What Could Cause Sudden Darkness in Vision?
Occasionally experiencing a sudden blackout of vision is generally not a serious issue, and may be caused by brief cerebral hypoxia or anemia. However, if this occurs frequently, it could be a sign of coronary heart disease, carotid stenosis, cervical spondylosis, glaucoma, or other conditions. Middle-aged and elderly individuals should take this seriously and promptly seek medical attention for a thorough examination to ensure better treatment.
If your vision suddenly turns black, it may be a case of transient amaurosis. Transient amaurosis refers to the inability to see or see clearly when looking at objects, manifesting as a clinical symptom of darkened vision. Besides the darkened vision, it may also be accompanied by headache, dizziness, blurred vision, and dark spots. This occurrence indicates a problem with the blood supply to the eye arteries. Gradual recovery from the sudden blackout indicates that the blood vessels are gradually recovering from spasms or that small emboli have been flushed to other areas by the blood flow.
2.1 Coronary Heart Disease: Besides bradycardia, darkened vision can also be a sign of coronary heart disease. Blockages in the coronary arteries can lead to poor heart pump function and reduced ejection fraction, resulting in insufficient blood and oxygen supply to the brain. When the brain is not receiving enough oxygen, symptoms such as dizziness and, in severe cases, darkened vision may occur. If symptoms such as chest tightness, chest pain, toothache, and stomach pain occur recently, it is crucial not to take them lightly as they may be signs of a heart attack.
2.2 Carotid Stenosis: The formation of plaques on the walls of the carotid arteries can lead to narrowing and impaired blood flow. Since the ophthalmic artery branches off from the carotid artery, carotid stenosis can result in insufficient blood supply to the eyes, causing sudden blackouts. If not treated promptly, plaques in the carotid arteries can detach and block the cerebral arteries, leading to cerebral infarction. In severe cases, this can cause extensive ischemia of brain tissue, resulting in hemiplegia, aphasia, and other symptoms commonly known as "stroke". Therefore, when patients experience transient dizziness and darkened vision, they should undergo carotid color Doppler ultrasonography to avoid misdiagnosis and mistreatment of carotid stenosis.
2.3 Cervical Spondylosis: Cervical spondylosis can also lead to dizziness and darkened vision. This often occurs when standing or walking and suddenly turning the head, resulting in a loss of support and falling. After falling, the individual quickly recovers consciousness without any consciousness impairment or sequelae. Such patients may also experience symptoms of autonomic nervous system dysfunction such as dizziness, nausea, vomiting, and sweating. This is due to the compression of the vertebral arteries by cervical hyperplasia, leading to a disturbance in the blood supply to the basal arteries and resulting in transient cerebral ischemia.
2.4 Glaucoma: Glaucoma refers to a common and challenging ophthalmic condition characterized by intermittent or persistent elevation of intraocular pressure. Patients with glaucoma may also experience sudden blackouts of vision, accompanied by the appearance of tiny blind spots in the peripheral vision (peripheral vision), which gradually enlarge and spread. Other symptoms include blurred vision, colored halos when looking at light, and difficulty adjusting to dark environments.
