AIM:To investigate the effect of dry eyes on corneal thickness measurement with Pentacam imaging system.METHODS:Totally 60 dry eyes 30 cases were enrolled in this study.The Pentacam imaging system and ultrasound was used for each eye,corneal thickness was examined and compared before and after treatment.RESULTS:The corneal thickness was 504.5±37.3μm in dry eyes(ranged from 428 to 557μm)with Pentacam imaging system and 532.7±32.4μm(ranged from 477 to 596μm)with ultrasound,the difference between two measurement methods was significant(P<0.05).After treatment,the corneal thickness was 541.2±41.1μm(ranged from 469 to 607μm)with Pentacam imaging system and 538.4±30.7μm(ranged from 472 to 593μm)with ultrasound,the difference between two measurement methods was not statistically significant(P>0.05).CONCLUSION:The dry eyes have significant effect on corneal thickness measurement with Pentacam imaging system.It should be treated in order to obtain accurate results.