Fig. 2

The best corrected visual acuity (BCVA) in the study cohort of RP patients, stratified by sex and age. Bar graph demonstrated the distribution of BCVA in the sampled RP patients at first clinical presentation. a: more than half of the RP patients presented visual acuity deterioration at first clinical presentation and no significant difference was observed between gender. b: patients over the age of 44 showed a lower proportion of normal vision than patients under 44 at first presentation, and the proportion of blindness at first presentation in patients over 44 (45–64y: 34.6%; ≥65y: 43.8%) was higher than in patients under 44 (≤15y: 8.5%; 16–44y: 14.8%). The percentage of blindness significantly increased with age in the sampled RP patients (p = 0.000)