gleam in one's eye; sparkle of one's eyes
Refers to the sharp, piercing light or intensity in someone's eyes, often implying strong will, keen perception, or a formidable presence.
The gleam in his eyes was sharp and intimidated the other person.
insight; discernment; power of observation
Figurative extension: the ability to see through things, judge accurately, or perceive hidden truths. Often used in phrases like 眼光紙背に徹す (reading between the lines).
His insight was sharp, and he immediately saw through to the heart of the problem.
with shining, piercing eyes
reading between the lines
Compound of 眼 (eye) and 光 (light). The literal meaning 'light of the eyes' naturally extended to the figurative sense of keen perception or insight.