This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
盰 combines 目 (eye) with 干, but the exact historical development is uncertain. It may have originally related to the white of the eye, but this is not well established.
The left side is an eye 目, and the right side is 干. Picture an eye with a dry, white appearance, but remember that the meaning is uncertain.
For カン, imagine a can of eye drops: can -> カン, and the drops are for the eye 目.