Comparison of anterior chamber depth measurements of Nidek AL-Scan and Galilei Dual Scheimpflug Analyzer

• Nidek AL-Scan and Galilei Dual Scheimpflug Analyzer showed good agreement for measuring the ACD in healthy eyes. but
• One measures from the anterior corneal surface and that the influence of making a correction for central corneal thickness needs to be evaluated further.
• Further studies are needed, especially on IOL calculation formulas that include ACD and its effect on postoperative spherical equivalent values.

PurposeWe aimed to compare anterior chamber depth (ACD) measurements between the Nidek AL-Scan and the Galilei Dual Scheimpflug Analyzer.SettingTurgut Ozal University Medical Faculty, Ankara, Turkey.DesignProspective masked bilateral randomized study.MethodsSixty-three individual patient eyes with normal ocular examination findings and no prior ocular surgery were analyzed. Paired two-tailed t-test was used to evaluate agreement between devices. Interobserver repeatability was evaluated in 22 patients using intraclass correlation coefficient (ICC) and Bland–Altman analysis.ResultsThe mean ± standard deviation (SD) ACD for Nidek and Galilei was 3.57 ± 0.29 (range from 2.92 to 4.32) and 3.65 ± 0.29 (range from 3.01 to 4.40), respectively. Comparing the two instruments using paired samples t-test, a statistically significant difference was found between the measurements obtained for ACD (P = 0). Two observers’ intraclass correlation coefficients (ICC) were 0.996 for Nidek and 0.968 for Galilei. For Nidek, ACD mean difference was 0 mm (P < 0.001); 95% limits of agreement was from −0.05 to 0.05. For Galilei ACD mean difference was −0.01 mm (P < 0.001); 95% limits of agreement was from −0.14 to 0.12. The Galilei Dual Scheimpflug Analyzer measured longer ACD values than the Nidek AL-Scan.ConclusionThis comparative study showed that the difference in ACD between the measurements of the Nidek AL-Scan and the Galilei Dual Scheimpflug Analyzer was statistically significant but clinically it was negligible. Further studies are needed, especially on IOL calculation formulas that include ACD and its effect on postoperative spherical equivalent values.