expression
seeing the light; scales falling from one's eyes
Idiomatic expression, abbreviated from 目から鱗が落ちる. Used when a sudden realization or new understanding dramatically changes one's perspective.
See also: 目から鱗が落ちる
彼の説明を聞いて、目からウロコだった。
When I heard his explanation, the scales fell from my eyes.
この本を読んで、目からウロコの連続だった。
Reading this book was a series of eye-opening revelations.
The full idiomatic phrase; 目からウロコ is a common abbreviation used in the same meaning, often as a standalone exclamation or in the pattern 目からウロコだ.
Abbreviation of the idiom 目から鱗が落ちる, literally 'scales fall from one's eyes', a biblical metaphor for sudden enlightenment.