Comparison of anterior chamber depth measurements using Orbscan II and IOLMaster.

PURPOSE To evaluate and compare anterior chamber depth (ACD) measurements using Orbscan II (Bausch & Lomb, Rochester, NY) and IOLMaster (Carl Zeiss Meditec AG, Jena, Germany). METHODS In this prospective clinical study, the authors measured ACD of 145 phakic eyes of 30 healthy volunteers and 115 patients using Orbscan II and IOLMaster. Average patient age was 52.9+/-19.4 (range 16 to 87) years. ACD was evaluated from corneal epithelium to anterior lens surface. Additionally, axial length (AL) was measured using the Zeiss IOLMaster to calculate the regression coefficient between AL and ACD. RESULTS Mean ACD was 3.35+/-0.43 mm (range 2.01 mm to 4.37 mm) using Orbscan II and 3.36+/-0.41 mm (range 2.09 mm to 4.24 mm) using IOLMaster. Mean total axial length was 24.04 mm +/- 2.1 mm (range 20.7 mm to 31.41 mm). The linear regression coefficient of ACD between both methods was R=0.95. ACD and AL correlated only slightly (R=0.57). The Spearman coefficients of rank correlation were 0.94 and 0.61, respectively. A p value less than 0.01 (paired Wilcoxon test) was considered statistically significant. However, a significant difference was not calculated comparing ACD measurements using both systems and the Bland-Altman-Plot showed 95% of the differences ranging between 0.25 and -0.27 mm. CONCLUSIONS Regarding clinical application, both systems seem to be equally good and interchangeable in clinical practice in terms of ACD evaluation.