Hello and thank you for writing to Hcm I read your question and understand your concern. First of all dont worry and relax,if this symptoms are a one time event for you some more details of your history would have helped like: age and sex? are you new to working out? is this abnormal vision happening to you the first time? do you drink,smoke or both? any other medical history like diabetes,thyroid disease or cardiac disease or any drug history? do you have recurrent headache or any vision disorders? Coming directly to your query,its normal to have such instance as a one off event. if i were your treating doctor,i would diagnose your symptoms as due to over exertion which lead to low blood sugar or low blood pressure or both(if you have no other known diseases) i would advise that whenever you are exercising, start slow and maintain a moderate pace and keep sessions to 30 to 45minutes and stay hydrated and eat a small meal half an hour before starting workouts i would also recommend you get a blood test,fasting blood sugar,thyroid function test ,ophthalmologic examination if this occurs on multiple occasions even after trying above changes and consult a doctor if that happens Hope i have clarified and hope it helps followup if needed. take care and good day