As long as you're high for. Depends on the person too. Some people's eyes don't dialate very much and some people's eyes turn completely black.
just to give you an idea... i went to an all night massive dance party, dropped my first pill at about 2am...dropped my 2nd pill at about 6am...i got home after the party at about noon, and my eyes were still massive.. it was kinda hard to say hey to the parents without them noticing...quickly said hi, booked it to the bathroom, had a quick bath and then had a niiiiice sleep anyways, im trailing off...sweet, sweet E... so yeah, for some people their eyes can still be dilated a while after coming down, for others it's hard to even notice..different for everyone really, but most likely your eyes will be dilated even a while after you come down kris
for me, I have a good 12 hours of pupil dialation after I start to roll. Way after I'm high, my eyes are still huge. my eyes are a little freaky. One got cut with a sharp piece of plaster when I was little (I remember I was 5 and it was Christmas. I was pissed) and the one pupil won't dialte as much as the other one. When we trip my friends look at me eyes and get bugged out. It's a very noticable difference when I'm on something.
Honestly you shouldn;t be to concerned about it. usually in most lights inside are bright enough that your pupils will be larger then normal but not too dialiated so long as you've come down mostly. Neon lights are espshially good for this making your star-E eyes(lol) hardly noticable