Usher syndrome — clinical case

This long case tests the candidate's ability to integrate the cochlear implant history with the new visual symptoms, recognise Usher syndrome as the single most common cause of dual deaf-blindness, and construct a management plan that addresses the retinal degeneration, the educational and mobility implications, and the genetic counselling of the whole family. The key teaching points are the two-wave presentation, the role of electroretinography in confirming subclinical retinal disease years before symptomatic visual field loss, and the rationale for baseline ophthalmology in every deaf child of unknown cause. ^[4]

The case unfolds in three phases. The first phase establishes the history of the congenital hearing loss and the cochlear implant outcome, confirming that the aetiology was never molecularly resolved. The second phase focuses on the night blindness and visual field constriction, the ophthalmology and electroretinographic findings of retinitis pigmentosa, and the molecular confirmation of an Usher gene variant. The third phase addresses the multidisciplinary management: low-vision support, mobility and orientation training, educational planning for progressive visual impairment, genetic counselling for the autosomal-recessive recurrence risk, and cascade testing of the younger sibling who currently has normal hearing. ^{[2] [4]}