pressure, corneal curvature and ocular axis growth.(5) The refractive state was closely related to the match of the refractive factors, especially the match of the ocular axis length and corneal curvature.(6) The multiple linear regression equation for the relationship between the static diopter (D), ocular axis length (AL) and mean value of the corneal curvature (K) was D=84.271-0.937×K-1.878×AL (R=0.871).Conclusion:(1) In the same individual, the myopia developing degree of the right eye is earlier than the left, which may be irrelevant with the impact of the dominant eye.(2) In the period of5to13years old, the myopia developing trend of girls is earlier than boys.(3) In the development of human eyes, the refractive factors change correspondingly. The refractive state changes from hyperopia to emmetropia gradually, and then to myopia. The total process is irreversible.(4) The ocular axis length and height development of children have a close relationship. (5) With the increase of age, there is a common "inflection point" in the relationship of the intraocular pressure, corneal curvature and ocular axis growth.(6) The static diopter (D) of the children aged from5to13years old can be predicted by the ocular axis length (AL) and corneal curvature (K), which can be used to prevent myopia reasonably.