Blurry vision affecting only one eye, sometimes called unilateral blurriness or monocular diplopia, means one eye sees objects as indistinct or out of focus while the other maintains clear vision. This common visual complaint can range from minor, temporary issues to more serious conditions that could affect long-term vision.
Common Causes of Blurry Vision in One Eye
Many factors can lead to blurry vision in a single eye, often stemming from less severe conditions. Refractive errors are frequently responsible, occurring when the eye’s shape prevents light from focusing correctly on the retina. These include astigmatism, where an irregularly shaped cornea or lens distorts vision, or myopia (nearsightedness) and hyperopia (farsightedness), which can be more pronounced in one eye. If one eye has a significantly different prescription, it may work harder, contributing to blurriness and strain.
Presbyopia, an age-related condition affecting near vision, can initially manifest more noticeably in one eye, making close-up tasks difficult. Dry eye syndrome, where the eyes do not produce enough quality tears, can lead to discomfort and fluctuating blurry vision that may improve with blinking. Eye strain or fatigue, often from prolonged visual tasks or uncorrected vision differences between the eyes, can also cause temporary blurriness. Additionally, a corneal abrasion (a scratch on the eye’s surface) or a foreign body can cause pain and blurry vision. Mild allergic reactions can also lead to inflammation and temporary blurriness.
Serious Conditions Affecting One Eye’s Vision
More severe or sight-threatening conditions can also present as blurry vision in one eye, necessitating prompt medical evaluation. Cataracts, a common age-related condition, involve the clouding of the eye’s natural lens, which can cause hazy or dim vision, difficulty with night vision, and sometimes double vision. While cataracts often affect both eyes, differing degrees of clouding can make one eye appear blurrier.
Other serious conditions include:
Glaucoma: Particularly acute angle-closure glaucoma, which can cause a sudden and rapid increase in eye pressure, leading to blurry vision, severe eye pain, headache, and halos around lights. This condition can cause permanent vision loss if not addressed quickly.
Retinal detachment: Occurs when the retina, the light-sensitive tissue at the back of the eye, pulls away from its normal position, potentially causing sudden blurry vision, flashes of light, new floaters, or a shadow resembling a curtain in the visual field.
Macular degeneration: Especially the “wet” form, can result in sudden, significant vision loss and blurriness in one eye due to abnormal blood vessel leakage in the macula, the central part of the retina.
Optic neuritis: An inflammation of the optic nerve, causing blurry vision, pain with eye movement, and reduced color vision.
Eye infections: Such as keratitis (corneal inflammation) or uveitis (inflammation of the middle layer of the eye), can lead to blurry vision, redness, pain, and light sensitivity.
Vascular issues: Like retinal vein occlusion or retinal artery occlusion, involve blockages in the blood vessels supplying the retina, which can cause sudden, painless vision loss or blurriness in the affected eye.
Neurological conditions: Including a transient ischemic attack (TIA) or stroke affecting visual pathways in the brain, can result in sudden blurry vision, often with other neurological symptoms.
When to Seek Medical Care
Prompt medical attention for blurry vision in one eye is important, particularly if certain symptoms accompany it. Seeking immediate emergency care is advised for a sudden onset of blurriness, especially if vision loss is significant or complete. Associated symptoms such as eye pain, flashes of light, or new, numerous floaters warrant urgent evaluation.
Other indicators for immediate medical consultation include redness or swelling of the eye, double vision (monocular diplopia), or a recent eye injury. The presence of a severe headache, nausea, or vomiting accompanying the blurry vision also suggests a need for urgent care. Any significant or rapid change in vision quality in one eye should be assessed by an eye care professional to determine the underlying cause and ensure timely intervention.
Diagnosis and Management by an Eye Care Professional
When blurry vision affects one eye, an eye care professional, such as an optometrist or ophthalmologist, conducts a thorough examination to determine the cause. The diagnostic process typically begins with a comprehensive eye exam, including a visual acuity test to measure sharpness of vision and refraction to check for refractive errors. A slit-lamp examination allows the doctor to view the eye’s front and internal structures in detail. Tonometry measures intraocular pressure, which is important for detecting glaucoma. A dilated fundus exam, performed after administering eye drops, provides a clear view of the retina and optic nerve.
Additional tests may be necessary depending on the initial findings. Optical coherence tomography (OCT) uses light waves to create cross-sectional images of the retina and optic nerve, aiding in the diagnosis and management of various retinal diseases and glaucoma. Visual field testing assesses peripheral vision and can detect blind spots. Fluorescein angiography involves injecting a fluorescent dye to highlight retinal blood vessels, helping identify issues like blockages or abnormal growth. Treatment strategies for unilateral blurry vision vary widely and depend on the specific underlying condition diagnosed, ranging from corrective lenses for refractive errors to medications for infections, or procedures and surgery for conditions like cataracts or retinal detachment.