The Effects of Dry Eye on the Corneal Thickness Measured by Orbscan and Ultrasonic Pachymetry.

Purpose : To evaluate the effect of dry eye on the corneal thickness measured by Orbscan and ultrasonic pachymetry. Methods : The central corneal thickness was measured by both ultrasonic and Orbscan pachymetry in 30 eyes with dry eye (dry eye group) and in 30 eyes of normal subjects (control group). Dry eye was diagnosed when a Schirmer test result was less than 10 mm (after topical anesthesia) and the test for tear osmolarity was also performed. Results : Tear osmolarity was 364.442.9 mOsm/L in dry eye group and 337.834.5 mOsm/L in control group. It was significantly higher in dry eye group than in the control group (p=0.011). Mean central corneal thickness measured by Orbscan pachymetry was 547.527.3 in dry eye group and 562.020.4 in the control group. It was significantly thinner in dry eye group than in the control group (p=0.023). Mean central corneal thickness measured by ultrasonic pachymetry was 535.727.2 in dry eye group and 547.620.1 in the control group with out significant difference between the two groups (p=0.059). Conclusions :The corneal thickness measured by ultrasonic pachymetry is less affected by dry eye compared to that measured by Orbscan pachymetry.