Comparison of anterior chamber depth measurements using Galilei, HR Pentacam, and Orbscan II.

BACKGROUND: Anterior chamber depth measurement is used frequently in cataract and refractive surgery for advanced intraocular lens (IOL) power calculation formulas and implantation of phakic IOLs. In this article, we show agreement in anterior chamber depth measurements in normal eyes among 3 noncontact systems, namely Galilei, HR Pentacam, and Orbscan II.

METHODS: The anterior chamber depth measurements were obtained with Galilei, HR Pentacam, and the Orbscan II in both eyes of 37 healthy subjects. Pearson's correlations were calculated, and mean anterior chamber depth measurements were compared. Bland-Altman plots were used to assess the difference between individual measurements for each patient.

RESULTS: The mean anterior chamber depth readings (+/- standard error of means) with Galilei, Pentacam, and Orbscan were 3.22 +/- 0.05, 3.25 +/- 0.05, and 3.54 +/- 0.07, respectively. The difference between Galilei and Pentacam was not statistically significant (P = 0.013). However, Orbscan measurements were larger than those of either Galilei or Pentacam (P < 0.001). The differences between Orbscan and either Galilei or Pentacam were increased with greater anterior chamber depths. The 95% limits of agreement between Orbscan and Galilei, Orbscan and Pentacam, and Pentacam and Galilei in different ranges of chamber depth were ([ < 3 mm, -0.43 to +0.71 mm]; [3 to 3.5 mm, -0.23 to +0.83]; [ > 3.5 mm, +0.41 to +0.53]), ([ < 3 mm, -0.43 to +0.71 mm]; [3 to 3.5 mm, -0.26 to +0.80]; [ > 3.5 mm, +0.38 to +0.54]), and ([ < 3 mm, -0.05 to +0.06 mm]; [3 to 3.5 mm, -0.06 to +0.10]; [ > 3.5 mm, -0.11 to +0.12]), respectively.

CONCLUSIONS: These data indicate that in the assessment of normal eyes, Orbscan gives consistently higher measurements for anterior chamber depth compared with Galilei and Pentacam. Because the differences between Orbscan and either Galilei or Pentacam were not within clinically acceptable levels, they are not interchangeable in every clinical situation. However, the differences among anterior chamber depth values measured with Galilei and Pentacam were within clinically acceptable levels. Thus, these 2 systems can be regarded as interchangeable.