«ثُمَّ فَتَحَ كَرِيمَتَيْهِ»
Then he opened his two eyes.
Karīmatayhi literally invokes two precious things but euphemistically refers to the eyes. With fataḥa, the setting clearly indicates opening them.
The dual object takes the -ay- form in the accusative/genitive cases and carries a pronominal suffix. The grammatical form and narrative revelation jointly exclude an interpretation involving two generous people.