Comparison of pattern VEP results acquired using CRT and TFT stimulators in the clinical practice
Comparison of pattern VEP results acquired using CRT and TFT stimulators in the clinical practice
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DOI：
10.1007/s10633-011-9270-5
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发表时间：
2011-06-01
影响因子：
1.4
通讯作者：
Varsanyi, Balazs
中科院分区：
文献类型：
--
作者：
Nagy, Balazs Vince;Gemesi, Szabolcs;Varsanyi, Balazs
有几种商业上可用的电生理系统。通常，由于不同显示类型的差异，控制组需要比较他们的结果。我们的目的是研究CRT刺激器和LCD/TFT刺激器在根据ISCEV标准进行的图形VEP反应中的差异。我们的目标也是检查不同对比度的阈值。为了获得更准确的结果，我们打算用光度方法测量监视器的强度和时间响应特性。为了记录VEP信号，使用了Roland RetiPort电生理系统。图形VEP测试按ISCEV协议在CRT和TFT监视器上连续进行。在三种不同的对比度水平(最大，75%，25%)下，使用1A度和15‘格子大小的消色差棋盘图案。根据基于几个DAC值测量的伽马函数，CRT和TFT显示器的亮度和对比度都是匹配的。通过光谱辐射仪器测量了显示器特有的亮度参数。显示器的电子信号和辐射信号之间的时间差是用专门为此目的制造的设备测量的。我们测试了6名视力至少为20/20的健康对照组受试者。每名受试者在不同的日子里进行了三次测试。我们发现CRT和LCD显示器在所有对比度水平和空间频率上都存在显著的时间差异。使用TFT刺激器的潜伏期平均延长9.0ms(+/-3.3ms)。该值与测量的TFT输入-输出时间差值的平均值(10.1+/-A 2.2毫秒)一致。根据我们的发现，利用充分校准的测量设置测量TFT监视器的时间参数，并用结果值校正VEP数据，可以将不同显示类型获得的VEP信号转换为可比较的。
There are several electrophysiological systems available commercially. Usually, control groups are required to compare their results, due to the differences between display types. Our aim was to examine the differences between CRT and LCD/TFT stimulators used in pattern VEP responses performed according to the ISCEV standards. We also aimed to check different contrast values toward thresholds. In order to obtain more precise results, we intended to measure the intensity and temporal response characteristics of the monitors with photometric methods. To record VEP signals, a Roland RetiPort electrophysiological system was used. The pattern VEP tests were carried out according to ISCEV protocols on a CRT and a TFT monitor consecutively. Achromatic checkerboard pattern was used at three different contrast levels (maximal, 75, 25%) using 1A degrees and 15' check sizes. Both CRT and TFT displays were luminance and contrast matched, according to the gamma functions based on measurements at several DAC values. Monitor-specific luminance parameters were measured by means of spectroradiometric instruments. Temporal differences between the displays' electronic and radiometric signals were measured with a device specifically built for the purpose. We tested six healthy control subjects with visual acuity of at least 20/20. The tests were performed on each subject three times on different days. We found significant temporal differences between the CRT and the LCD monitors at all contrast levels and spatial frequencies. In average, the latency times were 9.0 ms (+/- 3.3 ms) longer with the TFT stimulator. This value is in accordance with the average of the measured TFT input-output temporal difference values (10.1 +/- A 2.2 ms). According to our findings, measuring the temporal parameters of the TFT monitor with an adequately calibrated measurement setup and correcting the VEP data with the resulting values, the VEP signals obtained with different display types can be transformed to be comparable.