Objective: To assess the accuracy of photoscreening for detecting refractive amblyopia risk factors (ARFs) in Chinese preschool children aged 4 to 5 years. Methods: A cross-sectional study. Comprehensive ocular examinations were conducted for preschool children in Nanjing, China from September to December, 2016. Photoscreening (Plusoptix A12C) was applied for refractive screening without cycloplegia. Voluntary children and children suspected of eyes abnormalities received cycloplegic retinoscopy (CR). Results of photoscreening and CR were compared using Wilcoxon signed rank test, and Bland-Altman plot were used to assess the agreement between the photoscreener and CR. According to the updated preschool vision screening guidelines from American Association for Pediatric Ophthalmology and Strabismus (AAPOS) in 2013, CR was adopted for identifying children with ARFs, which was considered as a golden standard. Based on the golden standard, the accuracy of 5 sets of referral criteria (including sensitivity standard, Matta/Silbert standard, AAPOS2013 standard, Alaska Blind Child Discovery standard, specificity standard) for photoscreener were tested. Receiver operating characteristics curves were constructed applied to evaluate the quality of the photoscreener in refractive ARFs detection and to find probably the best cut-off points. Results: In total, 1 986 children [mean age, (4.57±0.29) years] received comprehensive examinations, including 1 084 boys and 902 girls. The test ability of photoscreening was 99.04% (1 967/1 986) in the preschool children, and 96.56%(1 827/1 892) of the children got a reliable result within three screening attempts. In 538 children who had data of CR, refractive error of one child exceeded the upper limit of the photoscreener value setting, which was directly categorized as hyperopia, so in the end, 537 children were included to analyze the comparison between the two tests. The measurement values of photoscreening were lower than those of CR in sphere, cylinder and spherical equivalent [(0.75 (0.50, 1.25) D vs. 1.25 (1.00, 1.75) D, Z=-10.36, P<0.01; -0.50 (-0.75, -0.25) D vs. -0.25 (-0.75, 0.00) D, Z=-11.10, P<0.01; 0.63 (0.38, 0.88) D vs. 1.00 (0.75, 1.50) D, Z=-13.33, P<0.01]. The 95% limit of agreement cover rates between the photoscreening and CR in sphere, cylinder and spherical equivalent was 96.28% (517/537), 95.34% (512/537) and 96.65% (519/537), respectively. Based on the golden standard, 47 (8.74%) children had refractive ARFs, and the range of sensitivity, specificity, Youden index, positive predictive values and negative predictive values for detecting refractive ARFs of the 5 common used referral criteria was from 63.83% to 97.87%, from 53.36% to 97.56%, from 0.51 to 0.80, from 16.73% to 74.51% and from 96.57% to 99.62%, respectively. Considering particular refractive ARFs on the basis of the receiver operating characteristic curves, the optimal cut-off point for astigmatism was set at 1.38 D. Conclusion: Photoscreening could be an applicable tool to detect refractive ARFs in preschool children. (Chin J Ophthalmol, 2020, 56: 189-196).
目的： 评估双目屈光筛查仪在4~5岁学龄前儿童视力筛查中判定屈光性弱视危险因素（ARF）的精确度。 方法： 横断面研究。于2016年9至12月在南京市雨花台区对4~5岁学龄前儿童使用双目屈光筛查仪进行非散瞳屈光度数筛查及综合性眼科检查。对其中疑似眼部异常儿童及主动接受详细检查的儿童进行睫状肌麻痹检影验光（CR）检查，采用Wilcoxon符号秩检验比较双目屈光筛查仪与CR检查屈光度数的差异，并用Bland-Altman法评估二者的一致性。参照美国斜视与小儿眼科学会（AAPOS）2013年发布筛查指南中的标准，以CR检查结果判定受试儿童是否具有屈光性ARF，并以此为金标准，评估双目屈光筛查仪以5种常用转诊标准（敏感性标准、Matta/Silbert标准、AAPOS2013标准、阿拉斯加州盲童探索组织2012标准、特异性标准）判定受试儿童屈光性ARF的准确度。采用受试者工作特征（ROC）曲线计算双目屈光筛查仪判定屈光性ARF的最佳截断值作为最佳转诊标准。 结果： 共有1 986名儿童行双目屈光筛查仪检查，年龄（4.57±0.29）岁，包括1 084名男童和902名女童。双目屈光筛查仪的检查成功率为99.04%（1 967/1 986）。共有1 892名儿童双目屈光筛查仪检查取得了检测数值，其中1 827名（96.56%）儿童可在3次检测内获得可信结果。共有538名儿童接受了CR检查，除外1名被双目屈光筛查仪直接识别为"远视"的儿童后，剩余537名儿童进行了屈光度数对比分析，结果显示双目屈光筛查仪较CR低估球镜度数[0.75（0.50，1.25）D与1.25（1.00，1.75）D比较；Z=-10.36，P<0.01]，高估柱镜度数[-0.50（-0.75，-0.25）D与-0.25（-0.75，0.00）D比较；Z=-11.10，P<0.01]，低估等效球镜度数[0.63（0.38，0.88）D与1.00（0.75，1.50）D比较，Z=-13.33，P<0.01]。一致性分析显示，分别有96.28%（517/537）、95.34%（512/537）、96.65%（519/537）儿童的双目屈光筛查仪及CR检测值在球镜度数、柱镜度数、等效球镜度数的95%一致性界限内。CR检查结果显示47名儿童（8.74%）具有屈光性ARF，以此为金标准，双目屈光筛查仪以5种常用转诊标准判定屈光性ARF的敏感度为63.83%~97.87%，特异度为53.36%~97.56%，约登指数为0.51~0.80，阳性预测值为16.73%~74.51%，阴性预测值96.57%~99.62%。ROC曲线计算得出双目屈光筛查仪判定散光性ARF的最佳转诊标准为散光度数>1.38 D。 结论： 双目屈光筛查仪在4~5岁学龄前儿童视力筛查中判定屈光性ARF的精确度较高。（中华眼科杂志，2020，56：189-196）.
Keywords: Amblyopia; Child, preschool; Refractive errors; Refractive screening.