I think this is involuntary -- I could be wrong. But, it seems we may be wired this way. I believe it may have been Billy Graham or some famous preacher who said that the first look is not the problem, it's the more deliberate ones that follow.
You are not going to automatically gravitate towards her eyes first if that's not what she's advertising. But, you can -- with some effort -- control where they go after that initial look. I'm practicing this at the gym.
In the meantime, continue to seek God for a purer and purer heart so that even when you have that initial, knee-jerk look at her cleavage, it doesn't cause you to lust after her. You may admire it and go "Nice, God!", but have no inappropriately carnal feelings generated from that.
I think I may have experienced something along those lines briefly in my life, back in maybe... 2013 or so? Not sure. It seems for two weeks I was loose and comfortable around women in a way I've never been in my whole life. I flirted, but even that felt clean, because of the attitude behind it. It just seemed that, for a brief period in my life, I may have been given a glimpse of what it was to be able to appreciate a woman's sexual attractiveness without the salivating -- before the fall.
I don't know if this is helpful, but continue to pray for a purer heart while understanding that -- as far as I understand this -- we men are simply wired that way, for the initial visual blast. (I could do without it either, but despite much prayer, God has never removed that instinct.)