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What Causes Blurry Vision in One Eye?
Visual clarity is necessary for performing everyday tasks or activities, maintaining your safety, and your overall quality of life. If one eye suddenly becomes blurry, it may indicate you need glasses, but it could also be an early sign of an ocular or systemic health condition.
Blur in one eye could be caused by a problem with the retina, optic nerve, an infection, inflammation, or even a type of vascular disease process affecting the eye. If you notice blurry vision in just one eye, you should seek medical care quickly to identify the cause and begin treatment to prevent permanent vision loss.
Symptoms Checklist: How Blurry Vision in One Eye Presents
Blurry vision in one eye can present in several different ways. Unilateral blurry vision in combination with other symptoms can indicate a more serious condition. Sudden vision loss or blurred vision can be a sign of a serious condition like retinal detachment, stroke, or optic neuritis. If the onset of the blur is gradual, the cause may be a refractive error, a cataract, or macular degeneration.
If the blurry vision presents with ocular pain with eye movement, the cause may be optic neuritis, but if the eye pain is constant and the eye is red, the likely cause is a corneal infection or inflammation. Unilateral blur in combination with a curtain over your vision, floaters, or flashes could be an indication of a serious eye condition like retinal detachment.
A monocular vision problem affects only one eye, and the issue is within the eye itself, such as a cataract, retinal detachment, corneal disease, or optic nerve disorder. A binocular vision problem involves both eyes and is often a neurological or systemic problem like a brain lesion, stroke, pituitary tumor, or demyelinating disease like multiple sclerosis.
Top Causes of Blurry Vision in One Eye (By System)
There are many causes for blurry vision in one eye, including ocular manifestations of a systemic disorder or a neurological cause.
Eye/Retina & Optic Nerve
1. Refractive Errors:
A refractive error is a common, benign cause for blurry vision, which affects how the eye focuses light on the retina. Myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (irregular corneal curvature) may cause blurred vision in one or both eyes.
2. Cataracts:
A cataract is a gradual clouding of the eye’s natural lens, which reduces the lens’s clarity and prevents light from focusing on the retina. It is caused by UV light. Cataracts rarely affect both eyes equally.
3. Macular Degeneration:
Macular degeneration causes gradual blur or distorted central vision. It typically affects older adults, and the disease progresses as the central retina layers degenerate. Objects usually appear wavy or distorted, but may progress to large blind spots (scotomas) of vision loss.
4. Retinal Detachment:
A retinal detachment is considered an ocular emergency and presents with blurry vision, flashes of light, floaters, and a curtain-like shadow in one’s peripheral vision.
5. Optic Neuritis:
Optic neuritis is inflammation of the optic nerve, which results in acute, unilateral blurred vision, pain on eye movements, and is often linked to the autoimmune condition multiple sclerosis (MS).
6. Diabetic Retinopathy:
Diabetic retinopathy can result in blurry vision if there is bleeding, swelling, or ischemia in the retina due to high sugar levels. An elevated A1c level and the number of years one has had diabetes increase the risk of developing retinopathy.
7. Corneal Issues:
The cornea is the eye’s primary focusing surface, so any irregularity, including a corneal ulcer or abrasion, can result in blurry vision in the affected eye. The cornea heals quickly, and the vision should improve over several days with treatment.
8. Uveitis:
Uveitis is inflammation inside the eye, which may cause clouding of the aqueous humor, intraocular swelling, and damage to the retina or nerve, resulting in blurry vision, pain, and light sensitivity.
9. Retinal Vein Occlusion (RVO):
A retinal vein occlusion (RVO) is a blockage of one of the veins that drain blood from the retina, which may lead to blood and fluid leakage within the retinal layers and blurry vision.
10. Dry Eye Syndrome:
Dry eye disease can result in transient, acute blurry vision in one or both eyes, which may be caused by either insufficient tear production or rapid evaporation of the tears from the ocular surface.
11. Optic Nerve Atrophy:
Optic nerve atrophy is damage or degeneration of the optic nerve, which may be a result of ischemic optic neuropathy, trauma, or glaucoma, and may cause unilateral blurry vision.
Neurologic & Intracranial Causes
1. Stroke/TIA:
A sudden loss or blurring of vision in one eye may be due to a neurological cause, like a stroke/TIA. Both conditions are emergencies and require urgent medical care. FAST and BEFAST are quick screening acronyms used to recognize the signs of a stroke so that treatment can be started immediately.
2. Multiple Sclerosis (Optic Neuritis):
Unilateral blurry vision can be caused by inflammation of the optic nerve called optic neuritis, which is often associated with the autoimmune condition Multiple Sclerosis.
3. Brain Tumors (Pituitary, chiasmal compression):
A tumor of the pituitary gland, which is located at the optic chiasm, can cause compression on the optic nerves, resulting in unilateral blurred vision.
When to Seek Medical Attention: Red Flags
Blurry vision in one eye can be a symptom of a serious medical emergency and necessitates a visit to see a physician. Sudden vision loss or blurring in combination with flashes, floaters, or a curtain-like shadow may indicate retinal detachment, which requires urgent treatment. Eye pain with blurry vision could be one of several different eye problems, including optic neuritis, a corneal ulcer, or acute glaucoma. If blurry vision presents with a neurological symptom like facial droop, weakness, or difficulty speaking, a stroke may have occurred, and one should go to the emergency room.
How Doctors Diagnose Blurry Vision in One Eye
To make a diagnosis, the doctor will ask the patient about their medical history, family history, and other factors related to their complaint of unilateral blur. The physician will want to know if the patient’s blurry vision onset was sudden or gradual, monocular vs. binocular, and if they had other presenting symptoms at the time, like pain, floaters, or a red eye.
A comprehensive exam includes a complete patient history, visual acuity testing, pupil testing, slit-lamp microscopy, an IOP check, and a dilated fundus exam. Based on the findings, the doctor may perform ocular testing, like a visual field or OCT, and/or systemic testing, like blood work or imaging.
Comprehensive Eye Exam
- History: A comprehensive, thorough medical history is vital to making a diagnosis, including the timing of the condition and other associated symptoms. The medical history helps a physician compile a list of possible diagnoses and rule out each one as the cause for the blurry vision in one eye.
- Visual Acuity and Slit-Lamp Exam: An eye exam typically begins with a Snellen test of visual acuity and a refraction to determine if refractive error is the cause of the blurry vision. A slit lamp exam is used to assess the anterior segment of the eye, which includes dry eye, cataracts, or corneal abnormalities.
- Pupil Reactions and Intraocular Pressure (IOP): A light is used to assess the constriction and dilation of the pupil for any abnormality, which could indicate an optic nerve or neurological condition. Tonometry or an intraocular pressure (IOP) test is information used to evaluate the eye for glaucoma.
- Fundus Exam: A fundus exam is a dilated eye exam where diagnostic equipment and lenses are used to assess the health of the retina, macula, and optic nerve.
Imaging and Tests
1. OCT (Optical Coherence Tomography):
Optical coherence tomography (OCT), including RNFL and ganglion cell analysis, is used to detect early damage to the optic nerve and retina. A database compares the patient's measurements to normal patient data and generates a report to help the eye care specialist diagnose and track disease progression.
2. Fluorescein Angiography:
Fluorescein Angiography (FA) is a diagnostic imaging test used to evaluate the blood vessels in the retina and choroid. A fluorescent dye called sodium fluorescein is injected into a vein. A special camera takes rapid-sequence photographs as the dye flows through the blood vessels in the eye to identify ischemia, leakage, or blockages in patients with a vascular condition.
3. Visual Field Test (Perimetry):
Perimetry is used to map a patient’s visual field, assess the extent of vision loss, and confirm a diagnosis. Patients are asked to fixate on a central point and push a button when they see the varying intensity of lights (Humphrey). The results demonstrate the extent and pattern of vision field loss and can also be used to assess whether a treatment is working.
4. MRI/CT scan:
An MRI or CT scan is used if a neurological cause is suspected. Imaging of the brain and orbits is used to identify a condition, such as optic neuritis, chiasmal compression, a stroke, or a tumor, that is suspected in a patient with blurry vision in one eye.
Treatment Options for Blurry Vision in One Eye (Condition-Specific)
Treatment options for blurry vision depend on the cause and severity of the condition.
Cataracts
Cataracts are removed with surgery when the clouding of the eye’s natural lens begins to interfere with the patient’s daily activities. During the surgery, the cloudy lens is removed and replaced with a clear artificial intraocular lens (IOL), which can correct for the patient’s refractive error, including nearsightedness, farsightedness, or astigmatism. Most patients can see right after surgery and are given drops to prevent any infection and to reduce inflammation.
Retinal Detachment
A retinal detachment repair is an emergency surgery to reattach the retina and prevent permanent vision loss. Three methods can be used by a surgeon to repair the retina. Pneumatic retinopexy is the insertion of a gas bubble into the eye to hold the retina back in place. The scleral buckle technique utilizes a silicone band placed around the eye to relieve the traction on the retina. In a vitrectomy, the vitreous gel is removed and replaced with gas or silicone oil to flatten the retina.
Optic Neuritis
Optic neuritis is treated using high-dose intravenous corticosteroids, which may be followed by a short course of oral steroids to reduce the inflammation of the optic nerve. Steroid treatment speeds up recovery time but does not change the long-term visual outcome. If optic neuritis is due to multiple sclerosis, additional long-term immunomodulating medications may be recommended.
Diabetic Retinopathy
Patients with diabetic retinopathy should work with their endocrinologist to reduce their blood sugar levels (A1C) and prevent further damage. Patients with non-proliferative mild to moderate retinopathy should be closely monitored. For proliferative diabetic retinopathy, anti-VEGF injections (such as Avastin, Eylea, or Lucentis) are the most common therapy. They stop abnormal blood vessel growth and bleeding, reduce swelling, and improve vision. Panretinal photocoagulation (PRP) is used to treat proliferative disease by shrinking abnormal new vessels. A focal or grid laser is used to seal leaking blood vessels in patients with macular edema.
Stroke or TIA
The goal of a treatment for a stroke or TIA (transient ischemic attack) is to restore blood flow as quickly as possible and to prevent a future event. An ischemic stroke is the most common type. It is treated with IV thrombolytic medication (tPA) if it is given within a narrow time frame or a mechanical thrombectomy, which is a procedure that removes a large clot directly from the brain’s blood vessel. Long-term prevention may include antiplatelet medications (aspirin), anticoagulants, medication for hypercholesterolemia, blood pressure control, diabetes management, and lifestyle changes such as smoking cessation and a healthy diet.
Prevention & Monitoring
You can prevent blurry vision and early detection of eye problems by scheduling an annual eye exam. Regular eye exams are extremely important for those with diabetes, high blood pressure, or a family history of eye disease for early detection and treatment. Managing systemic conditions and maintaining a healthy lifestyle can significantly reduce the risk of developing an eye condition. Wearing safety glasses and sunglasses can protect your eye health and prevent injury.
Special Considerations for Certain Groups
Blurry vision in one eye can be present in certain patient groups, including pregnant women, children, teens, and post-surgical patients. Hormonal changes during pregnancy can affect vision by altering the shape and thickness of the cornea, altering the tear film layer, and affecting tear production. These changes may lead to temporary blurred vision, dryness, or fluctuations in vision. Children and teens may have amblyopia (lazy eye) or strabismus (eye turn), which may lead to blurry vision in one eye and must be treated before the age of 8 for best results. For this reason, all children should have an eye exam before the age of 5, if not earlier. Blurry vision in one eye can occur after either cataract or refractive surgery. Your eye care professional will educate you on the normal recovery process and how you are progressing.
Frequently Asked Questions (FAQs)
Yes, blurry vision may improve on its own depending on the cause. If the cause for the blur is dry eye, eye strain, build-up on a contact lens, or ocular allergies, the condition may improve without treatment. If the reason for the blurry vision is a retinal tear/detachment, optic neuritis, an infection, acute glaucoma, or a systemic vascular problem that is affecting the retina, the condition will not improve without treatment and requires urgent care.
There is no way to know if your blurry vision is from a serious condition except for an evaluation by a specialist. Some signs of a more serious condition include flashes of light, new floaters, or a “curtain” over part of your vision, eye pain, double vision, a loss of side vision, a red eye with severe pain or nausea, or any neurologic symptoms such as weakness, numbness, trouble speaking, or dizziness.
Scheduling an annual eye exam to detect early disease is an important first step in the prevention of blurry vision. If you have any systemic disease, including diabetes, hypertension, and/or high cholesterol, you must control the condition with proper treatment and see your physician as advised. Eating healthy, exercising regularly, wearing your sunglasses for UV protection, and quitting smoking can also prevent blurry vision.
Yes, wearing the wrong prescription glasses may cause blurry vision. If the lenses are too strong, too weak, or are not customized for you, your vision may be blurry or feel strained. Your symptoms should improve with an accurate prescription unless your blurry vision is caused by a medical or systemic condition.
If you are experiencing blurry vision for the first time, you should see a doctor. If the onset of blurry vision is sudden, presents with a curtain over your vision or with new flashes and floaters, double vision, eye pain with nausea, a persistent headache, or with neurological symptoms like body weakness, numbness, difficulty speaking, or dizziness, certain ocular and systemic conditions must be ruled out as a possible diagnosis.
