Oculoplastics, Orbit and Lacrimal System
Core concepts
Know eyelid anatomy (levator aponeurosis, Müller muscle, tarsus) and the causes of ptosis: aponeurotic (most common, involutional), myogenic (myasthenia), neurogenic (Horner, third nerve), mechanical, and congenital. Understand the orbital compartments and the red flags of orbital disease: proptosis, pain, motility restriction, and optic nerve compromise.
Learn the lacrimal system: tear production (main and accessory), drainage (punctum → canaliculus → sac → nasolacrimal duct), and the difference between watering due to hypersecretion vs obstruction. Know dacryocystitis (sac inflammation, often obstruction) and its management.
Traps
- Missing thyroid eye disease in bilateral proptosis with lid retraction.
- Confusing epiphora from obstruction with dry eye (reflex tearing).
- Overlooking orbital cellulitis vs preseptal cellulitis (motility and vision).
- Forgetting that ptosis can signal serious systemic disease (myasthenia, Horner).
Rule of thumb
Proptosis + pain + motility restriction = urgent orbital assessment; and epiphora needs a dye disappearance or syringing test to distinguish obstruction from hypersecretion.
Worked example
A patient with a painful, proptotic eye, restricted motility, and fever. This suggests orbital cellulitis; urgent imaging and IV antibiotics are indicated, with surgery if an abscess is present. Preseptal cellulitis would lack motility restriction and proptosis.