Accuracy of Predicting Refractive Outcomes Using Swept-source Optical Coherence Tomography in Nuclear Cataracts

PURPOSE: To evaluate the accuracy of predicting refractive outcomes of swept-source optical coherence tomography based biometry (ARGOS; Movu Inc., Santa Clara, CA, USA) in nuclear cataracts. METHODS: A total of 107 eyes (107 nuclear cataract patients) were analyzed. Subjects were divided into three groups according to the maximum nuclear density of Pentacam HR (A, lower tertile; B, medium tertile; C, upper tertile). The keratometry and axial length measured by IOLMaster (Carl Zeiss Meditec, Jena, Germany) and ARGOS systems were compared for each group. The correlation between maximum nuclear density and axial length difference readings from the two instruments was evaluated. The mean absolute error between the predicted refraction and 2-month post-operative refraction was compared. RESULTS: The maximum nuclear densities were 28.31 ± 7.30, 51.37 ± 7.82, and 88.63 ± 11.23 for groups A, B, and C, respectively. The axial length measured by ARGOS was significantly longer than that obtained using IOLMaster for groups B and C (respectively, p = 0.035, p < 0.001). A significantly positive correlation was found between the maximum nuclear density and axial length difference of the two devices (p < 0.001). Mean absolute errors were not significantly different between IOLMaster and ARGOS in group A. However, in groups B and C, the mean absolute error using ARGOS (0.31 ± 0.22 D and 0.32 ± 0.20 D, respectively) was significantly lower than that of IOLMaster (0.43 ± 0.21 D and 0.50 ± 0.26 D, respectively) (Group B, p = 0.027; Group C, p = 0.001). CONCLUSIONS: Even in dense nuclear cataracts, accurate refractive outcome prediction was possible using swept-source optical coherence tomography based biometry.

Comparison of Anterior Segment Measurements between Dual and Single Scheimpflug Camera

PURPOSE: To assess the degree of agreement of two rotating Scheimpflug cameras, Galilei G6 and Pentacam HR, in measuring corneal refractive power (K), anterior chamber depth (ACD), and central corneal thickness (CCT). METHODS: Measurement agreement was assessed in 40 eyes of 40 outpatients at our hospital. Measurements of anterior and posterior corneal refractive power (K), ACD, and CCT were compared between the Galilei G6 and Pentacam HR. RESULTS: For Galilei G6 (4 mm), Pentacam HR (3 mm) and Pentacam HR (4 mm), the anterior corneal refractive powers (K) were 44.35 ± 1.38 D, 44.09 ± 1.32 D, and 44.12 ± 1.35 D, respectively, and the posterior corneal refractive powers (K) were 6.39 ± 0.23 D, 6.45 ± 0.23 D, 6.45 ± 0.22 D. The differences in the results were statistically significant. The average ACD measurements using Galilei G6 and Pentacam HR were 3.26 ± 0.42 mm and 3.17 ± 0.42 mm, respectively, and the average CCT measurements were 556.65 ± 30.12 µm and 553.78 ± 29.42 µm. The differences in the measurements were statistically significant. In addition, ACD 95% limits of agreement (LoA) between Galilei G6 and Pentacam HR were in the range of -0.14~0.32 mm, and CCT 95% LoA were in the range of -12.54~18.29 µm. CONCLUSIONS: There were significant differences in measurements of anterior and posterior corneal refractive power (K), ACD, and CCT between the two cameras. Agreement analysis suggests that Galilei G6 and Pentacam HR should not be used interchangeably.

Comparison of Anterior Segment Measurements between Dual and Single Scheimpflug Camera

PURPOSE: To assess the degree of agreement of two rotating Scheimpflug cameras, Galilei G6 and Pentacam HR, in measuring corneal refractive power (K), anterior chamber depth (ACD), and central corneal thickness (CCT). METHODS: Measurement agreement was assessed in 40 eyes of 40 outpatients at our hospital. Measurements of anterior and posterior corneal refractive power (K), ACD, and CCT were compared between the Galilei G6 and Pentacam HR. RESULTS: For Galilei G6 (4 mm), Pentacam HR (3 mm) and Pentacam HR (4 mm), the anterior corneal refractive powers (K) were 44.35 ± 1.38 D, 44.09 ± 1.32 D, and 44.12 ± 1.35 D, respectively, and the posterior corneal refractive powers (K) were 6.39 ± 0.23 D, 6.45 ± 0.23 D, 6.45 ± 0.22 D. The differences in the results were statistically significant. The average ACD measurements using Galilei G6 and Pentacam HR were 3.26 ± 0.42 mm and 3.17 ± 0.42 mm, respectively, and the average CCT measurements were 556.65 ± 30.12 µm and 553.78 ± 29.42 µm. The differences in the measurements were statistically significant. In addition, ACD 95% limits of agreement (LoA) between Galilei G6 and Pentacam HR were in the range of -0.14~0.32 mm, and CCT 95% LoA were in the range of -12.54~18.29 µm. CONCLUSIONS: There were significant differences in measurements of anterior and posterior corneal refractive power (K), ACD, and CCT between the two cameras. Agreement analysis suggests that Galilei G6 and Pentacam HR should not be used interchangeably.