Flashes of light in the corner of your eye, known as photopsias, are visual disturbances that appear as brief streaks, sparkles, or zig-zag lines. These perceptions occur without an external light source. While often harmless, these flashes can sometimes signal an underlying eye condition that requires prompt attention.
Common Explanations for Eye Flashes
The most frequent cause of flashes is a change in the vitreous humor, the clear, gel-like substance filling the eye. It helps maintain the retina’s position. As people age, the vitreous humor naturally shrinks, a process that can lead to its separation from the retina, known as posterior vitreous detachment (PVD).
During PVD, the shrinking vitreous can tug on the light-sensitive retina at the back of the eye. Since the retina only processes light, any mechanical stimulation, such as this tugging, registers as flashes. These flashes are often noticed in peripheral vision and may be more apparent in dim lighting. PVD is a common, age-related occurrence and usually does not directly threaten vision, though an eye examination is recommended to rule out complications.
Another common reason for flashes, particularly those appearing as shimmering zig-zag lines, is an ocular migraine, also referred to as a migraine with aura. These visual disturbances originate in the brain rather than the eye itself and can precede or accompany a migraine headache. The visual symptoms typically last between 10 to 60 minutes.
A rarer condition, retinal migraine, involves temporary vision loss or disturbances in only one eye, caused by spasms of blood vessels in the retina. Other less common causes of flashes can include eye strain or temporary pressure on the eye.
Understanding When Flashes Signal Something Serious
While many instances of eye flashes are harmless, certain characteristics or accompanying symptoms can indicate a more serious underlying condition that requires immediate medical attention. A sudden onset of new flashes, or a significant increase in their frequency or intensity, is a notable warning sign. This change suggests increased pulling on the retina.
The appearance of new or increased floaters alongside flashes also merits prompt evaluation. Floaters are small specks, spots, or cobweb-like shapes that drift across your vision. When flashes and new floaters occur together, it can signal a retinal tear or detachment.
A particularly urgent symptom is the perception of a dark curtain or shadow spreading across any part of your vision. This can appear as if a veil or curtain is being drawn over your sight, often starting from the side. Additionally, any sudden loss of peripheral or central vision should be considered a medical emergency.
These severe symptoms may indicate a retinal tear or, more critically, a retinal detachment. A retinal tear is a break in the retina, which can allow fluid to seep underneath. If this fluid accumulates, it can cause the retina to pull away from its normal position, leading to a retinal detachment. Untreated retinal detachment can result in permanent vision loss, making immediate evaluation by an eye care professional essential.
What to Expect at the Eye Doctor
When you visit an eye doctor for flashes, the appointment will begin with a thorough discussion of your symptoms. You will be asked about the nature of the flashes, their frequency, and any other visual changes you have noticed, along with your general medical and eye history.
Following the discussion, a comprehensive eye examination will be performed. A crucial part of this exam is dilation of your pupils. Dilation widens the pupils, allowing a clear view of the retina and vitreous humor at the back of your eye to inspect for tears, detachments, or other abnormalities.
The doctor will likely use an ophthalmoscope, a lighted instrument. A slit-lamp examination provides a magnified, three-dimensional view of the eye’s internal structures, including the vitreous. Specialized imaging tests like optical coherence tomography (OCT) or an ocular ultrasound may also be used for more detailed images if needed.
Based on the findings, the eye doctor will determine the diagnosis, which could range from a benign condition like a posterior vitreous detachment to a more serious issue such as a retinal tear or detachment. Treatment approaches vary depending on the diagnosis. For benign conditions, observation may be sufficient, as symptoms often subside over time. If a retinal tear is found, laser photocoagulation or cryotherapy might be performed to seal the tear and prevent detachment. Retinal detachment usually requires surgical intervention to reattach the retina and preserve vision.