"Look in" vs "look at"

[Banglardon]

Which of the following sentences is grammatical?


1- When I looked in Peter's eyes I saw a blood clot.


2- When I looked at Peter's eyes I saw a blood clot.

[Tarheel]

They are both grammatical. However, the second one is, I think, more likely.

[jutfrank]

They're both grammatical and both possible. But since they use different prepositions, they have different meanings, which means they would be used in different contexts.

Normally, when you look in someone's eyes, you want to make eye contact with that person.

When you look at something, you treat it as an object of your attention.