Palpebral fissures

The anatomic openings between the upper and lower eyelid margins that determine the visible portion of the globe. In healthy adults, the palpebral fissure measures approximately 10 mm vertically and 30 mm horizontally. Abnormal widening or narrowing may reflect neurological, muscular, endocrine, congenital, or craniofacial disorders.

Causes of vertical widening (increased palpebral fissure height)

• Graves' disease (thyroid eye disease)

• Facial nerve (cranial nerve VII) paralysis with lagophthalmos

• Cri-du-chat syndrome

• Eyelid retraction from sympathetic overactivity

• Proptosis (orbital tumors or inflammation)

Causes of vertical narrowing (decreased palpebral fissure height)

• Ptosis

• Blepharophimosis syndrome

• Trisomy 21 (Down syndrome)

• Marfan syndrome

• Noonan syndrome

• Fetal alcohol syndrome

• Oculomotor nerve (cranial nerve III) palsy

• Horner syndrome

• Myasthenia gravis

• Congenital ptosis

• Age-related aponeurotic ptosis

Causes of horizontal shortening (reduced palpebral fissure length)

• Blepharophimosis syndrome

• Congenital craniofacial syndromes

• Eyelid scarring or trauma

• Postsurgical eyelid shortening

Causes of horizontal widening (increased palpebral fissure length)

• Rare congenital craniofacial anomalies

• Traumatic eyelid disruption

• Reconstructive eyelid surgery or lateral canthotomy/cantholysis