Paul prays that God would open the Ephesians' eyes so that they might grow in their knowledge of God, understand their wonderful future that God has promised, and realize the rich and glorious inheritance God has given to them.
The Ephesians' eyes are limited by what they can see and experience...they are not yet aware that their church has great power through Jesus Christ.
God's great power operates for [toward] us who believe in Him.
This is same mighty power that raised Christ from the dead.