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 63.72 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) 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.

Central corneal thickness in children with growth hormone deficiency

“…The ultrasound pachimetry measurements GHD, growth hormone deficiency; SD, standard deviation. obtained in our study's control group correlate well with those described previously (Sohajda et al 2008).…”

Alterations in anterior chamber depth in primary open‐angle glaucoma patients during latanoprost therapy

“…However, the 20 consecutive measurements were conducted by a single experienced observer using the same device under the same physical conditions and no difference was detected between the baseline and 3-month measurements obtained in the control group, which indicates a good reproducibility. Moreover, Sohajda et al (2008) found a positive significant correlation between measurements obtained with different A-scan instruments.…”

Comparative evaluation of tomographic and biometric characteristics in bilateral keratoconus patients with unilateral corneal Vogt&rsquo;s striae: a contralateral eye study

“…This device is reliable in clinical use and we also applied this system for A-scan biometry. 28 Biometry was performed at the end of the measurements to avoid its probable influence on the other imaging modalities due to corneal flattening after applanation with the ultrasound probe. The mechanism of this device and its measurement method has been discussed in other studies.…”

“…The mechanism of this device and its measurement method has been discussed in other studies. 28 Before performing A-scan ultrasonography, in order to anesthetize the cornea, one drop of tetracaine 0.5% (Anestocaine; Sina Darou, Iran) was instilled in each eye. Since there was no study to assess the repeatability of ultrasound biometry in the KCN eyes, the measurements were repeated three times (10 results for each measurement) per eye and the mean value of the measurements was recorded.…”