Vasudevan Balamurali, Ciuffreda Kenneth J
State University of New York/State College of Optometry, New York, NY 10036, USA.
Invest Ophthalmol Vis Sci. 2008 Feb;49(2):836-41. doi: 10.1167/iovs.07-0197.
To determine the additive effect, if any, of NITM after 1 and 2 hours of reading in different refractive groups.
Fifteen early-onset myopes (EOMs), 14 late-onset myopes (LOMs), and 15 emmetropes (EMMs), as well as progressive myopes (PMs) and stable myopes (SMs), were tested. Subjects read binocularly for 2 hours at a distance of 35 to 40 cm. Distance refractive state of the right eye was assessed every 2 seconds for 30 seconds after the first hour of reading, and then every 2 seconds for 120 seconds after the second hour of reading. NITM was calculated as the difference in posttask distance refractive state compared with the pretask distance refractive state after each hour.
Initial NITM values (mean +/- SE) recorded at the end of the near work tasks were 0.22 +/- 0.03 D and 0.29 +/- 0.03 D for the EOMs, 0.14 +/- 0.02 D and 0.20 +/- 0.03 D for the LOMs, 0.14 +/- 0.02 D and 0.15 +/- 0.02 D for the EMMs, 0.20 +/- 0.03 D and 0.27 +/- 0.03 D for the PMs, and 0.09 +/- 0.04 D and 0.20 +/- 0.05 D for the SMs, after the first and second hours of reading, respectively. After the second hour, only in the EOMs and LOMs was NITM significantly greater than that found after the first hour. Seventy percent of the myopes (EOMs and LOMs) but only 47% of the EMMs exhibited increased NITM in the second hour compared with the first hour. Only EOMs exhibited longer decay duration after the second hour of reading. NITM was increased in progressive myopes (PMs), but not in stable myopes (SMs), after the first hour of reading only. Within the PMs, NITM was increased after the second hour compared with the first hour. The time constant for decay was greater in the PMs than in the SMs. Lastly, many myopes (up to 46%) did not experience decay to baseline after the near task over the 120-second posttask period.
EOMs and LOMs demonstrated larger NITM than the EMMs and exhibited NITM additivity, but the EOMs also exhibited prolonged decay of NITM compared with the EMMs and LOMs. PMs, but not SMs, exhibited additivity of NITM. These findings may be attributed to impaired sympathetic function in the subjects with myopia. It is speculated that with repeated cycles of near work, residual NITM may contribute to the progression of permanent myopia.
确定在不同屈光组中阅读1小时和2小时后，负相对调节（NITM）是否存在累加效应。
对15名早发性近视患者（EOM）、14名迟发性近视患者（LOM）、15名正视者（EMM）、进行性近视患者（PM）和稳定性近视患者（SM）进行测试。受试者在35至40厘米的距离进行双眼阅读2小时。阅读第1小时后，每隔2秒评估右眼的远距离屈光状态，持续30秒；阅读第2小时后，每隔2秒评估120秒。NITM计算为每小时阅读任务后远距离屈光状态与任务前远距离屈光状态的差值。
在近工作任务结束时记录的初始NITM值（平均值±标准误），EOM组在第1小时和第2小时分别为0.22±0.03D和0.29±0.03D；LOM组为0.14±0.02D和0.20±0.03D；EMM组为0.14±0.02D和0.15±0.02D；PM组为0.20±0.03D和0.27±0.03D；SM组为0.09±0.04D和0.20±0.05D。第2小时后，仅EOM组和LOM组的NITM显著大于第1小时。70%的近视患者（EOM组和LOM组）在第2小时与第1小时相比NITM增加，而EMM组仅47%增加。仅EOM组在阅读第2小时后表现出更长的衰减持续时间。仅在阅读第1小时后，进行性近视患者（PM）的NITM增加，而稳定性近视患者（SM）未增加。在PM组中，第2小时与第1小时相比NITM增加。PM组的衰减时间常数大于SM组。最后，许多近视患者（高达46%）在近任务结束后的120秒后任务期内未恢复到基线水平。
EOM组和LOM组的NITM大于EMM组，并表现出NITM累加性，但与EMM组和LOM组相比，EOM组的NITM衰减也延长。PM组表现出NITM累加性，而SM组未表现出。这些发现可能归因于近视患者交感神经功能受损。推测随着近工作的反复循环，残余的NITM可能导致永久性近视的进展。
