The comparative study of two recently developed A-scan devices: Determination of central corneal thickness, anterior chamber depth and axial length

Abstract

Purpose: The clinical use and comparison of two recently developed A-scan ultrasound devices. Methods: The same investigator determined central corneal thickness (CCT), anterior chamber depth (ACD) and axial length (AL) with an OcuScan RxP (Alcon, Forth Worth, Texas, USA) and an AL-2000 (Tomey, Erlangen, Germany) ultrasound device in 80 eyes of 40 patients. The mean patient age was 63.72years [standard deviation (SD) 18.92]. The patients did not suffer from any systemic or eye disease affecting the anterior and posterior segments of the eye, and their refractive error (spherical and astigmatic) did not exceed ± 3.0 dioptres. Results: The value of the CCT was 541.55 (SD 34.97) μm with the OcuScan RxP, and 547.46 (SD 35.70) μm with the AL-2000 device (P < 0.001). With respect to the ACD and AL, significantly lower values were obtained with the AL-2000 instrument (P < 0.001). The ACD was 2.92 (SD 0.48) mm with the AL-2000 and 3.07 (SD 0.47) mm with the OcuScan RxP device. The AL was 22.67 (SD 0.84) mm with the AL-2000 and 22.81 (SD 0.87) mm with the OcuScan RxP instrument. However, a positive and significant correlation could be demonstrated between the devices (r = 0.88 CCT, r = 0.86 ACD and r = 0.91 AL; P < 0.001). Conclusion: The instruments are reliable in clinical use; however, statistically significant differences were found between the devices. During patient follow-up, the devices cannot simply be used interchangeably. © 2007 The Authors Journal Compilation 2007 Acta Ophthalmol Scand.