the lighting is lovely, the eye itself is beautiful, as are the skin tones. but, this falls down because the focus is on the eyelashes, which quickly becomes distracting. we want it to be on that amazingly coloured eye. there's another eye closeup, which i actually like less than yours, but i rated it higher purely due to the focus.
Nice try, but the exposure has let this down a bit - too much glare around the skin, and perhaps generally over-exposed half-stop or so. It would have more impact, more sense of tone and depth, if the brightness overall were reduced. Oh, and of course, it isn't really a square crop now, is it?