The speaker takes off their glasses and the night goes blurry, and that blur becomes the way into the whole poem. The dark feels soft, like a leather strop, the strip used to sharpen a blade, so the image already hints at cutting and smoothing at once. The stars smear into fuzzy lights, and the speaker can't tell fluorescent from incandescent. Sight is limited, and the poem treats this as a kind of surgery done "with fewer instruments," as if less clarity means a stripped-down, more exposed way of looking inward.
Sounds step in where sight falls short. A train whistle becomes "a black dog's bark," one thing mistaken for another. A meteor cuts across the sky and the dark closes over it within a second. The ending turns toward feeling: the "open heart" always misses its cage, which suggests that emotion won't stay contained, or that the speaker can't quite hold it in. The mood is quiet, dreamy and a little vulnerable, though not unhappy.