Ординатура / Офтальмология / Английские материалы / Moorfields Manual of Ophthalmology_Jackson_2007

Alphabet Patterns

Background Alphabet pattern refers to a change in the angle of horizontal strabismus in up/downgaze.

Classification

■‘V’: a ‘V’ pattern is a relative divergence of >15 prism dioptres

on upgaze compared to downgaze. The normal physiological ‘V’ pattern measures <15 prism dioptres.

■‘A’: a relative divergence of ≥10 prism dioptres or more on downgaze compared to upgaze.

■‘X’: relative increase in elevation and depression, usually in an exodeviation.

■‘Y’: relative exodeviation on upgaze. Downgaze and primary positions have similar deviations

■‘Y’: relative exodeviation on depression. Upgaze and primary positions have similar deviations.

Aetiology The main causes are bilateral oblique and vertical rectus muscle dysfunction, e.g. inferior recti overactions producing adduction on depression (‘V’ pattern). Conversely, inferior recti underactions produces an ‘A’ pattern. Super oblique underaction can produce a ‘V’ pattern, and overaction can produce an ‘A’ pattern. High medial recti insertions can produce a ‘V’ Eso pattern and low lateral recti insertions a ‘V’ Exo pattern. There is a high incidence of ‘A’/‘V’ patterns in children with craniofacial abnormalities.

Symptoms Possible diplopia where the deviation is greatest.

Signs Chin elevation or depression to achieve binocular single vision. May have vertical deviation in primary position if vertical recti/oblique actions are asymmetrical.

Examination Cover test for near, distance, depression, and elevation by moving the head up and down. Look for bilateral asymmetrical muscle dysfunctions during eye movement testing.

Investigations Hess chart: slanting sides indicate an ‘A’ or ‘V’ pattern.

Treatment Usually surgical. If there are oblique overactions these should be weakened. For a ‘V’ pattern, inferior obliques are recessed or disinserted. Superior oblique posterior tenotomies are used for ‘A’ patterns. Weakening the obliques may cause a relative esodeviation. Where no oblique overactions occur, transposing the horizontal recti by a half or full muscle width, as shown in Figure 13.1 below, can reduce ‘A’ or ‘V’ patterns. This can be combined with recession/resection of horizontal recti.

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Alphabet patterns

MR MR

Fig. 13.1: Transposition of horizontal recti in ‘A’ and ‘V’ patterns. The arrows indicate the direction of muscle transposition.

Duane’s Syndrome

Background Duane’s syndrome is a spectrum of congenital motility disorders with anomalous innervation of the lateral rectus muscle, together with retraction of the globe, and narrowing of the palpebral fissure on adduction. There is hypoplasia of the 6th nerve nucleus and/or absence of the 6th nerve, with the lateral rectus being innervated by a branch of the 3rd nerve. Secondary myogenic factors are also involved.

The condition usually presents in childhood but mild cases are sometimes picked up incidentally in adults. It is more common for the left eye and females to be affected. The condition may also be bilateral, although very asymmetrical in some cases. Systemic abnormalities may coexist: hearing defects, ear malformations, Goldenhar’s syndrome, Klippel-Feil syndrome, or spinal abnormalities.

Classification

■The essential underlying pathophysiology is similar in all types, but they differ in the degrees of abnormality of the lateral and medial rectus innervations (Table 13.3).

■Alternatively, Duane’s syndrome is sometimes referred to as typical (mainly limited abduction), or atypical (mainly limited adduction).

History and examination Check for anisometropia and amblyopia. Observe any abnormal head posture (AHP): usually a face-turn to the affected side in types 1 and 3 and to the opposite side in type 2. Most patients have fusion and stereopsis, often maintained by the AHP. Diplopia is rare.

■Cover test :

1.Types 1 and 3: orthophoria/esophoria/esotropia

2.Types 2 and 3: exophoria/exotropia.

■Ocular movements : lids show narrowing of the palpebral fissure on adduction with retraction of the globe on attempted adduction (Fig. 13.2). The palpebral fissure often widens on abduction. Upshoot or downshoot of the eye may occur on

Table 13.3: Classification of Duane’s syndrome

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adduction. Retraction on adduction is often best observed from the side. Palpebral fissure changes can be subtle.

Treatment Treat associated refractive error and amblyopia if <8 years (p. 589). Prisms and botulinum toxin have a limited role.

Surgery : has a limited role and patients/carers must understand that normal eye movements cannot be restored. Indications include a large primary position deviation, noticeable AHP, marked globe retraction or up/downshoots, and large decompensating phorias.

■Type 1: ipsilateral/bilateral medial rectus recession(s).

a. With large deviation and no abduction beyond midline: vertical muscle transposition (superior rectus and inferior rectus moved to lateral rectus).

■Type 2: ipsilateral/bilateral lateral rectus recessions.

a. With globe retraction: ipsilateral medial and lateral rectus recessions.

b. With up/downshoots: lateral rectus recession and splitting.

Brown’s syndrome

Brown’s Syndrome

Background A condition with limited elevation in adduction due to mechanical restriction rather than inferior oblique paresis. Commonly congenial but can be acquired. May be constant or intermittent. Congenital cases were previously thought to be due to a short superior oblique tendon sheath, but are now considered to be caused by anomalies of the tendon–trochlear complex. Causes of acquired Brown’s syndrome include trauma of the trochlear region, sinus surgery, inflammatory conditions, and following superior oblique surgery.

History and examination

■In congenital cases, parents may not notice reduced elevation but instead the overaction of the contralateral eye on elevation. Acquired cases usually complain of diplopia.

■Abnormal head posture (AHP): if present, this is usually a chin elevation but there may be a head tilt to the affected side ± face turn away from the affected side.

■Cover test : often straight in the primary position with binocular single vision (BSV) or less commonly, hypotropia in the affected eye/hypertropia in the unaffected eye.

■Ocular movements : features include limited elevation in adduction, usually good elevation in abduction (Fig. 13.3), overaction of the contralateral superior rectus, and no/minimal ipsilateral superior oblique overaction (Fig. 13.4). A ‘V’ pattern

A

B

Left eye

Rect.sup. Obl.inf.

Green before left eye

Obl.inf. Rect.sup.

Rect.int. Rect.int. Rect.ext. Rect.ext.

Obl.sup. Rect.inf.

Obl.sup. Rect.inf.

Green before right eye

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Brown’s syndrome

is often present. There may be down-drift in adduction and widening of the palpebral fissure in adduction. There is resistance to passive elevation of the eye in adduction (positive forced-duction test). Check for an audible/palpable click on elevation. Diplopia, if present, is usually on elevation.

Treatment

■Treat any refractive error and amblyopia, if present (p. 589). Most patients do not require surgery as BSV is present in primary position and downgaze. Also, spontaneous improvement can occur in congenital cases, particularly in cases with a click/discomfort on elevation in adduction.

■If associated with an acquired inflammatory condition local, peritrochlear steroid injections can be beneficial.

■Surgery is indicated if there is significant hypotropia in the primary position or marked AHP. Surgical options include superior oblique tenotomy/tenectomy (be aware of the risk of palsy requiring further treatment), silicone band, or suture spacer on the tendon. Patients with Brown’s syndrome secondary to trauma often have a poor surgical outcome.

Thyroid Eye Disease

Background Patients with thyroid eye disease (TED) may experience diplopia due to inflammatory change that is then followed by extraocular muscle fibrosis. For other aspects of TED, see page 81.

History Diplopia is commonly intermittent, vertical, and in either upgaze or primary position. It may be worse in the morning (fusion interrupted overnight) and evening (from decompensation).

Examination Note any abnormal head posture (commonly chin elevation to maintain binocular single vision because of limited elevation) perform cover test, and examine eye movements. A tight inferior rectus is most common (restricted elevation, maximum in abduction, hypodeviation, and possible excyclotorsion) followed by medial rectus (restricted abduction, esodeviation) and then superior rectus (limited depression maximum in abduction). Hypoand esodeviations often coexist. Look for bilateral signs that may be asymmetric. An ‘A’ esodeviation is common, especially following orbital decompression.

Investigations Compare the Hess chart to ocular motility. Be aware that patients with moderately limited elevation may guess the upper points when plotting the Hess chart (using visual fields, or moving head). Consider testing field of binocular single vision and monocular eye movements (uniocular fixation).

Management Prisms are often helpful if diplopia is present in the primary position. Occlusion of one eye may be necessary for very large incomitant deviations. Await stability for at least 6 months before undertaking corrective surgery. Both horizontal and vertical surgery may be required. Use recession not resections, preferably with adjustable sutures. Recess the inferior rectus for hypotropia or restricted elevation. Recess the medial rectus for esotropia. Bilateral surgery is common, e.g. bilateral inferior recti recessions for bilateral limited elevation. Four muscles can be recessed at one operation (two in each eye); usually one eye has the medial and inferior recti on adjustable sutures.

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3rd nerve palsy

3rd Nerve Palsy

Background Signs and symptoms vary depending on the site of the lesion. A painful, unilateral 3rd nerve palsy suggests a posterior communicating artery aneurysm, requiring an emergency neurological referral. Microvascular, pupil-sparing 3rd nerve palsies are commonly associated with diabetes and hypertension. Other causes of 3rd nerve palsy include trauma, neoplasm, infection, migraine, congenital cases, and giant cell arteritis (rare).

Signs A total 3rd nerve palsy affects all extraocular muscles except the superior oblique and lateral rectus, which act unopposed to give exotropia and hypotropia (‘down and out’) plus a dilated pupil with paralysis of accommodation. The extent to which the 3rd nerve is affected can depend on various factors, including aetiology, e.g. pupil-sparing 3rd nerve palsies are commonly ischaemic (microvascular). Superior division involvement produces ptosis and superior rectus underaction.

There may be aberrant regeneration as the affected nerve fibres are misdirected during recovery, producing retraction of the upper lid on attempted adduction ± depression, adduction

on attempted elevation (+ rarely depression), pupil constriction on attempted adduction ± depression, retraction of the globe on attempted elevation ± depression. Aberrant regeneration is rare with microvascular causes.

History Ask about the duration of onset, diabetes, hypertension, headache, trauma, features of giant cell arteritis, myasthenia gravis, and MS.

Examination Check BP, other cranial nerves including visual fields, fundus for retinopathy and optic disc swelling. Examine the temporal arteries if aged >50 years. Exclude proptosis, lid fatigue with sustained upgaze, and Cogan’s lid twitch (overshoot of lid when going from sustained downgaze to primary position). Check eye movements and cover test.

Investigation

■Orthoptic testing

■Pupil sparing : fasting glucose. ESR and CRP if age >50 years. Request CT or MRI if age <50 years and no diabetes or hypertension.

■Pupil or other cranial nerves involved, or optic disc swelling : urgent CT or MRI via a neurologist.

■Myasthenia suspected : consider Tensilon test via a