Flashes of light in your vision, known as photopsias, are visual disturbances originating from within the eye or brain, not from external light sources. While often benign, their sudden appearance warrants attention due to potential underlying conditions. Understanding the causes of these flashes helps determine when to seek professional eye care.
Common Reasons for Flashes
One frequent cause of flashes is Posterior Vitreous Detachment (PVD), a natural part of aging. The vitreous, a gel-like substance filling the eye, is normally attached to the retina. As people age, this gel can shrink and become more liquid, pulling away from the retina. This tugging on the retina stimulates it, leading to the perception of flashes, often in the peripheral vision.
Migraine aura is another common reason for visual flashes, even without a headache. These disturbances, which can include bright flashing lights, zigzag lines, or shimmering spots, result from an electrical or chemical wave across the brain’s visual cortex. This temporarily affects the brain’s processing of visual signals. Auras usually last 5 to 60 minutes and can occur before or during a migraine attack, or sometimes without a headache.
A more serious cause of flashes is a retinal tear or detachment. The retina senses light and sends signals to the brain for vision. When the vitreous gel pulls too strongly, it can tear the retina or cause it to detach from the back of the eye, separating it from its blood supply. This physical stimulation translates into flashes, often described as lightning streaks. Retinal tears and detachments are serious conditions requiring prompt medical attention to prevent permanent vision loss.
Other less common causes for flashes include ocular inflammation or certain medications. Eye injuries can also cause flashes due to sudden pressure on the retina. In rare instances, flashes may be a symptom of neurological conditions like occipital epilepsy.
Urgent Signs to Watch For
While some flashes are benign, certain accompanying symptoms signal a need for immediate medical evaluation. A sudden onset or significant increase in flash frequency or intensity warrants urgent attention. This change can indicate new or worsening traction on the retina, potentially leading to a tear or detachment.
The appearance of new or a significant increase in “floaters” (small dark spots, threads, or squiggly lines drifting across your vision) alongside flashes is another urgent sign. These floaters are often clumps of cells or vitreous debris casting shadows on the retina. A sudden shower of new floaters, especially with flashes, can suggest bleeding or a retinal issue.
Any perception of a curtain or shadow appearing in your field of vision, or a loss of peripheral vision, is a particularly concerning symptom. This often indicates a portion of the retina has detached and is no longer functioning correctly. Such a visual obstruction requires immediate intervention to prevent permanent vision loss. Flashes accompanied by eye pain or a sudden decrease in overall vision also warrant emergency care.
What to Expect at the Eye Doctor
When experiencing flashes, an eye care professional will begin with a detailed discussion of your symptoms and medical history. They will inquire about the nature, frequency, and duration of the flashes, and any other visual changes. This initial conversation guides the diagnostic process.
A visual acuity test will assess the sharpness of your vision. Following this, eye drops will dilate your pupils. Pupil dilation allows the doctor a broader and clearer view of the internal structures of your eye, especially the retina and optic nerve, which are otherwise difficult to examine thoroughly.
Once your pupils are dilated, a slit lamp examination will be conducted. You will rest your chin and forehead on a support while the doctor uses a specialized microscope to examine the front and inside of your eye. This allows for a close inspection of the vitreous, retina, and other structures for abnormalities. Finally, a fundus examination will view the back of your eye, including the retina, using an ophthalmoscope. In some cases, additional imaging tests may further assess the retina’s condition.
Approaches to Management
The management of visual flashes depends on the underlying cause identified during the eye examination. For benign conditions like Posterior Vitreous Detachment (PVD) without complications, active treatment is usually not necessary. In these instances, flashes and floaters often become less noticeable over time as the brain adapts, and the condition is primarily monitored.
When flashes are caused by a retinal tear or detachment, prompt intervention is crucial to preserve vision. Small retinal tears can often be sealed using laser therapy (photocoagulation) or cryotherapy (freezing), which create scar tissue to secure the retina and prevent fluid accumulation. For a full retinal detachment, surgical procedures such as vitrectomy, scleral buckling, or pneumatic retinopexy may reattach the retina. These procedures aim to flatten the retina and ensure its proper position, often involving vitreous gel removal or gas/oil bubble injection.
For flashes associated with migraine aura, management typically focuses on addressing the migraine itself. This may involve lifestyle adjustments, such as maintaining regular sleep patterns and avoiding triggers, and medication. While no specific treatment exists solely for the aura, managing underlying migraine attacks can reduce the frequency and severity of these visual symptoms. If other, less common causes are identified, treatment will be directed at the specific underlying condition to alleviate the flashes.