Visual acuity decreases due to progressive irregular astigmatism in keratoconus (KC). Although glasses can be useful in the initial stages of vision rehabilitation, contact lenses (CL) are needed in many patients due to irregular astigmatism. Although rigid gas permeable (RGP) CLs provided the patient with a better visual acuity than glasses, their effects on corneal tissues and caused comfort problems. Although soft CL produced for KC have solved some of these problems, they could not increase visual acuity as much as RGPs in advanced stage KC. For this reason, new searches for vision rehabilitation and comfort in KC have continued. In this context, piggyback contact lenses (PBCL) have been used in vision rehabilitation. Hybrid CLs have gained popularity due to the fact that PBCLs cause corneal neovascularization and giant papillary conjunctivitis. Scleral CLs have been developed for limited benefit in some patients with advanced KC. Scleral CLs provided good vision rehabilitation. The biggest problem of scleral CLs is the application and removal difficulty. All these CL modalities try to improve the quality of life and delay surgical procedures by increasing the level of vision in patients with KC.
Part of the book: Eyesight and Imaging