When a person sees flashes of light, especially when blinking, it can be an unsettling experience. These visual phenomena, known as photopsias, are perceived as brief streaks, dots, or sparks of light that appear suddenly within the field of vision. This sensation arises from internal processes within the eye, rather than from external light sources.
What Are Eye Flashes?
Eye flashes manifest in various ways, appearing as zigzags, jagged lines, shimmering lights, brief streaks, or sparkling dots. These are internal sensations generated within the eye. Flashes often become more noticeable in dim lighting conditions or in peripheral vision. They can also be triggered by eye movement or blinking.
The Eye’s Inner Workings and Flashes
The eye contains a gel-like substance called the vitreous humor, which fills the space between the eye’s lens and the retina. The vitreous humor allows light to pass unobstructed to the retina. The retina, a light-sensitive layer of tissue lining the back of the eye, converts light into electrical signals that are then sent to the brain.
As people age, the vitreous humor naturally undergoes changes, becoming more liquid and shrinking. Tiny fibers within the vitreous are attached to the retina’s surface. When the shrinking vitreous pulls or tugs on the retina, it stimulates the light-sensitive cells, leading to the perception of flashes of light. The retina sends a signal to the brain, which interprets it as light, even without an external light source.
Common Causes of Eye Flashes
One primary cause of eye flashes is Posterior Vitreous Detachment (PVD), a natural aging process where the vitreous gel separates from the retina. PVD is common, particularly in individuals over 50, and typically does not cause pain or vision loss. While often benign, it always warrants an eye examination to rule out potential complications.
Other causes of eye flashes include mechanical stimulation. Rubbing the eyes too hard, a sudden cough, or even a blow to the head can create pressure on the retina, causing a brief perception of flashes or “stars”. In such instances, the flashes are a direct result of physical force stimulating the retina.
Red Flags and Urgent Situations
While many eye flashes relate to aging, some characteristics suggest a more serious underlying condition requiring immediate medical attention. A sudden increase in the number or intensity of flashes, especially when accompanied by new or increased floaters (small specks or cobweb-like shapes), can be a warning sign. These symptoms may indicate a retinal tear, where the vitreous gel pulls forcefully enough to create a break in the retina. Fluid can then pass through this tear, potentially leading to a retinal detachment.
Retinal detachment is a serious condition where the retina separates from the back of the eye, potentially leading to permanent vision loss if untreated. Urgent symptoms include a shadow or “curtain” appearing in the field of vision, a loss of peripheral vision, or blurred vision. A vitreous hemorrhage, which is bleeding into the vitreous gel, can also cause flashes and a sudden shower of dark floaters, requiring prompt evaluation.
What to Expect at the Doctor
When seeking medical care for eye flashes, a thorough dilated eye examination is performed. Eye drops are used to widen the pupils, allowing the eye care professional to gain a clear view of the retina and the vitreous humor. This examination helps identify any retinal tears or detachments.
Depending on the diagnosis, treatment approaches vary. For benign PVD without complications, observation is often sufficient. If a retinal tear is found, laser treatment or cryopexy (freezing) may be performed to seal the tear and prevent retinal detachment. In cases of retinal detachment, surgical intervention is usually required to reattach the retina.