A comparative study on accommodative microfluctuation between emmetropic and myopic school-aged children / 中华实验眼科杂志

ABSTRACT

Background The incidence of myopia is increase.Some researches documented that formation of myopia is closely related with weakness of the accommodative response,enhancement of accommodative lag and accommodative microfluctuations in short-distance use of eyes.However,there still is controversy.Objective This study sought to compare the accommodative microfluctuations among emmetropic and myopic school-aged children at reading,and to discuss its potential relationship with the onset and development of myopia.Methods A casecontrolled study was designed.Eighty-nine children aged 8-12 years old were recruited in this study,including 47emmetropic children and 42 myopic children.Refractive error were checked by subjective refraction in phoropters and binocular vision and stereopsis were examined in all the subjects.A Grand Seiko WAM5500 auto-refractor was used to measure the accommodative responses and accommodative microfluctuations with different stimulus in 40 cm and 25 cm.The differences in accommodative response and accommodative microfluctuations at 25 cm and 40 cm reading distance were compared between the emmetropic children and myopic children using independent sample t test,and change of accommodative microfluctuations in myopic children at 25 cm and 40 cm reading distance was evaluated by paired t test.Results When the reading distance was 25 cm and 40 cm,the accommodative responses of emmetropes were (2.67 ±0.31) D and (1.70 ±0.23) D,and they were higher than (2.31 ± 0.33) D and (1.49 ±0.24) D of myopes,showing significant differences (t =5.330,P =0.000; t =4.140,P =0.000).Accommodative microfluctuation of myopes was(0.35 ±0.16)D in 25 cm reading distance and that of emmtropes was(0.26±0.08)D,with significant difference between them (t =3.180,P =0.002).However,there was not significant difference in accommodative microfluctuation at 40 cm reading distance between the myopic children and emmtropie children [(0.27±0.10) D vs.(0.24±0.09) D] (P=0.220).In myopic children,the accommodative microfluctuation at 25 cm reading distance was(0.35±0.16) D,showing a much increase than(0.27±0.10) D at 40 cm reading distance(t=3.850,P =0.000),but an insignificant difference in the accommodative mierofluctuations was seen between the 25 cm and 40 cm reading distance in the emmetropic children (P =0.145).Conclusions With the increased accommodative stimulus,myopic children present lower accommodative responses and larger accommodative microfluctuations.