My puppy 5 or 6 months old eyes get red sometime i need help?

idk my puppy her eyes get red from times to time and im not gonna rly worry about it cuz i give her worm medicine every month and she got her shot she need till she turns one. but i would like to know howsw this is cause becasue the dogs whites are suspossed to stay white unless like gunk buildup or something like that.maybe she going blind ? idk help me plz