Brief Answer:
It looks like subconjunctival hemorrhage.

Detailed Answer:
Hello
Welcome to Health Care magic.

I am Dr. Dadapeer , an ophthalmologist andI answer problems related to eye.
It seems from the history that your eye is filled with bright red blood on one side and it is not affecting vision and there is no pain.

This indicates sub conjunctival hemorrhage and it is because of collection of blood under the conjunctiva.
This occurs following eye injuries or rubbing of eyes or in systemic diseases like diabetes or sometimes spontaneously also.
For a single episode of subconjunctival hemorrhage there is no need to worry, if it is recurrent then you require evaluation.
Subconjunctival hemorrhage will get resolved by itself and no treatment is required for it. It will get absorbed over 2-4 weeks depending on the size of the hemorrhage.

Hope I have answered hour question and the information is helpful to you.

Thank you

---