A Toddler With Periodic Strabismus

Monica Verma, MD; Kimberly G. Yen, MD


September 08, 2010

Clinical Presentation

A 3-year-old boy presented to the clinic for evaluation of occasional ocular misalignment during the previous 6 weeks. The patient's father reported that the child's right eye was crossing inward for 2 to 3 days each week. He stated that on some days, the eyes were misaligned during the entire day, and on other days, the eyes were completely straight throughout the day. The father also reported that on some days, the eyes were misaligned for only part of the day. During the month of March 2010, he documented the dates and times of day when the child's eyes were misaligned (Table).

Table. Occurrence of Patient Eye Misalignment

Date AM PM
March 6, 2010 -    +  
March 7, 2010 +   +  
March 9, 2010 +   +  
March 12, 2010 +   -  
March 18, 2010 +   -  
March 20, 2010 -   +  
March 22, 2010 +   -  

AM indicates the patient woke up in the morning (6:30 AM) with misaligned eyes; PM indicates he woke up from his nap (2 PM) with misaligned eyes. A "+" in both columns indicates that the eyes were misaligned the entire day.

On initial examination, the child had no ocular misalignment by both the cover-uncover and the alternate cover tests. Visual acuity was 20/20 in both eyes, with alternate fixation preference. Stereopsis measured 50 seconds at 15 minutes of arc. Versions were normal, and he had no nystagmus. The pupils were equal, round, and briskly reactive to light with no afferent pupillary defect. The slit lamp and dilated fundus examinations were normal for both eyes. Cycloplegic refraction revealed mild hyperopia with a refractive error of +1.25 sphere in the right eye and +0.75 +0.50 x 090 in the left eye.

At the follow-up visit 4 weeks later, the father reported that the ocular misalignment had become more frequent, now occurring 3-4 days per week. He also reported that the degree of misalignment was greater. On questioning, the patient denied having diplopia. On examination, visual acuity was 20/20 in both eyes. He had 35 prism diopters of esotropia at both distance and near. Stereopsis measured 200 seconds at 15 minutes of arc. Versions and head posture were normal, and he had no nystagmus. The father brought photographs of the patient demonstrating a day when the eyes were straight and a day when the eyes were misaligned (Figures 1 and 2).

Figure 1. The patient's eyes are aligned.

Figure 2. The patient has significant ocular misalignment.

What is the most likely diagnosis?

A. Basic (acquired) esotropia
B. Accommodative esotropia
C. Cyclic esotropia
D. Cranial nerve VI palsy
E. Spasm of the near synkinetic reflex

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Which of the following is a feature of this condition?

A. Estimated incidence of 1:3000 to 1:5000 strabismus cases
B. Typically begins during preschool years
C. Defective or absent fusion and binocular vision on the strabismic day
D. Conversion to a constant strabismus with occlusion therapy
E. All of the above

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