What are the brands of automatic computerized visual field meter

The earliest batch of Tektronix, Beo, Elsie, these devices are some of the LED lights inside, the principle is to control its current to change the size of the light bright and dark, but the current increases by half, the brightness does not increase by half, so the background light and stimulation of the light are not standard! Chongqing Shangbang optical field of view meter and Germany Zeiss high-end better, the background light and projected light is more standard, there is a very important dynamic field of view and blue and yellow detection!