<p>Comparative Analysis of Swept-Source Optical Coherence Tomography and Partial Coherence Interferometry Biometers in the Prediction of Cataract Surgery Refractive Outcomes</p>

Abstract

Purpose: To compare the accuracy of pre-operative corneal measurements obtained with four devices, and the refractive outcomes of two optical biometers. Setting: Private practice. Design: Retrospective. Methods: Data taken from biometric measurements on 299 consecutive eyes prior to cataract surgery were retrospectively analyzed using the Argos SS-Optical Biometer and the Lenstar LS900 PCI optical biometer. As part of the standard cataract surgery preoperative exam, patients also underwent placido disk topography and Scheimpflug tomography. Keratometry, anterior chamber depth, corneal diameter, pupil diameter, central corneal thickness and axial length were all measured. The comparable measurements were compared. Finally, for those eyes where cataract surgery was performed, the post-operative refractive results were compared to the predictive results of the two biometers. Results: The SS-OCT Argos was able to measure all eyes, while five eyes could not be measured with the Lenstar LS900 PCI. Axial length measurements were performed only with the Argos and Lenstar devices. The eyes that could not be measured by the Lenstar LS900 PCI included dense grade IV nuclear sclerosis and large posterior subcapsular cataracts. In the primary endpoints, there was strong correlation between the Argos and the Lenstar devices in eyes with an axial length between 20 and 30 mm. Conclusion: The predictive accuracies of the Argos Optical Biometer and Lenstar LS900 PCI are similar, except in medium and long eyes, in which the predictive accuracy of Argos SS-OCT biometry was higher. The Argos system was found easier to use by technicians when compared to the other biometry devices.

Comparison of different methods to calculate the axial length measured by optical biometry

“…10 However, some caution is suggested, as CMAL revealed a proportional bias leading to lower AL values in longer eyes: this means that, in eyes longer than 30.0 mm, CMAL is likely to provide AL values shorter than Argos with subsequent IOL power overestimation. This difference may depend on the fact that CMAL was developed from AL measurements obtained by optical low-coherence reflectometry, which can provide different measurements of LT when compared with swept-source OCT. 5 Overall, the 2 optical biometers calculated similar IOL powers using the SRK/T formula, as only 9% of eyes revealed a difference in IOL power >0.50 D. The percentage would probably have been higher if more eyes with AL >30 mm had been enrolled, as the difference between the Argos and the IOLMaster is proportional to AL, as previously noted. Future studies are required to confirm this hypothesis.…”

“…3,4 Several authors subsequently demonstrated that the Argos displays a tendency to measure long eyes shorter in comparison to optical biometers using the group refractive index, such as the IOLMaster 700 (Carl Zeiss Meditec), the LENSTAR LS900 (Haag-Streit AG), the OA-2000 (Tomey), and the Pentacam AXL (Oculus). [5][6][7] The aim of this study was to confirm that AL measurements by the Argos in myopic eyes are shorter than those provided by an optical biometer relying on the group refractive index (IOLMaster 700) and to assess whether they are similar to those obtained by using the most important corrections recently developed to shorten the AL measured in long eyes by biometers based on the group refractive index: the original Wang-Koch AL adjustment, Holladay polynomial equations, and Cooke-modified AL (CMAL). [8][9][10]…”

Technical failure rates for biometry between swept-source and older-generation optical coherence methods: a review and meta-analysis

“…Several studies have been excluded as they have compared results of optical biometry in healthy but not in cataract patients [ 17 – 22 ], did not compare outcomes of PCI/LCOR with SS-OCT devices [ 23 – 29 ] or both [ 30 ]. Finally, fourteen studies were included in the final analysis (Table 1 ), which presented results of 2,459 eyes of at least 1,853 patients (since in one study [ 31 ] only the number of eyes, and not patients was reported).…”

“…The risk of bias assessment [Supplementary Table 1 ] represents that several of the studies did not explain in detail the reason for technical failure [ 13 , 24 , 31 , 34 , 36 , 38 – 40 ]. There are some usability differences between the devices.…”

“…A significant limitation of the meta-analysis is that some studies included results for both eyes [ 13 , 32 , 34 , 35 , 40 , 41 ], while others did not present the number of patients nor the laterality but just the number of eyes [ 31 ]. Using a combined measurement from both eyes is likely to be an underestimate of the true variance of a sample [ 52 , 53 ].…”