Objective To observe the changes in corneal shape， corneal thickness and corneal biomechanics in keratoconus patients who wore RGPCL for more than 1 year. Methods In this retrospective case series study， 15 patients （30 eyes） with moderate or worse keratoconus were recruited. Average spherical and astigmatic powers were -9.53±3.60 D and -3.42±2.13 D， respectively. The RGPCL were fitted for diagnosed keratoconus eyes， and a paired t-test was used to compare corneal parameters between before and after 1 year of lens wear. Measured parameters included spherical and astigmatism power， corneal flat and steep K values， corneal thickness， corneal hysteresis （CH） and the corneal resistance factor （CRF）. Results Some changes occurred to keratoconus eyes after 1 year of wear： corneal steep K values decreased from 49.21±4.06 D to 47.95±3.16 D （t=3.156， P<0.05）； the corneal surface regularity index （SRI） and surface asymmetry index （SAI） decreased from 0.47±0.15 and 0.49±0.16 to 0.36±0.14 and 0.38±0.19 （t=2.314， 2.253， P<0.05）； corneal astigmatism decreased from -3.42±2.13 D to -2.63±1.57 D （t=-5.270， P<0.01）； corneal thickness had no significant change； corneal biomechanical CH increased from 8.26±0.39 mmHg to 10.23±0.49 mmHg （t=-5.954， P<0.01）； and corneal biomechanical CRF increased from 7.53±0.56 mmHg to 9.05±0.58 mmHg （t=-5.340， P<0.01）. Conclusion By following the change in corneal shape after 1 year of RGPCL wear， corneal biomechanical properties have significant increases in eyes with moderate or worse keratoconus. The patient′s condition and corneal biomechanics can be the key indicators for the efficacy of treating keratoconus patients with RGPCLs.
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