Closing one eye and finding the other blurry can be unsettling. While often temporary and harmless, it may also signal an underlying vision issue. Understanding the reasons behind this blurriness can help determine if professional evaluation is needed.
Understanding Why This Happens
The brain combines images from both eyes into a single, clear, three-dimensional view through binocular vision. When one eye is closed, this integrated system is disrupted, forcing the brain to rely solely on the open eye. This can make any existing blurriness in the open eye more apparent, as the brain can no longer compensate with the clearer image from the closed eye.
Many individuals have a dominant eye, which the brain preferentially uses for clearer vision. If the dominant eye is closed, the brain processes input from the less clear eye, highlighting subtle or previously unnoticed visual imperfections.
Temporary blurriness can also result from changes in the tear film. Blinking spreads the tear film evenly across the eye’s surface, which is crucial for clear vision. If the tear film is unstable or insufficient, as in dry eye conditions, closing and reopening an eye can temporarily affect its distribution, leading to a momentary blurring sensation before it resettles.
Potential Underlying Causes
Several conditions can lead to blurriness in one eye that becomes noticeable when the other eye is closed.
Refractive Errors
These include myopia (nearsightedness), hyperopia (farsightedness), and astigmatism, where the eye’s shape prevents light from focusing correctly. Presbyopia, an age-related loss of focus on nearby objects, can also contribute.
Dry Eye Syndrome
Insufficient or poor-quality tears lead to fluctuating vision and blurriness, often more pronounced in one eye. This occurs when the tear film becomes irregular.
Cataracts
Clouding of the eye’s natural lens can cause blurry or hazy vision, reduced color vibrancy, and glare sensitivity. Cataracts often develop at different rates in each eye.
Ocular Migraines
These induce temporary visual disturbances, including blurriness, blind spots, or flashes of light, typically affecting one eye.
Glaucoma
This condition damages the optic nerve, often due to elevated eye pressure. It can cause peripheral vision loss and may progress to blurriness in one eye.
Retinal Issues
Conditions like macular degeneration (affecting central vision) or diabetic retinopathy (damaged retinal blood vessels) can lead to blurriness. A retinal detachment, an emergency where the retina pulls away, causes sudden blurriness with flashes of light or increased floaters.
Optic Nerve Problems
Conditions such as optic neuritis (inflammation) can cause blurriness, pain, and reduced color vision, typically affecting one eye.
Eye Infections and Corneal Issues
Infections, inflammation (like uveitis), or corneal problems such as abrasions or dystrophies can also lead to localized blurriness.
When to Seek Professional Help
Certain symptoms accompanying one-sided blurriness indicate a need for prompt professional evaluation by an eye care specialist. A sudden onset of blurriness in one eye, especially if it occurs without a clear explanation, warrants immediate attention. If the blurriness is accompanied by eye pain, redness, or any unusual discharge, it could signal an infection or inflammation that requires urgent treatment.
The appearance of flashes of light or a sudden increase in the number of floaters (small specks or cobwebs that drift across your vision) should also prompt an immediate visit to an eye doctor, as these can be signs of a retinal detachment. Experiencing a loss of peripheral vision, double vision, or blurriness that progressively worsens over time are also concerning symptoms. Additionally, if the blurriness develops after any form of eye injury, even a seemingly minor one, it is advisable to seek professional medical advice to rule out underlying damage.
Diagnosis and Management
When you consult an eye care professional for one-sided blurriness, they will conduct a comprehensive eye examination to determine the cause. This begins with a visual acuity test to measure vision sharpness in each eye. A slit-lamp examination allows the doctor to view the structures at the front of your eye, including the cornea, iris, and lens.
A dilated eye exam is often performed to get a clear view of the retina and optic nerve at the back of the eye, which can reveal conditions like macular degeneration or diabetic retinopathy. Tonometry, a test to measure intraocular pressure, screens for glaucoma. Additional specialized tests may be conducted, such as optical coherence tomography (OCT) for retinal imaging or visual field tests to assess peripheral vision.
Treatment approaches vary based on the underlying diagnosis. For refractive errors, corrective lenses such as glasses or contact lenses are prescribed. Dry eye syndrome is managed with lubricating eye drops, lifestyle adjustments, or prescription medications.
Eye infections or inflammation may require specific eye drops or oral medications. Conditions like cataracts or retinal detachments often necessitate surgical intervention. Glaucoma management typically involves eye drops to lower eye pressure, though laser procedures or surgery may be considered to prevent further optic nerve damage. Early detection and appropriate management are important for preserving vision and preventing complications.