20 Extraocular Muscles

COMPLICATIONS

●A-pattern can be converted to V-pattern.

●Conversion of A-pattern to V-pattern after superior oblique weakening is less likely if inferior oblique underaction was present before surgery.

●Torsional diplopia can occur after superior oblique weakening.

●The risk is significant if the patient has high-grade fusion before surgery.

●Superior oblique weakening should be done judiciously if patient has measurable stereopsis before surgery.

●Superior oblique weakening should not be done if patient has normal stereopsis (e.g. 40 seconds arc stereo or better) because torsional diplopia may occur.

●Graded superior oblique weakening with spacers may reduce the risk of this compared to tenotomies or tenectomies.

REFERENCES

Helveston EM: A-exotropia, alternating sursumduction and superior oblique overaction. Am J Ophthalmol 67:377–380, 1969.

Urist MJ: The etiology of the so-called A and V patterns. Am J Ophthalmol 46:825, 1958.

von Noorden GK: Binocular vision and ocular motility. 5th edn. St Louis, CV Mosby, 1996.

Wright K: Superior oblique silicon expander for Brown syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus 28:101–107, 1991.

215 ABDUCENS (SIXTH NERVE)

PARALYSIS 378.54

Raghu Mudumbai, MD

Seattle, Washington

Sixth nerve palsy is a common neuro-ophthalmic disorder. Because of the long intracranial course of the sixth nerve, abducens function may be compromised by multiple etiologies. Palsies may be unilateral or bilateral. They may be treated both medically, for example with prisms or injections of botulinum toxin, and surgically, for example by recess/resect and transposition procedures.

ETIOLOGY/INCIDENCE

In childhood, several etiologies – congenital, neoplasm, raised intracranial pressure, trauma, and post-infection – are common. Etiologies are similar in adult patients, but vasculopathies such as hypertension and diabetes are also significant causes. Sixth nerve palsy is a rare initial presentation of multiple sclerosis.

DIAGNOSIS

Clinical signs and symptoms

Symptoms include diplopia, worse in the field of the palsy and better on the opposite side except in bilateral cases. Esotropia is maximum in the field of the palsy and decreases at near. If mild, diplopia may be resolved when the patient looks towards the side opposite the palsy. Diplopia may not be present if the eye is directed towards the nose, which can block binocularity.

Differential diagnosis

Thyroid-related ophthalmopathy commonly involves the medial rectus muscle to produce a restrictive esotropia. Forced ductions or differential intraocular pressure measurements may be helpful signs. Myasthenia gravis is produced by acetylcholine receptor antibodies leading to any combination of ptosis, orbicularis weakness and extraocular muscle weakness, including isolated lateral rectus involvement. Forced generation testing reveals the weakness. Edrophonium chloride testing, the ice test and laboratory testing for acetylcholine receptor antibodies are helpful in the diagnosis. Blow-out fracture of the medial wall of the orbit can lead to entrapment of the medial rectus muscle and a restrictive esotropia. Forced ductions reveal a restriction. Duane’s syndrome (Type 1), due to malformation of the sixth nerve nucleus and abnormal innervation of the lateral rectus by the third nerve, leads to unilateral or bilateral esotropia, limited abduction, enophthalmos, and narrowing of the lid fissure on abduction. Multiple sclerosis commonly produces internuclear ophthalmoplegia, which is a lesion of the medial longitudinal fasiculus and not a sixth nerve palsy. It is distinguished by contralateral abduction nystagmus and ipsilateral adduction deficit.

Sixth nerve palsy can occur in combination with other deficits leading to definable syndromes. Bilateral congenital sixth and and seventh nerve palsies occur in Mobius syndrome. In Gradenigo’s syndrome, inflammation of the petrous bone, most commonly from an otitis media, leads to a sixth and seventh nerve palsies. Cavernous sinus syndrome includes third, fourth, oculosympathetic, and first division trigeminal palsies. Orbital apex syndrome adds vision loss. One and a half syndrome, resulting from a lesion of the sixth nerve nucleus and the medial longitudinal fasciculus, is recognized by an ipsilateral horizontal gaze palsy and a contralateral internuclear ophthalmoplegia. Sixth nerve palsy may be the first sign of a cavernous sinus syndrome, as the nerve travels within the substance of the sinus and thus may be the first nerve affected. Other nerves affected can include the III, IV, V1, V2 and the sympathetics. Orbital apex syndrome is similar, except that it does not involve V2 and includes optic neuropathy.

TREATMENT

Ocular

Patients with mild palsies may compensate with a head turn toward the palsied side in order to maintain fusion. Large

palsies or bilateral involvement may lead to voluntary closing of one eye to prevent diplopia. In cases where there is a high likelihood of improvement, occlusion by fogging one lens with tape or the use of a patch is highly useful to prevent diplopia as the amount of esotropia decreases with time. In patients unlikely to improve or who have reached maximal improvement with small residual deviation, base out prism may benefit to help patients maintain fusion. It can also be placed over the non-involved eye to decrease contracture of the medial rectus on the involved side. Permanent ground in prism is limited by the weight of the glasses and optical aberrations induced by the prism.

Botulinum toxin type A has been used in acute cases of sixth nerve palsy. Its effect lasts from weeks to several months. Two and a half to 5 units are injected into the antagonist medial rectus muscle (treatment is localized with the aid of an electromyographic electrode). This treatment may prevent long term contracture and aid in resolution of the deviation. It is more useful with smaller deviations of less than 30–40 prism diopters.

maintain fixation in primary gaze by head rotation, a partially successful strategy. Patients, especially those with traumatic sixth nerve palsy from head trauma, should be warned that central disruption of fusion is a possibility even with good alignment.

COMMENTS

Sixth nerve palsy can result from numerous etiologies due to the long intracranial course of the nerve. Careful history taking and clinical examination supplemented by appropriate neuroimaging and laboratory testing usually leads to the correct diagnosis. While waiting for resolution, patients can be managed in the short term by patching, prism or selective use of botulinum toxin. In cases of non-resolving sixth nerve palsy, surgical improvement may be obtained with recess/resect procedures or a transposition procedure. Adjustable suture technique may also be of benefit, given the variability of recovery of lateral rectus function.

Surgical

Once it is clear that no more improvement will occur (6 to 12 months), surgical options can be employed. With time, the incomitant deviation becomes more comitant, a phenomenon known as spread of comitance. When there is some residual forced generation found in the lateral rectus, a horizontal recess/resect of the medial and lateral recti can be attempted. In complete sixth nerve palsies, a medial rectus recession can be combined with transposition of the superior and inferior recti to the lateral rectus muscle. Use of the adjustable suture technique can help improve outcomes.

An appropriate preoperative evaluation should be carried out prior to surgery. Necessary components include measurement of the deviation and evaluation of the relative strength of the lateral and medial recti. The deviation should be measured in primary, left and right gaze. Upgaze and downgaze measurements are helpful in determining if a V or A pattern is present. Muscle tone can be measured by comparing the active forced generation of the medial and lateral recti. Estimating saccadic velocity by observation or with electro-oculography may also be beneficial to gauge the amount of sixth nerve paresis. Abduction past the midline is also helpful in judging lateral rectus function. Forced duction can provide information as to whether contracture of the medial rectus is present.

In patients found to have medial rectus contraction, recession of the medial rectus should be part of the surgical plan. Maximum recession is 12 millimeters from the limbus, and additional effect can be achieved by recessing the overlying conjunctiva and Tenon’s to the original insertion. The medial rectus can be placed on an adjustable suture and its resection can be combined with a resection of the lateral rectus up to 9 millimeters.

When there is minimal lateral rectus function, a transposition procedure of the vertical recti to the lateral rectus will probably be required. Transposition can either be total or by the Jensen procedure. In this procedure, the vertical recti are split and joined to adjacent halves of the lateral rectus but without disinsertion. This has the theoretical advantage of preserving anterior ciliary artery circulation to the anterior segment. There can be simultaneous medial rectus recession on an adjustable suture.

Single binocular vision in primary gaze with a limited range of fusion is a reasonable goal. Patients adapt by learning to

REFERENCES

Ellis FD, Helveston EM: Special considerations and techniques in strabismus surgery. Int Ophthalmol Clin 16:247–254, 1976.

Hotchkiss MG, Miller NR, Clark AW, et al: Bilateral Duane’s retraction syndrome: a clinical-pathologic case report. Arch Ophthalmol 98:870– 874, 1980.

Lee MS, Galetta SL, Volpe NJ, et al: Sixth nerve palsies in children. Pediatr Neurol 20:49–52, 1999

Miller NR, Newman NJ, eds: Walsh and Hoyt’s clinical neuro-ophthalmol- ogy. 6th edn. Maryland, Lippincott, Williams and Wilkins, 2004.

Sanders SK, Kawasaki A, Purvin VA: Long-term prognosis in patients with vasculopathic sixth nerve palsy. Am J Ophthalmol 134:81–84, 2002.

216 ACCOMMODATIVE ESOTROPIA

378.35

Henry S. O’Halloran, MD, DOphth, FRCSI

San Diego, California

William Barry Lee, MD

Atlanta, Georgia

INTRODUCTION

Accommodative esotropia is one of the most common types of strabismus occurring in childhood. The incidence of this disorder is estimated at 0.67% to 2% in the population; however, the deviation has been found to occur as infrequently as 1 in 373 cases in some studied populations. Accommodative esotropia represents an acquired esodeviation with variable severity and intermittent onset with potential progression to a constant deviation. The disorder is most commonly hereditary in nature with some studies finding nearly 80% of affected first-or seconddegree relatives, yet no pattern of inheritance or genetic locus have been identified. Less commonly, trauma or illness may be a precipitating factor. The typical age of onset is between 6 months and 5 years, with an average age of onset at 2.5 years and reports of this disease in children as young as 3 months old.

Surgical

●Strabismus surgery is indicated for any significant esodeviation that is still present after the completion of amblyopia therapy, refractive lens correction, and orthoptics. The surgery may be unilateral or bilateral depending on the surgeon’s preference and whether the eyes freely alternate.

●Unilateral surgery consists of weakening (recession) of the medial rectus muscle and strengthening (resection) of the lateral rectus muscle. Some surgeons prefer performing unilateral surgery on patients who have a strong preference for fixation in one eye. In these cases, surgery is usually performed on the nonfixating eye.

●Bilateral medial rectus recessions are performed depending on the surgeon’s preference or if the eyes are freely alternating.

●Small deviations (less than 15 prism diopters) may require a recession of only one medial rectus muscle. Deviations between 15 and 45 prism diopters usually require surgery on two muscles (recession-resection on one eye or bilateral recessions). Deviations of more than 45 prism diopters may require surgery on three or four muscles depending on the severity of the angle; however, some surgeons prefer to operate on only two muscles during the initial operation regardless of the size of the deviation.

●The use of adjustable sutures in strabismus surgery in older children and adults has significantly improved the postoperative result; this can be done with topical anesthesia at the time of surgery or within 1 day after the surgical procedure.

●Botulinum toxin type A (Oculinum) injection into an ocular muscle creates an intentional temporary paralysis that may result in improved alignment in carefully selected cases.

●Prism adaptation therapy, in which prisms are used before surgery, has been found to improve the results of surgery for acquired esotropia. Fresnel prisms are placed on eyeglasses until the angle of deviation is neutralized or fusion is obtained. This ‘adapted’ angle becomes the goal for a surgical correction and may reduce the reoperation rate.

●No surgery should be attempted unless preoperative measurements are accurate and consistent. At least three sets of measurements should be taken before strabismus surgery is undertaken.

Early detection

●Early detection of strabismus and amblyopia is vitally important. Children treated at an early age for amblyopia respond better to occlusion therapy than do older children. If amblyopia cannot be reversed, the prognosis for alignment of the eyes and fusion is significantly worsened.

●In patients requiring surgery, fusional results are significantly better in children who underwent surgery at an early age. In addition, obvious psychologic sequelae have been noted in children with late surgical treatment of a longstanding and cosmetically displeasing esodeviation.

REFERENCES

Abel LA, Troost BT: Acquired cyclic esotropia in an adult eye. Am J Ophthalmol 91:805–806, 1981.

Biglan AW, Burnstine RA, Rogers GL, Saunders RA: Management of strabismus with botulinum A toxin. Ophthalmology 96:935–943, 1989.

Dankner SR, Mash AJ, Jampolsky A: Intentional surgical overcorrection of acquired esotropia. Arch Ophthalmol 96:1848–1852, 1978.

Delisle P, Strasfeld M, Pelletier D: The prism adaptation test in the preoperative evaluation of esodeviations. Can J Ophthalmol 23:208–212, 1988.

Eino D, Kraft SP: Postoperative drifts after adjustable suture strabismus surgery. Can J Ophthalmol 32:163–169, 1997.

Helveston EM: Atlas of strabismus surgery. 4th edn. St Louis, CV Mosby, 1992.

Jampolsky A: Current techniques of adjustable strabismus surgery. Am J Ophthalmol 88:406–418, 1979.

Kani K: Magnetic resonance imaging measurements of extraocular musclepath shift and posterior eyeball prolapse from the muscle cone in acquired estropia with high myopia. Am J Ophthalmol 136:482–489, 2003.

Kitzmann AS, Mohney BG, Diehl NN: Short-term motor and sensory outcomes in acquired nonaccommodative estropia of childhood. Strabismus. 13:109–114, 2005.

Kraft SP, Enzenauer RW, Weston B: Stability of the postoperative alignment in adjustable-suture strabismus surgery. J Pediatr Ophthalmol 28:206– 211, 1991.

Metz HS: Acquired cyclic esotropia in an adult eye. Am J Ophthalmol 91:804–805, 1981.

Parks MM, Mitchel PR, Wheeler MB: Ocular motility and strabismus. In: Duane TD, ed: Clinical ophthalmology. Philadelphia, JB Lippincott, 1990.

Prism Adaptation Study Research Group: Efficacy of prism adaptation in the surgical management of acquired esotropia. Arch Ophthalmol 108:148–156, 1990.

Repka MX, Wentworth D: Predictors of prism response during prism adaptation. J Pediatr Ophthalmol Strabismus 28:202–205, 1991.

Rosenbaum AL: The current use of botulinum toxin therapy in strabismus. Arch Ophthalmol 114:213–214, 1996.

Scott AB: Botulinum toxin injection into extraocular muscle as an alternative to strabismus surgery. J Pediatr Ophthalmol Strabismus 17:21–25, 1980.

von Noorden GK: Binocular vision and ocular motility: theory and management of strabismus. 5th edn. St Louis, CV Mosby, 1995.

Ward JB, Niffenegger AS, Lavin CW, et al: The use of propofol and mivacurium anesthetic technique for the immediate postoperative adjustment of sutures in strabismus surgery. Ophthalmology 102:122– 128, 1998.

often with a reduced positive fusion amplitude and reduced convergence.

TREATMENT/COMPLICATIONS

The clinical management of X(T) presents a dilemma. Conservative treatments are often ineffective and surgery may be required. However, surgical overcorrection is common, especially in younger patients, and while there may be a good cosmetic outcome despite a small overcorrection, this will be at the expense of impaired near binocular functions.

Treatment is usually requested because of the cosmetic appearance of the observed deviation. The treating physician may be concerned about the possibility of deteriorating binocular function if the strabismus is not treated. Usually the child has straight eyes and good binocular vision for near fixation, for example when reading. As the fixation distance increases, there is an increasing tendency for the eyes to diverge.

Ocular

Conservative treatments for X(T) include minus lenses, prisms, orthoptic exercises and occlusion. They may be used in isolation, or as a temporising measure in young children vulnerable to the effects of surgical overcorrection. Significant refractive errors, even hyperopic ones, should be corrected in intermittent exotropia as this will sharpen the retinal images and improve fusion. Minus lenses are sometimes used to stimulate accommodative convergence. They may be particularly helpful in patients with high AC/A ratios. Small angle X(T) (measuring <20 prism dioptres) is usually non progressive and treated conservatively, either by observation, orthoptic exercises or occlusion.

TABLE 218.1 – The Newcastle control score for intermittent exotropia

HOME CONTROL

1Squint/monocular eye closure seen occasionally for distance

2Squint/monocular eye closure seen frequently for distance

3Squint/monocular eye closure seen for distance & also near

CLINIC CONTROL NEAR

0Manifest only after cover test and resumes fusion without need for blink or refixation

1Blink or refixate to control after CT

2Manifest spontaneously or with any form of fusion disruption without recovery

CLINIC CONTROL DISTANCE

0Manifest only after cover test and resumes fusion without need for blink or refixation

1Blink or refixate to control after CT

2Manifest spontaneously or with any form of fusion disruption without recovery

NCS TOTAL (HOME + CLINIC NEAR + CLINIC DISTANCE) =

Surgical

Larger angle deviations (measuring >20 prism dioptres) are usually treated, especially if there is evidence of deterioration. Traditionally, surgical treatment has been recommended for such squints if they are observed by carers to be present at least 50% of waking hours and are poorly controlled on clinical examination. Measurements of home and clinic control of the strabismus can be combined into a score which can be used to monitor progression and as a guide to surgery (Table 218.1). While there are clear functional indications for surgery in those children who have deteriorating control of the deviation for near fixation, accompanied by deteriorating near stereoacuity, for most children with X(T) measuring >20 prism dioptres at distance fixation, the criteria for, and the benefits of, surgical intervention are poorly defined.

Most interventions, however, particularly surgery, affect the alignment of the visual axes at near almost as much as at distance. This leads to the common postoperative problem of overcorrection of the deviation at near, with potential loss of stereopsis and amblyopia, especially in younger children. Surgical conservatism, however, leads to undercorrection with a recurrence of the deviation, thought to be because of persistence of suppression mechanisms. The desired result is said to be a small initial postoperative overcorrection in order that the suppression mechanisms are disrupted, followed by a drift to alignment of the eyes over days to weeks. It is well recognized that achieving such results is difficult and unpredictable, partly because of the influence of convergence mechanisms.

Surgical tables for exotropia tend not to distinguish between different types of exotropia. The figures used by the authors,

TABLE 218.2 – Suggested surgical numbers for intermittent exotropia

who aim at a small initial postoperative overcorrection, are shown in Table 218.2. These should be used as a guide and individual surgeons should audit their results and alter practice accordingly.

The surgical procedure should probably be bilateral lateral rectus recessions for true divergence excess exotropias, but for simulated divergence excess and basic intermittent exotropias, recess resect procedures have been demonstrated to be equally effective. Bilateral lateral rectus recessions allow easy access to the inferior oblique muscles, should there be significant oblique overaction. While many cases of intermittent exotropia have a small V pattern, oblique surgery is usually not necessary unless there is significant oblique overaction.

COMPLICATIONS

Possible complications from surgery should always be kept in mind. These include overaction of the inferior oblique muscle from superior oblique tenotomy, which may require addition surgery on the inferior oblique muscle. The superior oblique must be completely isolated in order to prevent inadequate surgery from missed fibers. Ptosis of the upper lid may ensue. Careful dissection that stays close to the superior rectus muscle must be performed to prevent orbital fat from herniating and scarring which can lead to ocular restriction.

COMMENTS

Brown’s syndrome is defined by limitation, both actively and passively, of upgaze in adduction. The congenital form is secondary to a tight superior oblique tendon. Acquired Brown’s syndrome may occur in after an operation that disrupts the function of the superior oblique, as well as from inflammation of the superior oblique tendon as in rheumatoid arthritis. If the patient is asymptomatic, observation is appropriate. If diplopia, hypotropia in primary position, or a head turn is present, multiple surgical options are available. They include superior oblique weakening procedures with or without concomitant ipsilateral inferior oblique weakening procedures and the use of spacers to increase the length of the superior oblique tendon.

REFERENCES

Moore AT, Morin JD: Bilateral acquired inflammatory Brown’s syndrome. J Pediatr Ophthalmol Strabismus 22:26, 1985.

Sprunger DT, von Noorden GK, Helveston EM: Surgical results in Brown syndrome. J Pediatr Ophthalmol Strabismus 28:164–167, 1991.

von Noorden GK, Oliver P: Superior oblique tenectomy in Brown’s syndrome. Ophthalmology 89:303, 1982.

Wilson ME, Eustis HS Jr, Parks MM: Brown’s syndrome. Surv Ophthalmol 34:153–72, 1989

Wright KW: Results of the superior oblique elongation procedure for severe Brown’s syndrome. Trans Am Ophthalmol Soc 98:41–48, 2000

220 CONGENITAL ESOTROPIA 743.69

(Infantile Esotropia)

Laura B. Enyedi, MD

Durham, North Carolina

Edward G. Buckley, MD

Durham, North Carolina

ETIOLOGY/INCIDENCE

Congenital esotropia is the most common childhood strabismus, occurring in approximately 1% of children. The cause of

COURSE/PROGNOSIS

These children are at a significant risk for developing amblyopia, although some patients maintain equal vision by alternating fixation between the two eyes (cross-fixation). Early diagnosis and treatment can result in the restoration of normal function and a delay in treatment beyond 2 years of age is associated with poor binocularity, absent fusion and no stereopsis.

DIAGNOSIS

Clinical signs and symptoms

The crossing is rarely present at birth, but usually develops by the end of the third month and is present, by definition, by age 6 months. The esotropia is large angle (30 to 70 prism diopters), constant and does not resolve with hyperopic correction. Although most patients are otherwise healthy, some have associated ocular or neurologic abnormalities that require further evaluation. There is no clear inheritance pattern, but congenital esotropia can be familial and infants with a strong family history should be observed closely for the development of strabismus. Prematurity and perinatal hypoxia are also risk factors for congenital esotropia.

Laboratory findings

The opththalmologic examination includes visual function testing by fixation preference, fix and follow response and/or preferential looking tests. The deviation is measured using prisms and alternate cover testing if possible. Krimsky or Hirschberg testing may also be used to estimate the angle of esotropia. Duction testing may reveal mild limitations of abduction and versions are examined for A- or V- patterns, indicating overaction of superior or inferior oblique muscles, respectively. Dissociated vertical deviation is commonly associated with congenital esotropia, but is not often seen on presentation. Cycloplegic refraction may reveal significant refractive errors, especially hyperopia, which may need to be corrected with spectacles prior to surgical alignment. Complete anterior segment and fundus examinations are critical to rule out structural abnormalities (e.g. cataract, coloboma, optic nerve hypoplasia, or retinoblastoma) which may cause sensory esotropia.

Differential diagnosis

The differential diagnosis of congenital esotropia includes common disorders such as psedoesotropia and accommodative esotropia as well as less common disorders such as Duane’s syndrome, nystagmus blockage syndrome, sixth nerve palsy and Mobius syndrome. Sensory esotropia secondary to loss of vision from ocular or optic nerve disease must always be considered. Pseudoesotropia in which epicanthal folds and a wide nasal bridge create the false appearance of esotropia is frequently mistaken for true esotropia. Accommodative esotropia in which there is high hyperopia and / or a high ratio of accommodative convergence to accommodation usually presents in toddlers, but may also be seen in infants. The distinguishing

221 CONGENITAL FIBROSIS OF THE

EXTRAOCULAR MUSCLES 378.62

Forrest James Ellis, MD

Cleveland, Ohio

ETIOLOGY/INCIDENCE

Congenital fibrosis of the extraocular muscles (CFEOM) is a rare condition characterized by hypoplasia and fibrosis of the extraocular muscles. CFEOM falls in the group of syndromes characterized by congenital limitation of eye and eyelid movements (congenital cranial nerve dysinnervation syndromes). Primary neurodevelopmental abnormalities of cranial nerve nuclei occur in CFEOM type 2, while genetic defects affecting axonal transport of molecules necessary for normal extraocular muscle function and development occur in CFEOM type 1. Possible prenatal orbital penetration has been reported in isolated unilateral cases.

Three genetic subtypes of CFEOM have been identified.

●CFEOM 1 is characterized by congenital bilateral ptosis with the eyes fixed in a position of 20 to 30 degrees infraduction. Affected individuals often adopt a chin-lift posture. Passive movement of the globes is significantly limited with forced ductions. Volitional eye movements are often limited, and convergent or divergent movements may occur with attempted vertical or horizontal gaze. Amblyopia and refractive errors are common. Penetrance appears to be complete with striking phenotypic homogeneity. The CFEOM 1 genetic locus is in the centromeric region of human chromosome 12. There is a missense mutation in an axonal transport kinesin motor protein encoded by KIF21A. The absence of the superior division of the oculomotor nerve and its corresponding midbrain a motor neurons have been described at necropsy.

●CFEOM 2 is an autosomal recessive disorder. Affected individuals have bilateral congenital ptosis and restricted extraocular movements with the eyes positioned in abduction. The locus for CFEOM 2 has been mapped to chromosome 11q13 and involves the ARIX gene. This is believed to result in hypoplasia of the III and IV cranial nerve nuclei.

●CFEOM 3 is an autosomal dominant disorder with incomplete penetrance and variable expressivity. Affected individuals demonstrate ptosis with the eyes fixed in abduction and infraduction. This disorder is clinically and genetically distinct from CFEOM 1 and CFEOM 2. The gene maps to markers on chromosome 16q.

During examination at the time of a surgical intervention, the extraocular muscles are typically thin and inelastic. Histopathologic examination of the affected extraocular muscles has demonstrated a reduced number of muscle fibers and increased fibrous tissue. CFEOM is typically an isolated phenomenon, although cases in association with other systemic disorders have been reported. Whereas most other myopathies are progressive, CFEOM is congenital and non-progressive.

●Congenital nonprogressive condition.

●Typically bilateral, but may be unilateral.

●Limitation of ocular motility, typically with ptosis of the eyelid.

●Positive forced duction.

●Synkinetic eye movements in some cases.

●A reduced number of muscle fibers and increased fibrous tissue on histopathologic examination of the affected extraocular muscles.

●Examination of family members for similar abnormalities of ocular motility.

●Family history for autosomal dominant inheritance common.

●Radiologic imaging possibly helpful in the evaluation of selected patients.

Differential diagnosis

●Duane’s syndrome.

●Double elevator palsy.

●Brown’s syndrome.

●Progressive external ophthalmoplegia.

●Progressive dystrophic ophthalmoplegia.

●Möbius syndrome.

●Myasthenia gravis.

●Congenital or acquired paralysis of the extraocular muscles.

●Congenital or acquired ptosis.

●Extraocular muscle entrapment (orbital fracture).

●Thyroid-related strabismus.

TREATMENT

Systemic

●Genetic counseling.

●Physical and neurologic examinations.

Ocular

●Correction of refractive error.

●Occlusion or penalization therapy for amblyopia.

●Lubrication for exposure keratopathy.

COURSE/PROGNOSIS

●Nonprogressive.

●No spontaneous improvement.

●Vision affected by amblyopia.

DIAGNOSIS

Clinical signs and symptoms

Clinical findings vary from bilateral generalized fibrosis to fibrosis of only a single extraocular muscle. The ophthalmic findings are present at birth and are typically nonprogressive.

Surgical

●Goal of achieving a functional position of the eyes and eyelids; horizontal and vertical binocular alignment with the eyes in a position of slight infraduction.

●Large rectus muscle recessions typically required and preferred to rectus muscle resections.

●Conjunctival recessions augment rectus muscle surgery.

●Frontalis suspension procedures typically required for ptosis repair.

REFERENCES

Crawford JS: Congenital fibrosis syndrome. Can J Ophthalmol 5:331–336, 1970.