I don't think it's ever been explicitly stated that the Sharingan glows, but it has been suggested.
(Sasuke's eyes glowing in the anime)
(Itachi's whole is face shaded, but no shading at all on his eyes implying there is light)
Then there's the Infinite Tsukuyomi which actually uses the moon as an eye and the moon starts glowing.
What do you think? Can Uchiha's illuminate their eyes?
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(Sasuke's eyes glowing in the anime)
You must be registered for see images
(Itachi's whole is face shaded, but no shading at all on his eyes implying there is light)
Then there's the Infinite Tsukuyomi which actually uses the moon as an eye and the moon starts glowing.
What do you think? Can Uchiha's illuminate their eyes?