玻璃体切割术前ERG检查对术后视力预测的评价

The prognostic value of preoperative electroretinography in vitrectomy

为确定玻璃体切割术前ＥＲＧ检查对术后视力预测的数量评价，为临床医生提供准确的判断标准，对由各种原因引起的玻璃体混浊７２眼，玻璃体切割术前作双眼ＥＲＧ检查，以术后较长时间的随访视力作为标准，术后视力大于或等于０．０５，小于０．０５两组眼的ｂ波振幅均数作为临界点，如ｂ波振幅大于３１６．６６５μｖ（临界值），９２．３％的眼获得０．０５以上的术后视力（阳性预测值）；术后视力０．０５以上（包括０．０５）的眼中，５４．５０％的眼ｂ波振幅大于３１６．６６５μｖ（敏感度）；同样地，ａ波的阳性预测值、敏感度分别为８１．２５％、５９．１％。ｂ波振幅小于３１６．６６５μｖ的眼中５６．５％的术后视力低于０．０５（阴性预测值），术后视力低于０．０５的眼中９２．９％的眼术前ｂ波振幅低于３１６．６６５μｖ（特异度）；ａ波的阴性预测值、特异度分别为５５％、７８．６％。在评价视网膜电图方面作者利用正常人ｂ与ａ波间的函数关系来评价视网膜整体功能，可克服不同病人间因玻璃体混浊情况不同，不同实验室间因刺激条件不一致所引起的相互间不能比较。所得结果与ｂ波一致，但这种方法是以ＥＲＧ各成份的起源为基础，结果较准确。结果：显示ｂ波预测术后视力较ａ波好，并?

Purpose:An investigation was carried out into the prognostic value of different intensity flash electroretinography(ERG) recorded for 72 eyes with opaque vitreous prior to vitrectomy.Method:We use the mean value of the bwave amplitudes of two groups as cutoff point,two groups were formed acording to the outcome of surgery,one group have a visual acuity(VA)of 005 or better,the other less than 005,The Positive predictive value for ERG bwave is 923%,The sensitivity for ERG bwave is 545%.The positive predictive value and sensitisity for ERG awave are 8125% and 591%,respectively.A low bwave less than the cutoff point in the ERG was associated with a poor visual outcome (VA<005) in 565% of cases (negative predicitive value),and 929% of the eyes with a poor visual outcome had a low bwave (specificity)The corresponding values for the ERG awave are 55% and 786%,respectively,when relationship between the amplitudes of the bwave and the awave is used as an index for evaluating the electroretinogram,the result in the same as ERG bwave,but this method is based on physiological considerations regarding the origin of the ERG components,such a method will facilitage data exchange between centres and can also be used for clinical assessment of the retina more accurately.Result:ERG bwave is a better index of final visual acuity for vitrectomy than awave.The bwave more than the cutpoint in the ERG have a good predictive vale.Conclusion:normal bwave amplitude have good predictive value in vitrectomy abnormal bwave amplitude(less than the cutpoint)have poor predictive value.