Felius Joost, Wang Yi-Zhong, Birch Eileen E
Retina Foundation of the Southwest, Dallas, TX 75231, USA.
J AAPOS. 2003 Dec;7(6):406-12. doi: 10.1016/j.jaapos.2003.07.009.
To study the accuracy of the newly proposed Amblyopia Treatment Study (ATS) visual acuity testing protocol for 3- to 6-year-old children. Because no "gold standard" is available for acuity testing in pediatric patients, accuracy was evaluated using computer simulations based on a psychometric model.
Monte Carlo simulations of ATS acuity data were generated using a psychometric model that accounts for true acuity, noise in the visual system, and the rate of inadvertent misses. We varied true acuity from 20/15 to 20/400 (-0.1 to 1.3 logMAR). Visual system noise was represented by the slope beta of the psychometric function and ranged from 1 (noisy) to 8 (not noisy). The rate of inadvertent misses ranged from 0% to 10%. Accuracy of the ATS protocol was evaluated in terms of precision, bias, and stimulus range limitations. The same model was fitted to experimental ATS acuity data, thus allowing us to study the distributions of acuity, visual system noise, and level of attentiveness in 126 children ages 3 to <7 years.
For conditions with little noise in the visual system (beta > 2), precision was well within 0.1 logMAR (corresponding to one line on a logMAR letter chart), except for acuities worse than 1.2 logMAR, and decreased to 0.15 to 0.2 logMAR for beta = 1. Bias was negligible, except in noisy conditions, where the ATS protocol tended to overestimate acuity by one line at the poor end of the true acuity range and underestimate acuity at the good end of the true acuity range. Effects of the rate of inadvertent misses were small. Fits to the real data showed a wide range of slope parameters, but only 11% had beta < or = 2. The rate of inadvertent misses was < or = 2% in 89% of cases.
The simulations suggest that the ATS protocol offers an accurate method for assessing visual acuity in children in the range of 3 to 6 years of age with both precision and bias within 0.1 logMAR for typical values of the psychometric parameters.
研究新提出的弱视治疗研究（ATS）视力测试方案用于3至6岁儿童的准确性。由于儿科患者的视力测试没有“金标准”，因此基于心理测量模型通过计算机模拟来评估准确性。
使用考虑真实视力、视觉系统噪声和意外漏检率的心理测量模型生成ATS视力数据的蒙特卡洛模拟。我们将真实视力从20/15改变至20/400（-0.1至1.3 logMAR）。视觉系统噪声由心理测量函数的斜率β表示，范围从1（有噪声）至8（无噪声）。意外漏检率范围从0%至10%。根据精密度、偏差和刺激范围限制评估ATS方案的准确性。将相同模型拟合至实验性ATS视力数据，从而使我们能够研究126名3至<7岁儿童的视力分布、视觉系统噪声和注意力水平。
对于视觉系统噪声较小的情况（β>2），除了视力差于1.2 logMAR外，精密度在0.1 logMAR以内（相当于logMAR字母视力表上的一行），而对于β = 1，精密度降至0.15至0.2 logMAR。偏差可忽略不计，除了在有噪声的情况下，此时ATS方案在真实视力范围较差端倾向于高估视力一行，而在真实视力范围较好端低估视力。意外漏检率的影响较小。对实际数据的拟合显示斜率参数范围较宽，但只有11%的β≤2。在89%的病例中，意外漏检率≤2%。
模拟表明，对于心理测量参数的典型值，ATS方案为评估3至6岁儿童的视力提供了一种准确的方法，精密度和偏差均在0.1 logMAR以内。
