不同阅读距离对儿童近视调节反应的影响

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

目的研究不同阅读距离对儿童近视调节反应的影响,推测它和近视发生的可能关系。方法应用Shin-NipponNVision-K5001红外线自动验光仪,在阅读距离分别为50cm、33cm、20cm时,测量77例7岁～14岁近视儿童的调节状态。结果在阅读距离为50cm、33cm、20cm时,所需的调节需求分别为(1.90±0.03)D、(2.85±0.05)D和(4.75±0.08)D;调节反应分别为(0.87±0.42)D、(1.76±0.54)D、(3.52±0.66)D,调节滞后则为(1.03±0.36)D、(1.08±0.52)D、(1.23±0.63)D。在近距离阅读中,儿童近视者的调节反应均表现为调节滞后,且随着阅读距离减小,调节滞后增加;三个不同阅读距离间的调节滞后差别有统计学意义(P=0.014),其中50cm与20cm、33cm与20cm的阅读距离的调节滞后差别有统计学意义(P<0.05)。结论阅读距离为儿童近视者的调节反应影响因素之一,阅读距离越近者调节滞后越明显,形成远视性离焦越明显,从而可能导致儿童近视的加深。

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 （P 〈 0. 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.