Waking up to discover blurry vision in one eye can be an unsettling experience. While often temporary, this symptom can sometimes indicate a more significant underlying issue. Understanding the possibilities, from benign factors to serious medical conditions, helps determine the appropriate course of action.
Temporary Causes
One frequent cause is dry eyes, which can occur if tears evaporate during sleep, especially in dry environments or if the eyelids do not fully close. Blinking multiple times upon waking usually helps to remoisten the cornea and resolve the blurriness.
Pressure on the eye during sleep can also lead to temporary blurriness. Sleeping face down or with an arm pressing against the eye can temporarily distort the cornea, the clear front surface of the eye. This distortion typically corrects itself as the day progresses and the cornea regains its normal shape.
The presence of sleep crust or debris, which are dried secretions and foreign particles that accumulate overnight, can temporarily obstruct vision. A gentle rinse with artificial tears or saline solution can often clear this away. Mild eye strain from prolonged focus the previous day, such as from extensive screen use, can also manifest as slight blurriness upon waking.
Potential Medical Conditions
Ocular migraines, also known as retinal migraines, involve temporary visual disturbances in one eye, which can include blurry vision, blind spots, or flashing lights. These episodes typically last from 10 to 60 minutes and may precede or accompany a migraine headache.
Acute angle-closure glaucoma is a medical emergency where the pressure inside the eye suddenly and significantly increases. This can cause sudden blurred vision, severe eye pain, headache, nausea, and seeing halos around lights.
Retinal detachment occurs when the light-sensitive tissue at the back of the eye pulls away from its supporting layers. Symptoms often include a sudden increase in floaters (specks or cobwebs), flashes of light, and a dark “curtain” or shadow spreading across vision.
Inflammation of the optic nerve, known as optic neuritis, typically affects one eye and can cause blurred vision, dim vision, pain with eye movement, and colors appearing less vibrant. Corneal abrasions or infections, such as keratitis, can also lead to blurry vision, often accompanied by eye pain, redness, and a feeling of something being in the eye. In rare but serious instances, a transient ischemic attack (TIA) or stroke can cause sudden blurry vision in one eye due to temporary or permanent disruption of blood flow to the brain or eye.
Urgent Care Indicators
If the blurry vision is sudden and severe, or does not improve quickly, it warrants urgent evaluation. Severe eye pain, especially with eye movement, is a warning sign.
Additional red flags include flashes of light, an abrupt increase in floaters, or a shadow or “curtain” appearing in the field of vision, as these can indicate a retinal detachment. Neurological symptoms such as double vision, a sudden severe headache, weakness or numbness on one side of the body, difficulty speaking, or confusion alongside blurry vision suggest a possible TIA or stroke and require emergency care. Any recent eye injury or chemical exposure that results in blurry vision also necessitates immediate medical assessment.
Diagnosis and Evaluation
The healthcare provider will ask about the onset, duration, and nature of the blurriness, as well as any other accompanying symptoms and past medical conditions. This initial discussion helps narrow down the potential causes.
A comprehensive eye examination follows, which generally includes a visual acuity test to measure how well one sees at various distances. The eye doctor will also measure eye pressure, as elevated pressure can indicate conditions like glaucoma.
A slit-lamp examination allows the doctor to examine the front and internal structures of the eye, including the cornea, iris, and lens, in magnified detail. Depending on the initial findings, a dilated eye exam may be performed, where eye drops are used to widen the pupils, allowing for a better view of the retina and optic nerve at the back of the eye. Further specialized tests, such as optical coherence tomography (OCT) to image retinal layers, or visual field tests to detect blind spots, may be conducted to identify the underlying cause and guide appropriate treatment.