Red vessels begin to appear from the two canthi on the white of the eye and gradually spread inward. This is often caused by a diet rich in greasy and heavy foods, leading to an exuberance of heart fire that disturbs the eye. This condition should be differentiated from "hyperemia of ocular conjunctiva," where the lesion does not start from the two canthi but can originate from any part of the white of the eye, with vessels becoming tortuous and congested.