Miscellaneous Ocular Deviations






  • 1.

    What is the differential diagnosis of exotropia?





    • Congenital exotropia



    • Sensory exotropia



    • Third-nerve palsy



    • Duane’s syndrome



    • Craniofacial abnormalities with divergent orbit (e.g., Apert’s syndrome or Crouzon syndrome)



    • Myasthenia gravis



    • Thyroid disorder



    • Medial wall fracture



    • Slipped medial rectus muscle or excessively resected lateral rectus



    • Orbital inflammatory pseudotumor



    • Convergence insufficiency



    • Internuclear ophthalmoplegia



  • 2.

    A mother notices that her 4-month-old infant seems to be “wall-eyed.” What is your concern as a physician?


    First, check whether deviation or pseudostrabismus is present. A wide interpupillary distance or temporal dragging of the macula from retinopathy of prematurity or toxocariasis may cause pseudoexotropia. The light reflex test or cover testing elucidates this point. Also, make sure that the eyes move normally. Have the patient follow a light or a brightly colored toy to exclude paralysis or muscle restriction. If this test is normal and you notice true strabismus, quantify it with prisms at near and far. Check the cycloplegic refraction, and do a complete dilated exam. Anisometropic amblyopia may cause an eye to deviate, but it usually presents as esotropia in the younger age group. Also, a corneal lesion, cataract, glaucoma, or retinal lesion such as a toxoplasmosis scar or retinoblastoma may cause the deviation. These conditions must be ruled out.


    Once you have determined that the remainder of the exam is normal, you realize that the infant has an alternating exotropia of 40 prism diopters. Congenital exotropia is much rarer than congenital esotropia, but they have much in common. Both have a large angle of deviation and rarely develop amblyopia because of alternating fixation. The refractive error is normal. Early surgery is recommended to allow development of stereoacuity.


  • 3.

    A mother notices that her 2-year-old boy has a left eye that deviates outward when he is tired or has a fever. What is your concern as a physician?


    Intermittent exotropia, which is the most common type of exotropia. The onset varies from infancy to 4 years of age. It may progress through the following three phases:




    • Phase 1: Exophoria at distance and orthophoria at near occur when the patient is fatigued or daydreaming. He has diplopia and often closes one eye. When aware of the deviation, he is easily able to straighten his eyes, often after a blink.



    • Phase 2: Exotropia at distance and exophoria at near. When the exotropia becomes more constant, suppression develops and the diplopia becomes less frequent. The exotropia remains after a blink.



    • Phase 3: The exotropia is constant at distance and near. There is no diplopia because of suppression.



    Vision must be equalized by correcting any significant refractive error and patching the nondeviating eye. Surgery should be done when the patient progresses beyond phase 1, but preferably before phase 3.


  • 4.

    An 18-year-old patient complains of blurred near vision and headaches while reading. Do you believe her, or is she just trying to get out of doing her homework?


    Check her ocular deviations at near and far. She may be experiencing convergence insufficiency, which is common in teenagers and young adults. It is rare in children under 10 years of age. It is often idiopathic but may be exacerbated by fatigue, drugs, uveitis, or an Adie’s tonic pupil. Exodeviation is greater at near than at distance and causes asthenopia. Exophoria at near may be all that is seen. The near point of convergence is more distant than normal (>3 to 6 cm for patients younger than age 20; >12 cm for patients older than age 40), and the amplitude of accommodation is reduced.


    Her fusional ability will be decreased. If you have her focus on a target at the reading distance that forces her to accommodate, you will see that she will have a low break point or a low recovery point when slowly increasing the amount of base-out prism in front of one eye. The break point is when she begins to see double vision with increasing prism; the recovery point is when she can fuse to single images working down from the higher amount of prism. Ten to 15 prism diopters is considered low.


    Because she is symptomatic, treat her with base-in prisms for reading to help convergence. Near-point exercises or “pencil push-ups” can improve fusional amplitudes. These exercises are performed by having the patient slowly move a pencil from arm’s length toward the face while focusing on the eraser. Have the patient concentrate on maintaining one image of the eraser. Repeat 10 times several times a day. Once this is mastered, pencil push-ups can be done while holding a 6-D base-out prism over one eye. Rarely, medial rectus resection may be necessary.


  • 5.

    What if the fusional capacities are normal and there is no exodeviation?


    The problem may be accommodative insufficiency, which has similar symptoms in the same age group. However, accommodation is reduced. First check the manifest and cycloplegic refraction. The patient may be underplussed and need a stronger hyperopic refraction. If refraction is normal, plus-lens reading glasses will help.


  • 6.

    How do you differentiate a patient with convergence insufficiency versus accommodative insufficiency clinically?


    In accommodative insufficiency, a 4-D base-in prism will cause blurring during reading, whereas patients with convergence insufficiency will note that print becomes clearer.


  • 7.

    Some patients have the opposite problem: esotropia that is worse at distance than at near. What is this condition called?


    This is divergence insufficiency. Fusional divergence is reduced. Treatment is with base-out prisms and, rarely, lateral rectus resections. However, divergence insufficiency is a diagnosis of exclusion, and divergence paralysis must be ruled out because it may be associated with pontine tumors, head trauma, and other neurologic abnormalities. Neuro-ophthalmic evaluation is necessary.


  • 8.

    What is Duane’s syndrome? What are the different types of this disorder?


    Duane’s syndrome is a congenital motility disorder characterized by limited abduction, limited adduction, or both. The globe retracts, and the palpebral fissure narrows on attempted adduction. A “leash effect” may cause upward deviation at the same time. There are three types of the syndrome:




    • Type 1—limited abduction (most common) ( Fig. 26-1 )




      Figure 26-1


      Duane’s syndrome affecting the right eye. In primary position (middle), the eyes are aligned. There is reduction in the right palpebral fissure height on left gaze (top) and right upper eyelid retraction as well as an abduction deficit on right gaze (bottom).

      (From Burde RM, Savino PJ, Trobe JD: Clinical decisions in neuro-ophthalmology, ed 3, St. Louis, Mosby.)



    • Type 2—limited adduction



    • Type 3—both limited abduction and limited adduction (rarest type)



    There are three females to every two males afflicted with Duane’s syndrome. The left eye is involved in 60% of cases; in 18% of cases, both eyes are involved. Sixty percent of patients also have an associated esotropia, 15% have exotropia, and 25% are orthophoric. A and V patterns are common. Amblyopia, attributable to anisometropia, occurs in approximately one-third of cases. Surgery is done to correct a head turn, but resection should not be performed because it exacerbates the narrowing of the fissure and globe retraction.


  • 9.

    What is the cause of Duane’s syndrome?


    The cause is unclear, but it appears that the lateral rectus muscle is innervated by the third nerve, causing cocontraction of the medial and lateral rectus muscles. This theory explains the globe retraction and fissure narrowing.


  • 10.

    What other features may be associated with Duane’s syndrome?


    Goldenhar’s syndrome, deafness, crocodile tears, and uveal colobomas.


  • 11.

    What is the differential diagnosis of hypertropia?





    • Myasthenia gravis



    • Thyroid eye disease



    • Orbital inflammatory pseudotumor



    • Orbital trauma (may cause inferior rectus entrapment)



    • Fourth cranial nerve palsy



    • Pseudohypertropia



    • Skew deviation—see Chapter 30




Jul 8, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Miscellaneous Ocular Deviations

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