Blurry vision in one eye can be a concerning symptom, often signaling an underlying issue. Monocular blurry vision means one eye sees unclearly while the other maintains clarity. Causes vary from minor issues to serious conditions requiring prompt attention.
Common and Temporary Explanations
Temporary blurry vision in one eye often stems from less serious factors. Refractive errors (astigmatism, nearsightedness, farsightedness) can develop or worsen in one eye, causing blurriness. An irregular shape of the cornea or lens in one eye can prevent light from focusing correctly on the retina, leading to blurriness. These conditions often result in blurriness at various distances and may also cause headaches or eye strain.
Dry eye syndrome is another frequent cause, where the eye doesn’t produce enough tears or they evaporate too quickly. This compromises the tear film, essential for a smooth eye surface, leading to fluctuating vision. Prolonged visual focus (e.g., screen use, reading) can cause eye strain, leading to temporary blurriness, fatigue, or light sensitivity. A minor foreign object (e.g., dust, eyelash) can also cause irritation, tearing, and temporary blurriness until removed. These causes are typically not emergencies and often resolve with rest, artificial tears, or corrective lenses.
More Significant Eye Conditions
Significant eye conditions can also cause blurry vision in one eye, requiring medical intervention. Cataracts involve clouding of the eye’s lens, gradually leading to blurriness. Although cataracts can affect both eyes, the clouding may progress at different rates, causing a noticeable difference in vision between them.
Glaucoma, particularly closed-angle glaucoma, involves increased eye pressure that can damage the optic nerve. This elevated pressure can lead to permanent vision loss, often affecting one eye initially. Macular degeneration, affecting the macula (central retina), impacts central vision and can begin unilaterally. In its “wet” form, abnormal blood vessels can grow and leak fluid or blood, causing sudden vision loss in one eye.
Retinal detachment is a serious condition where the retina pulls away from supporting tissue. This can cause sudden blurred vision, flashes of light, new floaters, and a “curtain” or shadow in the visual field. Optic neuritis involves inflammation of the optic nerve. This inflammation can lead to sudden vision loss or blurriness, often with pain worsening on eye movement.
Other conditions affecting the cornea can also lead to blurriness. These include corneal abrasions (scratches), infections like keratitis, or conditions like keratoconus where the cornea thins and bulges, distorting vision. Inflammation inside the eye, such as uveitis, can also cause blurry vision, eye pain, and sensitivity to light, affecting one or both eyes.
When Immediate Medical Attention is Needed
Certain symptoms accompanying blurry vision in one eye signal a need for immediate medical attention. A sudden onset of blurriness or vision loss, especially if rapid, is a red flag. Eye pain alongside blurry vision also prompts urgent evaluation, indicating conditions like acute glaucoma, infection, or optic nerve inflammation.
New flashes of light or a sudden increase in floaters (small dark spots or squiggly lines) can be a warning sign of a retinal tear or detachment. A shadow or “curtain-like” effect obscuring vision is a more definite symptom of retinal detachment. Other symptoms include double vision, recent eye injury or trauma, or systemic symptoms like severe headache, nausea, or one-sided weakness, which could indicate neurological issues. Even without these specific red flags, persistent or worsening blurry vision in one eye warrants a visit to an eye care professional for timely evaluation and vision protection.
Diagnostic Steps and Management
An eye care specialist performs a comprehensive eye examination to determine the underlying cause of blurry vision in one eye. This often begins with a visual acuity test. Further diagnostic steps include measuring eye pressure for glaucoma, a slit-lamp examination of front structures, and a dilated eye exam to thoroughly inspect the retina and optic nerve. Specialized imaging tests, such as optical coherence tomography (OCT) or fluorescein angiography, might also be used to detect subtle changes in the retinal layers or blood vessels.
Once a diagnosis is established, appropriate management will be determined. For refractive errors, this might involve prescribing new eyewear like glasses or contact lenses. Conditions like dry eye syndrome can often be managed with medicated eye drops or other therapies to improve tear production and quality. More complex conditions may require laser procedures, surgical interventions, or referral to a specialist, such as a retinal surgeon or neuro-ophthalmologist. Adhering to the recommended treatment plan is important for maintaining eye health and preserving vision.