be unable to believe one's eyes

be unable to believe one's eyes (third-person singular simple present is unable to believe one's eyes or cannot believe one's eyes, present participle being unable to believe one's eyes, simple past was unable to believe one's eyes or could not believe one's eyes, past participle been unable to believe one's eyes)

1. To be amazed by what one sees.
   • 2021, Miya Kazuki, Ascendance of a Bookworm: Part 3‎, volume 4, J-Novel Club, →ISBN:

     He blinked a few times, as though he had seen something so dazzling that he was unable to believe his eyes, and his mouth slowly formed a smile.

See also translations at believe one's eyes

• “be unable to believe one's eyes”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.