The verb inoculate and the noun inoculation both refer to the "eye"
These terms are used as references to something that looks like or is suggestive of a person's organ of sight. Undeveloped buds on a potato are common examples of the use of eye.
In the eighteenth century, medical researchers discovered that introducing a small amount of an infective agent into someone made that person immune to a normal attack of the same disease.
The idea of implanting, or grafting, a bud into another plant carried over into the process of inserting an infective agent into the body; and so, inoculate and inoculation have become more common for their medical applications than for their botanic procedures.
The words inoculate and inoculation were originally gardening terms; however, when a doctor inoculates anyone, the person is being "planted" in the body with a small seedling of a germ that causes the disease in order to make the person immune to a more serious attack.
As stated earlier, the word inoculate at first was a purely horticultural term and meant to insert an eye, or bud, into a plant for propagation.
Other "eye" words from ocul- are available.