Blepharospasm is a rare disorder, affecting approximately 20 to 50 people per million worldwide. It is more common in individuals over the age of 50 and is seen more frequently in women than men. The condition can occur sporadically or in association with other neurological disorders.

The exact cause of blepharospasm is not fully understood, but it is believed to result from dysfunction in the basal ganglia, a region of the brain involved in movement control. Potential contributing factors include:

• Genetic predisposition: Some cases run in families, suggesting a hereditary component.

• Abnormal neurotransmitter activity: Dysfunction in dopamine or other brain chemicals may play a role.

• Eye irritation or dryness: Chronic eye strain, dry eye syndrome, or photophobia (light sensitivity) may trigger or worsen symptoms.

• Stress and fatigue: Symptoms may worsen with emotional stress, lack of sleep, or prolonged use of screens.

• Other adult onset dystonias: development of other types of dystonia, such as in the neck and fingers, have been linked to cases of blepharospasm in the eyelids

Some genetic risk factors that are still being researched in relation to blepharospasm are mutations in the DRD5 gene and TOR1A gene.

The primary symptom of blepharospasm is involuntary eyelid closure due to muscle spasms, but other symptoms may include:

• Excessive blinking or twitching that worsens with fatigue or bright light.

• Involuntary eyelid closure that can make it difficult to keep the eyes open.

• Eye irritation, dryness, or burning sensation due to frequent blinking.

• Facial muscle involvement in some cases, leading to mild facial spasms.
  Symptoms usually start mildly and progressively worsen over time, potentially leading to severe visual impairment due to functional eyelid closure.

Blepharospasm is diagnosed based on clinical symptoms and a thorough neurological and ophthalmologic examination. There are no definitive laboratory tests, so diagnosis is based on the exclusion of other conditions, such as hemifacial spasm, Tourette syndrome, or myasthenia gravis.

• Clinical examination: A neurologist or ophthalmologist assesses the pattern of eyelid movements and triggers for spasms.

• Slit-lamp examination: Evaluates eye health to rule out underlying eye conditions like dry eye syndrome.

• Electromyography (EMG): In some cases, EMG testing of the facial muscles may be performed to assess muscle activity.

MRI or CT scan: Brain imaging may be used to exclude other neurological disorders, particularly if symptoms are atypical.

While there is no cure for blepharospasm, various treatment options can help manage symptoms:

• Botulinum toxin (Botox) injections: The most effective and widely used treatment, botulinum toxin temporarily weakens the muscles responsible for eyelid spasms, providing symptom relief for several months at a time.

• Medications: Some individuals may benefit from muscle relaxants (baclofen), dopamine-modulating drugs, or anticonvulsants (clonazepam) to reduce symptoms.

• Surgery: In severe cases, myectomy (removal of some eyelid muscles) may be performed to reduce spasms.

• Lifestyle modifications: Avoiding bright lights, managing stress, and using lubricating eye drops can help alleviate symptoms.

The prognosis for individuals with blepharospasm varies. While the condition is not life-threatening, it can significantly impact daily life, particularly if left untreated. With regular botulinum toxin injections and other therapies, most patients can achieve good symptom control. However, in some cases, the condition may progress and become more severe over time, requiring ongoing treatment and lifestyle adjustments.

1. Medline Plus - Benign essential blepharospasm

2. Brain Foundation - Blepharospasm

3. EyeWiki - Blepharospasm

4. Cleveland Clinic - Blepharospasm

5. Yale Medicine - Blepharospasm