Hasegawa S, Abe H
Department of Ophthalmology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Niigata 951-8510, Japan.
Invest Ophthalmol Vis Sci. 2001 Dec;42(13):3341-8.
To objectively measure a visual field and to sensitively detect glaucomatous visual field defects by measuring the contrast sensitivity function (CSF), using multifocal visual evoked cortical potentials (MVEPs).
MVEPs of normal subjects (n = 28) and of patients with glaucoma (n = 12) or ocular hypertension (OH, n = 1) were recorded. A multi-input procedure was used to obtain 37 local VEP responses to each scaled hexagon, composed of 24 triangular patterns, reversing in a counterphase manner. Two pattern contrasts of 32% and 8% were used for measuring the contrast threshold. To improve the signal-to-noise ratio, 37 MVEPs were averaged into 20 groups. The root-mean-square (RMS) measures at both contrasts were calculated. Contrast thresholds were estimated by extrapolating the regression line of the amplitude versus contrast to the mean noise levels.
RMS amplitudes of each local MVEP decreased as the eccentricity increased and as the pattern contrast decreased in normal subjects. It was also revealed that the amplitudes were smaller in the upper-half field than those in the lower-half field. Compared with the RMS amplitudes, CSFs estimated by MVEPs were relatively constant without being strongly influenced by retinal eccentricity. In patients with glaucoma, the CSFs, even from the locations where the mean perimetric sensitivities ranged to more than 30 dB, were significantly smaller than those in the normal control subjects (P < 0.001, Mann-Whitney test). CSFs in the 20- to 30-dB and 100 to 20-dB groups were also significantly smaller than those in the more-than-30-dB or 20- to 30-dB groups, respectively (P < 0.001, Mann-Whitney test). A significant correlation was found between the logarithmic function of the CSF and perimetric sensitivity (r = 0.57, P < 0.001, n = 216). The CSFs were evaluated on the basis of normal SD. Mappings of the CSFs agreed well with those of the perimetric sensitivity in all patients with glaucoma and was even more sensitive in detecting slight optic nerve damage by glaucoma than was perimetry.
Local optic nerve damage caused by glaucoma can be sensitively detected by measuring contrast sensitivity using the MVEP.
通过使用多焦视觉诱发电位（MVEPs）测量对比敏感度函数（CSF），客观测量视野并灵敏检测青光眼性视野缺损。
记录正常受试者（n = 28）、青光眼患者（n = 12）或高眼压症患者（OH，n = 1）的MVEPs。采用多输入程序获取对每个由24个三角形图案组成并以反相方式反转的缩放六边形的37个局部VEP反应。使用32%和8%的两种图案对比度测量对比阈值。为提高信噪比，将37个MVEPs平均分为20组。计算两种对比度下的均方根（RMS）测量值。通过将幅度与对比度的回归线外推至平均噪声水平来估计对比阈值。
在正常受试者中，每个局部MVEP的RMS幅度随着偏心度增加和图案对比度降低而减小。还发现上半视野的幅度小于下半视野的幅度。与RMS幅度相比，由MVEPs估计的CSF相对恒定，不受视网膜偏心度的强烈影响。在青光眼患者中，即使来自平均视野敏感度范围超过30 dB的位置的CSF也明显小于正常对照受试者（P < 0.001，曼-惠特尼检验）。20至30 dB组和100至20 dB组的CSF也分别明显小于超过30 dB组或20至30 dB组（P < 0.001，曼-惠特尼检验）。在CSF的对数函数与视野敏感度之间发现显著相关性（r = 0.57，P < 0.001，n = 216）。根据正常标准差评估CSF。在所有青光眼患者中，CSF的映射与视野敏感度的映射吻合良好，并且在检测青光眼引起的轻微视神经损伤方面比视野检查更敏感。
通过使用MVEP测量对比敏感度，可以灵敏地检测青光眼引起的局部视神经损伤。
