Congrats sa pregnancy, mama! Honestly, slight blurring happens sa iba, kaya hindi ka nag-iisa, a few of my mum friends had the same thing during pregnancy dahil sa hormonal changes at fluid retention, pero since you're only 18 weeks pa lang and it's bothering you, mas safe na i-mention mo talaga sa OB mo sa next check-up para ma-rule out kung may underlying issue tulad ng gestational diabetes or preeclampsia. Better safe than sorry lagi pag pregnancy, especially sa mata!