This statement expresses the depth of someone's affection and preoccupation with a particular person. It signifies that even when they close their eyes, this person is the sole focus of their thoughts and imagination.
The phrase "Every time I close my eyes" suggests that thoughts of this person are constantly on the speaker's mind, day and night.
The declaration "You are the only thing I see" underscores the exclusivity and intensity of their feelings. It implies that this person occupies a central place in the speaker's heart and mind, serving as a constant source of inspiration and affection.