How do I know if my eye injury is severe enough to see a doctor?

It was in the woods, and a branch popped back and hit my eye. It bled for a while, but I could still see through it.

Now it is very red and my sight is slightly blurry.

You should have gone to the emergency room right away. If there is blood or constant running of water (not tears) from the eye, your eye should be looked at by a doctor.

You should go to be safe instead of waking up sorry in the morning.

See a doctor and find out

OMG, you should have gone right away. eye injuries are important, ur lucky you haven't lost your eye. That happened to my friend and his eye is lazy now, it never moves at all. Seek attention right away.

Any eye injury that causes chnages in vision should be seen by a Dr in order to preserve as much vision as possible.
RN

Every apparent eye injury should be treated as a medical emergency; the consequences of a bad decision are so dire that they should be avoided at almost any cost.

If you have to ask the question, it's time to get it looked at. If you were sure it wasn't a problem, you wouldn't even be asking.

Time to head to the ER and have them take a look - you don't want to get an infection and lose the sight in that eye.

You don't - that's why you should get it checked out.

if vision is affected and your eyes are red it is already more than severe enough to seek appropriate medical advice

There is no injury too small to not go and see a Doctor. It isn't like the Doctor's going to apprehend you for the non-seriousness. Doctors are concerned, knowledged people and they'd most likely explain to you what has happened, and what you should do.
Otherwise they'd lose their jobs! =)

So what're you waiting for? You should def go NOW

It is possible that the tree branch could have a microscopic fungus growing on it. Fungus can spread like wildfire if it gets onto the cornea of your eye. Don't wait to go to the eye doctor. An emergency room may not be equipped to take care of that type of eye injury. Get to an optometrist or ophthalmologist right away.