Evaluating early-onset Stargardt disease

A 33-year-old male attended to University of Alabama at Birmingham Eye Care complaining of blurry vision with either eye at both distance and near. He had a history of spectacle lens wear since childhood but also admitted to losing his glasses in most cases shortly after receiving them. His most recent eye examination was three years ago elsewhere. His most recent physical examination was over seven years ago when he was treated for a gunshot wound to the right thigh and knee.

Further elements of his ocular history include headaches while wearing spectacle correction, improved visual acuity at night than during the day, and that his right eye wanders at random times. 

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Review of systems was negative. Other than mentioned above, the patient’s ocular history, although vague, was unremarkable, as was the family ocular and medical histories. He is currently unemployed and takes no medications. Pupillary responses were all intact and intraocular pressure (IOP) was 11 mm Hg in each eye. Extraocular muscle movements were fully intact. Constant right exotropia was present and was greater at near than distance with a small hyper component.

Entering visual acuity was 20/200 in each eye, not improving with pinhole or refraction.  Other than a pinguecula nasally on the right eye, the anterior segment of each eye was unremarkable. 

Dilated fundus evaluation revealed an area of geographic area of macular atrophy 2 DD horizontally X 1.5 DD vertically with retinal pigment epithelium (RPE) remodeling throughout that was present and relatively symmetrical in each eye. The foveal reflex was absent in each eye (see Figure 1).

The clinical appearance as well as the rather vague ocular history was consistent with Stargardt macular degeneration despite an absence of confirmed family history. The diagnosis was confirmed with optical coherence testing (see Figure 2). Based on the history and extent of macular involvement, it is likely that this patient had early-onset Stargardt disease.¹

Management consisted of scheduling for low-vision evaluation as well as a discussion of the hereditary implications for his offspring. The patient was advised that his visual acuity did not meet the legal requirement for driving in the state of Alabama. 

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Discussion

Stargardt macular degeneration is a progressive genetic eye disorder that is the most common form of juvenile macular degeneration. Signs and symptoms generally begin early in life. The estimated prevalence is one in between 8,000 to 10,000 individuals.

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In most cases, Stargardt macular degeneration is caused by mutations in the ABCA4 gene. Less often, mutations in the ELOVL4 gene are responsible. Accumulation of toxic metabolic products of at the level of the photoreceptors results in formation of lipofuscin and cell death. Depending on mutations, inheritance patterns differ. Mutations in the ABCA4 result in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

We were unable to establish a history consistent with the patient’s ancestors being affected. 

Reference

1. Lambertus S, van Huet RA, Bax NM, et al.  Early-onset Stargardt disease: phenotypic and genotypic characteristics. Ophthalmology. 2015 Feb;122(2):335-44.