Stargardt disease is the most common form of macular dystrophy in young people and is a frequent hereditary cause of central vision impairment. It is estimated to affect between 1 in 8,000 and 1 in 10,000 individuals. The disease was first described in 1909 by Karl Stargardt. Despite significant advancements in understanding its genetics and pathology, as well as the development of imaging techniques for diagnosis, no effective treatment has yet been found.
Pathophysiology
Stargardt disease is primarily caused by mutations in the ABCA4 gene, inherited in an autosomal recessive manner, although some autosomal dominant pedigrees have been identified. Mutations in the ABCA4 gene lead to the accumulation of all-trans-retinal in photoreceptors and the retinal pigment epithelium (RPE), which is converted into N-retinylidene-N-retinylethanolamine (A2E), a component of lipofuscin that is toxic to the RPE and photoreceptors. These mutations are also responsible for other retinal degenerations.
Clinical Presentation
Stargardt disease typically manifests during the second or third decade of life and is characterized by a progressive and gradual decline in vision in both eyes. The onset and progression of symptoms vary significantly among affected individuals. The term “fundus flavimaculatus” describes a specific phenotypic expression of this condition, marked by widespread spots across the fundus.
Imaging Characteristics
Fluorescein angiography (FA), fundus autofluorescence (FAF), and spectral-domain optical coherence tomography (SD-OCT) are essential for the diagnosis and characterization of the disease.
The hallmark feature is a “dark choroid” on FA. FAF reveals hyperautofluorescence in areas of lipofuscin accumulation and hypoautofluorescence in areas of RPE atrophy. SD-OCT can show loss or disruption of photoreceptor segments.
Prognosis and Management
The impact on vision varies widely among individuals. In many cases, visual acuity may decrease to 20/200 or worse, stabilizing at this lower level.
Currently, there is no definitive cure; however, ongoing research into the pathophysiology and potential gene therapies offers hope for future solutions.
Patients are advised to adopt preventive measures such as sun protection, smoking cessation, and monitoring vitamin A intake to limit lipofuscin accumulation and slow disease progression.
See also this interesting case: Stargardt Disease in Heterozygotic Twin Siblings
