Child presents with bilateral poor vision
There was moderate temporal pallor of the right optic nerve and severe temporal pallor of the left optic nerve that was more diffuse.
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A 7-year-old boy presented to a satellite office of the New England Eye Center after referral from a local optometrist for persistently decreased vision despite appropriate spectacle correction for myopia and astigmatism. The optometrist had diagnosed him with refractory amblyopia and referred him for further evaluation given minimal improvement in vision with glasses and a short trial with patching.
The patient had a history of mild developmental delays and an unspecified behavioral disorder for which he was being evaluated by a behavior specialist. He was otherwise healthy and was prescribed no medications. He did not complain of headaches. He had no significant family medical history.
Examination
Upon examination, the patient’s best corrected visual acuity was 20/50 in the right eye and 20/100 in the left eye. Pupillary exam was slightly asymmetric with possible early release of the left pupil. IOP was within normal limits in each eye. Motility was grossly full. Color vision was full in the right eye (9.5/10 Ishihara plates) and decreased in the left eye (1/10 Ishihara plates). Cycloplegic refraction was –3.75 +1.00 at 90° in the right eye and –4.25 +1.50 at 85° in the left eye. There was no improvement in his vision with repeat refraction in the office.
External examination and slit lamp examination were unremarkable. On fundoscopy, there was moderate temporal pallor of the right optic nerve and severe temporal pallor of the left optic nerve that was more diffuse. The optic nerve rims were intact with a 0.3 cup-to-disc ratio in each eye.
What is your diagnosis?
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Bilateral poor vision
Refractive amblyopia occurs when uncorrected refractive error leads to the failure of normal visual development. Unilateral refractive amblyopia is seen when there is a significant difference in the refractive error of each eye. Bilateral refractive amblyopia can occur when there is a substantial but similar refractive error in each eye. Generally, unilateral refractive amblyopia is more likely in the setting of 3 D to 4 D of anisomyopia, and bilateral refractive amblyopia is more likely in the setting of 5 D to 6 D of myopia. Astigmatism is more amblyogenic compared with myopia, with bilateral refractive amblyopia likely to occur in the setting of only 2 D to 3 D of astigmatism.
Source: Sarah E. Thornton, MD, and Catherine Choi, MD
Optic nerve atrophy refers to pallor of the optic nerve caused by the death of retinal ganglion cells and axons. Injury to retinal ganglion cells anywhere along their path from the retina to the lateral geniculate body can result in optic nerve pallor and atrophy. The differential diagnosis of pediatric optic nerve atrophy is broad and includes inflammatory, ischemic, compressive, nutritional, traumatic and hereditary causes. A study by Mudgil and colleagues examining 272 children younger than 10 years of age found complications related to premature birth as the most frequent etiology of optic atrophy (16% of patients) followed by tumors (15% of patients). Other common causes identified in this study included hydrocephalus, ischemia, brain malformations, trauma, genetic disease and inflammatory conditions.
In this case, the patient’s degree of refractive error was less likely to cause a unilateral or bilateral refractive amblyopia. The patient’s mother denied history of premature birth or trauma.
Workup and management
The patient underwent additional in-office testing including OCT of the retinal nerve fiber layer (RNFL), which revealed diffuse thinning of the left optic nerve more than the right (Figure 1). OCT of the macula of each eye showed normal foveal contour. Humphrey visual field testing revealed a dense temporal hemifield defect respecting the vertical meridian in the right eye and diffusely depressed fields in the left eye more prominent nasally (Figure 2). The findings were concerning for a right homonymous field defect with more diffuse field loss in the left eye.
Given the clinical history and examination findings, the patient was sent urgently for brain MRI, which revealed a large enhancing mixed cystic and solid mass centered in the optic chiasm/suprasellar cistern without involvement of the pituitary gland (Figure 3a). The mass resulted in obstructive hydrocephalus with enlargement of the lateral ventricles (Figure 3b).
The patient underwent right frontal craniotomy for a transventricular partial tumor resection, biopsy and external ventricular drain placement. Final pathology of the intracranial mass was consistent with juvenile pilocytic astrocytoma. He is currently undergoing chemotherapy treatment with carboplatin and vincristine.
The patient was seen at the New England Eye Center for follow-up 5 months after his original diagnosis. At that time, his vision was stable at 20/40 in the right eye and 20/100 in the left eye. He had slight progression of optic nerve thinning bilaterally on OCT RNFL testing. His visual field testing showed stable deficits.
Discussion
Juvenile pilocytic astrocytoma (JPA) is the most common glioma of childhood and typically presents with a well-circumscribed mass in the cerebellum or near the optic chiasm and hypothalamus. Presenting symptoms vary depending on tumor location but may include vision loss with lesions in the optic pathway, headache and vomiting with lesions causing obstructive hydrocephalus and elevated intracranial pressure, or ataxia with lesions in the cerebellum.
In pediatric patients, JPA tends to have a relatively benign course with a 10-year survival rate of greater than 90%. The prognosis is especially good with tumors that can be completely resected.
Diagnosis of JPA may be suspected based on characteristic neuroimaging findings. On CT imaging, tumors appear round and smooth with clear enhancement and frequent cyst formation. The presence of vasogenic edema is uncommon. On MRI, the well-circumscribed tumors appear hypointense on T1-weighted images and hyperintense on T2-weighted images.
JPA is primarily managed surgically with the aim to resect as much tumor as possible. A greater extent of surgical resection is associated with better prognosis and overall survival rates. Residual tumor can be targeted with chemotherapy or radiation.
- References:
- Al-Haddad C, et al. BMC Ophthalmol. 2014;doi:10.1186/1471-2415-14-53.
- Braverman RS. Types of amblyopia. www.aao.org/disease-review/types-of-amblyopia. Published Oct. 21, 2015. Accessed Oct. 11, 2019.
- Lee YY, et al. AJR Am J Roentgenol. 1989;doi:10.2214/ajr.152.6.1263.
- Mudgil AV, et al. Clin Exp Ophthalmol. 2000;doi:10.1046/j.1442-9071.2000.00254.x.
- Osaguona VB. Community Eye Health. 2016;29(96):71-74.
- Recht LD, et al. Treatment and prognosis of diffuse (grade II) and anaplastic (grade III) astrocytomas in adults. www.uptodate.com/contents/treatment-and-prognosis-of-diffuse-grade-ii-and-anaplastic-grade-iii-astrocytomas-in-adults.
- Repka MX, et al. Am J Ophthalmol. 1988;doi:10.1016/0002-9394(88)90833-1.
- For more information:
- Sarah E. Thornton, MD, and Catherine Choi, MD, can be reached at New England Eye Center, Tufts University School of Medicine. 800 Washington Street, Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Alison J. Lauter, MD, and Sarah E. Thornton, MD. They can be reached at the New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.