minuteness, squint
眇 centers on seeing something as very small or narrow: squinting to focus on minute details, or the quality of minuteness itself.
眇 combines 目 (eye) with 少 (few/little), suggesting an eye that sees little or focuses on small things. The exact historical development is uncertain.
The eye 目 sees only a little 少, as if squinting to make out tiny details. Picture someone narrowing their eyes to read fine print.
For ビョウ, imagine a tiny, minute creature called a 'byou' that you can only see by squinting hard: byou -> ビョウ.