Two novel CHN1 variants identified in Duane retraction syndrome pedigrees disrupt development of ocular motor nerves in zebrafish.

Duane retraction syndrome (DRS) is a rare congenital eye movement disorder causing by the dysplasia of abducens nerve, and has highly variable phenotype. MRI can reveal the endophenotype of DRS. Most DRS cases are sporadical and isolated, while some are familial or accompanied by other ocular disorders and systemic congenital abnormalities. CHN1 was the most common causative gene for familial DRS. Until now, 13 missense variants of CHN1 have been reported. In this study, we enrolled two unrelated pedigrees with DRS. Detailed clinical examinations, MRI, and the whole exome sequencing (WES) were performed to reveal their clinical and genetic characteristics. Patients from pedigree-1 presented with isolated DRS, and a novel heterozygous variant c.650 A > G, p. His217Arg was identified in CHN1 gene. Patients from pedigree-2 presented with classic DRS and abnormalities in auricle morphology, and the pedigree segregated another novel heterozygous CHN1 variant c.637 T > C, p. Phe213Leu. A variety of bioinformatics software predicted that the two variants had deleterious or disease-causing effects. After injecting of two mutant CHN1 mRNAs into zebrafish embryos, the dysplasia of ocular motor nerves (OMN) was observed. Our present findings expanded the phenotypic and genotypic spectrum of CHN1 related DRS, as well as provided new insights into the role of CHN1 in OMN development. Genetic testing is strongly recommended for patients with a DRS family history or accompanying systemic congenital abnormalities.

Relationship between the length of macular Bruch's membrane on fundus photograph and myopia occurrence in pre-myopia children aged 3-6 years: A 3-year longitudinal study.

PURPOSE: To evaluate the occurrence and influencing factors of myopia occurrence in pre-myopia children aged 3-6 years. METHODS: This study included 204 pre-myopia (-0.50D-0.50D). The length of macular BM was shorter in Myopia group than that in Non-myopia group (P < 0.001). Baseline SE and the length of macular BM were independent influencing factors which associated with myopia occurrence (OR, 0.031; 95 % CI, 0.008-0.117, P < 0.001 and OR, 0.204; 95 % CI, 0.055-0.763, P = 0.018, respectively) by multivariate binary logistic regression analysis. SE changing process represented the changes of SE, Myopia group had bigger SE changes (P < 0.001). And in the multivariate liner regression analysis, age was the common influencing factor of SE changing process in total participants, Non-myopia group and Myopia group (B = 0.234, P < 0.001; B = 0.078, P = 0.010; B = 0.161, P = 0.046, respectively) CONCLUSIONS: Initial SE and the length of macular BM in pre-myopia children aged 3-6 years were the independent factors of the occurrence of myopia. And initial age was the common factor that associated with SE changing process.

Temporal vascular arcade angle in fundus image was associated with the rate of spherical equivalent refractive error and axial length changes in myopia children with young school age.

PURPOSE: To evaluate temporal vascular arcade angle and its influencing factors in myopic children. METHODS: It was a retrospective study, we reviewed the records of 119 patients aged 6-10 years with myopia (spherical equivalent refractive error (SER) ≤ -0.05D) in the third year of follow-up in Beijing Hyperopia Reserve Research. We measured temporal vascular arcade angles on the fundus photographs and measured 3-year rate of spherical equivalent(D/year) and axial length (AXL) changes(mm/year). RESULTS: Mean age at initial visit was 7.71±1.20 years and mean SER was -1.32±1.09D. Children were divided into two groups according to the refractive status of children at baseline: Myopia onset group (SER>-0.50D at baseline) (n = 107) and Myopia progression group (SER≤-0.50D at baseline) (n = 12). The mean SER in Myopia progression group was much smaller than Myopia onset group (P < 0.001) and mean AXL in Myopia progression group was much longer than Myopia onset group (P = 0.042). AXL (r=-0.320, P < 0.001), SER change rate (r=-0.209, P = 0.022) and AXL change rate (r=-0.232, P = 0.011) were associated with temporal vascular arcade angle in all participants. In Myopia onset group, AXL (r=-0.317, P < 0.001) and AXL change rate (r=-0.190, P = 0.05) were associated with temporal vascular arcade angle. There were no parameters were associated with temporal vascular arcade angle (all P > 0.05) in Myopia progression group. Only AXL (r=-0.306, P = 0.018) was associated with temporal vascular arcade angle in girls while AXL (r=-0.370, P = 0.004), SER change rate (r=-0.317, P = 0.013) and AXL change rate (r=-0.365, P = 0.004) were all associated with the Angle in boys. CONCLUSION: Temporal vascular arcade angle was associated with the rate of SER and AXL changes in myopia onset children, and showed gender differences. These may suggest that lamina cribrosa location has different influencing factors in different genders and different stages of myopia development. Due to the small number of people in Myopia progression group, large sample size studies are still needed in the future.

Tessellated fundus occurs earlier than myopia in children aged 3-6 years.

BACKGROUND/OBJECTIVES: Tessellated fundus can exist in normal healthy eyes. This study aims to evaluate the occurrence and influencing factors of tessellated fundus in preschool children aged 3-6 years. SUBJECTS/METHODS: This kindergarten-based cross-sectional study included 1716 children with an age range of 3-6 years. All participants underwent a comprehensive eye examination and a questionnaire. According to the number of quadrants occupied by tessellated fundus around the optic disc in fundus photographs, it was divided into four grades. RESULTS: 600 (35.0%) children had peripapillary tessellation. According to the spherical equivalent (SE), the subjects were divided into three groups: Hyperopia group (SE > + 0.75D, n = 1194)；Pre-myopia group (-0.50D < SE ≤ + 0.75D, n = 455); Myopia group (SE ≤ -0.50D, n = 67). The proportion of peripapillary tessellated fundus was 33.0%, 38.0%, 50.7% respectively. According to the regression analysis, in the non-myopia group (Pre-myopia group and Hyperopia group), the occurrence of peripapillary tessellated fundus was associated with longer axial length (OR, 1.566; 95% CI: 1.229-1.996, p < 0.001) and larger corneal radius of curvature (OR, 1.837; 95% CI: 1.006-3.354, p = 0.048). However, in Pre-myopia group, the corneal radius of curvature was not associated with the occurrence of peripapillary tessellated fundus (p = 0.830). In Hyperopia group, the corneal radius of curvature was associated with the occurrence of peripapillary tessellated fundus (OR, 2.438; 95% CI: 1.160-5.122, p = 0.019). CONCLUSIONS: The occurrence of peripapillary tessellated fundus is more than 30% in 3-6 year old preschool children. Tessellated fundus can also occur in non-myopic children, and is related to the length of axial length and large radius of corneal curvature.