Luo H-D, Gazzard G, Liang Y, Shankar A, Tan D T H, Saw S-M
Singapore Eye Research Institute, Singapore 117597, Republic of Singapore.
Br J Ophthalmol. 2006 Mar;90(3):362-6. doi: 10.1136/bjo.2005.079657.
To determine the association of spherical equivalent (SE) with low uncorrected visual acuity (VA) along with a proposed definition for myopia using logMAR VA >0.3 as the criteria.
1334 Chinese schoolchildren (mean age 7.8; range 7-9 years) were enrolled in the study after those who had hyperopia > or =+2.00 dioptres (D) and astigmatism > = -2.00 D were excluded. Uncorrected logMAR VA was measured for both eyes. Cycloplegia autorefraction was achieved by the instillation of three drops of 1% cyclopentolate 5 minutes apart. The average of five successful consecutive refraction and keratometry readings were obtained with calibrated Canon RK5 autokeratorefractometers by well trained optometry students, at least 30 minutes after the instillation of the third drop of cyclopentolate. SE cut-off points (-0.25 D, -0.5D, -0.75 D, -1.0 D) were evaluated.
Using different SE cut-off points, the myopia prevalence rates of this sample of schoolchildren varied from 45.8% (SE at least -0.25 D) to 30.7% (SE at least -1.0 D). The cut-off point of > or =-0.75 D had a sensitivity and specificity of 91.8% (95% CI, 89.2 to 94.4) and 93.7% (95% CI, 92.1 to 95.3), respectively, to predict low vision defined as uncorrected logMAR VA > 0.3 (either eye). The next best cut-off point of -0.5D had a higher sensitivity (93.3%), but lower specificity (87.9%).
The cut-off points of -0.75D and -0.5D in SE refraction are appropriate for the prediction of uncorrected logMAR VA worse than 0.3, which is the criterion for the US common state adult driver licensing standard.
确定等效球镜度（SE）与低矫正视力（VA）之间的关联，并提出以logMAR VA>0.3为标准的近视定义。
排除远视≥+2.00屈光度（D）和散光≥-2.00 D的儿童后，1334名中国学龄儿童（平均年龄7.8岁；范围7 - 9岁）被纳入研究。测量双眼的未矫正logMAR VA。通过每隔5分钟滴入三滴1%环喷托酯实现睫状肌麻痹验光。由训练有素的验光专业学生使用校准后的佳能RK5自动角膜曲率计，在滴入第三滴环喷托酯至少30分钟后，获取连续五次成功的验光和角膜曲率测量读数的平均值。评估SE的截断点（-0.25 D、-0.5D、-0.75 D、-1.0 D）。
使用不同的SE截断点，该样本学龄儿童的近视患病率从45.8%（SE至少为-0.25 D）到30.7%（SE至少为-1.0 D）不等。≥-0.75 D的截断点预测定义为未矫正logMAR VA>0.3（任一眼）的低视力时，敏感性和特异性分别为91.8%（95% CI，89.2至94.4）和93.7%（95% CI，92.1至95.3）。下一个最佳截断点-0.5D具有较高的敏感性（93.3%），但特异性较低（87.9%）。
SE验光中的-0.75D和-0.5D截断点适用于预测未矫正logMAR VA差于0.3的情况，这是美国普通州成人驾驶执照标准的标准。
