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.

Comparison of Ocular Biometry Measurements Using A-Scan Ultrasound and Two Types of Partial Coherence Interferometers

PURPOSE: To compare the measurement results of 3 ocular biometry devices, A-scan ultrasound and two types of partial coherence interferometers in normal and cataractous eyes. METHODS: This study included 42 normal eyes and 40 cataractous eye. Axial length and anterior chamber were measured using three ocular biometry measurements, ultrasonography (HiScan®, Optikon 2000, Rome, Italy), IOL Master® (Carl Zeiss, Jena, Germany), and AL-scan® (Nidek, Gamagori, Japan), and mean corneal curvature and corneal diameter were measured using two partial coherence interferometers. The results were compared in each group. RESULTS: Significant differences in measurements existed among the 3 ocular biometry devices (A-scan ultrasound, IOL Master® and AL-scan®) in normal eyes (p < 0.001) and cataractous eyes (p = 0.034). However, the measurements were not significantly different between the 2 partial coherence interferometers (IOL Master® and AL-scan®) in both groups. We confirmed lower agreement among the 3 ocular biometry devices in cataractous eyes compared with normal eyes in terms of a larger range of 95% agreement and error in cataractous eyes. CONCLUSIONS: Significant differences in measurements were observed when using the 3 ocular biometry devices in both normal and cataractous eyes. Because of low agreements between ocular biometry devices in cataractous eyes, complementing the measurements between ocular biometry devices is necessary when measuring cataractous eyes.