Three-year-old girl presents with vomiting, vision changes
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A previously healthy 3-year-old girl was transferred to Tufts Medical Center from an outside hospital for persistent vomiting, mild gait abnormality and newly reported subjective vision changes in the left eye.
Five days prior, she had three episodes of non-bloody, non-bilious emesis and was noted by her parents to be unable to tolerate any oral intake other than Pedialyte and toast. Her parents reported that she had been febrile to 100°F at home. When she subsequently developed weakness, decreased urinary output and further inability to tolerate food or liquids, along with persistent vomiting, her pediatrician advised presenting to their local emergency department. There, she was noted to be afebrile, with review of systems negative for headache, upper respiratory infection symptoms, abdominal pain or diarrhea. The family had been traveling out of state for a family reunion when symptoms began, but the patient had no known sick contacts.
Source: Angell Shi, MD, and Catherine Choi, MD
Her medical history included constipation, and she had no ocular history. She had been born full term with normal development, had met all her developmental milestones on time, and lived at home with both parents and two older brothers. Her parents had noted some intermittent deviations of the left eye since birth, but these had never been persistent, and they had never noted any perceived vision abnormalities.
A physical exam demonstrated that the patient had a slightly unsteady gait, but the remainder of the exam was otherwise benign, with no focal neurologic deficits noted. An abdominal X-ray demonstrated a moderate to large stool burden. The patient was admitted for dehydration and electrolyte repletion with a differential diagnosis of viral enteritis vs. post-viral gastroparesis vs. constipation.
Two days later, while the patient was still admitted, her parents noted a worsening in her gait abnormality as well as an eye deviation in upward gaze. Specifically, she was noted to seem unwilling to walk without support. The child also reported seeing “sparkles” in her left eye and consistently complained of not being able to see the television when her right eye was covered. She was then transferred to Tufts Medical Center for further ophthalmologic and neurologic evaluation.
Examination
Initial evaluation occurred overnight, when the ophthalmology service was consulted, and the patient’s participation in visual acuity testing was limited by her fatigue. Her admission to the pediatric ICU also necessitated examination at bedside. She was noted to be able to fix and follow with both eyes. With the right eye, she could correctly identify objects at distance and near, but with the left eye, she stated that she could not see. Her pupils were round, symmetric and equally reactive to light with no relative afferent pupillary defect. The red reflex appeared duller in the left eye. Extraocular motility was full in both eyes, although she was noted to have an intermittent left esotropia. IOPs were soft to palpation bilaterally. Anterior and posterior segment exams were grossly normal in both eyes with no evidence of disc edema or retinal pathology.
A sedated MRI of the brain with and without contrast was performed the following day, along with a repeat ocular exam. At this time, visual acuity was noted to be 20/40 in the right eye and counting fingers in the left. Bedside examination revealed full motility and an approximately 30 prism diopters (PD) left esotropia as well as a left hypertropia by Hirschberg testing. Other than a dull red reflex on the left, the anterior and posterior segment exams were again unremarkable. Initial bedside cycloplegic retinoscopy demonstrated a refractive error of +0.25 D in the right eye and approximately –16.50 +1.00 × 110 in the left.
Review of the MRI demonstrated a gross asymmetry of the axial lengths (Figure 1). The radiologic read noted a “questionable enhancement” of the left optic nerve as well as a few nonspecific FLAIR white matter hyperintensities (Figure 2). The MRI was otherwise unremarkable.
The patient was treated with intravenous fluids and ondansetron. By the third day of admission, she was noted to be walking well and tolerating a normal diet without nausea, and it was determined she was medically stable for discharge. On follow-up in the pediatric ophthalmology clinic a few days later, she was found to have a 10 PD left esotropia at distance and near, as well as a 6 PD left hypertropia at near by Krimsky testing. Cycloplegic retinoscopy in the office revealed a refractive error of +1.25 D sphere on the right and –14.50 +2.00 × 080 on the left. Best corrected visual acuity on the left was 20/800.
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Vision changes
This pediatric patient with poor vision in one eye, esotropia and left hypertropia, and axial length asymmetry has a dense refractive amblyopia secondary to long-standing anisometropia due to high axial myopia. She also has a sensory esotropia and left hypertropia.
In the setting of her systemic symptoms, she likely had a viral or post-viral gastrointestinal illness leading to acute decompensation of her ocular alignment and the manifestation of her underlying amblyopia. Her gait instability and imbalance were thought to be related to her overall weakness. Despite an initial clinical picture concerning for an acute neurological process (with nausea, vomiting and new report of vision changes), reassuringly, the MRI did not show evidence of a space-occupying lesion, hydrocephalus or other acute intracranial abnormalities. Although there was a question of left optic nerve “enhancement,” further review of images demonstrated that this was due to asymmetric imaging sections secondary to long axial length of the myopic left eye (Figure 3).
Workup and management
In pediatric patients presenting with vision loss (or in patients too young to verbalize symptoms or any abnormal visual behavior), a complete ophthalmic examination is critical. Assessment of the binocular red reflex (also known as the Brückner test) can be a helpful preliminary tool for any practicing ophthalmologist, as an asymmetric red reflex can clue in the examiner that visually significant pathology may be present. Retinoscopy can and should be obtained to determine whether refractive error may be the cause of decreased vision, especially given the prevalence and treatability of uncorrected refractive error. In children who also have systemic and/or neurologic symptoms in the setting of vision loss, neuroimaging is essential to rule out neoplasms and other acute intracranial pathology. Although not present in this case, true optic nerve enhancement on MRI and/or clinical concern for optic neuritis warrants consideration of treatment with intravenous steroids. History is important to obtain from family members, particularly regarding any pertinent birth, developmental or family history. Involving the child in age-appropriate discussions of their symptoms can be useful as well, although unreliable in some cases.
Management of the patient’s conditions includes correction of her refractive error, along with treatment of the amblyopia and potential surgery for her ocular misalignment. In anisometric amblyopia, refractive correction alone can improve visual acuity and resolve amblyopia, although this typically occurs in cases of better visual acuity and lesser anisometropia at baseline. In children with very large refractive errors and/or initial visual acuity of 20/200 or worse in the amblyopic eye, as in this case, failure rates tend to be higher.
Treatment of amblyopia can be initiated with occlusion therapy or patching, in addition to refractive correction or optical treatment. The Pediatric Eye Disease Investigator Group studies have demonstrated that patching 6 hours per day has been shown to improve visual acuity in severe amblyopia (vision range 20/100 to 20/400). Pharmacologic treatment, typically with 1% atropine solution, can also be considered and has been shown to be successful for treatment of severe amblyopia, both in addition to and in lieu of patching. Instillation of atropine into the non-amblyopic eye causes defocus at near and encourages the brain to use the amblyopic eye. Families should be counseled on side effects of topical atropine treatment, which can include a transient reduction in visual acuity, photosensitivity, ocular irritation, and systemic side effects such as dry mouth, fever, tachycardia and delirium.
Newer technologies in the treatment of amblyopia include binocular or dichoptic digital therapy, such as with contrast-rebalanced images through video games or movies, with some promising results. Current studies are actively investigating the efficacy, duration and dosage of such strategies to treat amblyopia.
Treatment of amblyopia is adjusted based on patient response. Typically, visual acuity that does not improve after 3 months necessitates a change in therapy, such as an increase in duration of patching and/or frequency of atropine or implementing combination therapy.
Discussion
Amblyopia is a disorder of visual development resulting from inadequate visual input to the brain in childhood. It has a prevalence range from 0.7% to 2.6% in children aged 2 to 6 years and is most often unilateral. Known risk factors include prematurity, small size for gestational age, developmental delay and positive family history. There are several causes, including deprivation amblyopia, strabismic amblyopia (in which the amblyopia arises from ocular misalignment, thereby precluding normal visual input) or refractive amblyopia (which can also cause a secondary eye deviation). Occlusion or reverse amblyopia may also occur when children are undergoing treatment of amblyopia in the fellow eye.
Unilateral amblyopia is diagnosed when children display an objection to occlusion of the better-seeing eye, a fixation preference for the better-seeing eye, a four-card difference in the preferential looking test, or a difference of two or more lines between the two eyes (with normal vision in the better-seeing eye). It is commonly associated with strabismus, which occurs in 19% to 50% of cases. Ocular misalignment can lead to amblyopia through suppression of the visual signal from one eye, or it can be a sequela of decreased visual acuity, which then leads to the inability to maintain normal ocular alignment. This type of sensory deviation can often occur as esotropia in children younger than 4 years of age, while sensory exotropia occurs more in older children and adults. Although strabismus surgery can help facilitate management of amblyopia, in most cases surgery alone is insufficient, and patients still require adjuvant treatment.
Refractive error is also commonly associated with unilateral amblyopia and is present in 46% to 79% of cases. High axial myopia and axial length asymmetry may contribute to the development of refractive amblyopia, as in this case. Most children have an axial length at birth of approximately 17 mm, with a period of rapid growth until 18 months. On average, axial length at around age 3 years is 21.45 mm ± 0.696 mm. Measurements obtained from our patient’s MRI demonstrated axial lengths of 20 mm on the right and 23 mm on the left.
Children with a high degree of anisometropia are more likely to have amblyopia, and the amblyopia that develops tends to be more severe. Leon and colleagues found that more than 60% of children with 4 D of anisometropia or more have moderate or severe amblyopia, corresponding to a 6.2 times greater risk of amblyopia development. In contrast, approximately 22.5% of children with less than 2 D of anisometropia had amblyopia. These data show that early identification and initiation of treatment is critical, particularly for children with significant anisometropia who are at high risk for amblyopia.
The American Academy of Ophthalmology, American Academy of Pediatrics and American Association for Pediatric Ophthalmology and Strabismus recommend vision screening beginning at birth (for basic eye health such as red reflex, blink and pupil responses), between 6 to 12 months (for basic eye health including eye alignment and movement), 12 to 36 months (for healthy eye development), and 3 to 5 years of age and older (for vision and eye alignment). Screening can be done by pediatricians, family practitioners, optometrists and other trained health professionals, in addition to ophthalmologists.
Clinical course continued
After hospital discharge, the patient was reevaluated by neurology and noted to have normal gait and balance function. At her initial outpatient pediatric ophthalmology follow-up, she was dispensed a glasses prescription with polycarbonate lenses for significant anisometropic refractive error and scheduled urgently with the contact lens clinic. She was then successfully fit with a –10 D soft contact lens in the left eye and wore the residual refractive correction in glasses over the contact lens. She was started on patching 3 hours per day and atropine twice per week.
The patient was followed closely over the span of 19 months. During this time, her patching was increased to 4 to 6 hours per day and atropine increased to three times per week, with improvement in her visual acuity to a plateau of 20/200 in the left eye. However, her sensory left esotropia became increasingly noticeable to her parents (measuring 25 PD at distance and 30 PD at near). The decision was made to proceed with strabismus surgery, and the patient underwent a left medial rectus recession of 6 mm with improvement in her postoperative alignment. At 5 months postoperatively, she had a left esotropia of 2 PD at distance and 8 PD at near. Visual acuity was 20/20 in the right eye and 20/150 in the left eye while wearing glasses over her contact lens. She continues with patching 6 hours per day and atropine every other day and will continue to be monitored for improvement in her vision and stability of her ocular alignment.
Conclusion
Amblyopia is an important — and treatable — cause of decreased vision in young children. Retinoscopy is an essential diagnostic tool for refractive error, one of the most common causes of amblyopia. Correction of refractive error, patching and atropine are the mainstays of treatment, and new and developing technologies are underway. Early diagnosis and treatment are essential to help ensure optimal outcomes and visual function for these children.
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- For more information:
- Edited by Jonathan T. Caranfa, MD, PharmD, and Angell Shi, MD, of New England Eye Center, Tufts University School of Medicine. They can be reached at jcaranfa@tuftsmedicalcenter.org and ashi@tuftsmedicalcenter.org.
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