Objective To detect macular foveal by CirrusTM HD-OCT using the post acquisition fovea detection and to study its influence on the results of measurement of central retina thickness (CRT).Methods In this retrospectively studies,the 512 × 128 cube scans from 50 eyes of normal subjects and 50 eyes of macular edema patients were analyzed.Three methods for the foveal detection were used,the scan center (SC),the automated detected foveal (AF) and the manually identified foveal (MF).The foveal detected by MF was set as the reference.Radial distances from SC and AF to MF were calculated.Subfields retinal thickness acquired from different groups using different foveal detection methods were compared by paired Student's t test for normal data or Wilcoxon-Mann-Whitney for non-normal data.Results For normal subjects,it is reliable determing the foveal by special tomography features.The means of the radial distance from the MF was (35.0 ± 23.O) μm in scan center group and was (6.0 ± 9.0) μm in automated center (t=-3.732,P ＜0.05).The average CRT difference between the SC and MF groups was (7.4 ±10.4) μm.The median difference between the AF and MF groups was 0 μm (0 to 3),which is significantly less than that between the SC and MF groups (Z =-2.956,P ＜ 0.05).In subjects with macular edema,the means of the radial offset was (59.0 ± 26.0) μm in SC group and was (34.0 ± 23.0)μm in AF group (t =-4.555,P ＜ 0.05).The average CRT difference between the SC and MF groups was (28.0 ± 36.0) μm,which was not significantly greater than the difference between the AF and MF groups (23.0 ± 31.0) μm in macular edema eyes.Conclusions Post acquisition detection of foveal reduces the radial offset to the real fovea,and may improve the reproducibility and reliability of the central retinal thickness qtantification using spectral domain OCT in normal subjects.%目的 研究频域相干光断层扫描(OCT)中,黄斑中心凹定位及其对视网膜厚度测量结果的影响.方法 回顾性系列病例研究.应用频域OCT的512×128区域扫描模式,测量50例正常人和50例黄斑水肿患者的黄斑中心凹区视网膜厚度,均纳入1只眼的检测数据进行分析.黄斑中心凹位置根据常用的扫描中心(SC)、自动检测黄斑中心凹(AF)、手动检测黄斑中心凹(MF)3种模式确定.以MF为标准点,计算SC和AF至MF的距离偏差；分析黄斑中心凹定位对视网膜厚度测量结果的影响.对黄斑中心凹定位偏差和中心凹区视网膜厚度偏差进行比较,符合正态分布的计量数据采用配对t检验；不服从正态分布的计量数据,采用两样本秩和检验.结果 (1)正常人组:黄斑中心凹定位可以通过频域OCT断面扫描特征确定.SC至MF距离为(35.0 ±23.0)μm,经过软件校正的AF至MF距离为(6.0±9.0)μm,偏差较小(t=-3.732,P ＜0.05).SC的视网膜厚度偏差为(7.4±10.4)μm；AF的视网膜厚度偏差范围为0～3 μm,中位数为0,偏差较小(Z=-2.956,P＜0.05).(2)黄斑水肿患者组:黄斑中心凹定位相对困难,SC至MF距离为(59.0 ±26.0)μm,AF至MF距离为(34.0 ±23.O) μm,差异有统计学意义(t=-4.555,P＜0.05).SC的视网膜厚度偏差为(28.0±36.0) μm,AF的视网膜厚度偏差为(23.0±31.0) μm,差异无统计学意义(t=0.968,P＞0.05).结论 频域OCT检测中的黄斑中心凹定位能够影响视网膜厚度的测量结果,通过软件校正的黄斑中心凹位置能够提高视网膜厚度测量的准确性.
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