不同阅读距离的调节准确度与早发性近视眼的相关性

The relationship between accommodative accuracy at different near-work distances and early-onset myopia

目的探讨早发性近视眼儿童的调节准确度与早发性近视眼发生发展的相关性。方法病例对照研究。7—13岁早发性近视眼未矫正者41例，戴镜者39例，正视者37例。运用综合验光仪双眼融像性交叉柱镜（FCC）测量所有入选者的屈光度数及20、30、40、50cm阅读距离下的调节准确度。比较3个组之间以及不同阅读距离之间调节准确度的差异，分析调节准确度与近视眼屈光度数的相关性。3个组之间性别比例、调节滞后比例、调节准确度的差异采用非参数检验，年龄、屈光度数、调节滞后量FCC值的差异采用单因素方差分析，阅读距离与调节准确度之间的相关性、近视眼屈光度与FCC值之间的相关性以及与调节准确度之间的相关性采用Spearman相关分析。结果大部分受试者包括正视眼的调节准确度都存在滞后现象，不同阅读距离的滞后比例分别是75．21％（50cm）、87．18％（40cm）、92．31％（30cm）、98．29％（20cm）。所有受试者随阅读距离的缩短，调节滞后的比例及FCC值增加、调节准确度降低。3个组之间30和20cm调节准确度的差异有统计学意义（30cm：χ2=7．852，P=0．020，20cm：χ2=6．480，P=0．039），其余距离差异无统计学意义（P〉0．05）。3个组之间30和20cmFCC值的差异有统计学意义（30cm：F=3．626，P=0．030；20cm：F=3．703，P=0．028），两两比较，仅近视眼未矫正组FCC值[30cm：（1．25±0．44）D，20cm：（1．76±0．43）D）]与正视组[30cm：（0．95±0．52）D，20cm：（1．41±0．58）D]的差异有统计学意义（30cm：P=0．012，20cm：P=0．008），其余差异无统计学意义（P〉0．05）。近视眼屈光度数与不同阅读距离的调节准确度之间均无显著的相关性，但与20cm的FCC值有显著的相关性（r=0．246，P=0．028）。结论早发性近视眼尤其是未矫正眼随阅读距离的拉近，调节准确度降低的程度较正视眼显著。戴镜可能通过改善调节阈值和敏感度提高了较近阅读距离的调节准确度。早发性近视眼的发生发展与调节准确度可能无关，但是与较近阅读距离（〈30cm）的调节滞后量密切相关，调节滞后量越高，近视屈光度数越高。

Objective To observe the accommodative accuracy of children with early-onset myopia at different near-work distances, and discuss the relationship between accommodative accuracy and early- onset myopia. Methods This was a case-control study. Thirty-seven emmetropie children, 41 early-onset myopic children without correction, and 39 early-onset myopic children with spectacles, aged 7 to 13 years, were included. Measures of refractive errors and accommodative accuracy at four near-work distances, including 50 cm, 40 cm, 30 cm, and 20 cm, were made using the binocular fusion cross cylinder （FCC） of an automatic phoropter. Results Most candidates showed accommodative lags, including the children with emmetropia. The ratio of lags in all candidates at different near-work distances was 75.21% （50 cm）, 87.18% （40 cm）, 92.31% （30 cm）, and 98.29% （20 cm）, respectively. All accommodative accuracies became worse, and the accommodative lag ratio and values of FCC increased, along with the shortening of the distance. The difference in accommodative accuracy among groups was statistically significant at 30 cm （χ2=7.852, P=0.020） and 20 cm （χ2=6.480, P=0.039）. The values of FCC among groups were significantly different at 30 cm （F=3.626, P=0.030） and 20 cm （F=3.703, P=0.028）, but not at 50 cm and 40 cm （P〉0.05）. In addition, the FCC values of 30 cm and 20 em had a statistically significant difference between myopic children without correction [（1.25±0.44） D and （1.76±0.43） D] and emmetropie ehildren [（0.95±0.52） D and （1.41±0.58） D] （P=0.012, 0.008）. The correlation between diopters of myopia and aeeommodative accuracy at different near- work distances was not statistically significant （P〉0.05）. However, the correlation between diopters of myopia and the accommodative lag value （FCC） at 20 cm was statistically significant （r=0.246, P=0.028）. Conclusions The closer the near-work distance is, the worse the accommodative accuracy is. This is more significant in early-onset myopia, especially myopia without correction, than emmetropia. Wearing spectacles may improve the threshold and sensitivity of accommodations, and the accommodative accuracy at near-work distances （〈30 cm） to some extent. The poor accommodative accuracy at near-work distances may be not related to early-onset myopia, but the value of FCC （20 cm） is related to early-onset myopia. The higher the FCC value is, the higher the diopter is.