AIM:To investigate the effect of wearing corneoscleral contact lens on visual acuity, and corneal parameters in keratoconus patients.METHODS:In this prospective study, 43 cases(83 eyes)with keratoconus were included and examined. A corneoscleral contact lens was fitted, and thorough exams were carried out at baseline, 3 and 6 mo after wearing lenses, including slit lamp examination, objective and subjective refraction, uncorrected visual acuity(UCVA), and best-corrected visual acuity(BCVA), keratometry(Kmax, K1 and K2), central corneal thickness and endothelial cells count.RESULTS: Mean BCVA(LogMAR)improved from 0.34±0.23 with the spectacles to 0.03±0.05 with the corneoscleral contact lenses in 6 mo(P<0.001). Kmax changed from 52.80±5.93 D to 51.51±5.64 D in 6 mo(P<0.001), central corneal thickness changed from 483.84±34.69 μm to 476.28±35.38 μm(P<0.001), and endothelial cell count changed from 2559.18±275.7 cells/mm2 to 2572.73±274.3 cells/mm2 after wearing corneoscleral contact lens for 6 mo(P<0.001).CONCLUSION: Corneoscleral lenses could significantly increase visual acuity, since there were no clinical noticeable changes in the corneal parameters, this lenses can be used safely in patients with keratoconus.