Abrasions can be very very painful and need to be treated by an ophthalmologist as severe corneal complications such as ulcers can occur.
Episcleritis and scleritis can be serious and the redness is often accompanied by pain. You would need urgent ophthalmological assessment by your specialist and treatment. Sometimes these conditions, especially scleritis can be associated with autoimmune diseases.
Lid disease like blepharitis also requires attention because it is so common and causes sore ,red, scratchy eyes for a long period of time. Special lid care shampoos containing tea tree oil have been developed that can be used together with ointments and proper lid hygiene to help eradicate blepharitis mites and bacteria. Blepharitis occurs in at least 33% of the population!
Conjunctivitis is either due to bacteria or viral causes and needs medical treatment with antibiotics or steroid topical solutions.
Blurred vision is a bad sign so please see your eye specialist if this occurs together with a red eye.