Hence, using SEM to define high myopia, which is affected by lens and eye shape, does not convey the direct effects of PAX6. However, high myopia defined by axial length, which is determined by changes to the shape of the eye only, demonstrates the direct effects of PAX6. This is why previous studies showed a significant association only in extreme myopia; almost all cases of extreme myopia present an abnormal eye shape. The gene discussed is PAX6; the disease is myopia.