Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Investigations

Imaging

Patients with proptosis require imaging, with a few exceptions such as mild thyroid eye disease. When viewing an orbital mass consider the following:

1.Physical characteristics: size, shape (round suggests benign), and internal structure (e.g. fluid level).

2.Location: tissue of origin and surgical space.

3.Biologic behaviour: longstanding benign masses may induce bone remodelling or ‘scalloping’, whereas malignant lesions often destroy tissue, producing irregular bony erosion.

Plain X-ray Redundant when CT is available. Blowout fracture is a clinical diagnosis and easily missed on plain X-ray.

Computed tomography (CT) First-line imaging modality for orbital disease. Indications include proptosis, orbital masses, bony lesions, trauma and hyperacute haemorrhage. CT is relatively cheap, readily available, and good for showing bone and metal foreign bodies. Main disadvantages are radiation exposure and contrast reactions. Contrast is often helpful, especially with tumours, but is contraindicated in patients with iodine allergy, dehydration, cardiac failure, hyperthyroidism, or renal impairment. Diabetics have a ≈9% risk of contrast-induced renal failure. Request fine axial cuts (2 mm for orbit, 1 mm for optic canal) and direct or reformatted coronal sections ± reformatted sagittal sections. View bone using bone ‘windows’, looking for hyperand hypo-ostotic lesions, bony erosion, or fractures. Use soft tissue ‘windows’ to systematically examine extraocular muscles, optic nerve, lacrimal gland, fat, vessels, extraorbital structures (brain, sinuses, nose), any mass lesions, or vascular changes. 3 D reconstructions are useful in trauma cases. CT angiography is mainly useful for neuro-ophthalmic problems.

Magnetic resonance imaging (MRI) Mainly indicated for disease at the orbitocranial junction, e.g. optic sheath tumours. Orbital MRI requires fat-suppression to allow delineation of soft tissue structures. Cortical bone has a very low signal intensity and appears black. Cancellous bone has a moderate signal intensity. MRI is contraindicated if metal foreign bodies are suspected (See also p. 629)

Ultrasound Internal tumour reflectivity may aid diagnosis. Doppler flow studies may help diagnose and monitor vascular lesions such as haemangiomas.

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Investigations

Other tests

Blood tests As appropriate, e.g. thyroid function tests.

Perimetry Useful for assessing optic nerve function and temporal change.

Biopsy In general, it is preferable to obtain tissue by open biopsy (incisional or excisional), rather than CT or ultrasoundguided fine-needle aspiration cytology, as histology gives better structural representation than cytology, and multiple stains are available.

Congenital Disorders

Dermoid and epidermoid cysts

Background A choristoma (normal tissue in abnormal location) arising from surface ectoderm trapped at sites of embryologic folding. Cysts are classified by their contents and lining:

■Epidermoid: squamous epithelial lining only with associated keratin.

■Dermoid: lined by squamous epithelium and dermis. Hairs, sebaceous glands/oil, and keratin may be present.

■Conjunctival: conjunctival lining with mucus contents.

Epidermoid and dermoid cysts may have intraand extraorbital components (temporalis fossa, CNS, nose) with an interconnecting ‘stalk’ traversing bone, a so-called ‘dumb-bell’ configuration.

Clinical features Typically, a firm, mobile, nontender lump is noted soon after birth in the superotemporal quadrant (STQ) (Fig. 3.2) or less commonly, superonasal quadrant (SNQ), sometimes attaching to the zygomaticofrontal or frontonasal suture. Patients may have episodes of inflammation following trauma, or skin discharge with very superficial, ruptured or incompletely excised lesions. Deep orbital lesions can present in adulthood with proptosis and recurrent orbital inflammation.

Investigations CT is not required unless it is not possible to palpate behind the equator of the cyst.

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Congenital disorders

Management Arrange nonurgent intact excision before school age, when the risk of trauma increases. Removal may require periosteal dissection ± bone removal (e.g. ‘dumb-bell’ cyst). The preferred approach for STQ/SNQ lesions is via the upper lid skin crease. If deep extension is found unexpectedly and the surgeon is not familiar with removal of complex lesions, leave the cyst intact, close the wound, and refer to an experienced orbital surgeon: do not remove lesions incompletely. If accidental rupture occurs, perform a thorough washout of the surgical field to remove proinflammatory cyst contents.

Dermolipoma

Background A choristoma of dermal elements (ectopic skin) occurring on the ocular surface, typically the STQ.

Clinical features Discharge and irritation from abnormal conjunctival wetting and surface hairs, and poor cosmesis. Look for a STQ firm, immobile, pale-yellowish mass closely applied to the globe (Fig. 3.3).

Differential diagnosis Orbital fat prolapse, lacrimal gland prolapse, and subconjunctival lipoma (all mobile under the conjunctiva).

Management Conservative microsurgical excision by an experienced surgeon, avoiding damage to the lacrimal gland

ductules and lateral rectus. Careful conjunctival closure without tension helps prevent ocular motility restriction.

Corneolimbal (epibulbar) dermoid

A choristoma of conjunctival origin, often protruding over the cornea (Fig. 3.4). May produce discomfort, exposure, or astigmatism. May be associated with Goldenhar’s syndrome that may also feature eyelid colobomas, accessary auricular appendages, poor hearing, hemifacial microsomia, and vertebral abnormalities. Manage symptomatic dermoid lesions with topical lubricants/steroids or excision (superficial sclerokeratectomy/ lamellar keratoplasty). Asymptomatic conjunctival lesions tend to be stable and excision is rarely required.

Microphthalmos and anophthalmos

Background Rare, often sporadic, idiopathic disorder of multifactorial aetiology. May be associated with: hemifacial microsomia (e.g. Goldenhar’s syndrome); renal, cardiac, and cerebral abnormalities; CHARGE and other rare congenital syndromes; cleft palate; and polydactyly.

Clinical features An absent or small eye is noted soon after birth. Microphthalmos may be associated with a variably sized cyst arising from the eye or its vestigial remnant; reduced lid and orbit

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Congenital disorders

growth; microcornea; colobomata; cataract; glaucoma and aniridia.

Management Leave cysts intact to stimulate orbital and lid growth, unless excessively large. In the absence of a cyst, insert progressive orbital and socket expanders, either as serial solid shapes or expanding implants. Once final orbital and lid growth is achieved, further expansion of the orbit (orbital implants, bony grafts), fornices (mucous membrane grafts), and lids is often required.

Thyroid Eye Disease

Background An idiopathic autoimmune disorder resulting in an active orbital inflammatory phase (months–years) and subsequent ‘inactive’ fibrotic phase, largely involving extraocular muscles and connective tissues. There is a female preponderance with peak incidence at age 30–50 years. Severe cases are more common in older patients, males, and smokers. Usually associated with hyperthyroidism, but patients may be hypoor euthyroid. A minority of cases develop sight-threatening optic neuropathy or exposure keratopathy.

Classification

The ‘Clinical Activity Score’1 measures activity and scores 1 for each of 10 features:

■Pain: (i) retrobulbar, (ii) on eye movement.

■Redness: (iii) lid, (iv) conjunctiva.

■Swelling: (v) lids, (vi) conjunctiva, (vii) caruncle, (viii) ≥2 mm increase in proptosis over 1–3 months.

■Loss of function: (ix) ±5˚ decrease in eye movement over 1–3 months, (x) loss of ≥1 Snellen line over 1–3 months

‘NOSPECS’2 classifies severity as:

■No symptoms or signs.

■Only lid retraction ± lid lag.

■Soft tissue involvement (lid, conjunctival inflammation).

■Proptosis.

■Extraocular muscle involvement ± diplopia.

■Corneal disease.

■Sight-threatening optic neuropathy.

Symptoms include injection, redness dryness/watering, photophobia, ache, visual loss (colour, VA, fields), and diplopia. Ask about smoking, family history of thyroid eye disese (TED) or other autoimmune disorder and past thyroid problems.

Signs Look for proptosis (usually axial); optic neuropathy (reduced VA; colour vision; RAPD; field loss); exposure keratopathy; upper lid retraction (Fig. 3.5); lid ‘lag’ on downgaze (descent of upper lid slower than that of the globe); lagophthalmos; increased IOP on (typically) upgaze, but also

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