Blurry vision in one eye, also known as monocular blurry vision, means one eye struggles to see clearly. This common symptom can range from a minor, temporary issue to a sign of a more serious underlying condition. Understanding its potential causes is important for knowing when to seek professional medical attention.
Common and Less Serious Causes
Many instances of blurry vision in one eye stem from common, often easily correctable issues. Eye strain, for example, can occur from prolonged focus on digital screens or close-up tasks, leading to temporary blurring as the eye’s focusing muscles become fatigued. Dry eyes, a condition where the eyes do not produce enough quality tears, can also cause blurry vision that often improves with blinking. Insufficient lubrication interferes with the smooth surface needed for clear sight.
Refractive errors are a frequent cause of monocular blur. They occur when the eye’s shape prevents light from focusing correctly on the retina. Astigmatism, where the cornea or lens has an irregular shape, can cause distorted vision at all distances in one or both eyes. Changes in nearsightedness (myopia) or farsightedness (hyperopia) affecting only one eye can also lead to a noticeable difference in clarity between the two eyes.
Mild cataracts, which involve the clouding of the eye’s natural lens, commonly develop with age and can affect vision gradually. While cataracts often occur in both eyes, the degree of clouding can differ, causing one eye to appear blurrier than the other. A foreign body in the eye, such as dust or debris, can cause irritation, pain, and blurred vision until removed. These objects can scratch the cornea, leading to temporary visual disturbance.
Serious or Urgent Causes
While many causes are benign, blurry vision in one eye can also signal more serious conditions that require prompt evaluation. Retinal detachment is an eye emergency where the retina pulls away from its supporting layers. This can cause sudden blurry vision, often accompanied by new flashes of light, a sudden increase in floaters, or a curtain-like shadow obscuring part of the visual field.
Optic neuritis involves inflammation and damage to the optic nerve. This condition leads to sudden vision loss in one eye, often with pain that worsens with eye movement, and can affect color perception. Macular degeneration, particularly the wet form, affects the macula, the central part of the retina. It can cause blurry or distorted central vision, sometimes affecting one eye more, and may lead to dark spots or wavy lines.
Angle-closure glaucoma is an eye emergency characterized by a rapid increase in eye pressure. This can cause sudden blurry vision, severe eye pain, headache, and sometimes nausea.
In rare cases, blurry vision in one eye can be a symptom of a stroke or transient ischemic attack (TIA), which affect blood flow to the brain and can impact visual processing areas. These neurological events often present with additional symptoms like severe headache, confusion, difficulty speaking, or one-sided weakness.
Posterior vitreous detachment (PVD), a natural age-related change where the vitreous gel pulls away from the retina, usually causes floaters and flashes. While often not sight-threatening, it can sometimes lead to complications like retinal tears or detachment, causing more significant blurry vision.
When to Seek Professional Help
It is advisable to consult an eye care professional for any new or concerning changes in vision. Immediate medical attention is necessary if blurry vision in one eye appears suddenly, especially if accompanied by severe eye pain. Seek emergency care for sudden vision loss or a rapid decrease in clarity.
Other warning signs include new flashes of light, a sudden increase in floaters, or a shadow moving across your field of vision, which can indicate a retinal tear or detachment. If blurry vision in one eye is accompanied by symptoms like double vision, peripheral vision loss, severe headache, nausea, or recent head trauma, it warrants urgent medical evaluation. These symptoms may point to conditions requiring prompt treatment to prevent permanent vision loss or address a systemic health issue.
Diagnosis and Management
A comprehensive eye examination is the first step toward diagnosing blurry vision in one eye. An eye care professional begins with a visual acuity test to measure vision clarity. This is followed by a refraction test to determine if corrective lenses are needed.
The examination may include a slit lamp exam to inspect the eye’s front and inside structures, and a dilated eye exam to evaluate the retina and optic nerve. Additional tests, such as measuring eye pressure, might be performed to check for glaucoma. Depending on the suspected cause, further investigations like imaging studies may be recommended.
Management of monocular blurry vision depends on the underlying cause. Refractive errors can be corrected with prescription eyeglasses, contact lenses, or refractive surgery. Dry eye syndrome can be managed with artificial tears or prescription eye drops. For infections, antibiotic or antiviral medications may be prescribed.
More serious conditions like cataracts, glaucoma, or retinal detachment may require surgical intervention. If a systemic condition like diabetes contributes to blurriness, managing the underlying disease is part of the treatment plan.