This refers to an involuntary spasmodic contraction of the orbicularis oculi muscle supplied by the facial nerve.
Etiology: In addition to photosensitivity and increased tear production, blepharospasm will also accompany inflammation or irritation of the anterior chamber. (Photosensitivity, epiphora, and blepharospasm form a triad of reactive clinical symptoms.) Causes of the disorder include extrapyramidal disease such as encephalitis or multiple sclerosis. Trigeminal neuralgia or psy-chogenic causes may also be present.
Symptoms: Clinical symptoms include spasmodically narrowed or closed palpebral fissures and lowered eyebrows.
Treatment: This depends on the cause of the disorder. Mild cases can be controlled well with muscle relaxants. Severe cases may require transection of the fibers of the facial nerve supplying the orbicularis oculi muscle. The disorder may also be successfully treated with repeated local injections of botulinum toxin.
Prognosis: The prognosis is good where a cause-related treatment is possible. Essential blepharospasm does not respond well to treatment.
2.5 Disorders of the Skin and Margin of the Eyelid 2.5.1 Contact Eczema
Epidemiology: Light-skinned patients and patients susceptible to allergy are frequently affected.
Etiology: Contact eczema is caused by an antigen - antibody reaction in patients with intolerance to certain noxious substances. Cosmetics, adhesive bandages, or eyedrops and eye ointments are often responsible, particularly the preservatives used in them such as benzalkonium chloride.
2.5 Disorders of the Skin and Margin of the Eyelid Contact eczema. -
Fig. 2.10 This disorder is frequently caused by preservatives such as those used in eyedrops. They cause typical reddening, swelling, and lichenifica-tion of the skin of the eyelid.
Symptoms: Reddening, swelling, lichenification, and severe itching of the skin of the eyelid occur initially, followed by scaling of the indurated skin with a sensation of tension (Fig. 2.10).
Prognosis: The prognosis is good if the cause can be identified.
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