Monsalve P, Ren S, Triolo G, Vazquez L, Henderson A D, Kostic M, Gordon P, Feuer W J, Porciatti V
Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
Head and Neck Department, IRCCS St. Raffaele Hospital, Milan, Italy.
Doc Ophthalmol. 2018 Jun;136(3):157-164. doi: 10.1007/s10633-018-9633-2. Epub 2018 May 19.
To investigate within-test variability of the steady-state PERG (SS-PERG).
SS-PERGs were recorded in response to black-white horizontal gratings (1.6 cycles/deg, 98% contrast, 15.63 reversals/s, LED display, 25 deg square field, 800 cd/sqm mean luminance) using skin electrodes. PERG and noise (± reference) signals were averaged over 1024 epochs (~ 2.2 min) and Fourier analyzed to retrieve SS-PERG amplitude and phase. SS-PERGs were split into 16 partial averages (samples) of 64 epochs each, and corresponding amplitudes and phases combined in polar coordinates to assess their dispersion (within-test variability). To assess time-dependent variability, samples were clustered in four successive time segments of ~ 33 s each. Amplitude adaptation was defined as amplitude difference between initial and final clusters, and PERG phase adaptation as the corresponding phase difference. To determine the dynamic range of SS-PERG adaptation, recording was performed in normal controls of different age (n = 32) and patients with different severity of optic nerve dysfunction (early manifest glaucoma, EMG, n = 7; non-arteritic ischemic optic neuropathy, NAION, n = 5).
Amplitude adaptation was largest in younger controls (amplitude adaptation ÷ noise, SNR = 9.5, 95% CI 13.1, 5.9) and progressively decreased with increasing age (older subjects, SNR = 5.5, 95% CI 9.2, 1.8) and presence of disease (EMG: SNR = 2.4, 95% CI 3.5, 1.4; NAION: SNR = 1.9, 95% CI 6.5,-2.2). In 11 young subjects, amplitude adaptation was repeatable (test-retest in two sessions a week apart; intraclass correlation coefficient = 0.59). Phase adaptation was not significantly different from zero in all groups.
SS-PERG adaptation accounts for a sizeable portion of the within-test variability. As it has robust SNR, sufficient test-retest variability, and is altered in disease, it may have physiological and clinical significance. This study suggests that SS-PERG protocols should include adaptation in addition to SS-PERG amplitude and phase/latency.
研究稳态图形视网膜电图（SS-PERG）的测试内变异性。
使用皮肤电极记录对黑白水平光栅（1.6 周期/度，98%对比度，15.63 次反转/秒，发光二极管显示屏，25 度方形视野，平均亮度 800 坎德拉/平方米）的 SS-PERG。PERG 和噪声（±参考）信号在 1024 个周期（约 2.2 分钟）内进行平均，并进行傅里叶分析以获取 SS-PERG 的振幅和相位。SS-PERG 被分成 16 个部分平均值（样本），每个样本包含 64 个周期，相应的振幅和相位在极坐标中合并以评估其离散度（测试内变异性）。为了评估时间依赖性变异性，样本被聚类到四个连续的时间段，每个时间段约 33 秒。振幅适应性定义为初始和最终聚类之间的振幅差异，PERG 相位适应性定义为相应的相位差异。为了确定 SS-PERG 适应性的动态范围，在不同年龄的正常对照组（n = 32）和不同严重程度的视神经功能障碍患者（早期显性青光眼，EMG，n = 7；非动脉炎性缺血性视神经病变，NAION，n = 5）中进行记录。
振幅适应性在年轻对照组中最大（振幅适应性÷噪声，信噪比 = 9.5，95%可信区间 13.1，5.9），并随着年龄的增加（老年受试者，信噪比 = 5.5，95%可信区间 9.2，1.8）和疾病的存在（EMG：信噪比 = 2.4，95%可信区间 3.5，1.4；NAION：信噪比 = 1.9，95%可信区间 6.5，-2.2）而逐渐降低。在 11 名年轻受试者中，振幅适应性是可重复的（每周两次测试-复测；组内相关系数 = 0.59）。所有组的相位适应性与零无显著差异。
SS-PERG 适应性占测试内变异性的相当大一部分。由于它具有强大的信噪比、足够的测试-复测变异性，并且在疾病中会发生改变，它可能具有生理和临床意义。本研究表明，SS-PERG 方案除了应包括 SS-PERG 振幅和相位/潜伏期外，还应包括适应性。
