Fundus albipunctatus

Fundus albipunctatus is a rare inherited retinal dystrophy classified as a form of congenital stationary night blindness. It is characterized by the presence of numerous small, white-yellow punctate (dot-like) deposits scattered throughout the retina, predominantly in the mid-periphery, which are visible on fundoscopic examination. The condition primarily affects the eyes, specifically the photoreceptor cells and the retinal pigment epithelium (RPE). Patients typically present with night blindness (nyctalopia) from early childhood, which results from a markedly delayed regeneration of both rod and cone photopigments. Unlike many other retinal dystrophies, fundus albipunctatus has traditionally been considered a stationary or very slowly progressive condition, meaning that central visual acuity and visual fields are generally preserved throughout life in most patients. The disease is most commonly caused by biallelic mutations in the RDH5 gene, which encodes 11-cis retinol dehydrogenase, an enzyme critical for the visual cycle that regenerates visual pigment (rhodopsin) in the RPE. Mutations in RDH5 impair the conversion of 11-cis retinol to 11-cis retinal, leading to delayed dark adaptation. Some patients with RDH5 mutations may also develop cone dystrophy or macular atrophy later in life, suggesting the condition may not always be entirely stationary. Rarely, mutations in the RLBP1 gene (encoding cellular retinaldehyde-binding protein) have also been associated with a similar phenotype. Diagnosis is based on characteristic fundus findings, prolonged dark adaptation testing, and electroretinography (ERG), which typically shows reduced rod responses that normalize after prolonged dark adaptation. Genetic testing confirms the diagnosis. Currently, there is no specific curative treatment for fundus albipunctatus. Management is supportive and includes regular ophthalmologic monitoring, use of visual aids for night vision difficulties, and genetic counseling for affected families. Research into gene therapy and pharmacological approaches targeting the visual cycle is ongoing.

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