The genetics of myopia

Myopia is the most common eye condition worldwide and its prevalence is increasing. While changes in environment, such as time spent outdoors, have driven myopia rates, within populations myopia is highly heritable. Genes are estimated to explain up to 80% of the variance in refractive error. Initial attempts to identify myopia genes relied on family studies using linkage analysis or candidate gene approaches with limited progress. More genome-wide association study (GWAS) approaches have taken over, ultimately resulting in the identification of hundreds of genes for refractive error and myopia, providing new insights into its molecular machinery. These studies showed myopia is a complex trait, with many genetic variants of small effect influencing retinal signaling, eye growth and the normal process of emmetropization. The genetic architecture and its molecular mechanisms are still to be clarified and while genetic risk score prediction models are improving, this knowledge must be expanded to have impact on clinical practice

Size, shape and age-related changes of the mandibular condyle during childhood

OBJECTIVE: To determine age-related differences in the size and shape of the mandibular condyle in children to establish anatomical reference values. METHODS: A total of 420 mandibular condyles in 210 children (mean age, 7 years) were retrospectively analysed by using computed tomography (CT) imaging. The greatest left-right (LRD) and anterior-posterior (APD) diameters and the anteversion angles (AA) were measured by two readers. An APD/LRD ratio was calculated. The shape of the condyles was graded into three types on sagittal images. Correlations of parameters with the children's age were assessed by using Pearson's correlation analyses. RESULTS: The LRD (mean, 14.1 +/- 2.4 mm), APD (mean, 7.3 +/- 1.0 mm) and LRD/APD ratio (mean, 1.9 +/- 0.3) increased (r (LRD) = 0.70, p < 0.01; r (APD) = 0.56, p < 0.01; r (rat) = 0.28, p < 0.01) while the AA (mean, 27 +/- 7 degrees ) decreased significantly (r (antang) = -0.26, p < 0.001) with age. The condylar shape as determined on sagittal images correlated significantly with age (r = 0.69, p < 0.05). Boys had significantly higher anteversion angles (p < 0.01), greater LRDs (p < 0.05) and greater mean ratios (p < 0.05). CONCLUSION: The mandibular condyle is subject to significant age-related changes in size and shape during childhood. As the size of the condyles increases with age, the anteversion angles decrease and the shape of the condyle turns from round to oval