Photopsia, the medical term for seeing flashes of light, describes fleeting sparks, streaks, or shimmering patterns not actually present in your environment. This unsettling experience can signal various underlying conditions, from benign age-related changes to more serious eye health concerns. Understanding their potential causes is important for knowing when to seek medical advice.
What Are Flashing Lights in Your Vision?
Photopsia refers to the perception of light flashes originating within the eye, not from an external source. These flashes can appear as brief streaks, bright spots, or lightning-like flickers, often in peripheral vision. The sensation arises when the retina, the light-sensitive tissue at the back of the eye, is abnormally stimulated, sending electrical signals to the brain interpreted as light.
This abnormal stimulation occurs when the vitreous humor, a clear, gel-like substance filling the eye’s main cavity, shifts or pulls on the retina. While flashes and “floaters” (small specks or cobweb-like shapes) can occur together, they are distinct. Floaters are shadows cast by debris within the vitreous, whereas flashes result from direct mechanical stimulation of the retina.
Common Ocular Causes
Many instances of flashing lights are linked to changes within the eye, particularly those involving the vitreous gel and retina. One common age-related occurrence is Posterior Vitreous Detachment (PVD). This happens when the vitreous gel, which is attached to the retina at birth, begins to liquefy and shrink, eventually separating from the retina.
The pulling or tugging of the vitreous on the retina during this separation process can trigger the sensation of flashes. PVD is a very common condition, affecting approximately 66% of individuals between 66 and 86 years of age. While usually harmless, it warrants examination to ensure no complications have arisen.
A more serious concern arises if the vitreous gel pulls too strongly on the retina, causing a retinal tear. This tear is a small rip or hole in the retina, which can lead to fluid passing through and lifting the retina away from the back of the eye, a condition known as retinal detachment. Both retinal tears and detachments can cause flashing lights because the retina is abnormally stimulated as it is pulled or separated. Retinal detachment is a medical emergency that can lead to permanent vision loss if not treated promptly. Symptoms like repeated flashes, especially with a sudden increase in floaters, can indicate a retinal tear or detachment.
Neurological and Other Causes
Beyond conditions originating within the eye, flashing lights can also be a symptom of processes occurring elsewhere in the body, most notably in the brain. Migraine aura is a common non-ocular cause, where visual disturbances precede or accompany a migraine headache, or sometimes occur without a headache at all. These visual auras are thought to be caused by an electrical or chemical wave that spreads across the visual cortex of the brain. The flashes in migraine aura often appear as zigzag lines, shimmering lights, or bright spots, and typically last between 10 to 30 minutes. About 20% to 33% of people who experience migraines will have an aura.
Other less common causes of photopsia include head trauma, often described as “seeing stars,” which results from the physical impact stimulating the retina. Certain systemic conditions or medications can also rarely induce visual flashes as a side effect. Distinguishing these causes from ocular ones is important, as their underlying mechanisms and required treatments differ.
When to Seek Medical Care
Any new onset of flashing lights in your vision should prompt evaluation by an eye care professional, such as an ophthalmologist. This is important if flashes are accompanied by other symptoms indicating a serious condition. Warning signs include a sudden increase in floaters, a dark “curtain” or shadow blocking part of your vision, or any noticeable vision loss.
These accompanying symptoms may signal a retinal tear or detachment. Early diagnosis and intervention are important to prevent permanent vision loss. Delaying medical attention can have severe consequences for your eyesight.
What to Expect at the Doctor
When you visit an eye doctor for flashing lights, they will likely perform a comprehensive dilated eye exam. This involves using special eye drops to enlarge your pupils, allowing the doctor to get a clear and detailed view of the retina and vitreous gel at the back of your eye. The doctor will carefully inspect for any signs of retinal tears, detachment, or other abnormalities.
In some cases, additional diagnostic tests may be conducted. These can include optical coherence tomography (OCT), which provides high-resolution cross-sectional images of the retina, or an ultrasound, which uses sound waves to create images of the eye’s internal structures. The specific tests performed will depend on the initial findings and the suspected cause of your symptoms. Once a diagnosis is made, the eye care professional will discuss the appropriate treatment plan, which varies depending on the underlying cause.