Seeing flashes or streaks of light when coughing is a common and often surprising experience. This phenomenon is usually brief and harmless, a fleeting visual sensation. These “lights” are not external, but rather originate from within the eye itself, appearing as brief flashes, spots, or streaks. This is a known physiological response.
Understanding the Phenomenon
The visual sensations experienced when coughing are known as phosphenes. These are perceptions of light that occur without actual light entering the eye. Phosphenes can manifest as various patterns, shapes, or colors, and are typically temporary. This common occurrence is generally benign and does not indicate a serious eye condition. It is a normal response to physical stimuli, including mechanical pressure on the eye.
Why It Happens
Coughing creates sudden pressure changes within the body, which momentarily affect the eyes. When you cough, muscles in your chest and abdomen contract, leading to a rapid increase in intra-abdominal and intrathoracic pressure. This surge briefly elevates venous pressure, including within the blood vessels around the head and eyes.
This transient pressure increase can mechanically stimulate the retina, the light-sensitive tissue at the back of the eye, or the optic nerve. Photoreceptor cells in the retina, or nerve pathways that send visual information to the brain, interpret this mechanical stimulation as light, even though no actual light source is present. This occurs because the eye’s delicate structures are momentarily affected by the internal pressure changes.
When to Be Concerned
While seeing lights when coughing is typically harmless, certain accompanying symptoms or persistent visual disturbances warrant medical attention. It is advisable to consult an eye care professional if you experience persistent or frequent flashes unrelated to coughing, especially if they are new or worsen. Other concerning signs include a sudden increase in floaters (small specks or lines that drift across your vision) or a partial loss of peripheral vision (often described as a curtain or shadow). Eye pain, redness, headaches, dizziness, or any sudden, significant changes in vision occurring alongside flashes should prompt a medical consultation. Although rare, violent coughing can, in some instances, lead to more serious conditions like retinal hemorrhage or detachment, particularly if there are underlying risk factors.