Comparison of the measurements of a novel optical biometry: Nidek AL-Scan with Sirius and a ultrasound biometry

Abstract

To investigate the accuracy of the measurements of Nidek AL-Scan by comparing with Sirius (CSO, Florence, Italy), a corneal tomography which also employs the Scheimpflug principle, and a commonly used device, ultrasound biometry (UB) (Aviso A/B, Quantel Medical, MT, USA). Right eyes of 85 healthy volunteers (58 women 27 men) with a mean age of 39.24 ± 14.37 years (range 15-68) were enrolled into this comparative prospective study. Average K 2.4, average K 3.3, CCT (central corneal thickness), WTW (white to white distance), ACD (anterior chamber depth) and AL (axial length) were obtained from the AL-Scan and compared with average SimK, CCT, WTW (horizontal anterior chamber diameter) and ACD obtained from Sirius and also compared with ACD and AL obtained from UB. The statistically significant difference was found between all of the measurements (p < 0.001) except the average keratometry values (K2.4, K3.3, SimK) (p = 0.083). There was a perfect correlation between keratometry, CCT and AL measurements of the devices (ICC = 0.977, 0.954, 0.923, respectively) and there was a strong correlation between the WTW measurements of AL-Scan and Sirius (ICC = 0.865). While ACD parameter of AL-Scan and UB showed a perfect correlation (ICC = 0.977), there was a moderate correlation between AL-Scan and Sirius and also between UB and Sirius (ICC = 0.608 and 0.664, respectively). There was a high correlation between the all measurements, besides ACD, of AL-Scan and Sirius and they can be used interchangeably for average keratometry and WTW confidently. However, ACD and CCT have a broader 95 % LoA (-0.039 to 0.744 and -24.985 to 3.691, respectively). In addition, AL-Scan and UB were in good agreement regarding ACD, while differences in AL measurements of UB and AL-Scan were clinically important (95 % LoA = -0.091 to 0.703). Furthermore, UB and Sirius have a moderate agreement regarding ACD (95 % LoA = -0.047 to 0.680).

Comparison of central corneal thickness measurements with standard ultrasonic pachymetry and optical devices

“…Central corneal thickness measurements with AS‐OCT and Sirius were found to be thicker than optical biometry AL‐Scan measurements in our study. Also, Çağlar et al reported that optical biometry AL‐Scan gives central corneal thickness lower than the Sirius device . Differences between devices have been attributed to different technological methods.…”

Comparison of anterior segment measurements using Sirius Topographer® and Nidek Axial Length-Scan® with assessing repeatability in patients with cataracts

“…found good agreement with Nidek AL-Scan ® and Sirius in a healthy population. [ 10 ] In our study, there was no good agreement in WTW between Sirius and AL-Scan ® (mean difference = −0.23, P = 0.014).…”

“…enrolled 43 healthy volunteers to evaluate the accuracy of Nidek AL-Scan ® and Sirius and showed that AL-Scan ® tends to measure CCT less than Sirius with the moderate agreement. [ 10 ] However, they did not explain this. We attributed this divergence to alignment differences, measurement area, and study population.…”

Estudio comparativo entre los biómetros ópticos IOL Master 500 versus IOL Master 700 en pacientes con catarata y análisis de repetibilidad

“…La distancia blanco-blanco, solo es necesaria en algunas fórmulas y es particularmente útil en el cálculo de lentes fáquicos 18,19 .…”