Corneal disease or trauma can result in front surface irregularity that may required specialty contact lenses to achieve the best vision possible. Examples of conditions that might result in corneal irregularity include: keratoconus, corneal dystrophy, corneal transplant, ocular surgery, or ocular trauma. Gas-permeable (GP) lenses are able to mask corneal irregularity by providing the anterior segment with smooth optical surface. Some patients find the smaller, more common corneal GP lenses harder to use and uncomfortable. Scleral lenses can often be successful for these patients because they are inherently more stable and comfortable to wear.