valonvälähdykset

Valonvälähdykset, sometimes referred to as phosphenes, are the visual perception of light without actual light entering the eye. They can manifest as flashes, streaks, or shimmering patterns. These phenomena are not caused by external stimuli but originate from within the visual system itself.

Several factors can trigger valonvälähdykset. Gentle pressure on the eyeballs, such as when closing the eyes tightly or rubbing them, is a common cause. This pressure can stimulate the retina and optic nerve, leading to the perception of light. Certain physiological changes, like sudden head movements or changes in blood pressure, can also induce these visual sensations. Migraine aura is another well-known association, where flickering lights or geometric patterns often precede a migraine headache.

In some cases, valonvälähdykset can be a symptom of more serious underlying conditions affecting the eye or brain. These can include retinal detachment, where the retina pulls away from the underlying tissue, or vitreous detachment, a common age-related change where the vitreous humor pulls away from the retina. Neurological conditions, such as epilepsy or stroke, can also sometimes present with visual disturbances like flashes of light.

While often benign and temporary, persistent or sudden changes in the frequency or appearance of valonvälähdykset should be evaluated by a medical professional to rule out any serious causes. A comprehensive eye examination and potentially other diagnostic tests may be necessary.