Blurred vision during or immediately after exercise could be caused by something as simple as sweat getting in your eyes or your eyes drying out from dehydration. It could be from low blood sugar because you did not eat before your workout, or these changes in your vision could be a sign of something more serious.
Sweat in the Eyes
Perhaps the simplest reason for blurred vision while exercising is getting sweat in your eyes. Sometimes this is accompanied by burning or stinging because of the difference in pH between sweat and your natural tears. Sweat, with a pH between 4 and 6.8, is usually more acidic than tears, which range from 6.5 to 7.6 on the pH scale, note Konrad Diem in Documenta Geigy Scientific Tables and Mark Abelson, in Normal human tear pH by direct measurement, a study published in "Archives of Ophthalmology."
To prevent sweat from entering your eyes, wear an absorbent headband during exercise and dab your forehead frequently with a towel. If your vision remains blurry after exercise, put in a drop of over-the-counter artificial tears to help rinse your eyes out. This will also alleviate any burning or stinging you may experience.
Dry Eyes
Dry eyes are a common cause of blurred vision. Your eyes can become dehydrated along with the rest of your body while you exercise if you sweat out all your fluids. To prevent this, drink plenty of water before and during exercise. A drop of over-the-counter artificial tears will also help treat the blurred vision by replenishing the tears on the surface of your eye.
Hypoglycemia
Blurred vision can be caused by hypoglycemia, or low blood sugar. You may experience this while exercising because your body is using your stored glucose for energy. Among other symptoms, the Mayo Clinic reports, hypoglycemia can cause blurred vision, heart palpitations, tremor, anxiety and even loss of consciousness. To prevent your vision from getting blurry from hypoglycemia, eat before you work out.
Blood Pressure Spikes
Vigorous exercise can cause a temporary spike in your blood pressure because of the increase in your heart rate. Weightlifting can have the same effect. The long-term benefits of regular, moderate exercise far outweigh the risk of a temporary spike for most people. However, even a momentary increase in blood pressure can cause blurred vision, headaches and dizziness. Listen to your body while exercising; if it is telling you to stop or slow down, do so.
