Comparison of Anterior Segment Parameters Obtained by Anterior Segment Optical Coherence Tomography and Dual Rotating Scheimpflug Camera

PURPOSE: To compare the anterior segment measurements with a Galilei® dual Scheimpflug analyzer and anterior segment optical coherence tomography (Cirrus OCT®). METHODS: Forty-eight eyes of 24 normal young adults were assessed for repeatability with two identical measurements of the central corneal thickness, minimum corneal thickness, anterior chamber depth, and anterior chamber angle using the Galilei® dual-Scheimpflug analyzer and Cirrus OCT®. RESULTS: The central corneal thickness, anterior chamber depth, and anterior chamber angle were highly reproducible and repeatable (intraclass correlation coefficient ≥ 0.90). Repeatability of the minimum corneal thickness was slightly lower (intraclass correlation coefficient ≥ 0.69). The mean corneal thickness measured using the Galilei® dual Scheimpflug analyzer was 0.26 ± 7.11 µm thinner than that measured using the Cirrus OCT®, and the mean corneal thickness was 0.37 ± 7.35 µm thicker, but was not statistically significant. The anterior chamber depth was 0.22 ± 0.08 mm deeper than the Cirrus OCT® (p < 0.007), and the anterior chamber angle was 7.87°± 1.32° larger than the Cirrus OCT® (p = 0.04). The 95% agreements of the central corneal thickness, anterior chamber depth, and anterior chamber angle between instruments were 85.30 µm, 1.43 mm, and 27.90°, respectively, and showed a high correlation (r ≥ 0.90; p < 0.001). The repeatability of the minimum corneal thickness was slightly low (r = 0.69; p < 0.001), and the range of agreement was larger (109.58 µm). CONCLUSIONS: The anterior segment measurements obtained with the dual rotating Scheimpflug camera and new anterior segment OCT in normal eyes was comparable and reproducible. However, the agreement ranges of the measured values were relatively large, so it was difficult to exchange values between instruments.

Astigmatic Correlation between the Automated Refractometry and Dual Scheimpflug Analyzer in Pseudophakic Eyes

PURPOSE: To examine the relationship between the refractive astigmatism by automated refractometry and the corneal astigmatism by a dual Scheimpflug analyzer in pseudophakic eyes. METHODS: Prospectively, 75 patients (100 eyes) were enrolled in the present study. Refractive astigmatism was obtained by automated refraction. Corneal astigmatism was obtained using automated keratometry (ARK-530A®) and dual Scheimpflug scanning analysis (Galilei G4®). All refractive values were converted to the power vector components J0 and J45 for comparison and regression analysis of refractive versus corneal astigmatism. Bland-Altman plots were created to estimate the agreement between measurements. RESULTS: The average astigmatism from each measurement was -1.11 ± 1.44 D (refractive astigmatism from automated refraction), -0.77 ± 1.06 D (corneal astigmatism from automated keratometry), -0.93 ± 1.02 D (simulated K from Galilei G4®), and -1.11 ± 1.48 D (total corneal power from Galilei G4®). Refractive J0 and keratometric J0 were significantly correlated (r = 0.557, p ≤ 0.001), as well as the corresponding J45 values (r = 0.655, p = 0.025). Refractive astigmatism and total corneal power components were also significantly correlated (J0: r = 0.618, p ≤ 0.001; J45: r = 0.608, p = 0.04). In the Bland-Altman plots, keratometric J0 and total corneal power J0 showed the best agreement. CONCLUSIONS: The accuracy of measurements for corneal refraction and astigmatism in pseudophakic eyes is higher using the dual Scheimpflug analyzer, especially for total corneal power. This value of astigmatism can take into account the refractive astigmatism of pseudophakic eyes and can be used in evaluating postoperative corneal astigmatism.

Comparison and Repeatability of Anterior Segment Parameters Obtained by Galilei and Slit-lamp Optical Coherence Tomography

PURPOSE: To evaluate the repeatability and comparability of anterior chamber depth (ACD) and central corneal thickness (CCT) measurements obtained by Galilei dual Scheimpflug analyzer (Ziemer, Port, Switzerland) and slit-lamp optical coherence tomography (SL-OCT; Heidelberg Engineering, Dossenheim, Germany). METHODS: ACD and CCT were measured by Galilei and SL-OCT in 68 eyes of 68 healthy young subjects. Each measurement was performed 3 times by a single examiner, and the repeatability of 3 consecutive measurements was analyzed. ACD and CCT measurements were compared between the 2 devices. RESULTS: Both Galilei and SL-OCT showed high repeatability (ICCs > or = 0.994) for ACD and CCT measurements. The mean ACD and CCT measured by Galilei were greater than SL-OCT measurements by 0.11 +/- 0.09 mm and 14.01 +/- 7.38 microm, respectively. The 95% limit of agreement values for ACD and CCT measurements were 0.36 mm, 27.66 microm, respectively, and were highly correlated (correlation coefficients > or = 0.89, p < 0.001). CONCLUSIONS: Although the repeatability of each device was high, ACD and CCT obtained by Galilei and SL-OCT were significantly different. These differences should be considered when interpreting ACD and CCT measurements obtained by the 2 devices.

Comparison of central corneal thickness measurements with the Galilei dual Scheimpflug analyzer and ultrasound pachymetry.

Purpose: To compare corneal pachymetry assessment by the Galilei dual Scheimpflug analyzer with that done by ultrasound (US) pachymetry. Materials and Methods: Forty six patients (92 eyes) were subjected to corneal pachymetry assessment by Galilei dual Scheimpflug analyzer and US. All the readings were taken by a single operator. Intraoperator repeatability for the Galilei was assessed by taking 10 readings in one eye each of 10 patients. To study the interoperator reproducibility for the Galilei, two observers took a single reading in both the eyes of 25 patients. Results: The mean central corneal thickness (CCT) measured by US was 541.83 ± 30.56 μm standard deviation (SD) and that measured by Galilei was 541.27 ± 30.07 μm (SD). There was no statistically significant difference between both the methods (P < 0.001). The coefficient of repeatability was 0.43% while the coefficient of reproducibility was 0.377% for the Galilei. Conclusion: Objective, noncontact measurement of the CCT with the Galilei dual Scheimpflug analyzer was convenient, had excellent intraoperator repeatability and interoperator reproducibility, and findings were similar to those obtained with standard US pachymetry.