Abstract
BACKGROUND: X-linked retinitis pigmentosa (XLRP) is the most severe form of retinitis pigmentosa (RP) and accounts for 15-20% of all RP cases. In this study, we investigated the progression of visual acuity loss across age groups in female carriers and compared it to affected males. METHODS: A PubMed literature search was conducted, and RP2 cases were included based on specific inclusion criteria. Visual acuity (VA), refractive error spherical equivalent (SE), and retinal findings were recorded. Cross-sectional analyses investigated the relationship between VA and age in carrier females and affected males. Genotype-phenotype VA correlations were studied using t-tests. RESULTS: 35 carrier females and 28 affected males with confirmed RP2 mutations were collected from 13 studies. The mean age and logMAR VA of carrier females were 44.2 ± 17.4 years, and 0.5 ± 0.5, respectively. 78.8% of carrier females showed abnormal XLRP-related fundus findings and had significantly reduced VA compared to those with normal fundi (0.6 ± 0.5 vs. 0.1 ± 0.1; p = 0.03). Compared to affected males, no statistical correlation was found between logMAR VA and advancing age in carrier females (p = 0.75). Statistically significant linear correlations were found between logMAR VA and SE in each of carrier females (p = 0.01). There were no observed differences in logMAR VA based on mutation type (p = 0.97) or mutation location (p = 0.83). Anisometropia was observed in 38% of carrier females and 68% of affected males; these prevalence numbers are statistically significant between the two groups (1.7 ± 0.3 vs. 3.9 ± 10.9 dioptres; p = 0.03). CONCLUSIONS: RP2 carrier females generally maintain good VA throughout their lifetime, as opposed to affected males, whose vision progressively declines. Our study provides important VA prognostic data that is crucial for patient counseling.