Transient Ischemic Attacks (TIAs) are commonly referred to as mini-strokes. These are brief episodes of brain dysfunction, caused by ischemia (lack of blood flow) to a focal area of the brain, spinal cord, or retina. Symptoms of a TIA may include the sudden onset of temporary weakness, numbness or paralysis of one side of the body, temporary trouble with speech, transient vertigo or loss of balance/coordination, and transitory loss of vision in one eye.
All TIAs should be treated as medical emergencies and should be evaluated in the same way that strokes are assessed. This includes imaging of the brain and cranial blood vessels, and investigation of cardiac risk factors, such as high blood pressure, cholesterol issues, and diabetes.
When a TIA occurs in the eye, patients often experience a transient graying out or blacking out of the vision in one eye, typically lasting for seconds to minutes (not more than an hour), and then the vision returns to normal. This is called Amaurosis Fugax. If you think you may have experienced a vision loss following this pattern, you need to call for an emergency assessment of your eyes, even if the vision change has resolved. Your optometrist or ophthalmologist will rule out ocular causes for the visual symptoms and may refer you urgently to the Emergency Department for a stroke assessment.
It is important to emphasize that the vision loss caused by a TIA is monocular – it will happen in the right eye OR the left eye but not both. It is important to check - by covering one and then the other – if vision changes are in one eye or both. Ocular migraines, for example, cause transient vision changes in both eyes (sometimes on the same side of vision in both eyes), and this is a much less worrisome issue than Amaurosis Fugax.
There is an elevated risk of stroke following a TIA; roughly 10% of patients will have a stroke in the first 90 days following the TIA, with most strokes occurring in the first 2-7 days. This is why getting prompt assessment and referral for a stroke work-up is so crucial. If you experience sudden vision loss in one eye, call your doctor of optometry immediately for same-day assessment.