Effects of different reading distances on the accommodation of children with myopia

Objective To study the effect of different reading distances on the accommodation of children with myopia and to reveal its relation to the development of myopia.Methods There were 77 children with myopia investigated.The children′s ages between 7 to 14 year-old.Shin-Nippon NVision-K 5001 autorefractor was used to measure accommodative refraction while they viewed target placed at 50cm,33cm and 20cm respectively.Results The results demonstrate that the accommodative demands were 1.90±0.03D,2.85±0.05D and 4.75±0.08D respectively.And the accommodative response were 0.87±0.42D,1.76±0.54D,3.52±0.66D respectively.The accommodative lags were 1.03±0.36D,1.08±0.52D and 1.23±0.63D respectively.When the subjects read in near distance,they responded with accommodative lag.When reading distances decreased,accommodative lag increased.The accommodative lag shows a statistically significant difference among the three reading distances(P=0.014).There was statistically significant difference between 50cm and 20cm,33cm and 20cm,respectively(P0.05).Conclusions Reading distance will affect the accommodative response of children with myopia.Accommodative lag increases with reading distance decreasing.This induces hyperopic retinal defocus.Thus it may be inferred that for the children with myopia,their eyes longer to compensate the effect of retinal defocus.