Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

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Figure 14.2 Thyroid eye disease with bilateral exophthalmos associated with lid retraction and scleral show. See insert for color version.

Box 14.1 Emergencies in thyroid eye disease

Acute progressive optic neuropathy

Optic neuropathy in TED may arise from compression of the nerve by involved tissues (mainly muscles) or proptosis-induced stretch.

•Assess optic nerve function (VA, color, visual fields, pupillary reactions).

Treatment

•Systemic immunosuppression (coordinate with endocrinologist). This is usually oral corticosteroids (e.g., 1 mg/kg 1x/day PO prednisone) but may be pulsed (e.g., 500 mg IV methylprednisone 1x/day for the first 3 days); other immunosuppresives may be added for additional control and as steroid-sparing agents.

•If this fails, then urgent surgical decompression is required. This varies in extent but must decompress the orbital apex where compression is often maximal. Some medical centers also use orbital radiotherapy in the acute setting.

Exposure keratopathy

Exposure keratopathy in TED may arise from proptosis and lid retraction.

•Assess corneal integrity, tear film, lid closure, and proptosis.

•Treatment: lubricants, acute immunosuppression (e.g., systemic corticosteroids) ± orbital decompression (or lid-lengthening surgery).

THYROID EYE DISEASE: GENERAL 477

Systemic

Systemic signs depend on the thyroid status (overor underactivity) and underlying disease (goiter in Graves’ or Hashimoto’s; pretibial myxedema, thyroid acropachy in Graves’) (see Table 14.4).

Additionally, there is an increased frequency of other autoimmune diseases in association, e.g., pernicious anemia, vitiligo, diabetes mellitus, and Addison’s disease.

Table 14.4 Common systemic features of thyroid dysfunction

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Thyroid eye disease: assessment

The diagnosis and management of thyroid eye disease depends on accurate clinical assessment. Grading systems aim to formalize this process but generally are not a substitute for careful clinical documentation of disease status (severity and activity). Similarly, while investigations may support a diagnosis of TED, they are not diagnostic in their own right.

Rundle’s curve

The natural history of thyroid eye disease can be described in terms of an active phase of increasing severity, a regression phase of declining severity, and an inactive plateau phase (Rundle’s curve). While specific to each patient, these time courses can be plotted graphically and broadly categorized according to mild, moderate, marked, or severe disease (Rundle a–d).

Assessment of disease severity

Grading systems used to document severity include the NOSPECS classification (Table 14.5). This is now used sparingly by ophthalmologists, who generally wish to document disease severity and extent in greater detail. It is still widely used by PCPs and endocrinologists.

Assessment of disease activity

The most widely used score of clinical activity is the Mourits system, although a standardized protocol based on comparison to clinical photographs has also been devised (Table 14.6).

Table 14.5 NOSPECS disease severity score

0N No signs or symptoms

1O Only signs, no symptoms

2S Soft tissue involvement

3P Proptosis

5C Corneal involvement

6S Sight loss (dVA)

On Werner’s modified NOSPECS, categories 2–6 can be further graded as o, a, b, or c (e.g., degree of visual loss for category 6).

THYROID EYE DISEASE: ASSESSMENT 479

Investigation

•Thyroid function tests: usually TSH and free T4, but check free T3 (the active metabolite) if there is strong clinical suspicion but otherwise normal biochemistry (Table 14.7).

•Thyroid autoantibodies: anti-TSH receptor, antithyroid peroxidase, and antithyroglobulin antibodies (Table 14.8).

•Orbital imaging: CT head gives better bony resolution and is preferred for planning decompression. MRI (T2-weighted and STIR) gives better soft tissue resolution and identifies active disease; the bellies of the muscles show enlargement and inflammation but the tendons are spared (Fig. 14.3).

•Orthoptic review may include field of binocular single vision, field of uniocular fixation, Hess/Lees chart, and visual fields.

Table 14.6 Clinical activity score

Source: Mourits MP, et al. (1989). Clinical criteria for the assessment of disease activity in Graves’ ophthalmopathy: a novel approach. Br J Ophthalmol 73:639–644.

Table 14.7 Biochemical investigations in thyroid eye disease

THYROID EYE DISEASE: MANAGEMENT 481

Thyroid eye disease: management

Treatment of eye disease

General

•Multidisciplinary input from endocrinologist and ophthalmologist.

•Supportive: counseling, ocular lubricants, tinted glasses, bed-head elevation, prisms for diplopia, support group.

Medical

Consider immunosuppression in active disease, particularly if function (motility or vision) is threatened. This is usually by systemic corticosteroids but cyclosporine, methotrexate, and azathioprine have all been used. Radiotherapy is popular in some centers; it may transiently worsen disease.

Surgical

For acute disease

Acute progressive optic neuropathy or corneal exposure may require emergency orbital decompression.

For burnt-out disease

Surgery (usually staged) may improve function and cosmesis. Decompression, motility, or lid surgery are performed as required, and in that order. Decompression can be 1-, 2-, or 3-wall and by a variety of approaches (e.g., coronal, lower lid, etc.) to hide scars.

Prognosis

TED is a self-limiting disease that usually resolves within 1–5 years. Once stable, dramatic improvements in ocular motility and appearance can be achieved with a staged surgical approach. However, good long-term vision depends on successfully guarding against sight-threatening complications in the acute phase (see Box 14.2).

Box 14.2 Poor prognostic factors in TED

•Older age of onset

•Male

•Smoker

•Diabetes

•dVA

•Rapid progression at onset

•Longer duration of active disease

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Treatment of hyperthyroidism

Carbimazole and propylthiouracil

Carbimazole or propylthiouracil is used to block the production of thyroid hormones. The initial dose (15–40 mg for carbimazole; 200–400 mg for propylthiouracil) is continued until the patient is euthyroid and then gradually reduced while maintaining normal free T4 levels. Therapy is generally required for 12–18 months.

An alternative regimen is blocking-replacement, in which higher doses of carbimazole are given simultaneously with thyroxine replacement.

Patients should be warned of the risk of agranulocytosis and to seek medical review (including CBC) if they develop infections, particularly sore throat.

Radioactive iodine

A single dose of radioactive sodium iodide (I131) is given. The patient must avoid close contact with others, particularly children, for a period after administration. Subsequent hypothyroidism is common and requires thyroxine replacement.

There is some controversy over the possibility that radioactive iodine worsens TED (or whether this is related to a subsequent hypothyroid dip); typically, patients with moderate to severe TED will have progression of disease during radioactive iodine therapy. Patients with mild eye disease typically do not have progression. It is common practice to give prophylactic oral steroids when administering radioactive iodine in this higher-risk group of patients.

Surgical (ablation/thyroidectomy)

This may be used for large goiters or in patients who have moderate to severe eye disease and significant risk progression with radioactive iodine therapy.

In pregnancy and breast-feeding

Carbimazole and propylthiouracil cross the placenta and can cause fetal hypothyroidism. Consequently, the lowest dose possible should be used and the blocking-replacement regimen avoided.

Radioactive iodine is contraindicated in pregnancy.

Treatment of hypothyroidism

Levothyroxine

Thyroxine replacement is started at a dose of 25–100 μg (50 μg if >50; 25 μg if cardiac disease) and cautiously increased at intervals of 4weeks to a maintenance dose of 100–200 μg. Treatment is monitored against thyroid function tests and clinical status.

Rapid increases or excessive doses may result in angina, arrhythmias, and features of hyperthyroidism.

OTHER ORBITAL INFLAMMATIONS 483

Other orbital inflammations

A number of inflammatory diseases may affect the orbit (Table 14.9). These may be purely orbital or related to systemic disease (e.g., thyroid eye disease). The purely orbital diseases may be diffuse (e.g., idiopathic orbital inflammatory disease) or focal (e.g., myositis).

Idiopathic orbital inflammatory disease (pseudotumor)

This is an uncommon chronic inflammatory process of unknown etiology. It may simulate a neoplastic mass (hence the term pseudotumor), but histology shows a pure inflammatory response without cellular atypia.

It is a diagnosis of exclusion and may in fact represent a number of poorly understood entities. It may occur at almost any age. It is usually unilateral.

Clinical features

•Acute pain, redness, lid swelling.

•Conjunctival injection, chemosis, lid edema, proptosis, restrictive myopathy, orbital mass.

Investigation

•Orbital imaging: B-scan (low to medium reflectivity, acoustic homogeneity); MRI (hypointense, cf. muscle on T1; hyperintense, cf. muscle on T2; moderate enhancement with gadolinium).

•Biopsy is required when there is diagnostic doubt.

Treatment

•Immunosuppression: usually with systemic corticosteroids, although cytotoxics (e.g., cyclophosphamide) and radiotherapy are sometimes used.

Idiopathic sclerosing inflammation of the orbit

This is a rare, relentlessly progressive idiopathic fibrosis akin to retroperitoneal fibrosis. There is no known cause and no effective treatment, and visual deterioration is common.

Table 14.9 Inflammatory diseases affecting the orbit (selected)

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Myositis

In myositis, the inflammatory process is restricted to one or more extraocular muscles, most commonly the superior or lateral rectus. The disease may occur at almost any age and is usually unilateral.

Clinical features

•Acute pain (especially on movement in the direction of the involved muscle), injection over muscle ± mild proptosis.

Investigations

•Orbital imaging: MRI gives better soft tissue resolution; the whole of the muscle and tendon shows enlargement and inflammation (cf. TED).

Treatment

•Immunosuppression: normally very sensitive to systemic corticosteroids.

Tolosa—Hunt syndrome

In this rare condition, there is focal inflammation of the superior orbital fissure ± orbital apex. The disease presents with orbital pain, multiple cranial nerve palsies, and sometimes proptosis.

It must be differentiated from other causes of the superior orbital fissure syndrome: carotid-cavernous fistula, cavernous sinus thrombosis, Wegener’s granulomatosis, pituitary apoplexy, sarcoidosis, mucormycosis, and other infections. The condition is very sensitive to steroids.

Dacryoadenitis

Lacrimal gland inflammation may be isolated or occur as part of diffuse idiopathic orbital inflammatory disease. It presents with an acutely painful swollen lacrimal gland that is tender to palpation, has reduced tear production, and results in an S-shaped deformity to the lid.

The condition must be differentiated from infection and tumors of the lacrimal gland. Isolated dacryoadenitis does not usually require treatment.

Wegener’s granulomatosis

This is an uncommon necrotizing granulomatous vasculitis that may have ophthalmic involvement in up to 50% of cases and orbital involvement in up to 22%. It is more common in males (M:F 2:1) and in middle age.

Clinical features

Ophthalmic

•Orbital disease: pain, proptosis, restrictive myopathy, disc swelling, dVA.

•Other ocular disease: epi/scleritis, peripheral ulcerative keratitis, uveitis, and retinal vasculitis.

Systemic

• Pneumonitis, glomerulonephritis, sinusitis, nasopharyngeal ulceration.

Investigation

• ANCA: most cases are c-ANCA positive.

Treatment

Treatment (coordinated by rheumatologist and physician) is usually with combined corticosteroids and cyclophosphamide.

CYSTIC LESIONS 485

Cystic lesions

Dacryops (lacrimal ductal cyst)

These cysts of the lacrimal duct tissue are relatively common and may arise from any lacrimal tissue (including the accessory lacrimal glands of Krause and Wolfring). Dacryops are often bilateral and protrude into the superior fornix. Treatment, if required, is by aspiration.

Dermoid cyst

Dermoids are a type of choristoma (congenital tumors of tissues abnormal to that location). They probably represent surface ectoderm trapped at lines of embryonic closure and suture lines.

They are most commonly located on the superotemporal orbital rim, but may extend deceptively far posteriorly. They comprise stratified squamous epithelium (with epidermal structures such as hair follicles and sebaceous glands) surrounding a cavity that may contain keratin and hair.

Clinical features

Superficial dermoids

•Present in infancy.

•Slowly growing firm smooth, round, nontender mass.

Deep dermoids

•Present from childhood on.

•Gradual proptosis, motility disturbance, dVA.

•May extend beyond the orbit into the frontal sinus, temporal fossa, or cranium.

Investigation

Orbital imaging: CT shows well-circumscribed lesion with heterogenous center; B-scan US shows well-defined lesion with high internal reflectivity.

Treatment

They should be excised completely without rupture of the capsule to avoid severe inflammation and recurrence. Intracranial spread of deep dermoid cysts requires coordination with neurosurgeons.

Mucocele

A mucocele is a slowly expanding collection of secretions resulting from blockage of the sinus opening. This may be due to a congenital narrowing or arise secondary to infection, inflammation, tumor, or trauma. Over time, erosion of the sinus walls permits the mucocele to encroach into the orbit. Orbit-involving mucoceles usually arise from frontal, ethmoidal, or, occasionally, the maxillary sinus.

Clinical features

These include headache, gradual nonaxial proptosis or horizontal displacement, and a fluctuant tender mass in medial or superomedial orbit.