Sudden vision loss, a rapid decrease in sight, is an alarming symptom that requires immediate attention. Understanding its potential origins is important for seeking appropriate care. This symptom can arise from issues within the eye, the optic nerve, or broader systemic conditions affecting the brain.
Recognizing Sudden Vision Loss and Its Urgency
Sudden vision loss is a rapid decrease in sight, occurring over minutes to hours, not gradually over days or weeks. This rapid onset demands prompt medical attention to preserve vision and address underlying causes.
The presence or absence of pain can offer initial clues. Some conditions cause painless vision loss, while others are accompanied by eye pain. Any sudden change in vision warrants an urgent medical evaluation, even if vision seems to improve, as it could signal a serious underlying issue.
Vascular Events Affecting Vision
Sudden vision loss can stem from vascular events that disrupt blood flow to the eye or optic nerve, leading to damage and impaired vision.
Central Retinal Artery Occlusion (CRAO)
CRAO occurs when the main artery supplying blood to the retina becomes blocked, often by a blood clot or cholesterol plaque. Patients experience a sudden, painless, and severe loss of vision in one eye. The retina can suffer irreversible damage from this blockage.
Branch Retinal Artery Occlusion (BRAO)
BRAO involves a blockage in a smaller branch of the central retinal artery. Similar to CRAO, BRAO presents as sudden, painless vision loss in one eye. The extent of vision loss varies depending on the affected retinal area. If the macula is involved, central vision may be significantly affected.
Anterior Ischemic Optic Neuropathy (AION)
AION results from insufficient blood supply to the front part of the optic nerve, leading to damage. There are two main types: non-arteritic AION (NAION) and arteritic AION (AAION). NAION is more common, causing sudden, painless vision loss in one eye, often associated with cardiovascular risk factors like high blood pressure, diabetes, and sleep apnea. AAION, a less common but more severe form, is caused by temporal arteritis, an inflammatory disease of arteries in the head.
Retinal and Optic Nerve Conditions
Conditions directly affecting the retina or the optic nerve can also lead to sudden vision loss.
Retinal Detachment
Retinal detachment occurs when the retina pulls away from underlying supportive tissues, causing it to lose its blood supply. Symptoms often include a sudden increase in floaters and flashes of light. As the detachment progresses, a dark shadow or “curtain” may appear over part of the visual field. This condition is typically painless but requires prompt surgical intervention to prevent permanent vision loss.
Vitreous Hemorrhage
Vitreous hemorrhage involves bleeding into the vitreous humor, the clear gel that fills the eye. The blood blocks light from reaching the retina, leading to sudden, painless vision loss. Symptoms can range from seeing floaters or hazy vision to a complete loss of sight. This condition is often associated with underlying diseases such as diabetic retinopathy, high blood pressure, or retinal vein occlusion.
Optic Neuritis
Optic neuritis is inflammation and swelling of the optic nerve, disrupting visual information transmission to the brain. Symptoms include pain with eye movement and temporary vision loss, usually in one eye. The vision loss develops over hours or days and can vary in severity. Optic neuritis has strong links to chronic conditions such as multiple sclerosis and other autoimmune diseases.
Neurological and Other Underlying Causes
Sudden vision loss can also be a symptom of broader neurological issues originating in the brain or systemic conditions affecting the entire body. These causes often present with other related symptoms.
Stroke or Transient Ischemic Attack (TIA)
A stroke or Transient Ischemic Attack (TIA) affecting the visual pathways in the brain can lead to sudden vision changes. A stroke occurs when blood flow to a part of the brain is blocked or interrupted, causing brain cells to die. A TIA, or “mini-stroke,” is a temporary disruption of blood supply to the brain, with symptoms typically resolving within minutes to a few hours. Both can cause symptoms such as blurry vision, double vision, or temporary vision loss in one or both eyes. Visual field defects are also common. These events often accompany other neurological signs like facial drooping, weakness on one side of the body, or speech difficulties.
Giant Cell Arteritis (GCA)
GCA, also known as temporal arteritis, is an inflammatory condition affecting arteries, most commonly those in the head. When GCA affects arteries supplying the eyes or optic nerve, it can cause sudden, painless, and severe vision loss. This condition is urgent because it can affect the other eye within days if left untreated. GCA typically affects individuals over 50 and can present with other systemic symptoms such as a new, persistent headache, scalp tenderness, jaw pain when chewing, fever, fatigue, and muscle aches.
Migraine with Aura
Certain types of migraine, specifically migraine with aura, can cause temporary visual disturbances. The aura typically precedes or occurs during the headache phase. Visual aura symptoms include flashing lights, zigzag lines, shimmering spots, blind spots, or temporary vision changes. These visual phenomena are generally temporary and resolve completely.