SFRP1 and keratoconus: In another study where tears from 33 keratoconus patients were analyzed by ELISA, secreted-frizzled related protein 1 (SFRP1), a protein associated with the Wnt signaling pathway, was observed at lower levels compared to age-matched controls, indicating a novel signaling pathway alteration in keratoconus [66] (Table 2).