Cause of enophthalmos in Horner's syndrome
- In Horner’s syndrome, enophthalmos is apparent, not real
- It cannot be demonstrated using an exophthalmometer
- Mechanism:
- The underlying cause is damage to sympathetic nerves (cervical sympathetic trunk or central sympathetic pathway)
- The upper lid drops down (ptosis) – due to paralysis of muller’s muscle (a part of levator palpebrae superioris)
- Lower lid is pulled up – due to paralysis of smooth muscle responsible for retraction of lower lid
- This causes narrowing of palpebral fissure causing an apparent enophthalmos
