[Petra Norr]

I think it needs the painting to work, and I don't think there's anything wrong with that. In fact, this poem is a marvellous take on the painting and it made me see and reflect on things I wouldn't have done otherwise. In the third stanza, the "it" definitely refers to the woman's eye. And in the painting one of her eyes is indeed visible; it's very tiny and I probably wouldn't have noticed it if the poem hadn't led my own eyes to it. The poet interprets the look in the woman's eye as "unsparing" (in the couplet). And as the poet implied earlier in S3, her (unsparing) gaze as she looks at herself in the mirror is akin to Lautrec's own way of gazing at things and seeing "unseen faults", faults that might not be visible to an ordinary onlooker.
Lots of layers in this poem, just as there are in a painting. I admire both the poem and Lautrec's painting.