Abstract: Objective: To evaluate the safety and the orthokeratic effect of longterm wearing of rigid gas permeable contact lens (RGPCL). Methods: A total of 366 eyes with keratoconus were subjected to wear proper RGPCL. Keratometer and corneal topography were used to determine the central cornea astigmatism, apex K value, apex decenteation distance, SRI and SAI before, 12 and 18 months after wearing RGPCL. Results: Of the slight keratoconus group: the above indexes significantly decreased(P＜0.05). Of the moderate group: the above indexes, except for the apex decentration distance significantly decreased at 12 months and more evidently at 18 months. Of the severe group, the K value significantly decreased at 12 months and other figures remained unchanged. However, all the indexes significantly decreased except that the apex decentration distance remained unchanged at 18 months. No corneal complications were found. Conclusion: Long-term wearing of RGPCL is safe and effect for keratoconus.

Key words: Keratoconus, Permeable contact lens, Orthokeratic effect