Soft contact lenses (SCLs) and soft toric contact lenses, rigid gas-permeable contact lenses (RGPCLs), piggyback contact lens system (PBCLs), hybrid contact lenses (HCLs), and scleral contact lenses (SsCLs) constitute the contemporary range of available lens types for the KC management with CLs.
In eyes in which this type of CLs proves to be inadequate, a piggyback system (PBCLs) could be a satisfactory option.
Graft characteristics might contraindicate corneal RGPCL readaptation , and in some cases, scleral RGPCLs or PBCLs might be the first choice.
 examined the immune histochemical effect of the PBCLs during 6 months of wear in patients with KC that never wore CLs before the study.
Furthermore, PBCLs have been used over intrastromal corneal ring segments (ICRS, Intacs[R]) in patients with KC.
Table 4 summarizes the characteristics and results of some of the most relevant studies on KC management PBCLs.
HCLs emerged as an alternative option to PBCLs and RGPCLs [106,107].
Furthermore, immunohistochemical changes have been studied in patients with KC fitted with ClearKone HCLs and PBCLs during 6 months .
C-ScCLs and ScCLs are not usually the first choice to fit but are commonly prescribed when other CLs (SCLs, RGPCLs, PBCLs , and HCLs [106,107,112,113]) show tolerance problems [117,118] or do not provide acceptable VA.