Vision disturbances after periods of exercise can result from dehydration and overheating or may signal faintness. In addition, vision changes can also be an early sign of many serious health conditions. Always consult a health care provider for assistance in diagnosing and treating unexplained vision changes.
Benign Vision Changes
Faintness after exercise is often accompanied by vision disturbances, such as blurred or tunnel vision, as well as dizziness, nausea and if not treated, loss of consciousness. Overexertion and dehydration are common causes of faintness after exercise. To avoid these symptoms, a proper warm-up and cool down routine is essential. Pay attention to your body's cues during exercise. Gradually increase your level of exertion over time and don't hesitate to reschedule a workout if you feel sick or especially fatigued.
Heat and humidity increase the risk of overheating and dehydration, so move your workouts to an air-conditioned gym or complete them in the cooler early morning or late evening hours. Drink plenty of water before, during and after your workout and consider an electrolyte replacement drink if you exercise at high intensity or for long periods of time.
Pigmented Tissue Disorders
Pigment dispersion syndrome is a disorder in which the pigment granules on the back of the iris are released into the clear fluid or aqueous humor of the eye. These granules block drainage from the eye and trigger an increase in eye pressure. Symptoms worsen during periods of exercise, which dislodges more pigmentfrom the iris, further blocking eye drainage. Over time, pigment dispersion syndrome may progress to pigmentary glaucoma if the increase in eye pressure causes lasting damage to the optic nerve.
Multiple Sclerosis
Multiple sclerosis a disease characterized by the demyelination, or destruction of the tissues that surround nerves. The symptoms of multiple sclerosis may increase during exposure to high temperatures, such as those that you may experience during exercise. Symptoms vary among individuals and over time but may include sensory problems, loss of muscle control, stiffness, pain and loss of strength. Multiple sclerosis is typically marked by a loss of central vision---the field of vision you use when looking straight ahead. In some cases, only one eye is affected and double vision results.
Migraine
Migraine headaches, which can occur in response to exercise, are often accompanied by vision disturbances. Even when a migraine is painless, eye problems can occur owing to changes in blood flow to areas of the brain that control vision. Symptoms may include blind spots, flickering lights or a shimmering line inside a central blind spot. A 2006 study in "Current Sports Medicine Reports" suggests that exercise-induced migraine can be managed by a good warm-up routine and proper nutrition and hydration.
Optic Neuritis
Optic neuritis refers to inflammation of the optic nerve, which transmits visual information to the brain. It may be caused by an autoimmune disorder and may be triggered by viral infection. Vision loss may be mild or severe and usually worsens with heat or exercise. Eye pain often becomes more severe with eye movement. Optic neuritis may also affect the color vision so that bright colors---particularly red---appear dull.
