title: The comparative study of two recently developed A-scan devices: determination of central corneal thickness, anterior chamber depth and axial length.
abstract: OBJECTIVE
  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 63.72 years [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) microm with the OcuScan RxP, and 547.46 (SD 35.70) microm 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Ophthalmology, Medical and Health Science Centre, University of Debrecen, Hungary. zoltansohajda@hotmail.com
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Sohajda
authors.forename: Júlia
authors.initials: J
authors.lastname: Papp
authors.forename: András
authors.initials: A
authors.lastname: Berta
authors.forename: László
authors.initials: L
authors.lastname: Módis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000000981:diagnostic imaging*; D003315:Cornea / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000295:instrumentation*