《黄帝内经·灵枢·大惑论》
眼的瞳子部分属于肾，黑睛属于肝，二者为阴脏的精气所滋养；白睛属肺，眼球的赤脉属于心，二者依赖阳脏的精气所滋养，因此，阴脏的精气和阳脏的精气相互结合而协调，才能使眼睛具有视物清晰的功能。
是故瞳子黑眼法于阴，白眼赤脉法于阳也，故阴阳合传而精明也。
The pupil of the eye belongs to the kidney, and the black of the eye belongs to the liver, and both are nourished by the vital Qi of the yin organs; the white of the eye belongs to the lung, and the red veins of the eyeball belong to the heart, and both rely on the vital Qi of the yang organs to nourish them, so the vital Qi of the yin organs and the vital Qi of the yang organs are combined and coordinated to enable the eyes to have Clear vision function.