X-linked retinitis pigmentosa (XLRP) is a type of severe retinal dystrophy, and female carriers of XLRP demonstrate markedly variable clinical severity. In this study, we aimed to elucidate the clinical findings of male patients with and female carriers of XLRP in a Japanese cohort and demonstrate the genetic contribution. Twelve unrelated families (13 male patients, 15 female carriers) harboring pathogenic mutations in RPGR or RP2 were included, and comprehensive ophthalmic examinations were performed. To identify potential pathogenic mutations, targeted next-generation sequencing was employed. Consequently, we identified 11 pathogenic mutations, of which five were novel. Six and five mutations were detected in RPGR and RP2, respectively. Only one mutation was detected in ORF15. Affected male patients with RP2 mutations tended to have lower visual function than those with RPGR mutations. Female carriers demonstrated varying visual acuities and visual fields. Among the female carriers, 92% had electroretinographical abnormalities and 63% had a radial autofluorescent pattern, and the carriers who had higher myopia showed worse visual acuity and more severe retinal degeneration. Our results expand the knowledge of the clinical phenotypes of male patients with and female carriers of XLRP and suggest the possibility that RP2 mutations are relatively highly prevalent in Japan.

To determine the central corneal thickness (CCT) in Japanese children and to investigate the changes in CCT with increasing age. Pachymetry was performed on 338 eyes of 169 patients undergoing eye muscle surgery under general anesthesia, and the intraocular pressure (IOP) was measured on 312 eyes of 156 of those same patients. Patients with abnormalities other than refractive errors and strabismus were excluded. Patients were divided into four groups: group 1, ≤1 year of age; group 2, 2–4; group 3, 5–9; and group 4, 10–18 years of age. Analysis of variance (ANOVA) was performed to determine the significance of the changes in CCT. The average CCT of the right eye was 544.3 ± 36.9 μm. The CCT was thinner in group 1 than in groups 3 and 4 (ANOVA, P = 0.02). There was a positive but weak correlation between IOP and CCT (IOP = 6.253 + 0.014 × CCT; r ² = 0.047, P = 0.007). CCT reaches the adult thickness in Japanese children by age 5 years. The average CCT is thinner in Japanese children than in Caucasians but thicker than in African American children.