Blurry vision in one eye, or monocular diplopia, is a loss of sharpness in a single eye, making objects appear out of focus. This symptom can range from a minor inconvenience to a significant underlying health issue. Understanding its causes is important for determining when medical attention is warranted. This article covers common and serious reasons for blurry vision.
Common Reasons for Blurry Vision
Common, less severe conditions can cause blurriness in one eye. Refractive errors are frequent culprits, occurring when the eye does not focus light correctly onto the retina. These include astigmatism (an imperfection in the eye’s lens or cornea), nearsightedness (myopia), or farsightedness (hyperopia), which can manifest more prominently in one eye.
Dry eye syndrome, where eyes do not produce enough tears or tears evaporate too quickly, causes intermittent blurriness, especially when blinking. Symptoms include gritty sensation, redness, or a feeling of something in the eye. Eye strain from prolonged visual focus (e.g., computer use) can also cause temporary blurriness that resolves with rest.
A foreign body, like a speck of dust or an eyelash, can temporarily obstruct vision and cause blurriness until removed. Irritants can also cause tearing and discomfort. Temporary blurriness can also occur as part of a migraine aura preceding a headache. These visual changes may appear as shimmering lights, zigzag lines, or blind spots affecting one side of the visual field.
Urgent Concerns and Serious Conditions
Blurry vision in one eye can signal a serious medical condition requiring prompt attention. Retinal detachment, where the retina pulls away from its supporting layers, causes symptoms like sudden floaters, flashes of light, or a dark “curtain” spreading across the field of vision.
Acute angle-closure glaucoma is characterized by a sudden increase in eye pressure, causing rapid onset of blurry vision, eye pain, redness, headache, and sometimes nausea or vomiting. Optic neuritis, inflammation of the optic nerve, can lead to sudden, painful vision loss or blurriness in one eye, often worsening with eye movement.
A stroke or transient ischemic attack (TIA) can affect the brain’s visual processing centers, leading to sudden, painless vision loss or blurriness. These events may also include neurological symptoms like weakness, difficulty speaking, or facial drooping. Eye infections (e.g., keratitis, uveitis) can cause blurry vision, pain, redness, and light sensitivity. Untreated, these infections can lead to permanent vision loss.
Cataracts, involving the clouding of the eye’s natural lens, develop gradually but can affect one eye more, causing progressive blurriness, dulling of colors, and increased glare sensitivity. Macular degeneration, damaging the macula (the central part of the retina), causes blurred central vision or a blind spot. This condition affects older adults and can lead to significant vision impairment.
When to See a Doctor
It is important to know when to seek medical attention for blurry vision in one eye. Immediate care is necessary for sudden, severe, or complete vision loss. Emergency evaluation is also required for a sudden onset of new flashes of light, a significant increase in floaters, or a dark “curtain” over your vision. Severe eye pain with blurriness, double vision, or vision changes after a head injury are urgent concerns.
If blurriness is persistent but develops gradually, or is accompanied by symptoms like eye discharge, redness, or increased light sensitivity, seek prompt care from an eye care professional within 24 to 48 hours. Blurriness not improving with rest or over-the-counter eye drops also warrants a timely visit. Consulting an optometrist or ophthalmologist for persistent or worsening blur ensures proper diagnosis and management.
Diagnosing and Treating Blurry Vision
Diagnosing blurry vision in one eye begins with a comprehensive eye examination. This includes visual acuity tests (measuring clarity), refraction tests (determining corrective lens needs), intraocular pressure measurement (for glaucoma), and a slit lamp examination (to view eye structures).
Pupil dilation allows a clearer view of the retina and optic nerve. Specialized tests like optical coherence tomography (OCT) for retinal images or visual field testing for blind spots may be ordered. Treatment for blurry vision depends on the underlying diagnosis.
For refractive errors, prescription glasses or contact lenses correct vision. Dry eye syndrome is managed with artificial tears, lubricating eye drops, or lifestyle adjustments. Infections like keratitis or uveitis are treated with specific eye drops (e.g., antibiotics, anti-inflammatory medications). Cataracts require surgical lens removal and replacement. Serious conditions like retinal detachment or acute angle-closure glaucoma may require surgical or other medical interventions to preserve vision.
Citations
American Academy of Ophthalmology. (2024). What Is Astigmatism?.
National Eye Institute. (2023). Refractive Errors.
American Academy of Ophthalmology. (2024). What Is Dry Eye?.
Mayo Clinic. (2024). Migraine with aura.
American Academy of Ophthalmology. (2024). What Is a Retinal Detachment?.
American Academy of Ophthalmology. (2024). What Is Glaucoma?.
National Institute of Neurological Disorders and Stroke. (2024). Optic Neuritis Fact Sheet.
American Stroke Association. (2024). Vision Problems After Stroke.
American Academy of Ophthalmology. (2024). What Is Keratitis?.
American Academy of Ophthalmology. (2024). What Is Uveitis?.
National Eye Institute. (2023). Cataracts.
National Eye Institute. (2023). Age-Related Macular Degeneration (AMD).
American Academy of Ophthalmology. (2024). What Is a Comprehensive Eye Exam?.