The perception of lights flickering when no external source is changing can be a disorienting experience. These flashes, sparks, or streaks of light arise from internal processes within the eye or brain. Understanding their various reasons can help determine if the experience is a benign visual peculiarity or a symptom that warrants medical attention.
Harmless Visual Peculiarities
Sometimes, the eye’s normal functions can create the illusion of flickering lights. Staring intently at a bright light source and then looking away can result in an afterimage, a lingering visual impression that might appear to flicker as it fades. This is a natural response of the retina.
Eye strain or fatigue, often from prolonged visual tasks like extensive computer use, can also contribute to visual distortions. Tired eyes may become more sensitive to subtle changes in light or struggle to maintain clear focus, leading to a perception of instability in ambient lighting. Environmental factors can also play a role in how light is perceived.
Fluorescent lights, particularly older models, rapidly cycle their illumination, producing a flicker imperceptible to direct vision but detectable in peripheral vision. Even poorly designed modern LED lights can exhibit this subtle flicker, sometimes leading to discomfort or fatigue. Benign eye floaters, small clumps within the vitreous gel, can also cast shadows on the retina that might be momentarily misinterpreted as light anomalies.
Medical Conditions to Consider
Perceiving flickering lights can signal underlying medical conditions requiring professional evaluation. One common age-related change is posterior vitreous detachment (PVD), where the vitreous gel shrinks and pulls away from the retina. This pulling stimulates the retina, causing brief flashes, often appearing as white or golden streaks in peripheral vision. While PVD is usually not vision-threatening, an eye care professional should examine the eye for complications.
More concerning ocular issues include retinal tears or detachments, occurring when the vitreous gel pulls hard enough to tear the retina or separate it from its support tissues. Flashes associated with these conditions are often sudden, like lightning streaks or stars, and may be accompanied by new floaters or a dark “curtain” obstructing vision. These symptoms indicate a serious condition needing immediate medical attention to prevent permanent vision loss.
Visual disturbances like shimmering lights, zigzag patterns, or flickering can also be symptoms of ocular migraines or migraine aura. Ocular migraines typically affect vision in one eye, while migraine aura can affect both eyes and may occur without a headache, a phenomenon known as silent migraine. These visual symptoms usually last between 5 and 60 minutes.
Certain neurological conditions, such as focal seizures, can also manifest with visual disturbances. Seizures originating in the brain’s occipital lobe can cause perceived flashing lights, colors, or simple patterns. In rare instances, other neurological issues like a transient ischemic attack (TIA) or stroke can cause vision changes, including perceived flashes. Additionally, some medications can have visual disturbances as a side effect, which should be discussed with a healthcare provider.
When Professional Help is Needed
While many instances of perceived light flickering are harmless, certain symptoms warrant prompt medical evaluation. Seek immediate medical attention if the flickering lights appear suddenly, worsen rapidly, or are accompanied by other concerning signs. These red flag symptoms include pain, vision loss, a dark “curtain” or shadow moving across the field of vision, or a sudden increase in floaters.
Additional symptoms necessitating urgent medical attention are severe headaches, weakness, numbness, or changes in speech, as these could indicate more serious neurological issues. If the perceived flickering becomes persistent, increases in frequency or intensity, or significantly interferes with daily activities or causes distress, consult a healthcare professional. For eye-related concerns, an ophthalmologist is the appropriate specialist; a general practitioner can provide an initial assessment and refer to a neurologist if a neurological cause is suspected.