When would I need to seek the help of a veterinarian for a cat eye issue?

If you suspect there's an eye issue, have it seen. Make sure of what you're dealing with. If it ends up being something minor, then that's great; you're lucky. But if it's not, it's better to address it sooner rather than later before something worsens or something irreparable happens with that eye. Give us a call and explain your situation ASAP. We'll help you decide whether you need to come in for an emergency, if you need to go to an emergency clinic, or if we can set an appointment for the next day, and we can go from there.