Mild to moderate keratoconus is best corrected with rigid gas permeable contact lenses, which provide a smooth surface in front of the cornea, making clear vision possible. Because the lens is rigid, the tears between the lens and the cornea form a ‘liquid lens,’ which smoothes the irregularities of the cornea and makes clear vision possible again. Soft lenses, which ‘wrap’ onto the cornea and take up its shape much more closely than rigid lenses, are less successful at correcting keratoconus. Unlike traditional contact lenses, the complex geometry built into the custom gas permeable lenses, closely mimic the cone-like shape of…