Red eyes can have various causes, ranging in severity from 'worrying' to 'needs attention'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose red eyes, we could:
Are the whites of one or both of your eyes bloodshot (with red/pink veins showing)? Only answer if you have had bloodshot eye(s) for more than 2 days, and it is not from rubbing them.
Possible responses:→ No / for under 2 days / from rubbing / don't know
→ Significant episodes in the past
→ A little - they appear slightly red colored
→ Significantly - numerous individual red veins
→ Seriously - there is a large, very red area
Dry eye may cause your eyes to always look red.