Left eye redness. What is the diagnosis.

According to your history, it seems to be subconjunctival hemorrhage. NOTE: As diagnosis is provisional, you should get it examined first by an ophthalmologist near you (to rule out other differentials and confirm the diagnosis) and then get treatment accordingly. A subconjunctival hemorrhage is blood that is located between the conjunctiva and the underlying sclera.  The most common causes are coughing, sneezing, straining, or any similar action that temporarily raises blood pressure in the veins, leading to a small rupture in a blood vessel or capillary. Subconjunctival hemorrhage can also occur because of trauma to the eye — even minor trauma such as rubbing the eye vigorously. Other common but less frequent causes of subconjunctival hemorrhage include diabetes mellitus, high blood pressure, and excessive amounts of certain medications such as aspirin or blood thinners like warfarin , which affect the body’s bleeding mechanisms. In your case, it seems to be High BP, which should be controlled and get better examined by physician for your High BP. Regarding Treatment, Usually, no treatment is needed. Some artificial tears drops can be applied to the eye if mild irritation is present. The eye does Not require a patch. The use of aspirin or other medication that inhibits clotting should be avoided for a period. .  This condition clears by itself within one to two weeks. Recovery is usually complete, without any long-term problems, similar to a mild bruise under the skin.