Dark Choroid: A Sign of Stargardt’s Disease

Photojournalism
The Journal of Ophthalmic Photography
Volume 21, Number 1    April 1999 

Introduction

 This 43-year-old white male presented at the clinic with complaints of central and peripheral metamorphopsia OU for approximately three to five years. He denied any night vision problems, and showed normal color vision testing. The patient reported a history of RPE degeneration OU for 4 years. He was taking medication for attention deficit disorder and hypothyroidism. The patient had a negative family medical and ocular history.

 The patient’s visual acuity measured 20/15 OU, with a normal anterior slit lamp exam. On dilated exam, nultiple linear and “fishtail shaped” subretinal deposits or flecks were seen around the macula and peripherally outside the arcades OU. The fundi had a deep red or vermillion appearance. A diagnosis of Stargardt’s disease was made, and a fluorescein angiogram was ordered to confirm the diagnosis. The fluorescein angiogram revealed a “silent”, or dark choroid thorughtout the study. The areas of flecks hyperfluoresced in an irregular fashion early in the study, and faded slightly in the later images.

Discussion

In 1909, Karl Stargardt described an autosomal recessive disorder in patients from two families with visual loss in the first two decades of life. The patients presented with normal fundi initially, then later associated with macular atrophy and yellowish retinal flecks.1  Stargardt’s disease, or fundus flavimaculatus, affects patients early in life, caused by excessive storage of lipofuscin within the RPE that prevents bisualization of any choroidal details. Patients develop visual loss without any evidence of flecks or RPE atrophy initially, but eventually develop atrophic macular changes and yellowish RPE flecks. The flecks may appear similar to drusen, but differ in that they are variable in size and shape. They are not usually round, oval or dome shaped like drusen, and when the flecks are located in the midperiphery, they are sometimes described as fishtail shaped, or pisciform. 2

In differentiating these flecks from drusen, fluorescein angiography reveals an irregular pattern of hyperluorescence, unlike the pattern of hyperfluorescence in drusen that corresponds with the exact size of the drusen. Because of the excessive storage of lipofuscin in the RPE, the choroidal fluorescence is blocked, producing a dark background with a high-contrast image. Along with the irregular hyperfluorescence of the subretinal flecks, this confirms the diagnosis of Stargardt’s disease.

From a photographic standpoint, this case produced excellent images due to the dark background, producing dramatic images of the retinal vasculature which is shown clearly against this dark background. The macula and retina can appear normal on dilated exam, but the dark choroid on an angiogram is the definitive sign. When performing a fluorescein angiogram in a patient with suspected Stargardt’s diseas, whatch for the silent choroid sign, and  e prepared to adjust the flash setting. The same is true for color fundus photographs, as they may appear darker than usual. This dark or vermillion fundus is a ture finding in patients with Stargardt’s, and not an artifact of processing.

References

1.     Gass JD. Stereoscopic Atlas of Macular Diseases, Diagnosis and Treatment, fourth edition. Mosby-Year Book Inc. 5:326-328, 1997

2.     Stargardt K. Uber Familiare, Progressive Degeneration in der Maclagegend des Auges Albert von Graefes Arch Ophthalmol. 71:534-550, 1990