Publication Exclusive: Young child referred for difficulty seeing in the dark

A 5-year-old boy was referred to the retina service for progressively worsening night vision that began approximately 6 months before presentation. He denied changes in vision in well-lit settings, eye pain, redness, new floaters, photopsias and headaches. He had no history of trauma.

His ocular history was remarkable for mild astigmatism not requiring correction. His medical history was remarkable for asthma, sinusitis and an equivocal work-up thus far for von Willebrand’s disease, which his mother has. He was born full-term without complications during the pregnancy or delivery. There was a family history of night vision difficulties, including his mother and grandmother. His maternal uncle was legally blind.

Examination

On examination, the patient’s best corrected visual acuity was 20/25 in each eye. Pupils were round, equal and reactive. Confrontational visual fields and extraocular motility were full, and he had no pain with eye movements. IOP was within normal limits. Eyelids were normal, and the anterior segment exam revealed white and quiet eyes with clear lenses and no evidence of previous inflammation or trauma. Dilated fundus exam revealed healthy, pink optic nerves, and the vasculature was of normal course and caliber bilaterally. Macular sheen and foveal pigmentation were normal bilaterally. Peripheral retinal exam was remarkable for blonde fundi and diffuse pigmentary changes throughout the periphery and encroaching upon the maculae. General physical exam revealed a well-appearing and developmentally appropriate child with no discernible neurological or physical abnormalities.

What is your diagnosis?

Nyctalopia

The history and presentation of this young, healthy patient with nyctalopia and bilateral pigmentary retinopathy are suggestive of an inherited retinal degeneration, although acquired etiologies must be considered. Congenital rubella is a well-known cause of pigmentary retinopathy, and other ophthalmic manifestations of this infection include microphthalmia, cataract, glaucoma and uveitis. Other infectious causes of pigmentary retinopathy include congenital syphilis as well as measles, mumps and herpes. Medications such as thioridazine, chlorpromazine, chloroquine, hydroxychloroquine and deferoxamine have demonstrated toxicity to the retina, evident as pigmentary changes. Trauma and prior retinal detachments might also result in retinal pigmentation; however, these aforementioned acquired causes are inconsistent with the patient’s medical history.

Retinal pigmentation is associated with a host of syndromes including Kearns-Sayre, Bardet-Biedl, Alagille, Batten, Usher, Zellweger and many others. The patient’s history was not suspicious for a syndromic etiology, and his exam did not reveal associated features such as ptosis and ophthalmoplegia in Kearns-Sayre syndrome or developmental delay and polydactyly in Bardet-Biedl syndrome, to name a few.

The patient’s symptoms and exam findings were consistent with a process affecting the peripheral retina and preserving macular function. The most likely inherited retinal degenerations in this case are retinitis pigmentosa and choroideremia. Inheritance patterns of retinitis pigmentosa include autosomal dominant, autosomal recessive and X-linked recessive. The classic manifestations of retinitis pigmentosa include peripheral pigmentary changes resembling bone spicules, waxy pallor of the optic disc and attenuation of the retinal vasculature. Choroideremia is inherited in X-linked recessive fashion and demonstrates progressive and extensive loss of the choroid, choriocapillaris and retinal pigment epithelium (RPE), typically beginning in the mid-periphery and advancing both anteriorly and posteriorly. The process of diffusely deteriorating RPE can manifest as scattered pigmentation. In both conditions, nyctalopia is a common initial symptom.

Click here to read the full publication exclusive, Grand Rounds at the New England Eye Center, published in Ocular Surgery News U.S. Edition, November 25, 2015.