Adult-onset foveomacular vitelliform dystrophy: A fresh perspective.

Adult-onset foveomacular vitelliform dystrophy (AFVD) was first described by Gass four decades ago. AFVD is characterized by subretinal vitelliform macular lesions and is usually diagnosed after the age of 40. The lesions gradually increase and then decrease in size over the years, leaving an area of atrophic outer retina and retinal pigment epithelium. This process is accompanied by a loss of visual acuity. Vitelliform lesions are hyperautofluorescent and initially have a dome-shaped appearance on optical coherence tomography. The electro-oculogram and full-field electroretinogram are typically normal, indicating localized retinal pathology. Phenocopies are also associated with other ocular disorders, such as vitreomacular traction, age-related macular degeneration, pseudodrusen, and central serous chorioretinopathy. A minority of AFVD patients have a mutation in the PRPH2, BEST1, IMPG1, or IMPG2 genes. A single-nucleotide polymorphism in the HTRA1 gene has also been associated with this phenotype. Accordingly, the phenotype can arise from alterations in the photoreceptors, retinal pigment epithelium, and/or interphotoreceptor matrix depending on the underlying gene defect. Excess photoreceptor outer segment production and/or impaired outer segment uptake due to impaired phagocytosis are likely underlying mechanisms. At present, no cure is available for AFVD. Thus, the current challenges in the field include identifying the underlying cause in the majority of AFVD cases and the development of effective therapeutic approaches.