Seeing bright flashes of light can be a startling experience. These visual disturbances often manifest as sparkles, lightning streaks, zigzag lines, or brief pops. They are perceived even when no external light source is present. While often harmless, these flashes can sometimes indicate underlying medical conditions that require prompt attention.
Common Ocular Explanations
Flashes of light commonly originate due to changes in the vitreous gel. This clear, jelly-like substance fills the majority of the eyeball, helping it maintain its shape and protecting the retina. As people age, the vitreous can naturally shrink and liquefy, pulling away from the retina, a process called posterior vitreous detachment (PVD). This pulling on the light-sensitive retina can stimulate it, causing the perception of flashes, especially in peripheral vision or in dim light. PVD is a common, age-related condition. While PVD is generally not sight-threatening, it is important to have it evaluated by an eye care professional to rule out more serious issues.
Another ocular cause for seeing flashes is an ocular migraine, also known as a retinal migraine. These visual disturbances, or auras, can include flickering lights, zigzag patterns, or temporary blind spots in one eye. Unlike typical migraines, ocular migraines may occur without a headache, though a headache can follow the visual symptoms. The visual symptoms usually last 10 to 60 minutes and resolve on their own.
Serious Eye Conditions
While many flashes are benign, they can also signal urgent eye conditions that require immediate medical attention. A retinal detachment or tear is a serious condition where the retina, the tissue lining the back of the eye, separates from its underlying supportive tissue or develops a break. When the vitreous gel pulls on the retina with enough force, it can cause a tear, allowing fluid to pass through and potentially detach the retina from the back of the eye. This pulling stimulates the retina, leading to the perception of flashes.
A retinal detachment is a medical emergency because it can lead to permanent vision loss if not treated promptly. Besides flashes, accompanying symptoms can include a sudden increase in floaters, which are small specks or cobweb-like shapes that drift across the vision. Individuals may also notice a dark “curtain” or “shadow” in their field of vision, or experience sudden vision loss. These symptoms indicate that the retina is not functioning correctly and requires urgent intervention to preserve sight.
Beyond the Eye
Beyond eye conditions, certain neurological events can also manifest with visual disturbances that resemble flashes. While less common for isolated flashes of light, transient ischemic attacks (TIAs) can cause temporary visual changes when blood flow to the brain’s visual processing centers is disrupted. Visual symptoms from a TIA are usually accompanied by other neurological signs, such as sudden weakness or numbness on one side of the body, difficulty speaking, or balance problems. Flashes alone are rarely the sole symptom of a TIA.
Some types of seizures can present with visual auras, including flashes or distorted vision. These visual disturbances are a type of focal seizure, originating in a specific area of the brain. While auras can involve simple flashes, they are typically part of a broader set of symptoms that signal an impending seizure. These visual phenomena are usually not isolated and are accompanied by other sensory, emotional, or motor symptoms characteristic of a seizure event.
When to Consult a Doctor
Seeking professional medical evaluation for flashes of light is always advisable. It is especially important to seek immediate medical attention if the flashes are sudden, new, or increasing in frequency or intensity. This urgency is heightened if the flashes are accompanied by a sudden increase in floaters, the appearance of a “curtain” or “shadow” in your vision, or any degree of vision loss. These combined symptoms could indicate a serious condition like a retinal tear or detachment, which necessitates prompt treatment to prevent permanent vision impairment.
Even if the flashes are recurring but stable, especially if a previous eye examination has not revealed any serious conditions, scheduling an appointment with an eye care professional is recommended. An ophthalmologist can perform a comprehensive dilated eye exam, which involves widening your pupils with eye drops to thoroughly inspect the retina and other parts of the eye. This examination is the most effective way to accurately diagnose the cause of the flashes and determine if any intervention is needed. Only a medical professional can provide a precise diagnosis and guide appropriate management.