Diagnostic accuracy and variability of autorefraction by the Tracey Visual Function Analyzer and the Shin-Nippon NVision-K 5001 in relation to subjective refraction

Purpose:  To determine the accuracy of distance autorefractions obtained by two 'open field' devices, the Tracey Visual Function Analyzer and the Shin-Nippon NVision-K 5001, by comparison with subjective refraction.
Methods:  Both eyes of 50 healthy phakic participants underwent subjective refraction. Autorefractions were then performed on undilated pupils using the Tracey and a modified Shin-Nippon autorefractor and these were repeated within 50 days. Agreement with subjective refraction was calculated for sphere, mean spherical equivalent (MSE) and cylindrical vectors J ₀ and J ₄₅. Intratest and intertest variability were also evaluated.
Results:  The mean age of the participants was 37.4 years. Subjective refraction MSE ranged from −6.25 D to +3.62 D, mean −0.49 D ± 1.79 D. Bias between subjective refraction and Tracey was −0.001 D, +0.045 D, +0.017 D, and −0.015 D for sphere, MSE, J ₀ and J ₄₅ respectively; these were not significant. Bias between subjective refraction and Shin-Nippon was +0.004 D, +0.033 D, +0.106 D, and −0.021 D; only the J ₀ vector was significantly different ( p  < 0.0001) although this difference was small. Intratest variability for Tracey was low, measured at 0.189 D for sphere and 0.178 for MSE, and for the Shin-Nippon 0.099 D and 0.086 D respectively. Tracey intertest variability revealed small, statistically significant bias for sphere and MSE (+0.071 D and +0.070 D, p  = 0.011, 0.013). Shin-Nippon reproducibility showed no significant bias.
Conclusions:  Autorefraction measurements captured by both the Tracey and Shin-Nippon devices agree well with subjective refraction. The Shin-Nippon shows lower intratest variability.     

Suresight手持式自动验光仪检测婴幼儿屈光状态对早期弱视筛查价值的探讨

目的通过Suresight手持式自动验光仪检测婴幼儿屈光结果的分析,寻找出弱视高危人群和可疑人群,为早期发现儿童弱视提供一种手段。方法对本院作健康检查的3岁以下婴幼儿1325名,2650只眼分成7组进行了屈光检查。结果获得了各年龄组球镜和柱镜的2603只眼的球镜值和柱镜值的频数分布、均数、标准差和P25～P75和P5～P95参考值范围。结论建议各组球镜度数偏离出P25～P75(D)和柱镜绝对值度数偏离出P75(D)者应列为弱视高危人群,球镜度数偏离出P5～P95(D)和柱镜绝对值度数偏离出P95(D)者应列为弱视可疑人群,相应地采取不同的管理措施以达到早期发现弱视的目的,这对儿童眼保健工作有直接的指导意义。     

手持自动验光仪筛查儿童屈光不正的可行性探讨

目的探讨NIDEKARK-30手持自动验光仪筛查学龄期儿童屈光不正的有效性与可行性，试确定在非睫状肌麻痹状态下筛查儿童屈光不正的阳性界值。方法样本来自人群为基础的流行病学调查资料，采用系统抽样方法，随机抽取7～16岁儿童300名，600只眼。用NIDEKARK-30手持自动验光仪分别在睫状肌麻痹前后测定其双眼屈光状态。分析睫状肌麻痹前后双眼屈光状态差异，计算不同筛查阳性界值的灵敏度、特异度、Youden指数和阳性预测值。结果睫状肌麻痹前后双眼等效球镜度变化差异有显著性，散瞳后近视度数减少、远视度数增加；柱镜度和散光轴向变化差异无显著性。比较各年龄组睫状肌麻痹前后等效球镜度数变化，发现7～8岁、9～10岁和11～12岁组差异无显著性，13～14岁和15～16岁组差异亦无显著性；而7～12岁与13～16岁组差异有显著性。在非睫状肌麻痹状态下设定不同的儿童屈光不正筛查界值，发现7～12岁组选用≥-2．50D，13～16岁组选用≥-2．0D作为筛查近视的阳性界值，具有较好的灵敏度、特异度、Youden指数和阳性预测值。结论利用NIDEKARK-30手持自动验光仪在非睫状肌麻痹状态下检查儿童屈光状态，可以作为筛查学龄期儿童屈光不正的有效手段之一。     

The influence of cycloplegia in objective refraction

The purpose of this study was to compare refractions measured with an autorefractor and by retinoscopy with and without cycloplegia. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 +/- 2.66 years. The measurements were performed first without cycloplegia and repeated 30 min later with cycloplegia. Data were analysed using Fourier decomposition of the power profile. More negative values of component M and J(0) were given by non-cycloplegic autorefraction compared with cycloplegic autorefraction (p < 0.0001). However more positive values for the J(45) vector were given by non-cycloplegic autorefraction, although this difference was not statistically significant (p = 0.233). By retinoscopy, more negative values of component M were obtained with non-cycloplegic retinoscopy (p < 0.0001); for the cylindrical vectors J(0) and J(45) the retinoscopy without cycloplegia yields more negative values (p = 0.234; p = 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to the accommodative response, the present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain the objective starting point for refraction under non-cycloplegic conditions.     

手持自动验光仪在学龄前儿童验光中的应用

目的：评估HAR-800手持验光仪对学龄前儿童屈光检查的准确性。

方法：对173例学龄前儿童进行检影验光,首先行HAR-800手持验光仪检查(试验组),然后应用阿托品眼膏进行扩瞳检影验光(对照组),比较两种检影验光的屈光差异。

结果：试验组球镜为1.59±0.61D,对照组为3.15±0.72D,两者有显著统计学差异(t=-82.89, P<0.01),且具有相关性(r=0.87,P<0.01)。试验组散光为-0.62±0.51D,对照组为-0.48±0.55D,两者有显著统计学差异(t=-6.97,P<0.01),且具有显著相关性(r=0.76,P<0.01)。

结论：HAR-800手持验光仪不能替代阿托品检影验光,但其结果可以反映学龄前儿童的屈光状况。     

青少年屈光不正患者扩瞳后验光结果与配镜处方的比较分析

目的：比较青少年屈光不正患者扩瞳后电脑验光、扩瞳后试镜与配镜处方的差异,探讨青少年屈光不正验光配镜的重点和注意事项。

方法：选取334例青少年屈光不正患者(包括212例近视和122例远视),进行扩瞳后电脑验光并试镜,恢复自然瞳孔后再试镜确定配镜处方。回顾性分析扩瞳后电脑验光、扩瞳后试镜和配镜处方之间的差异。

结果：扩瞳后电脑验光和扩瞳后试镜之间,总体数据中球镜和轴向的差异具有统计学意义(P<0.05),近视组中球镜、柱镜和轴向的差异均具有统计学意义(P<0.05),远视组中轴向的差异具有统计学意义(P<0.05)。总体数据和远视组中,扩瞳后电脑验光、扩瞳后试镜与配镜处方的球镜和轴向的差异有统计学意义(P<0.05)。远视组中扩瞳后电脑验光和扩瞳后试镜的球镜均大于配镜处方,且扩瞳后试镜与配镜处方柱镜的差异也有统计学意义(P<0.05)。近视组中扩瞳后电脑验光与配镜处方的球镜、柱镜和轴向的差异均有统计学意义(P<0.05),扩瞳后试镜与配镜处方的柱镜和轴向的差异均有统计学意义(P<0.05)。Bland-Altman分析提示,无论屈光性质,扩瞳后电脑验光和扩瞳后试镜的球镜、柱镜存在较好一致性,二者之间的差异在临床上可以接受,而轴向的一致性则较差。Bland-Altman分析提示,总体数据和远视组中,扩瞳后电脑验光、扩瞳后试镜分别与配镜处方的球镜和轴向的一致性较差,柱镜则存在较好一致性。近视组中扩瞳后电脑验光、扩瞳后试镜分别与配镜处方的球镜、柱镜具有较好的一致性,轴向的一致性则较差。

结论：扩瞳后电脑验光、扩瞳后试镜结果均不能作为配镜处方。扩瞳后电脑验光与扩瞳后试镜之间的差异有统计学意义,二者的球镜、柱镜存在较好的临床一致性。扩瞳后电脑验光和扩瞳后试镜的轴向不具有一致性,二者与配镜处方的一致性也较差。所以复光试镜时要加强对轴向的反复验证。     

两种电脑验光仪对1 138例中国儿童青少年屈光度测量的一致性

目的：比较两种电脑验光仪在近视筛查中对中国学龄期儿童屈光度测量的一致性。

方法：应用拓普康RM-8900和天乐RM-9000电脑验光仪对从天津东丽区四所中小学分层抽样得到的6～16岁学生测定非睫状肌麻痹下的屈光度。运用Sperman相关分析和Bland-Altman法评价两种方法测量球镜度、柱镜度和等效球镜度的一致性,同时分析两种方法测量的散光轴向差异分布情况。

结果：研究最终纳入1 138例患者2 276眼,平均年龄10.49±2.66岁。Spearman相关分析显示,天乐RM-9000测量的球镜度(r=0.958, P<0.0001)、柱镜度(r=0.769, P<0.0001)和等效球镜度(r=0.962, P<0.0001)均与拓普康RM-8900测量结果高度相关。Bland-Altman分析表明,天乐RM-9000测定的球镜度比拓普康RM-8900显著偏向远视(P<0.0001),平均差异为0.44 D(标准差：0.37; 95%置信区间：-0.27,1.16),其中95%置信区间内最大球镜度差值的绝对值(1.13 D)超出临床误差可接受范围(-0.50～+0.75D); 然而,两种方法测定的柱镜度差异无统计学意义(P=0.83),平均差异为-0.01 D(标准差：0.31; 95%置信区间：-0.62,0.61),其中95%置信区间内最大柱镜度差值的绝对值(0.62 D)在临床误差可接受范围(-0.50～+0.75D)内。两种仪器测定的柱镜轴向差异在20°以内的比例在柱镜度 ≤-0.25 D的散光眼中达到84.6%(1 503/1 777),而这一比例在柱镜度≤-0.75 D的散光眼(n=885)中升高至96.4%(853/885)。

结论：天乐RM-9000电脑验光仪测量的球镜度相比于Topcon RM-8900结果显著偏向远视,两种仪器对于柱镜度及柱镜轴向的测量一致性在临床可接受范围内。     

Systematic measurement errors involved in over‐refraction using an autorefractor (Grand‐Seiko WV‐500): is measurement of accommodative lag through spectacle lenses valid?

PURPOSE: Lags of accommodation in ametropic children are often evaluated through spectacle lenses (over-refraction). This study investigated the validity of over-refraction when using an autorefractor. METHODS: Using an autorefractor (Shin-Nippon SRW-500/Grand-Seiko WV-500), refractive readings were obtained in 25 cyclopleged eyes (mean +/- S.D. refraction: -3.44 +/- 3.56 D, range: from -10.56 to +0.25 D) while placing spherical lenses of different power (from -5.00 to +5.00 D) in front of the eye at a vertex distance of 12 mm. Based on the refractive readings with and without the lens, and the lens power, measurement errors were estimated. Similarly, the measurement errors were estimated also in model eyes of -10.00, -4.75, 0.00 and +10.00 D. The results were compared with ray-tracing simulations based on the internal specifications of the autorefractor. RESULTS: Measurement errors were found unless the power of the spectacle lens was equal to the refractive error of the eye. When the spectacle lens power was greater (less myopic or more hyperopic) than the refraction of the eye, the measurement error was negative in sign and greater than -0.3 D. It follows that, when an accommodative response is measured in myopic subjects, the refractive reading usually becomes more myopic than the refraction of the eye including the accommodative response; hence, the accommodative response is overestimated, and the lag of accommodation is underestimated. CONCLUSIONS: The autorefraction through spectacle lenses involved systematic measurement errors. The extent of the errors is usually small but needs to be taken into account in a comparative study of accommodative responses among different refractive groups.