经常看电视需要补充维生素Ａ人的视网膜是眼睛的感光结构，它是由两类感光细胞组成的：一类是短粗的锥状细胞，它能感受强光和颜色，在白天光线明亮的条件下，它能识别微小精细的目标，并能鉴别自然界的各种颜色；另一类是细长的柱状细胞，它能感受弱光，在黄昏或晚上光线... Often watch television need to add vitamin A human retina is the light-sensitive structure of the eye, which is composed of two types of photoreceptor cells: one is the short, thick cones, which can feel the light and color, light conditions in the daytime bright Under, it can identify tiny objects, and can identify a variety of colors in nature; the other is slender columnar cells, it can feel weak light, in the evening or evening light ...