Blurry vision after waking is a common phenomenon that often improves within a few minutes. However, if the condition persists or recurs frequently, it could indicate an underlying eye condition or blood sugar imbalance, requiring examination.

Dry eyes after a night's sleep

Dry eyes are the most common cause of blurry vision upon waking. While sleeping, the eyes continue to produce tears to nourish and protect the cornea. However, tears can evaporate or be unevenly distributed, leading to a dry eye surface.

Immediately after waking, if the cornea is not adequately lubricated, vision may appear blurry, or individuals might experience a sensation of a foggy veil over their eyes. This condition typically subsides after a few blinks as tears are evenly redistributed across the corneal surface.

Sleeping under a fan or air conditioning

Direct airflow to the face for several hours can cause tears to evaporate faster, even with closed eyes. Individuals who sleep with a fan blowing directly on their face or regularly use air conditioning may wake up with dry, itchy, and temporarily blurry eyes.

A fan left on all night can cause dry eyes and blurry vision the next morning. *AI-generated image*.

Eye allergies or irritation

Individuals with allergies to dust, dust mites, pet dander, or chemicals in laundry detergents for bedding may wake up with red, itchy, watery, and blurry eyes. Allergic reactions irritate the eyes and reduce the quality of the tear film, leading to dry eyes and temporary vision reduction in the morning.

Sleeping face down or eyelid compression

Sleeping face down can exert prolonged pressure on the eyelids. This increases the risk of floppy eyelid syndrome, a condition where the eyelids lose elasticity, causing a gritty sensation, watery eyes, and blurry vision upon waking. This condition is more common in overweight or obese men.

Fuchs' corneal dystrophy

If blurry vision persists for several hours after waking and only gradually improves later in the day, the cause could be Fuchs' corneal dystrophy. This hereditary condition leads to corneal endothelial cells losing function, causing fluid to accumulate in the cornea during sleep. Mild corneal swelling results in blurry vision in the morning, which then improves as the fluid gradually evaporates throughout the day. The disease typically appears after age 50 and is more common in women than men.

Medication side effects

Some medications taken before sleep can reduce tear production, including antihistamines for allergies, sleeping pills, cold medications, and certain blood pressure medications. If eyes become dry throughout the night, users may wake up with a gritty sensation and blurry vision.

Sleeping with contact lenses

Sleeping without removing contact lenses reduces oxygen supply to the cornea, increasing the risk of dry eyes and irritation. Upon waking, users may experience blurry vision, red eyes, or discomfort. In the long term, this habit also increases the risk of corneal inflammation and eye infections.

Blood sugar imbalances

Blurry vision in the morning can also be linked to abnormally high or low blood sugar. High blood sugar causes the eye's lens to absorb more fluid, altering its shape and ability to focus light, leading to blurry vision. When blood sugar stabilizes, vision often improves.

If this condition occurs frequently, especially when accompanied by excessive thirst, dry mouth, frequent urination, fatigue, or foot numbness, individuals should have their blood sugar checked, as these could be early signs of diabetes. Conversely, very low blood sugar can also cause blurry vision, along with shaking hands, sweating, dizziness, and intense hunger.

Bao Bao (Compiled)