Sudden Vision Loss in One Eye: What to Know
Understanding Sudden Vision Loss
Sudden vision loss refers to a rapid decline or complete loss of sight in one eye. It can happen over seconds, minutes, or a few hours. The vision loss may affect all of your sight in that eye or just part of it, such as a shadow or blank area in your field of vision.
This is different from the slow, gradual vision changes that happen with conditions like cataracts or age-related macular degeneration. Sudden vision loss signals that something has gone wrong inside the eye or in the blood supply to the eye. It demands urgent evaluation.
The retina is the thin layer of nerve tissue lining the back of the eye. It converts light into signals that travel to the brain. The retina depends on a constant supply of oxygen-rich blood. When that blood supply is cut off or the retina separates from its supporting tissue, serious damage can begin within minutes to hours.
Many causes of sudden vision loss are treatable if caught early. Delays in seeking care can lead to irreversible vision loss. In some cases, sudden vision loss in one eye can also be a warning sign of a stroke or other serious condition affecting the rest of the body.
Several retinal conditions can produce sudden vision loss in one eye. Each involves a different mechanism, but all share the need for prompt diagnosis and treatment.
- Central retinal artery occlusion (CRAO): a blockage in the main artery supplying blood to the retina
- Branch retinal artery occlusion (BRAO): a blockage in a smaller branch of the retinal artery
- Central retinal vein occlusion (CRVO): a blockage in the main vein that drains blood from the retina
- Branch retinal vein occlusion (BRVO): a blockage in a smaller branch of the retinal vein
- Retinal detachment: separation of the retina from the back wall of the eye
- Vitreous hemorrhage: bleeding into the clear gel that fills the eye
- Retinal tears: breaks in the retinal tissue that can lead to detachment
How These Conditions Affect the Eye
Retinal artery occlusion occurs when a blockage stops blood from flowing through the retinal artery. The blockage is often caused by an embolus (a small piece of cholesterol or debris that travels through the bloodstream) or a thrombus (a blood clot that forms in the vessel). Without oxygen, the retinal nerve cells begin to die rapidly.
CRAO is considered both an eye emergency and a medical emergency. The causes and risk factors for CRAO overlap significantly with those for stroke and heart attack. Research shows that among hospitalized CRAO patients, the rate of in-hospital stroke was about 12.9% (NIH, PMC).
CRVO is one of the leading causes of sudden, painless vision loss in adults. It occurs when the main vein draining blood from the retina becomes blocked. Three main factors contribute to this type of blockage: slowed blood flow, damage to the blood vessel wall, and increased blood clotting tendency.
When the vein is blocked, blood and fluid leak into the retina, causing swelling and vision loss. Retinal vein occlusion requires prompt evaluation and often ongoing treatment to manage fluid buildup in the retina.
A retinal detachment happens when the retina separates from the back wall of the eye. Once separated, the retina loses its blood supply and stops working properly. Without treatment, a retinal detachment can lead to severe and lasting vision loss in the affected eye.
Retinal tears are breaks in the retinal tissue. A tear can allow fluid to seep beneath the retina, leading to detachment. An acute retinal tear may cause a sudden burst of new floaters, along with flashes of light.
Vitreous hemorrhage is bleeding into the vitreous, the clear gel that fills the interior of the eye. Blood in the vitreous blocks light from reaching the retina, causing sudden blurry or dark vision. Vitreous hemorrhage can result from diabetic retinopathy, a retinal tear, or other conditions that damage blood vessels inside the eye.
Who Is at Risk
Retinal artery occlusion shares many risk factors with stroke and heart disease. People with high blood pressure, high cholesterol, diabetes, or a history of tobacco use are at increased risk. Most retinal artery occlusion patients are in their 60s, and the condition is more common in men than women (NIH, PMC).
CRAO patients tend to have higher rates of obesity, hypertension, long-term anticoagulant use, and tobacco use compared to acute ischemic stroke patients (NIH, PMC).
Age is a significant risk factor for many causes of sudden vision loss. Posterior vitreous detachment (separation of the vitreous gel from the retina) is rare in people under 40. It becomes increasingly common with advancing age. This separation can pull on the retina and cause tears.
Additional risk factors for retinal tears and detachment include myopia (nearsightedness), prior eye trauma, and recent eye surgery such as cataract removal. Giant cell arteritis, an inflammation of blood vessels, should be suspected in patients older than 50 who have scalp tenderness, jaw pain with chewing, and elevated inflammatory markers.
Vision loss affects millions of Americans. A 2017 meta-analysis estimated that approximately 7.08 million people in the United States were living with visual acuity loss, of whom about 1.08 million were living with blindness (NEI, 2017). In many cases, blindness and vision loss are preventable with early detection and treatment.
Warning Signs and Symptoms
Certain symptoms signal a retinal emergency. If you experience any of the following in one eye, see a retina specialist or go to the emergency room immediately.
- Sudden, painless loss of vision in one eye
- A dark curtain or shadow spreading across your field of vision
- A sudden increase in floaters, especially many new floaters at once
- Flashes of light, sometimes described as seeing stars
- A gray or dark area blocking part of your side vision
The classic warning signs of a retinal detachment include floaters, flashing lights, and a shadow or curtain in the peripheral (side) vision. This shadow may be stationary or may progress toward the center of your vision. If there is associated vitreous hemorrhage, you may also notice severely blurred vision.
A retinal detachment must be examined by a retina specialist right away. Without prompt treatment, you could lose vision in that eye.
CRAO typically causes sudden, painless, and often severe loss of vision in one eye. The vision loss usually happens within seconds. BRAO may cause loss of part of the visual field rather than total vision loss.
CRVO also causes sudden, painless vision loss, though it may develop over hours rather than seconds. The severity can range from mild blurring to significant vision loss. This depends on the extent of the blockage and resulting retinal swelling.
Diagnosis and Testing
A retina specialist will perform a comprehensive dilated eye exam to look at the retina directly. During this exam, special eye drops widen the pupil so the retina, optic nerve, and blood vessels can be seen in detail. This exam can reveal signs of a retinal tear, detachment, hemorrhage, or blood vessel blockage.
Several imaging tools help a retina specialist evaluate the cause and severity of sudden vision loss.
- Optical coherence tomography (OCT): a scan that creates detailed cross-section images of the retina to detect swelling, fluid, or structural changes
- Fluorescein angiography: a test that uses a special dye injected into a vein in the arm to photograph blood flow in the retina
- Ultrasound of the eye: used when bleeding or other conditions prevent a clear view of the retina
Because retinal artery occlusion shares risk factors with stroke and heart attack, a retina specialist may recommend additional medical evaluation. This can include blood pressure monitoring, blood tests for cholesterol and blood sugar, heart imaging, and carotid artery studies. Identifying and managing these systemic risk factors is an important part of care.
Treatment Options
CRAO is an ophthalmic and medical emergency. Treatment aims to restore blood flow to the retina as quickly as possible, though options remain limited. Research is ongoing into acute treatments including intravenous thrombolysis (clot-dissolving medication) and endovascular mechanical thrombectomy (physical removal of the clot).
Because CRAO is closely linked to cardiovascular disease, patients typically receive a full medical workup. The goal is to identify and treat underlying conditions that could lead to stroke or heart attack.
Retinal vein occlusion is often treated with intravitreal injections (injections of medication directly into the eye). Anti-VEGF medications block abnormal blood vessel growth and leakage. These include Eylea (aflibercept), typically given every 4 to 8 weeks after initial loading doses, and Lucentis (ranibizumab), typically given every 4 weeks. Avastin (bevacizumab), which is FDA-approved for cancer but used off-label for eye conditions, may be given every 4 to 6 weeks.
In some cases, a retina specialist may use corticosteroid implants such as Ozurdex (dexamethasone implant) to reduce swelling inside the eye. The choice of treatment depends on the type and severity of the vein occlusion.
Retinal detachment requires surgery to reattach the retina. Several surgical approaches are available depending on the type and extent of the detachment.
- Pneumatic retinopexy: a gas bubble is injected into the eye to push the retina back into place
- Vitrectomy (surgery to remove the gel inside the eye): allows the surgeon to directly repair the retina
- Scleral buckle: a silicone band is placed around the eye to gently push the wall of the eye against the detached retina
Retinal detachment repairs succeed in about 9 out of 10 cases, though sometimes more than one procedure is needed (ASRS).
Retinal tears are typically treated in an office setting before they progress to a full detachment. A retina specialist may use laser photocoagulation (thermal laser treatment) or cryopexy (a freezing treatment) to seal the tear. Both procedures create a scar that helps hold the retina in place.
What to Expect During and After Treatment
Intravitreal injections are performed in a clinical setting and take only a few minutes. The eye is numbed before the injection. Patients may feel pressure during the injection. Laser and cryotherapy treatments for retinal tears are also performed in the office.
Surgical procedures such as vitrectomy or scleral buckle are performed in an operating room, often under local anesthesia. The length of surgery varies depending on the complexity of the detachment.
Recovery time varies by condition and treatment. After retinal detachment surgery, you may need to maintain a specific head position for several days. This keeps a gas bubble in the correct location. Vision improvement can be gradual, sometimes taking weeks to months.
After treatment for retinal vein occlusion, multiple follow-up visits and repeat injections are usually necessary. Your retina specialist will monitor the retina with imaging tests and adjust the treatment plan based on your response.
The degree of vision recovery depends on the underlying cause, the severity of damage, and how quickly treatment was received. For retinal artery occlusion, significant and lasting vision loss is possible if blood flow is not restored quickly. For retinal detachment, visual outcomes are generally better when the detachment is repaired before it involves the macula.
For retinal vein occlusion, anti-VEGF treatment often improves vision, but the degree of improvement varies. Your retina specialist will discuss realistic expectations based on your specific situation.
When to See a Retina Specialist
See a retina specialist or go to the emergency room immediately if you experience sudden vision loss in one eye, a sudden increase in floaters, flashes of light, or a shadow or curtain moving across your vision. Do not wait to see if these symptoms improve on their own. Time is critical for preserving vision.
Optometrists and primary care doctors can screen for retinal problems and provide referrals. However, retinal emergencies require evaluation and treatment by a retina specialist (a vitreoretinal surgeon). If you are experiencing sudden vision changes, communicate the urgency so you can be seen as quickly as possible.
Questions and Answers
You should seek care immediately, ideally within minutes to hours. For conditions like CRAO, retinal nerve cells can begin to die within about 90 minutes of losing blood supply. For retinal detachment, same-day evaluation is critical, especially if the central vision has not yet been affected. Do not wait overnight or assume the problem will resolve on its own.
Yes. CRAO is closely associated with the same risk factors as stroke. Among hospitalized CRAO patients, the rate of in-hospital stroke was about a notable percentage (NIH, PMC). A retina specialist or emergency physician may recommend a full cardiovascular workup to check for stroke risk. This may include imaging of the brain and carotid arteries.
Vision recovery depends on the cause, the extent of damage, and how quickly treatment was started. Retinal detachment repairs succeed in about 9 out of 10 cases (ASRS), though the amount of vision recovered varies. For retinal artery occlusion, significant and lasting vision loss is possible. For retinal vein occlusion, anti-VEGF injections often help improve vision over time. Your retina specialist can provide a more specific outlook based on your condition.
Temporary vision loss that resolves within minutes, sometimes called amaurosis fugax, can be a warning sign of a future stroke or retinal artery occlusion. Even if your vision returns to normal, this symptom should be evaluated urgently. Temporary vision loss may indicate a blockage that briefly interrupted blood flow and could recur with lasting consequences.
A sudden increase in floaters, even without obvious vision loss, can indicate a retinal tear or the early stages of a retinal detachment. You should contact a retina specialist promptly for a dilated eye exam. If the floaters are accompanied by flashes of light or any shadow in your vision, seek evaluation the same day. Early treatment of a retinal tear can often prevent a full detachment.