Does Bell’s Palsy Cause Blurred Vision?

Bell’s palsy does not directly blur your vision the way a problem with the optic nerve or the eye’s lens would. Instead, it causes blurred vision indirectly, by paralyzing the muscles that close the eyelid on the affected side. When you cannot fully blink or shut your eye, the cornea dries out, the tear film becomes unstable, and the resulting irritation and surface damage produce blurry, uncomfortable vision. For some people the blur is mild and temporary; for others, especially when treatment is delayed, it can lead to corneal scarring and lasting visual impairment.

Why Bell’s Palsy Affects the Eye at All

Bell’s palsy is a sudden weakness or paralysis of the facial nerve (cranial nerve VII), which controls the muscles of facial expression on one side. One of those muscles is the orbicularis oculi, the ring-shaped muscle responsible for closing the eyelid. When that muscle stops working, the upper lid hangs partially open even when you try to blink or sleep. This condition, called lagophthalmos, is the leading cause of eye problems after Bell’s palsy. In fact, Bell’s palsy is the most common cause of paralytic lagophthalmos overall.¹

You may not realize how much work a normal blink does. Each blink spreads a thin film of tears across the cornea, delivers oxygen and nutrients, and sweeps away debris. When the lid cannot close fully, the exposed strip of cornea dries out within minutes. The reflex to blink is still firing, but the mechanical action is gone or weakened. Over hours and days, the corneal surface breaks down, and that is when vision starts to blur.

The Tear Film Breaks Down on the Affected Side

Research comparing the two eyes in people with one-sided facial palsy shows clear differences in tear quality and gland health. In one study, the affected eye had a significantly lower tear meniscus height and markedly more Meibomian gland loss than the unaffected eye. The upper eyelid Meibomian glands had lost roughly 30% of their tissue on the paralyzed side, and the lower glands had lost about 44%.² The worse the paralysis (measured on a standard grading scale), the more severe the gland damage, with a strong correlation between the two.

Meibomian glands produce the oily outer layer of the tear film, which keeps tears from evaporating too quickly. When those glands atrophy, the tear film becomes unstable and breaks apart between blinks. This is essentially the same mechanism behind ordinary dry eye disease, but amplified by the fact that the lid is not blinking properly either. The combination of poor tear quality and poor lid closure is why the eye feels gritty, waters paradoxically, and sees poorly.

Exposure Keratitis and the Risk of Real Damage

When the cornea stays exposed for long enough, it develops small epithelial defects: tiny breaks in the outermost layer. This is called exposure keratitis, and it is where blurred vision becomes more than an annoyance. A clinical review of facial nerve palsy patients found corneal epithelial defects in 20 out of the affected eyes examined, along with conjunctival redness in 19 and lagophthalmos in 24.³ These findings show that corneal damage is common, not rare, among people whose facial nerve is not working.

In more severe cases, exposure keratitis progresses to corneal ulceration, infection, or scarring. A case report described a patient with bilateral facial palsy who developed exposure keratitis in both eyes, causing constant tearing, pain, and blurred vision.⁴ Once scarring sets in, the blur does not resolve even after the nerve recovers, because the cornea itself has been permanently changed. This is the scenario doctors are trying to prevent from the first day of diagnosis.

How to Protect Your Eye During Bell’s Palsy

Eye protection starts immediately, even before anyone knows whether the palsy will resolve on its own. The standard first-line approach is aggressive lubrication. Artificial tears during the day and a thicker lubricating ointment at night are the interventions used most widely and for the longest duration. In a survey of facial nerve palsy patients, artificial tears and lubricating ointment were the most commonly used treatments and were rated highest for overall satisfaction. Patients reported that lubrication relieved dry eye symptoms and improved comfort outdoors.⁵ There is an ironic catch, though: both artificial tears and ointment can themselves cause temporary blurred vision, especially the ointment, which smears across the cornea and takes time to clear.

Taping the eyelid shut at night is another simple measure. A small strip of surgical tape holds the lid down while you sleep, preventing the cornea from drying out during the hours when you are not consciously protecting it. Moisture-retaining eye shields serve the same purpose and may feel more comfortable.

When the paralysis does not resolve quickly, or when the lagophthalmos is severe, doctors move to more durable solutions:

Gold weight implants: A small gold or platinum weight is surgically placed inside the upper eyelid. Gravity helps the lid close when the muscle cannot. Studies have shown this to be a simple and effective method for restoring eyelid closure.⁶ The weight is designed to be subtle enough that it does not noticeably change the eyelid’s appearance when the eye is open.⁷
Tarsorrhaphy: The outer edges of the upper and lower eyelids are partially stitched together, narrowing the opening. This reduces the exposed corneal area. It is effective but cosmetically noticeable, so it tends to be reserved for more urgent situations or as a temporary bridge to a longer-term fix.
Scleral contact lenses: Large-diameter lenses that vault over the entire cornea, trapping a reservoir of fluid against the eye’s surface. They keep the cornea constantly hydrated even when the lid is open and have been used successfully in cases of bilateral facial palsy where exposure keratitis was already causing pain and blurred vision.⁴
Botulinum toxin injection: Used in some cases to induce a temporary protective drooping of the upper lid (a controlled ptosis), keeping the eye covered while the nerve heals.

The choice among these depends on how complete the paralysis is, whether the cornea is already damaged, and how likely the nerve is to recover on its own. Most Bell’s palsy cases improve within weeks to months, so many people only need lubrication and taping. The surgical options are typically reserved for severe or prolonged cases.

Children Face Higher Stakes

Facial nerve palsy in children deserves separate attention because the visual consequences can be more serious and harder to detect. A study of 112 children with facial nerve palsy found that about one in five had moderate-to-severe visual impairment. Corneal scarring and strabismic amblyopia (where misaligned eyes cause one eye’s vision to weaken during development) were both frequent causes of that impairment.⁸

Children who had multiple cranial nerves affected, not just the facial nerve, were at even higher risk. Visual impairment was present in about 31% of eyes when multiple cranial nerves were involved, compared with 14% when only the facial nerve was affected.⁸ Young children cannot always articulate that their vision is blurry, and amblyopia specifically develops silently during the years when the visual system is still maturing. If a child develops Bell’s palsy, early and repeated eye exams are critical to catch problems before permanent vision loss sets in.

When the Palsy Involves More Than Just the Facial Nerve

Bell’s palsy, strictly defined, is an isolated paralysis of cranial nerve VII with no identifiable cause. But when a patient shows up with a drooping face and eye complaints, doctors need to check whether other cranial nerves are also involved, because that changes the diagnosis and the visual risks significantly. Bell’s palsy is an isolated mononeuropathy, and when other cranial nerve palsies are present, the examiner should look for other causes.⁹

The clinical review mentioned earlier found that paralytic strabismus (misaligned eyes causing double vision) occurred in patients who had palsy of the third, fifth, or sixth cranial nerve alongside the seventh.³ So if you are experiencing not just a drooping face and blurry vision but also double vision, eye movement problems, or numbness on one side of your face, the cause may be something other than Bell’s palsy, such as a stroke, a brain tumor, or an infection. Lyme disease, for instance, can cause facial palsy along with a range of other ocular problems including uveitis, episcleritis, and palsies of the nerve that controls side-to-side eye movement.¹⁰ The eye symptoms of these conditions overlap with Bell’s palsy, but the treatment and urgency are very different.

Eye Problems That Linger After the Nerve Recovers

Most people with Bell’s palsy recover good facial nerve function, but “recovered” does not always mean “back to normal.” As the nerve regrows, its fibers sometimes take wrong turns and reconnect to the wrong muscles or glands. This miswiring produces two distinctive long-term problems that affect the eye.

The first is facial synkinesis: involuntary co-contractions of facial muscles. The most common form is the eye narrowing or closing when you try to smile, purse your lips, or blow. The reverse also occurs, where the cheek twitches when you blink.¹¹ Synkinesis can make the eye feel tight or fatigued and can interfere with vision if the involuntary squinting is frequent. It is managed with physical therapy, botulinum toxin injections to selectively weaken the overactive muscles, and in some cases surgery.

The second is crocodile tears syndrome, where nerve fibers that were supposed to reconnect to the salivary glands instead reach the lacrimal (tear) gland. The result is that your eye waters heavily whenever you eat or even think about food. It usually shows up months after the initial palsy, once the nerve has had time to regrow.¹² The excessive tearing can itself cause intermittent blurred vision, since tears pooling over the cornea distort the light entering the eye. Botulinum toxin injected into the lacrimal gland has been used to reduce the overflow.

Why “Blurred Vision” Sometimes Gets Overlooked

One reason blurred vision from Bell’s palsy catches people off guard is that the facial droop dominates the picture. When half your face suddenly stops working, the cosmetic and functional impact on speaking, eating, and expressing emotion tends to command all the attention, both yours and your doctor’s. The eye symptoms creep in more gradually, starting as mild dryness or a foreign-body sensation and only progressing to noticeable blur over days or weeks.

There is also the fact that Bell’s palsy is usually managed by neurologists or emergency physicians, not ophthalmologists. The standard treatment focuses on the nerve itself: a short course of corticosteroids, sometimes antivirals, and reassurance that most cases resolve. Eye care sometimes amounts to a brief instruction to use artificial tears. The patient survey on ophthalmic management of facial nerve paralysis hinted at this gap: while lubrication worked well for comfort, patients also reported that ointment made their eye look “moist and shiny,” drawing unwanted social attention, and that both ointment and artificial tears caused blurred vision on their own.⁵ In other words, the very treatments meant to protect the eye come with a visual trade-off that nobody warns you about.

If you develop Bell’s palsy and notice your vision getting hazy, stingy, or watery on the affected side, it is worth asking specifically for an ophthalmic evaluation. The corneal surface can deteriorate quickly, and early intervention with aggressive lubrication, nighttime taping, or a referral to an ophthalmologist for a scleral lens or eyelid weight can make the difference between temporary discomfort and permanent scarring. The nerve usually heals on its own. The cornea, once scarred, does not.

1
PubMed. Lagophthalmos
2
PubMed Central. Epidemiology, Tear Film, and Meibomian Gland Dysfunction in Facial Palsy: A Comparative Analysis
3
Korean Journal of Ophthalmology. Ophthalmologic Clinical Features of Facial Nerve Palsy Patients
4
PubMed Central. A non-surgical approach to the management of exposure keratitis due to facial palsy by using mini-scleral lenses
5
BMJ Open. Patients’ perspectives of ophthalmic management of facial nerve paralysis
6
PubMed. Gold weight implantation and lateral tarsorrhaphy for upper eyelid paralysis
7
PubMed. Gold weight implants in the management of paralytic lagophthalmos
8
PubMed. Characteristics of facial nerve palsy in 112 children and risk factors for ocular complications
9
Saudi Journal of Ophthalmology. Neuro-ophthalmological approach to facial nerve palsy
10
PubMed. The expanding clinical spectrum of ocular lyme borreliosis
11
PubMed Central. Pathogenesis, diagnosis and therapy of facial synkinesis: A systematic review and clinical practice recommendations by the international head and neck scientific group
12
PubMed Central. Injection of Botulinum Toxin A in the Lacrimal Gland for Treatment of Epiphora in Crocodile Tears Syndrome – A Case Report