What could cause someone to have a sudden blackout in vision?

What could cause someone to have a sudden blackout in vision?

A great question from a Healthtap patient!

Main causes of sudden black out: dehydration/illness, blood pressure drop, blood sugar drop (pre-diabetes/diabetes), vasovagal reaction,  blood flow issue in brain (from dehydration, sugar level change, tumor of some type, intracranial pressure increase), seizure, medications, anemia, transient ischemic attacks/stroke, pregnancy.
Below is an even more complete list of causes of sudden black outs or syncope/fainting.

Related Diseases & Conditions

35 articles
  • Low Blood Pressure (Hypotension)
    • Low blood pressure, also referred to as hypotension, is blood pressure that is so low that it causes symptoms or signs due to the low flow of blood through
  • Anemia
    • Anemia is the condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood. The oxygen-carrying
  • Vertigo
    • Vertigo is the sensation of spinning or rocking, even when someone is at rest. Vertigo may be caused by a problem in the brain or spinal cord or a problem
  • Pregnancy (Week By Week, Trimesters)
    • There are many symptoms involved in the 1st, 2nd and 3rd trimesters of pregnancy. The first early pregnancy symptom is typically a missed period, but others
  • Diabetes (Type 1 and Type 2)
    • Diabetes is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are referred to as type 1 (insulin
  • Arrhythmia
    • An arrhythmia is an abnormal heart rhythm. With an arrhythmia, the heartbeats may be irregular or too slow (bradycardia), to rapid (tachycardia), or too
  • Dehydration
    • Dehydration is the excessive loss of body water. There are a number of causes of dehydration including heat exposure, prolonged vigorous exercise, and
  • Dizziness
    • Dizziness is a symptom that is often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure,
  • Hypoglycemia
    • Hypoglycemia is a syndrome caused by low blood sugar. Symptoms of hypoglycemia include palpitations, trembling, intense hunger, sweating, nervousness,
  • Premature Ventricular Contractions (PVCs)
    • Premature ventricular contractions (PVCs) are premature heartbeats originating from the ventricles of the heart. PVCs are premature because they occur
  • Mitral Valve Prolapse (MVP)
    • Mitral valve prolapse (MVP) is also also known as “click murmur syndrome” and “Barlow’s syndrome.” Mitral valve prolapse is the most common heart valve
  • Heart Attack
    • Heart attack happens when a blood clot completely obstructs a coronary artery supplying blood to the heart muscle. A heart attack can cause chest pain,
  • Parkinson’s Disease
    • Parkinson’s disease is a slowly progressive neurologic disease characterized by a fixed inexpressive face, a tremor at rest, slowing of voluntary movements,
  • Migraine Headache
    • Migraine headaches are severe headaches that are accompanies to sensitivity to light, sounds, and smells. They are often associated with nausea and vomiting.
  • Balance Disorders
    • Balance is a state of body equilibrium or stability. We often take for granted how dependent we are on a healthy balance system. When the system breaks
  • Heart Valve Disease
    • Heart valve disease occurs when the heart valves do not work the way they should. Symptoms of valve disease include shortness of breath, weakness or dizziness,
  • Aortic Stenosis
    • Aortic valve stenosis is an abnormal narrowing of the aortic valve of the heart. The causes of aortic stenosis are wear and tear of the valve in the elderly,
  • Stroke
    • A stroke is an interruption of the blood supply to part of the brain caused by either a blood clot (ischemic) or bleeding (hemorrhagic). Symptoms of a
  • Head Injury (Brain Injury)
    • In the United States, head injuries are one of the most common causes of death and disability. Head injuries due to bleeding are generally classified by
  • POT Syndrome
    • POT syndrome (POTS, postrual orthostatic tachycardia syndrome) is a nervous system disorder that causes lightheadedness and fainting when a person stands
  • Abnormal Heart Rhythms (Heart Rhythm Disorders)
    • Heart rhythm disorders vary from minor palpitations, premature atrial contractions (PACs), premature ventricular contractions (PVCs), sinus tachycardia,
  • Cyclic Vomiting Syndrome (CVS)
    • Cyclic vomiting syndrome is a condition in which affected individuals have severe nausea and vomiting that come in cycles. Researchers believe that cyclic
  • Pulmonary Hypertension
    • Pulmonary hypertension is an abnormal elevation of the pressure in the pulmonary circulation caused by the constriction of the blood vessels that supply
  • Orthostatic Hypotension
    • Orthostatic hypotension symptoms include lightheadedness, weakness, blurred vision, and syncope or passing out. Causes of orthostatic hypotension include
  • Paroxysmal Supraventricular Tachycardia (PSVT)
    • Paroxysmal supraventricular tachycardia (PSVT) is an abnormal conduction of electricity in particular areas of the heart. PSVT was referred to at one time
  • Chagas Disease
    • Chagas disease is an infection caused by the T. cruzi parasite. Symptoms of Chagas disease include rash, swollen lymph nodes, fever, fatigue, nausea,
  • Munchausen Syndrome
    • Munchausen syndrome is a factitious disorder and attention-seeking syndrome in which an individual pretends to have physical or psychological symptoms
  • Sudden Cardiac Arrest
    • Sudden cardiac arrest is an unexpected, sudden death caused by sudden cardiac arrest (loss of heart function). Causes and risk factors of sudden cardiac
  • Lewy Body Dementia (Dementia with Lewy Bodies)
    • Lewy body dementia (LBD or dementia with Lewy bodies) is one the most common causes of dementia. There are two types of LBD: 1) dementia with Lewy bodies,



Fainting Related Diseases & Conditions

Medical conditions are often related to other diseases and conditions. Our doctors have compiled a list of ailments related to the topic of Fainting. These conditions may be a cause or symptom of Fainting or be a condition for which you may be at increased risk.
  • Low Blood Pressure (Hypotension)
    Low Blood Pressure (Hypotension)Low blood pressure, also referred to as hypotension, is blood pressure that is so low that it causes symptoms or signs due to the…learn more »
  • Anemia
    AnemiaAnemia is the condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin…learn more »
  • Vertigo
    VertigoVertigo is the sensation of spinning or rocking, even when someone is at rest. Vertigo may be caused by a problem in the brain or…learn more »
    In This Article
  • Pregnancy (Week By Week, Trimesters)
    Pregnancy (Week By Week, Trimesters)There are many symptoms involved in the 1st, 2nd and 3rd trimesters of pregnancy. The first early pregnancy symptom is typically…learn more »
    In This Article
  • Diabetes (Type 1 and Type 2)
    Diabetes (Type 1 and Type 2)Diabetes is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are…learn more »
    In This Article
  • Arrhythmia
    ArrhythmiaAn arrhythmia is an abnormal heart rhythm. With an arrhythmia, the heartbeats may be irregular or too slow (bradycardia), to…learn more »
    In This Article
  • Dehydration
    DehydrationDehydration is the excessive loss of body water. There are a number of causes of dehydration including heat exposure, prolonged…learn more »
    In This Article
  • Dizziness
    DizzinessDizziness is a symptom that is often applies to a variety of sensations including lightheadedness and vertigo. Causes of…learn more »
    In This Article
  • Hypoglycemia
    HypoglycemiaHypoglycemia is a syndrome caused by low blood sugar. Symptoms of hypoglycemia include palpitations, trembling, intense hunger,…learn more »
    In This Article
  • Premature Ventricular Contractions (PVCs)
    Premature Ventricular Contractions (PVCs)Premature ventricular contractions (PVCs) are premature heartbeats originating from the ventricles of the heart. PVCs are…learn more »
  • Mitral Valve Prolapse (MVP)
    Mitral Valve Prolapse (MVP)Mitral valve prolapse (MVP) is also also known as “click murmur syndrome” and “Barlow’s syndrome.” Mitral valve prolapse is the…learn more »
    In This Article
  • Heart Attack
    Heart AttackHeart attack happens when a blood clot completely obstructs a coronary artery supplying blood to the heart muscle. A heart…learn more »
    In This Article
  • Parkinson's Disease
    Parkinson’s DiseaseParkinson’s disease is a slowly progressive neurologic disease characterized by a fixed inexpressive face, a tremor at rest,…learn more »
    In This Article
  • Migraine Headache
    Migraine HeadacheMigraine headaches are severe headaches that are accompanies to sensitivity to light, sounds, and smells. They are often…learn more »
    In This Article
  • Balance Disorders
    Balance DisordersBalance is a state of body equilibrium or stability. We often take for granted how dependent we are on a healthy balance system….learn more »
    In This Article
  • Heart Valve Disease
    Heart Valve DiseaseHeart valve disease occurs when the heart valves do not work the way they should. Symptoms of valve disease include shortness of…learn more »
    In This Article
  • Aortic Stenosis
    Aortic StenosisAortic valve stenosis is an abnormal narrowing of the aortic valve of the heart. The causes of aortic stenosis are wear and tear…learn more »
    In This Article
  • Stroke
    StrokeA stroke is an interruption of the blood supply to part of the brain caused by either a blood clot (ischemic) or bleeding…learn more »
    In This Article
  • Head Injury (Brain Injury)
    Head Injury (Brain Injury)In the United States, head injuries are one of the most common causes of death and disability. Head injuries due to bleeding are…learn more »
    In This Article
  • POT Syndrome
    POT SyndromePOT syndrome (POTS, postrual orthostatic tachycardia syndrome) is a nervous system disorder that causes lightheadedness and…learn more »
    In This Article
  • Abnormal Heart Rhythms (Heart Rhythm Disorders)
    Abnormal Heart Rhythms (Heart Rhythm Disorders)Heart rhythm disorders vary from minor palpitations, premature atrial contractions (PACs), premature ventricular contractions…learn more »
    In This Article
  • Cyclic Vomiting Syndrome (CVS)
    Cyclic Vomiting Syndrome (CVS)Cyclic vomiting syndrome is a condition in which affected individuals have severe nausea and vomiting that come in cycles….learn more »
    In This Article
  • Pulmonary Hypertension
    Pulmonary HypertensionPulmonary hypertension is an abnormal elevation of the pressure in the pulmonary circulation caused by the constriction of the…learn more »
    In This Article
  • Orthostatic Hypotension
    Orthostatic HypotensionOrthostatic hypotension symptoms include lightheadedness, weakness, blurred vision, and syncope or passing out. Causes of…learn more »
    In This Article
  • Paroxysmal Supraventricular Tachycardia (PSVT)
    Paroxysmal Supraventricular Tachycardia (PSVT)Paroxysmal supraventricular tachycardia (PSVT) is an abnormal conduction of electricity in particular areas of the heart. PSVT…learn more »
    In This Article
  • Chagas Disease
    Chagas DiseaseChagas disease is an infection caused by the T. cruzi parasite. Symptoms of Chagas disease include rash, swollen lymph nodes,…learn more »
    In This Article
  • Munchausen Syndrome
    Munchausen SyndromeMunchausen syndrome is a factitious disorder and attention-seeking syndrome in which an individual pretends to have physical or…learn more »
    In This Article
  • Sudden Cardiac Arrest
    Sudden Cardiac ArrestSudden cardiac arrest is an unexpected, sudden death caused by sudden cardiac arrest (loss of heart function). Causes and risk…learn more »
    In This Article
  • Lewy Body Dementia (Dementia with Lewy Bodies)
    Lewy Body Dementia (Dementia with Lewy Bodies)Lewy body dementia (LBD or dementia with Lewy bodies) is one the most common causes of dementia. There are two types of LBD: 1)…learn more »
    In This Article
  • Heart Attack Treatment
    Heart Attack TreatmentA heart attack involves damage or death of part of the heart muscle due to a blood clot. The aim of heart attack treatment is to…learn more »
    In This Article
  • Cardiomyopathy (Hypertrophic)
    Cardiomyopathy (Hypertrophic)Hypertrophic cardiomyopathy (HCM) affects many people today. Many people with HCM have no symptoms or only minor symptoms, and…learn more »
    In This Article
  • Cardiomyopathy (Dilated)
    Cardiomyopathy (Dilated)Dilated Cardiomyopathy is a condition where the heart’s ability to pump blood is decreased because the heart’s main pumping…learn more »
    In This Article
  • Preeclampsia (Pregnancy Induced Hypertension)
    Preeclampsia (Pregnancy Induced Hypertension)Preeclampsia is related to increased blood pressure and protein in the mother’s urine. Preeclampsia typically begins after the…learn more »
    In This Article
  • Drug Allergy
    Drug AllergyDrug allergies are cause when the immune system mistakenly creates an immune response to a medication. Symptoms of a drug…learn more »
    In This Article
  • Cardiomyopathy (Restrictive)
    Cardiomyopathy (Restrictive)Restrictive cardiomyopathy, the rarest form of cardiomyopathy, is a condition in which the walls of the lower chambers of the…learn more »
    In This Article

From: 

http://www.medicinenet.com/fainting/related-conditions/index.htm


Syncope/Collapse

Syncope is a temporary loss of consciousness (fainting) that happens when the brain does not get enough oxygen. It comes on suddenly, only lasts for a short time and you recover fully within a short time. It is often called a blackout, faint or collapse. It isn’t the same thing as a seizure which causes jerking. It is important to seek medical attention if you suffer from syncope, as it may be due to a serious underlying problem. The most common causes are mentioned below.
Syncope is when you become unconscious for a few seconds. It is also called fainting or passing out. You may feel sick and sweaty first or pass out with no warning at all. When you pass out, you fall to the ground. It isn’t the same thing as a seizure which makes you jerk. Usually, you come round after a few seconds and feel back to normal. Some people feel very tired after they’ve come round. Usually, syncope happens for a reason like when you’re in pain or have been standing for a long time in a hot place. It is very unusual for it to be due to any serious problem. The reason for syncope is that the brain needs a constant supply of oxygen and if that falls below a certain level, we fall to the ground until the more oxygen-rich blood can get to the brain.
Syncope is common at all ages and affects up to 4 in 10 people at least once in their lives. Most people never get medical help. Most people (95%) have their first attack of syncope before they’re forty years old. If you get it for the first time after 40, it is more likely to be due to a serious underlying problem. The most common cause is a common faint, also called neurally mediated syncope (NMS). Common faints usually happen for the first time in teenage years and affect girls more than boys. In older people, syncope is more likely to be due to underlying heart problems, low blood pressure or as a side-effect of their medication.
This list does not include all the possible causes of syncope but lists some of the more common causes including:
Common faint (NMS): this is also known as vasovagal syncope. It is the most common cause of syncope. NMS can occur in various situations. These include fear, severe pain or emotional distress, after extreme exercise, during vomiting or when wearing tight collars that constrict the neck. During attacks, you may look pale and feel sweaty. Your eyes will usually stay open.
Orthostatic hypotension: this is a fall in blood pressure on standing up which can cause syncope. It can be due to medication prescribed to lower blood pressure, after prolonged standing, especially in hot places (which is why soldiers on parade may faint), as a result of neurological diseases such as Parkinson’s disease or after a big meal.
Cardiac syncope: this occurs due to an underlying heart problem. There may be a family history of sudden death. The syncope may be preceded by chest pain or palpitations and may happen after exercise.
The doctor will want to know more about what you were doing when you blacked out. You will be asked whether you’ve recently started new medication. Try to remember whether you had any warning before you blacked out. Did anyone see you fall? How did you feel when you came round? These details will help the doctor to make a diagnosis. Your doctor will examine you. They will check your heart, including your blood pressure when sitting and standing and your pulse. You may be asked to have an electrocardiogram (ECG). You may have blood tests for anaemia and diabetes. Further tests of your heart and nervous system may be necessary.
The most common cause of blacking out is syncope. Other causes include epileptic seizures, psychosomatic syncope due to anxiety (psychogenic pseudosyncope) and other rare causes.
Other losses of consciousness may be due to low blood sugar (hypoglycaemia), lack of oxygen from a variety of causes (hypoxia) and over-breathing (hyperventilation).
You may also lose consciousness after a fall or blow to the head or due to excess alcohol or other drugs.
Strokes and mini strokes (transient ischaemic attacks) can also result in a loss of consciousness.
Prolonged unconsciousness, confusion after the event, incomplete recovery and tongue biting all suggest that the cause is not a simple faint.
Treatment will depend on the likely cause of your blackout. You may be asked to keep a diary of the circumstances in which it happened. Most cases will be managed by your GP but you may be referred for further investigation and treatment at a hospital.
  • Lie down flat with your legs up on a chair or against a wall or sit down with your head between your knees.
  • Squatting down on your heels can be very effective and is less noticeable in public.
  • When feeling better, get up carefully. If symptoms return, resume the position.
  • Discuss stopping any medication that may be responsible, with your doctor.
  • Avoid alcohol.
  • Drink plenty of fluids.
  • Raise the head of your bed.
  • Wear support stockings.
  • Do leg crossing and arm tensing exercises.
Driving is not a problem for a simple faint but greater restrictions apply if the situation is more complicated or if diagnosis is less clear.
If in doubt, contact the Driver and Vehicle Licensing Agency (DVLA).
The DVLA does not have to be informed of a simple faint but failure to notify other conditions can lead to a fine.
You should call an ambulance if you suffer from a blackout while exercising or lying down, if you have a family history of sudden and unexplained deaths or if you suffer from chest pain or palpitations. If the attacks recur or you do not make a complete recovery, you should also seek urgent medical attention. If you have lots of attacks, or you hurt yourself because of the faints, your GP may want you to see a specialist. They may also want a specialist to advise if your faints are affecting your driving. In all other cases, you should see your GP.
You will need to find the underlying cause and try to address it if possible. Common faints are by far the most common cause. Many people who faint know when it tends to happen and how to avoid attacks.
This depends on the underlying cause but is generally very good. In young people when the blackouts are not associated with any underlying heart or nervous system problem, there is no increased risk. In older people, any increased risk is due to the underlying condition and the risk from falling.
From: http://www.patient.co.uk/health/syncopecollapse
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