Seeing sudden flashes of light in the corner of your eye is a visual phenomenon known as photopsia. It involves perceiving light without an external source, appearing as sparkles, streaks, or jagged lines. While often harmless and temporary, these flashes can also signal underlying eye conditions that warrant attention. Understanding their causes helps individuals determine when to seek professional medical advice.
Common, Harmless Explanations
Flashes of light are often benign, resulting from mechanical stimulation of the eye. Eye rubbing is a common cause, applying pressure to the retina and optic nerve. This stimulates photoreceptors, creating the sensation of light known as phosphenes, which fade quickly once pressure is removed.
Temporary blood pressure changes can also induce phosphenes, such as when standing up quickly, leading to “seeing stars.” Simple eye strain, a strong sneeze, or a cough can similarly increase eye pressure, momentarily triggering these internal light perceptions. These instances are brief and do not indicate a serious eye problem.
Potentially Serious Conditions
While many flashes are harmless, some indicate concerning medical conditions affecting the eye’s internal structures. Posterior vitreous detachment (PVD) is a common age-related condition where the vitreous gel thins and pulls away from the retina. This separation can tug on the retina, causing flashes of light, often described as streaks of lightning or camera flashes, particularly noticeable in peripheral vision. PVD is not painful or sight-threatening, but it can lead to serious complications.
A retinal tear or detachment is a more severe cause of flashes. If the vitreous gel pulls too forcefully, it can create a tear, allowing fluid to pass behind the retina and cause it to detach. These flashes appear as sudden, bright bursts, like white or yellow streaks of lightning, and may be more apparent in dark environments. Retinal detachment is a medical emergency that can lead to permanent vision loss if not addressed promptly.
Ocular migraines, also known as migraine auras without a headache, are another cause of visual flashes. These flashes appear as jagged lines, shimmering colors, or “heat waves” that can expand across the visual field and affect both eyes. Unlike flashes from retinal issues, ocular migraine auras last between 20 to 60 minutes and resolve completely. These visual disturbances are caused by temporary blood vessel spasms in the brain and may or may not be followed by a headache.
When to See an Eye Doctor
While occasional, brief flashes of light can be benign, certain accompanying symptoms warrant immediate medical attention. A sudden onset of new flashes, especially if they increase in frequency or intensity, requires prompt evaluation by an eye doctor. This urgency is heightened if flashes are accompanied by new floaters, which appear as tiny specks, dots, or cobweb-like shapes drifting in your vision.
Other concerning signs include the sensation of a “curtain” or shadow blocking part of your vision, or any sudden loss of peripheral vision. These combined symptoms could indicate a retinal tear or detachment, requiring swift intervention to preserve vision. Even without pain, these visual changes signify a serious underlying condition, making a timely visit to an ophthalmologist or retina specialist important.
What to Expect During an Eye Examination
When you consult an eye doctor for flashes of light, they will conduct a comprehensive examination to determine the cause. A standard procedure involves a dilated eye exam, using special eye drops to widen your pupils. This dilation allows the doctor to gain a clear, magnified view of the retina and other internal structures, checking for tears, detachments, or other abnormalities.
The examination may also include visual acuity tests to assess your overall vision. If more detailed imaging is needed, an optical coherence tomography (OCT) scan or ultrasound may be performed. These non-invasive tests provide cross-sectional images of the retina and surrounding tissues, helping the doctor precisely locate any issues. The goal is to accurately diagnose the source of the flashes and recommend appropriate treatment if a serious condition is identified.