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Purpose: Synaptosomal actin dynamics are essential for synaptic structural stability. Whether actin dynamics are involved in structural and functional synaptic plasticity within the primary visual cortex (V1) or behavioral visual acuity in rats has still not been thoroughly investigated., Methods: Synaptosome preparation and western blot analysis were used to analyze synaptosomal actin dynamics. Transmission electron microscopy was used to detect synaptic density and mitochondrial area alterations. A visual water maze task was applied to assess behavioral visual acuity. Microinjection of the actin polymerization inhibitor or stabilizer detected the effect of actin dynamics on visual function., Results: Actin dynamics, the mitochondrial area, and synaptic density within the area of V1 are increased during the critical period for the development of binocularity. Microinjection of the actin polymerization inhibitor cytochalasin D into the V1 decreased the mitochondrial area, synaptic density, and behavioral visual acuity. Long-term monocular deprivation reduced actin dynamics, the mitochondrial area, and synaptic density within the V1 contralateral to the deprived eye compared with those ipsilateral to the deprived eye and impaired visual acuity in the amblyopic eye. In addition, the mitochondrial area, synaptic density, and behavioral visual acuity were improved by stabilization of actin polymerization by jasplakinolide microinjection., Conclusions: During the critical period of visual development of binocularity, synaptosomal actin dynamics regulate synaptic structure and function and play roles in behavioral visual acuity in rats.

Purpose: To describe prevalence and associations of anisometropia in children., Methods: The cross-sectional school-based study included children aged 4 to 18 years., Results: The study included 6025 (94.7%) of 6364 eligible children. Mean refractive anisometropia was 0.37 ± 0.57 diopters (median: 0.25 diopters; range: 0-7.88 diopters; prevalence [≥1 diopter]: 7.0% ± 0.3%). In multivariate analysis (regression coefficient r: 0.66), higher refractive anisometropia was associated with older age (P < 0.001; β: 0.07; B: 0.01; 95% CI: 0.01-0.02), higher maternal education level (P < 0.001; β: 0.04; B: 0.02; 95% CI: 0.01-0.03), more total time spent indoors reading or writing (P = 0.001; β: 0.04; B: 0.01; 95% CI: 0.01-0.02), larger intereye difference in axial length (P < 0.001; β: 0.57; B: 1.20; 95% CI: 1.15-1.24), shorter mean axial length of both eyes (P = 0.03; β: -0.03; B: -0.02; 95% CI: -0.03 to -0.001), larger intereye difference in best corrected visual acuity (BCVA) (P < 0.001; β: 0.14; B: 1.83; 95% CI: 1.54-2.12), and lower stereoacuity (P < 0.001; β: 0.08; B: 0.31; 95% CI: 0.22-0.39). Refractive anisometropia showed a U-shaped correlation with refractive error. Higher anisomyopia was associated (r: 0.57) with older age (P = 0.001; β: 0.05; B: 0.006; 95% CI: 0.002-0.009), higher level of paternal education (P = 0.001; β: 0.01; B: 0.01; 95% CI: 0.01-0.02), more total time spent indoors reading or writing (P = 0.01; β: 0.03; B: 0.01; 95% CI: 0.00-0.01), larger intereye difference in axial length (P < 0.001; β: 0.22; B: 0.26; 95% CI: 0.23-0.29), greater myopic refractive error (P < 0.001; β: -0.46; B: -0.07; 95% CI: -0.08 to -0.07), and lower corneal astigmatism (P < 0.001; β: -0.10; B: -0.06; 95% CI: -0.08 to -0.05). In the same multivariate model, hyperopic anisometropia was not significantly associated with time spent indoors with reading (P = 0.18). Cylindrical anisometropia (mean: 0.30 ± 0.32 diopters; prevalence [≥1 diopter]: 3.7% ± 0.2%) increased with higher refractive anisometropia (P < 0.001; β: 0.16; B: 0.09; 95% CI: 0.08-0.11), greater myopic refractive error (P < 0.001; β: -0.06; B: -0.01; 95% CI: -0.01 to -0.01), higher corneal astigmatism (P < 0.001; β: -0.22; B: -0.15; 95% CI: -0.17 to -0.13), and lower mean BCVA (P < 0.001; β: 0.11; B: 0.90; 95% CI: 0.68-1.17)., Conclusions: In 4- to 18-year-old children, refractive anisometropia and anisomyopia increased with systemic parameters such as age, parental education level, and lifestyle of the children, for example, more time spent indoors reading or writing. In contrast, hyperopic anisometropia and cylindrical anisometropia were not related with lifestyle parameters.

Purpose: To examine the thickness of the macular choroid and its associations in school children aged 6 to 18 years., Methods: The school-based cross-sectional Shandong Children Eye Study included 6026 (94.7%) of 6364 eligible children fulfilling the inclusion criterion of an age from 4 to 18 years. Spectral-domain optical coherence tomography (SD-OCT) was performed for a subgroup of 972 school children aged 6+ years. All participants underwent ocular examinations, including measurement of visual acuity, cycloplegic refractometry, biometry, and SD-OCT (enhanced depth imaging mode) for measurement of choroidal thickness., Results: The study included 972 children (501 girls) with a mean age of 11.3 ± 3.3 years (range, 6-18 years) and mean axial length of 24.10 ± 1.56 mm (range, 16.57-28.82 mm). Mean choroidal thickness was thicker (P < 0.001) at 500 μm temporal to the foveola (290 ± 67 μm) than in the subfoveal region (283 ± 67 μm; range, 113-507 μm) and the region 500 μm superior to the fovea (283 ± 66 μm), where it was thicker (P < 0.001) than at 500 μm inferior of the foveola (281 ± 66 μm), and it was thinnest (P < 0.001) at 500 μm nasal of the foveola (268 ± 67 μm). In multivariate analysis, thicker SFCT was (overall correlation coefficient r: 0.51) associated with shorter axial length (P < 0.001; standardized correlation coefficient β: -0.48; B: -23.7; 95% confidence interval [CI]: -27.2 to -20.3), male sex (P = 0.006; β: -0.08; B: -10.7; 95% CI: -18.3 to -3.11), and younger age (P = 0.04; β: -0.07; B: -1.46; 95% CI: -2.85 to -0.07)., Conclusions: As in adults, thicker SFCT in children and teenagers was markedly associated with shorter axial length, and to a lesser degree with male sex and older age. As in adults, increasing axial myopia in teenagers is associated with choroidal thinning and development of a leptochoroid.

Purpose: We examined the distribution of intraocular pressure (IOP) and its associated factors in children., Methods: Using a random cluster sampling from kindergartens, primary schools, and junior and senior high schools from rural Guanxian County and the city of Weihai, the school-based cross-sectional Shandong Children Eye Study included children aged 4 to 18 years. All participants underwent an ocular examination, including ocular biometry, cycloplegic refractometry, and noncontact tonometry., Results: Mean IOP was 17.6 ± 2.7 mm Hg (range, 10-28 mm Hg). The IOP increased up to an age of 10 years and subsequently decreased with older age. In multivariate regression analysis, higher IOP was associated with female sex (P < 0.001; standardized correlation coefficient β, 0.06; regression coefficient β, 0.34; 95% confidence interval [CI], 0.18, 0.50), higher body mass index (P < 0.001; correlation coefficient β, 0.09; regression coefficient β, 0.07; 95% CI, 0.04,0.09), younger age (P < 0.001; correlation coefficient β, -0.15; regression coefficient β, -0.13; 95% CI, -0.17,-0.10), maternal myopia (P < 0.001; correlation coefficient β, 0.05; regression coefficient β, 0.34; 95% CI, 0.15,0.53), and more time spent indoors with reading/writing (P = 0.002; correlation coefficient β, 0.05; regression coefficient β, 0.07; 95% CI, 0.03,0.11), and with the ocular parameters of longer axial length (P < 0.001; correlation coefficient β, 0.14; regression coefficient β, 0.29; 95% CI, 0.21,0.37) and smaller corneal horizontal diameter (P < 0.001; correlation coefficient β, -0.06; regression coefficient β, -0.31; 95% CI, -0.46,-0.15)., Conclusions: In children aged 4 to 18 years, IOP showed an M-shaped association with age. Higher IOP was associated with the nonocular parameters of female sex (P < 0.001), higher body mass index (P < 0.001), younger age (P < 0.001), maternal myopia (P < 0.001), and more time spent indoors with reading/writing (P = 0.002), and with the ocular parameters of longer axial length (P < 0.001) and smaller corneal horizontal diameter (P < 0.001)., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)