If it is just a blood "blister", a localized cyst-like spot full of blood, and not a bruise, then there is nothing you need to do about it at this point. Cool compresses can help limit additional bleeding. If this is a bruise (looks like you got hit), then you should see an ophthalmologist to determine if there is anything around the eye causing the bruising.
If this persists or you have multiple occurrences of this, or if you start to have eye pain or decreased vision, then you should consult your ophthalmologist about it.
Does that address your concern?
I am happy to be able to help you today. If you would be so kind, please help me get credit for my efforts in answering your questions and press the ACCEPT button for this encounter. I would also be happy to continue to answer any more questions you have until we have resolved your concern.
Also, any positive feedback and/or bonus you may feel prompted to provide would be welcomed and is appreciated.
DISCLAIMER: My opinion is solely informative and does not constitute a formal medical opinion or recommendation. For a formal medical opinion and/or recommendation you must be examined by your doctor.