OP2.1-8 | Lids, Adnexa and Orbit — Glossary

Commonest malignant lacrimal gland tumour; characterised by pain (perineural invasion), bone erosion, and poor prognosis.

Staging system for lymphoma; Stage IE = single extranodal site (e.g. orbit), no systemic disease; guides treatment allocation (radiotherapy vs systemic chemotherapy).

Common tendinous ring at the orbital apex from which all four rectus muscles originate; encircles the optic canal; swollen rectus muscles at this location cause compressive optic neuropathy in both TED and orbital cellulitis.

Enlargement of the rectus muscle bellies at the orbital apex that compresses the optic nerve within the tight annulus of Zinn; the mechanism of compressive optic neuropathy in TED, which can occur even without extreme proptosis.

Commonest type of acquired ptosis in adults; caused by dehiscence or disinsertion of the levator aponeurosis from the tarsus; characterised by good levator function and a high or absent lid crease.

Forward displacement of the globe along the orbital axis with no lateral or vertical component; characteristic of intraconal lesions.

Physiological reflex upward and outward rotation of the globe on attempted eyelid closure; protects the corneal visual axis from exposure in lagophthalmos, but the inferior cornea remains vulnerable.

Area of black necrotic tissue seen on the nasal mucosa or hard palate in Mucormycosis, resulting from angioinvasion and tissue infarction; a pathognomonic warning sign requiring emergency surgical assessment.

Chronic bilateral inflammation of the eyelid margins; anterior subtypes = staphylococcal (hard collarettes, madarosis) and seborrhoeic (soft greasy scales); posterior = meibomian gland dysfunction (MGD).

Irregular destruction of the bony orbital wall on CT; hallmark of an aggressive or malignant orbital tumour (rhabdomyosarcoma, adenoid cystic carcinoma, metastasis).

Smooth expansion of bony contours without cortical destruction; the CT hallmark of a slow-growing benign orbital tumour (cavernous haemangioma, pleomorphic adenoma, mucocele).

The commonest orbital vascular tumour of infancy; enlarges with Valsalva; spontaneously involutes by age 7–10; treated with oral propranolol if vision-threatening.

Commonest benign primary orbital tumour in adults; slow-growing, well-encapsulated, intraconal; characteristic progressive fill-in enhancement on MRI gadolinium.

Paired venous lake at the base of the skull, lateral to the sella turcica; contains CN III, IV, V1, V2 in its lateral wall and CN VI and the internal carotid artery in its lumen; connected to its counterpart via intercavernous sinuses.

Septic thrombosis of the cavernous sinus from orbital cellulitis via valveless ophthalmic veins; presents with bilateral proptosis, bilateral ophthalmoplegia, high fever, and meningism; Chandler Stage V; covered in detail in OP2.5.

Chronic, painless lipogranulomatous cyst of a meibomian gland caused by obstruction without infection; treated with warm compresses, steroid injection, or curettage.

Five-stage system for orbital infection: Stage I = preseptal oedema; Stage II = orbital cellulitis; Stage III = subperiosteal abscess; Stage IV = orbital abscess; Stage V = cavernous sinus thrombosis.

A 7-point scoring system for TED activity: 1 point each for retrobulbar pain at rest, pain on movement, eyelid erythema, eyelid oedema, conjunctival erythema, chemosis, caruncle oedema. CAS ≥3/7 = active disease.

Paralysis of the oculomotor nerve; produces ptosis, fixed dilated pupil (mydriasis from loss of pupilloconstrictor supply), and 'down and out' deviation (from unopposed lateral rectus and superior oblique action).

Paralysis of the lateral rectus muscle; produces esotropia (medial squint) and inability to abduct the eye past the midline; the first CN to be affected in CST because CN VI runs through the sinus lumen in direct contact with the venous blood.

Hard, fibrinous crusts tightly adherent to the bases of eyelashes; pathognomonic of staphylococcal anterior blepharitis; bleed on removal.

Compression of the optic nerve at the orbital apex by enlarged extraocular muscles in TED; presents with reduced VA, colour desaturation, RAPD, and visual field defects; requires emergency IVMP and orbital decompression.

Persistence of Hasner's membrane at the lower end of the nasolacrimal duct causing epiphora and mucopurulent discharge from birth; resolves spontaneously in 90% within 12 months; treated with Crigler's massage then probing.

Thrombosis of the dural venous sinuses (sagittal, transverse, or sigmoid) as a complication of CST spread; produces venous infarcts, haemorrhage, raised ICP, and seizures.

Occlusion of the central retinal artery, causing sudden painless vision loss in the affected eye; a rare but devastating complication of orbital cellulitis from pressure on or thrombosis of the artery.

Lacrimal sac massage technique for CNLDO; firm downward pressure applied over the lacrimal sac fossa to build hydrostatic pressure and rupture Hasner's membrane; performed 4–6 times daily.

Occlusion of the central retinal vein causing sudden painless vision loss, disc oedema, dilated tortuous veins, and flame haemorrhages throughout all four quadrants; can complicate CST from venous congestion.

Application of a cryoprobe (−20°C) to the lid margin to ablate lash follicles over a section; useful for multiple adjacent trichiatic lashes; risks depigmentation and lid notching in dark-skinned patients.

Upper lid retraction in TED causing a visible strip of sclera between the upper lid margin and the superior corneal limbus in primary gaze, producing the characteristic 'staring' appearance.

Area bounded by the upper lip and nose; its venous drainage communicates with the ophthalmic veins and thence with the cavernous sinus via the facial and angular veins; squeezing boils in this area risks propagating infected thrombus to the cavernous sinus.

Congenital choristoma occurring at cranial suture lines (typically frontozygomatic); contains dermis-derived elements (hair, keratin, sebum); rupture causes intense orbital inflammation.

Forward proptosis accompanied by lateral or vertical displacement of the globe; characteristic of extraconal lesions pushing the globe away from the mass.

Outward eversion of the eyelid margin away from the globe; subtypes include involutional (commonest), cicatricial, paralytic, and mechanical; causes epiphora and exposure conjunctivitis.

Permanent ablation of individual lash follicles using a fine radiofrequency needle electrode inserted alongside the follicle; used for permanent eyelash removal in trichiasis.

Surgical removal of a tumour as a single intact specimen without opening or breaching the tumour capsule; the required technique for lacrimal gland pleomorphic adenoma.

Inward inversion of the eyelid margin causing lashes to rub the cornea; subtypes: involutional, cicatricial (trachoma commonest cause), and spastic; leads to punctate keratopathy and corneal ulceration if untreated.

Mechanical extraction of individual aberrant eyelashes using epilating forceps under slit-lamp magnification; effective but temporary (lashes regrow in 4–6 weeks), requiring repeat treatment.

Inward (medial) squint of one or both eyes; in CST produced by CN VI (lateral rectus) palsy, so the eye is adducted at rest and cannot abduct.

European Group on Graves' Orbitopathy; provides classification and management guidelines for thyroid eye disease severity and activity.

European Group on Graves' Orbitopathy severity classification for TED: mild (no visual threat, limited QoL impact), moderate-severe (significant QoL impact, no visual threat), sight-threatening (compressive optic neuropathy or corneal breakdown).

Term used specifically for thyroid eye disease-related proptosis in older literature; in current usage interchangeable with proptosis.

The orbital space outside the muscle cone, between the cone and the bony orbital walls; divided by position into superior, inferior, medial, and lateral compartments.

Surgical resection of the upper tarsus and Müller's muscle to correct mild ptosis with fair levator function (5–11 mm) and MRD-1 of approximately 2 mm; performed from the conjunctival surface.

Mydriasis from CN III palsy due to loss of pupilloconstrictor fibres; the parasympathetic fibres to the pupil run on the outer surface of CN III and are compressed early by inflammation or herniation.

Surgical suspension of the upper lid from the frontalis muscle using autologous fascia lata or silicone rod; indicated in ptosis with poor levator function (<4 mm); the brow elevation mechanism opens the lid.

Minimally invasive endoscopic surgery to open and drain the paranasal sinuses; used in orbital cellulitis management to address the primary sinusitis source and drain medial subperiosteal abscesses endoscopically.

Instrument for measuring the forward protrusion of the globe using the lateral orbital rim as the reference; records measurements in millimetres.

Acute purulent infection of the glands of Zeis or Moll at the anterior eyelid margin (stye); presents as a painful red nodule at the lash base pointing externally.

Acute suppurative infection of a meibomian gland within the tarsal plate; more severe than externum, typically points to the palpebral conjunctival surface on eversion.

Triad of partial ptosis (Müller's muscle loss), miosis (pupil constriction), and anhidrosis; results from damage to the sympathetic plexus surrounding the internal carotid artery; can occur in CST from ICA involvement.

Venous connections between the right and left cavernous sinuses running anterior and posterior to the pituitary; allow infected thrombus to propagate to the contralateral side, causing the bilateral signs pathognomonic of CST.

The space within the muscle cone formed by the four rectus muscles; contains the optic nerve, ciliary structures, and associated orbital fat.

First-line immunosuppressive treatment for moderate-severe active TED; given as IV infusions (EUGOGO protocol: 12 weekly doses totalling 4.5 g); preferred over oral prednisolone for efficacy and side-effect profile.

Clinical sign of meningeal irritation: the patient is unable to extend the knee beyond 90° when the hip is flexed at 90°, due to pain from meningeal inflammation; positive in meningitis and CST with meningeal involvement.

Commonest benign lacrimal gland tumour; presents with slowly progressive superolateral orbital mass; incisional biopsy is contraindicated due to seeding risk.

Incomplete closure of the eyelids, exposing the cornea to desiccation; commonest cause is facial nerve palsy; managed with lubricants and, if permanent, gold weight implant.

The thin medial orbital wall (lateral wall of the ethmoid sinus); may have natural dehiscences; the primary route by which ethmoid sinusitis spreads into the orbit to cause medial subperiosteal abscess.

A surgical procedure for involutional ectropion: the lateral lid margin is disinserted and reattached to the periosteum of the lateral orbital rim to tighten horizontal laxity.

Excursion of the upper lid in millimetres from full downgaze to full upgaze with the brow neutralised by thumb pressure to exclude frontalis contribution; normal ≥15 mm; poor <4 mm, fair 5–11 mm, good ≥12 mm.

Antifungal agent of choice for Mucormycosis; given IV at 3–5 mg/kg/day; the liposomal formulation reduces nephrotoxicity compared to conventional amphotericin B.

Vascular malformation of lymphatic channels in the orbit; presents in childhood; may show acute haemorrhage into cyst (chocolate cyst) following viral illness, causing rapid proptosis.

Loss of eyelashes; a complication of chronic staphylococcal blepharitis, as well as leprosy and alopecia areata.

Mucosa-associated lymphoid tissue lymphoma; the commonest type of orbital lymphoma; low-grade B-cell; presents as salmon-patch subconjunctival mass; highly radiosensitive (30 Gy).

Obstruction and altered secretion of meibomian glands causing evaporative dry eye and posterior blepharitis; managed with warm compresses, lid scrubs, and oral doxycycline in severe cases.

Distance in millimetres from the corneal light reflex to the upper lid margin in primary gaze; normal = 4–5 mm; reduced in ptosis (mild = 3 mm, moderate = 2 mm, severe ≤1 mm).

Expansion of a paranasal sinus by retained mucus following ostial obstruction; commonly frontoethmoidal; produces eccentric proptosis with downward or lateral globe displacement.

Invasive fungal infection caused by Mucor/Rhizopus species; affects immunocompromised patients (diabetics, haematological malignancy, post-COVID); presents with black eschar of nasal/palatal mucosa; requires urgent surgical debridement and IV liposomal amphotericin B.

Sympathetically innervated smooth muscle running from the undersurface of the levator to the superior tarsal border; contributes approximately 2 mm of upper lid elevation; its loss in Horner syndrome causes mild ptosis.

Malignant tumour of neural crest origin arising from the adrenal medulla or sympathetic ganglia; metastasises to the orbit in children, producing bilateral periorbital bruising ('panda eyes').

Autosomal dominant disorder (chromosome 17q) associated with optic nerve gliomas, plexiform neurofibromas, Lisch nodules, and café-au-lait spots.

Werner classification mnemonic for TED severity: No signs, Only signs, Soft tissue, Proptosis, Extraocular muscles, Cornea, Sight loss.

Superior and inferior ophthalmic veins drain the orbit and connect posteriorly to the cavernous sinus without valves; the valveless nature allows retrograde spread of septic thrombus from orbital cellulitis to cavernous sinus.

Intraconal tumour of the optic nerve, predominantly in childhood; associated with neurofibromatosis type 1 in 30–50% of cases; causes axial proptosis and visual loss.

Meningioma arising from the arachnoid sheath of the optic nerve; causes visual loss disproportionate to proptosis; identified by optociliary shunt vessels and tram-track enhancement on MRI.

Retinociliary collateral veins at the disc margin that develop in response to chronic central retinal vein obstruction by an optic nerve sheath meningioma; pathognomonic of chronic optic nerve sheath compression.

Collection of pus within the orbital fat itself (intraconal or extraconal); Chandler Stage IV; characterised by severe proptosis, total EOM restriction, and reduced VA; requires urgent surgical drainage.

Acute bacterial infection of the orbital soft tissues posterior to the orbital septum, characterised by proptosis, restricted and painful EOM, and possible vision reduction; a sight- and life-threatening emergency.

Surgical removal of one or more orbital walls (typically medial and inferior) to enlarge the bony orbit and allow displaced orbital contents to herniate into adjacent sinuses, reducing proptosis and relieving apical crowding.

Fibrous fascial sheet extending from the periosteum of the orbital rim to insert into the tarsal plate; separates the preseptal space anteriorly from the orbital space posteriorly.

Venous malformation of the orbit that dramatically engorges with Valsalva, causing positional proptosis; managed with observation unless symptomatic or progressive.

Bilateral optic disc swelling from raised intracranial pressure; seen in CST as a fundoscopic finding; may cause transient visual obscurations; chronic papilloedema leads to optic atrophy and permanent vision loss.

Commonest benign lacrimal gland tumour; characterised by S-shaped ptosis and bone remodelling on CT; incisional biopsy is absolutely contraindicated.

Infection of the eyelid soft tissues anterior to the orbital septum; NO proptosis, full painless EOM, normal vision; treated with oral antibiotics; Chandler Stage I.

Acute bacterial infection of eyelid soft tissues anterior to the orbital septum; NO proptosis, full painless EOM, normal vision; managed with oral antibiotics.

Non-selective β-blocker; first-line systemic treatment for vision-threatening capillary haemangioma of infancy; causes vasoconstriction and reduced VEGF expression in haemangioma endothelium.

Abnormal forward displacement of the eyeball within the orbit; synonymous with exophthalmos when caused by thyroid disease.

Forward displacement of the globe from the orbit; in TED it is axial and bilateral (often asymmetric); measured by Hertel exophthalmometer (normal <21 mm Caucasian, <20 mm Asian).

Apparent forward displacement of the globe without true proptosis on Hertel measurement; caused by contralateral enophthalmos, ipsilateral lid retraction, high myopia, or buphthalmos.

Proptosis with a pulsation synchronous with the heartbeat; suggests an arteriovenous communication (carotid-cavernous fistula) or bony defect transmitting CSF pulsations (encephalocele).

Pupillary sign detected by the swinging flashlight test; paradoxical dilation of the pupil when light is swung from the normal to the affected eye, indicating reduced afferent (optic nerve) signal; present in compressive optic neuropathy.

Commonest primary orbital malignancy in children; rapidly progressive extraconal proptosis; requires urgent biopsy and paediatric oncology referral.

Breast metastasis with a fibrotic desmoplastic reaction that contracts the orbit, causing enophthalmos (sunken eye) rather than proptosis — a diagnostically important exception to the rule that metastases cause proptosis.

Antioxidant micronutrient used as first-line treatment for mild active TED; 200 mcg/day for 6 months; reduces CAS, soft tissue inflammation, and risk of progression per EUGOGO Grade A evidence.

Drainage or removal of the primary infectious focus that caused CST — dental extraction, abscess drainage, sinus surgery — to prevent ongoing bacteraemia reseeding the cavernous sinus thrombus.

Collection of pus between the periorbita and the orbital bone wall, most commonly located medially (from ethmoid sinusitis); Stage III of Chandler; CT shows a crescent-shaped hypodense collection with rim enhancement.

Characteristic CT/MRI finding in TED where the extraocular muscle belly is enlarged but the tendon insertion is normal; distinguishes TED from orbital myositis, in which both muscle and tendon are enlarged.

Autoimmune orbital disorder associated with Graves' disease, caused by TSH receptor antibodies (TRAb) stimulating orbital fibroblasts; characterised by proptosis, lid retraction, EOM restriction, and risk of compressive optic neuropathy.

Autoantibodies directed against the TSH receptor; causally linked to Graves' hyperthyroidism and TED; levels correlate with TED activity and risk of progression.

Inward misdirection of otherwise normally situated eyelashes without lid inversion; causes corneal epithelial erosion; distinguished from entropion where the whole lid margin turns inward.

Autoantibodies against the TSH receptor that drive Graves' disease and thyroid eye disease; most specific serum marker for TED.

Skin fold formed by the levator aponeurosis insertion into the pretarsal skin; normal height 8–10 mm in women, 6–8 mm in men; absent or high crease indicates aponeurotic disinsertion.

Chemotherapy regimen for rhabdomyosarcoma comprising vincristine, actinomycin D, and cyclophosphamide; the backbone of IRS trial-established treatment.

Mucosal fold at the distal opening of the nasolacrimal duct into the inferior nasal meatus; persistence of this membrane causes congenital nasolacrimal duct obstruction (CNLDO).

Superior and inferior ophthalmic veins that drain the orbit into the cavernous sinus; the absence of valves allows retrograde flow of infected thrombus from the orbit to the cavernous sinus.

Lid lag in TED: the upper eyelid lags behind the descending globe on downgaze, leaving a strip of sclera visible as the eye moves down.