。
The scales fell from my eyes.
Literal
Eye [from-から] scales [subject-が] fell.
A direct calque from the biblical story of Saul's conversion (Acts 9:18), fully naturalised in Japanese as a set idiom for a moment of sudden clarity — 'I suddenly saw X.' 鱗 ('scales,' as on a fish) is obscure vocabulary outside the idiom, but inside it the phrase is entirely idiomatic.