The passage should be rendered thus: “And it came to pass at that time that Eli was sleeping in his place; and his eyes had begun to grow dim; he could not see. And the lamp of God was not yet gone out, and Samuel was sleeping in the temple of the Lord where the ark of God was; and the Lord called Samuel, etc.” Eli’s old age and dimness of sight is probably mentioned as the reason why Samuel thought Eli had called him. Being a blind and feeble old man, he was likely to do so if he wanted anything, either for himself, or for the service of the temple.
Related Commentaries of 1 Samuel 3:2
1 Samuel 3:2
2 And it came to pass at that time, when Eli was laid down in his place, and his eyes began to wax dim, that he could not see;