Experiencing a momentary whiteout in vision, where the visual field briefly turns bright or blank, can be disconcerting. This temporary obscuring of sight, sometimes described as a greyout, signifies a transient change in how the eyes or brain process visual information. While often fleeting and harmless, understanding the causes can help demystify this phenomenon.
The Body’s Response to Brief Visual Changes
Vision momentarily turning white often arises from a temporary disruption in blood or oxygen supply to the brain or the retina, the light-sensing tissue at the back of the eye. The body’s intricate cardiovascular system constantly works to maintain consistent blood flow and pressure, including to the visual pathways. Sudden changes can challenge this regulation. For instance, a rapid shift in body position can cause blood to pool in the lower extremities, leading to a reduction in blood flow to the head and eyes. This reduces oxygen and nutrient supply to the brain and retina, which can manifest as temporary white or dimming vision.
Everyday Reasons for Temporary White Vision
Common and generally benign situations can lead to temporary white vision. Orthostatic hypotension, a sudden drop in blood pressure upon standing quickly, is a frequent cause. Gravity pulls blood downwards, and if the body’s mechanisms do not respond fast enough to maintain adequate blood flow to the brain, lightheadedness and a whiteout can occur. This can be particularly common if someone is dehydrated, has been sedentary for extended periods, or is taking certain blood pressure-lowering medications.
Dehydration also plays a role, as a reduction in overall body fluid volume can lead to lower blood pressure and decreased blood flow to the brain and eyes, contributing to transient visual disturbances. Hyperventilation, often a response to anxiety or panic, can alter the balance of gases in the blood, leading to blood vessel constriction and reduced blood flow to the brain, which may cause visual changes.
Vasovagal syncope, triggered by stressors like pain or emotional distress, involves a sudden drop in heart rate and blood pressure, similarly reducing blood flow to the brain and potentially causing a whiteout sensation before fainting.
Medical Conditions Associated with Fleeting White Vision
While often benign, certain medical conditions can also cause temporary white vision. Ocular migraines, for example, can cause visual disturbances known as auras, which may appear as flashes of light, zigzag patterns, or blind spots, even without a subsequent headache. These visual phenomena result from temporary electrical or chemical changes in the brain’s visual cortex.
Transient Ischemic Attacks (TIAs), often referred to as “mini-strokes,” involve a temporary blockage of blood flow to the brain or eye. Depending on the affected area, TIAs can cause sudden, painless vision loss in one or both eyes, sometimes described as a curtain. Amaurosis fugax is a specific type of temporary vision loss in one eye, resulting from a brief disruption of blood flow to the retina, often due to a small clot or plaque from a blood vessel in the neck or heart.
Retinal issues, such as a retinal vasospasm, involve temporary tightening of a blood vessel in the retina, reducing blood flow and leading to sudden, temporary vision loss that could be perceived as a whiteout or blackout. While less common for a pure “white out,” a retinal detachment can cause new flashes of light and floaters, along with a sensation of a curtain or shadow across the vision, and requires urgent medical attention.
When to Consult a Healthcare Professional
While temporary white vision is often harmless, certain signs warrant medical evaluation. Recurrent episodes, especially if increasing in frequency or duration, should be discussed with a healthcare provider. Attention is important if visual changes affect only one eye, as this can indicate more serious conditions like amaurosis fugax or retinal problems.
Additional neurological symptoms accompanying whiteout, such as weakness or numbness on one side of the body, difficulty speaking, or problems with balance, are red flags requiring urgent medical care. Individuals with cardiovascular risk factors (high blood pressure, high cholesterol, diabetes, or heart disease history) should also consult a doctor if they experience these changes. Assessment can help determine the cause and prevent long-term complications.