Sudden flashes of light in one’s vision, known as photopsia, are a visual sensation appearing without an external source. These can manifest as brief flashes, streaks, or sparkling lights. Photopsia is a common occurrence. While often harmless, they may also signal underlying conditions that warrant medical attention.
Understanding Ocular Flashes
Ocular flashes arise from stimulation or mechanical traction on the retina, the light-sensitive tissue at the back of the eye. The retina converts light into electrical signals that the brain interprets as vision. When something other than actual light stimulates the retina, it sends signals the brain perceives as flashes.
Flashes are distinct from eye floaters, though they often occur together. Floaters are shadows cast by tiny clumps of gel or cells moving within the vitreous humor, the gel-like substance filling the eye. Flashes, conversely, are perceptions of light, appearing as brief bright spots, streaks, or zigzag lines. These sensations indicate direct retinal stimulation.
Common Causes of Flashing Lights
One frequent cause of flashing lights is Posterior Vitreous Detachment (PVD), a natural age-related process. As individuals age, the vitreous humor, a gel-like substance, fills the eye. It can shrink and pull away from the retina.
This detachment can cause the vitreous to tug on the retina, leading to flashes. These are often described as brief white or golden yellow streaks, particularly noticeable in peripheral vision or dim lighting. While PVD is common and usually does not cause permanent vision loss, it can sometimes lead to more serious complications. Once the vitreous fully detaches, the flashes typically diminish and disappear as the pulling stops.
Another common trigger for visual flashes is ocular migraine, also known as migraine aura. These disturbances can occur with or without a headache, often presenting as shimmering lights, zigzag lines, or blind spots that slowly spread across the field of vision. The visual aura is temporary and usually resolves within about 20 minutes.
Serious Conditions Requiring Urgent Attention
While many eye flashes are benign, some indicate serious conditions requiring immediate medical evaluation. A retinal tear can occur if the vitreous humor pulls too strongly on the retina during PVD. This excessive tugging can create a break in the retinal tissue, causing sudden, persistent flashes, often described as lightning streaks or stars. Untreated, a retinal tear can progress to a more severe problem.
If a retinal tear is not addressed promptly, fluid can seep through the tear and accumulate under the retina, lifting it away from the back of the eye. This is retinal detachment, a medical emergency that can lead to permanent vision loss. Symptoms include new or worsening flashes, a sudden increase in floaters, and the sensation of a “curtain” or “veil” obscuring part of the vision. A dark shadow or curtain is a concerning symptom that does not come and go.
Other Potential Triggers
Beyond common causes, other factors can trigger flashing lights. Direct trauma to the head or eye can stimulate the retina, leading to temporary flashes or “seeing stars.” This transient event results from pressure on the eye or brain activity, or the impact can cause the vitreous to pull on the retina.
A sudden drop in blood pressure (orthostatic hypotension) can also cause temporary visual disturbances, including flashes or dimming vision. This typically occurs when standing up quickly, as blood temporarily pools in the lower body, reducing blood flow to the brain and eyes. Certain medications can also cause flashes. Other underlying eye conditions, distinct from vitreous and retinal changes, may also manifest with flashes.
When to Seek Medical Care
Any new, sudden, or worsening flashes of light warrant prompt medical attention. This is particularly important if flashes are accompanied by a sudden increase in new floaters, a dark curtain or shadow obscuring vision, or any vision loss. These combined symptoms could indicate a retinal tear or detachment, conditions requiring immediate intervention to preserve sight.
Only a thorough eye examination, often involving pupil dilation, can accurately diagnose the cause of flashes and determine if treatment is necessary. Delaying professional assessment for serious conditions like retinal detachment can lead to permanent vision loss. Seeking timely evaluation is crucial for maintaining eye health.