Late-onset night blindness with peripheral flecks accompanied by progressive trickle-like macular degeneration

To report the clinical and genetic characteristics of 6 cases with late-onset night blindness with peripheral flecks accompanied by progressive trickle-like macular degeneration. Clinical and genetic data were collected from 6 independent patients who complained of night blindness in their fifth to eighth decade of life. The ophthalmological examinations included ophthalmoscopy, fundus autofluorescence (FAF), and full-field electroretinography (ERG). Whole exome sequencing with target gene analysis was performed to determine the causative genes and variants. All of the patients first complained of night blindness at the ages of 40–71 years. Funduscopic examinations demonstrated white or atrophic flecks scattered in the posterior pole and peripheral retina bilaterally. FAF showed patchy hypo-autofluorescence spots in the posterior pole similar to that of the trickling type of age-related macular degeneration (AMD). The region of abnormal FAF rapidly expanded with age, and one eye developed a choroidal neovascularization. The full-field scotopic ERGs with 20 min of dark adaptation were severely reduced or extinguished in all cases. There was partial recovery of the ERGs after 180 min of dark adaptation. The cone ERGs were reduced in all cases. Whole exome sequencing revealed no pathogenic variants of 301 retinal disease-associated genes. The six cases had some common features with the flecked retina syndrome, familial drusen, and late-onset retinal degeneration although none had pathogenic variants causative for these disorders. These cases may represent a subset of severe trickling AMD or a new clinical entity of acquired pan-retinal visual cycle deficiency of unknown etiology.