Ophthalmology
Lids, Adnexa and Orbit
Lids and orbit for MBBS and NEET-PG: stye, chalazion, ptosis, dacryocystitis, preseptal versus orbital cellulitis, proptosis and orbital tumours, mapped to NMC codes OP2.
MedNext Academy | 3 min read
Lids, Adnexa and Orbit
Lids and orbit for MBBS and NEET-PG: stye, chalazion, ptosis, dacryocystitis, preseptal versus orbital cellulitis, proptosis and orbital tumours, mapped to NMC codes OP2.
This chapter covers the common disorders of the eyelids, the lacrimal drainage system and the orbit, from the everyday stye and chalazion to the sight-threatening emergencies. It emphasises separating preseptal from orbital cellulitis, the red flags of an orbital process, and the ordered assessment of proptosis and orbital tumours.
High-yield: Lids, Adnexa and Orbit
- A stye (external hordeolum) is an acute staphylococcal abscess of a lash follicle and its glands, treated with warm compresses and epilation of the affected lash.
- A chalazion is a chronic, painless, granulomatous swelling from a blocked meibomian gland and is treated by incision and curettage if it persists.
- Blepharitis is chronic inflammation of the lid margin, associated with seborrhoea and meibomian gland dysfunction, and is managed with lid hygiene.
- Entropion is inward turning of the lid margin, causing the lashes to abrade the cornea, while ectropion is outward turning that exposes the conjunctiva and causes watering.
- Ptosis is drooping of the upper lid; a congenital cause is levator dystrophy, and an acquired painful ptosis with a dilated pupil suggests a third nerve palsy.
- Dacryocystitis is infection of the lacrimal sac, presenting as a painful swelling below and medial to the medial canthus with regurgitation of pus on pressure.
- The regurgitation test and syringing localise the site of a nasolacrimal duct block in a watering eye.
- Preseptal cellulitis is anterior to the orbital septum and spares eye movement and vision, whereas orbital (postseptal) cellulitis threatens sight.
- The red flags of orbital cellulitis are proptosis, painful or restricted eye movements, reduced vision, a relative afferent pupillary defect and chemosis, and it is a medical emergency needing admission and intravenous antibiotics.
- Orbital cellulitis most often spreads from ethmoid sinusitis and can extend to cavernous sinus thrombosis.
- Cavernous sinus thrombosis is suggested by bilateral eye signs, involvement of cranial nerves III, IV, V1, V2 and VI, and rapidly worsening systemic illness.
- Proptosis is forward protrusion of the globe; the commonest cause in adults is thyroid eye disease and in children is orbital cellulitis.
- Thyroid eye disease features lid retraction, lid lag, proptosis and, in severe cases, optic nerve compression at the orbital apex.
- Any proptosis with reduced vision, colour desaturation, a relative afferent pupillary defect or severe pain is a sight-threatening emergency requiring urgent imaging and referral.
Preseptal versus orbital cellulitis
- **Site:** Preseptal lies anterior to the orbital septum; orbital lies behind it.
- **Eye movements:** Normal and painless in preseptal; restricted and painful in orbital.
- **Vision and proptosis:** Preserved in preseptal; reduced vision, proptosis and RAPD in orbital.
- **Management:** Preseptal often oral antibiotics; orbital needs admission, IV antibiotics and imaging.
NMC competencies in this chapter
- **OP2.1:** Common lid and adnexal disorders
- **OP2.2:** Symptoms and clinical signs of lid and adnexal disease
- **OP2.3:** Supervised lid and lacrimal procedures
- **OP2.4:** Orbital cellulitis: recognition and management
- **OP2.5:** Cavernous sinus thrombosis
- **OP2.6:** Proptosis: assessment and causes
- **OP2.7:** Orbital tumours
- **OP2.8:** Orbital tumour investigations and referral
Frequently Asked Questions
How do you tell a stye from a chalazion?
A stye is an acute, painful, red swelling at the lid margin from an infected lash follicle. A chalazion is a chronic, painless, firm lump within the tarsal plate from a blocked meibomian gland.
Why is orbital cellulitis an emergency?
It lies behind the orbital septum and can compress the optic nerve, cause proptosis and restricted movements, and spread to cavernous sinus thrombosis or the brain. It needs admission and intravenous antibiotics.
What is the commonest cause of proptosis in adults?
Thyroid eye disease is the commonest cause of unilateral and bilateral proptosis in adults. In children, orbital cellulitis is the leading cause.
What is dacryocystitis?
It is infection of the lacrimal sac, usually from a blocked nasolacrimal duct, presenting as a painful swelling below the medial canthus with regurgitation of pus on pressure over the sac.
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