Natural History of Photoreceptor Degeneration in USH1B: Clinical Parameters and Validation of Functional Vision Tests in MYO7A

Inherited retinal diseases (IRDs) are a group of degenerative disorders that cause progressive vision loss. Retinitis pigmentosa (RP) is the most common form, with a global prevalence of approximately 1 in 4,500. About 20-30% of these cases are syndromic, most notably Usher syndrome (USH), which combines hearing loss with visual impairment. Usher syndrome type 1 (USH1), the most severe form, presents at birth with profound sensorineural hearing loss, vestibular areflexia, and early-onset retinal degeneration. Biallelic mutations in the MYO7A gene, which define the USH1B subtype, account for 70% of USH1 cases. There is currently no treatment available for this serious condition. The objective of the study is to characterize the natural history of retinal degeneration in USH1B patients and to validate functional vision tests using virtual reality and patient-reported outcome questionnaires.