Myopia, hyperopia, astigmatism, presbyopia … the eye is a complex and fragile organ that can present defects. An eye that’s too long or too short, irregular curvature of the cornea, the slightest flexibility in the crystalline lens… every visual defect has a physiological explanation but also an appropriate corrective lens. These may be divergent or concave lenses for myopia, convergent or convex lenses for hyperopia, toric for astigmatism, near vision or progressive lens for presbyopia.