Eye of Horus
Ancient Egyptian medicine involved both practical treatments and rituals that invoked divine powers, and Egyptian medical papyri do not clearly distinguish the two. Healing rituals frequently equate patients with Horus, so the patient may be healed as Horus was in myth. For this reason, the Eye of Horus is frequently mentioned in such spells. The Hearst papyrus, for instance, equates the physician performing the ritual to "Thoth, the physician of the Eye of Horus" and equates the instrument with which the physician measures the medicine with "the measure with which Horus measured his eye". The Eye of Horus was particularly invoked as protection against eye disease. One text, Papyrus Leiden I 348, equates each part of a person's body with a deity in order to protect it. The left eye is equated with the Eye of Horus.