Swollen eyes can be caused by a few things.
Poor water quality
Chemicals
Chlorine
Infection
Low temps
If your turtle has swollen eyes, check
The parameters
The temps
For mucus
Trouble breathing
Lopsided swimming
If there are no signs of an RI, you can follow the guide on the poster for either adding cod liver oil or doing a carrot juice soak.
*Consult a vet if needed