Characterizing the non-pigmented retinitis pigmentosa in a Chinese cohort: Insights into phenotype, genotype, and disease progression.

PURPOSES: To characterize the comprehensive clinical and genetic spectrum of non-pigmented presentation of retinitis pigmentosa in a large Chinese cohort, addressing a significant knowledge gap in non-Caucasian populations. METHODS: This retrospective, cross-sectional study identified and characterized 80 patients with an absence of typical pigmentation from a cohort of 1063 individuals with retinitis pigmentosa at a single tertiary center. RESULTS: A proportion of 7.5% of the retinitis pigmentosa patients in our clinic-based cohort presented with the non-pigmented phenotype. This subgroup was characterized by a myopic shift (median spherical power: -1.00 D) and a distinct superior-to-inferior gradient of visual field defect. Survival analysis identified a critical window of accelerated functional decline between ages 34.5 and 52. Visual acuity decline was biphasic, with rates peaking within the first 5 years (0.044 logMAR/year) and after 40 years of disease (0.079 logMAR/year). Age significantly amplified the detrimental effect of disease duration on vision (β = 0.015 vs. 0.008 logMAR/year in older vs. younger patients). Structurally, horizontal ellipsoid zone width was a key biomarker. A definitive genetic diagnosis was achieved in 41.3% (33/80) of patients, most frequently EYS and USH2A. Genotype-phenotype correlations revealed that large structural deletions and truncating variants were significantly associated with ultra-early onset and more severe visual impairment, respectively. CONCLUSIONS: This study characterizes the non-pigmented presentation within the retinitis pigmentosa disease spectrum, detailing its phenotypic characteristics and natural history. The identified clinical, structural, and genetic biomarkers enable refined prognosis and inform stratified therapeutic trials.