Optical Low-coherence Reflectometry Research Articles

Association of refractive outcome with postoperative anterior chamber depth measured with 3 optical biometers.

This study evaluated the relationship between refractive outcomes and postoperative anterior chamber depth (ACD, measured from corneal epithelium to lens) measured by swept-source optical coherence tomography (SS-OCT), optical low-coherence reflectometry (OLCR), and Scheimpflug devices under the undilated pupil. Patients undergoing cataract phacoemulsification with intraocular lens (IOL) implantation in a hospital setting were enrolled. Postoperative ACD (postACD) was performed with an SS-OCT device, an OLCR device, and a Scheimpflug device at least 1month after cataract surgery. After adjusting the mean predicted error to 0, differences in refractive outcomes were calculated with the Olsen formula using actual postACD measured from 3 devices and predicted value. Overall, this comparative case study included 69 eyes of 69 patients, and postACD measurements were successfully taken using all 3 devices. The postACD measured with the SS-OCT, OLCR, and Scheimpflug devices was 4.59 ± 0.30, 4.50 ± 0.30, and 4.54 ± 0.32mm, respectively. Statistically significant differences in postACD were found among 3 devices (P < 0.001), with intraclass correlation coefficients (ICCs) and Bland-Altman showing good agreement. No significant difference in median absolute error was found with the Olsen formula using actual postACD obtained with 3 devices. Percentage prediction errors were within ± 0.50D in 65% (OLCR), 70% (Scheimpflug), and 67% (SS-OCT) calculated by actual postACD versus 64% by predicted value. Substantial agreement was found in postACD measurements obtained from the SS-OCT, OLCR, and Scheimpflug devices, with a trend toward comparable refractive outcomes in the Olsen formula. Meanwhile, postACD measurements may be potentially superior for the additional enhancement of refractive outcomes.

Multiple-Pass Enhanced Group Delay Measurement Scheme of FBG Based on Optical Low-Coherence Reflectometry

Multiple-Pass Enhanced Group Delay Measurement Scheme of FBG Based on Optical Low-Coherence Reflectometry

Long-range frequency-domain optical delay line based on a spinning tilted mirror for low-cost ocular biometry.

Optical biometers are routinely used to measure intraocular distances in ophthalmic applications such as cataract surgery planning or myopia monitoring. However, due to their high cost and reduced transportability, access to them for screening and surgical planning is still limited in low-resource and remote settings. To increase patients' access to optical biometry we propose a novel low-cost frequency-domain optical delay line (FD-ODL) based on an inexpensive stepper motor spinning a tilted mirror, for integration into a time-domain (TD)-biometer, amenable to a compact footprint. In the proposed FD-ODL, the axial scan range and the A-scan rate are decoupled from one another, as the former only depends on the spinning mirror tilt angle, while the A-scan rate only depends on the motor shaft rotational speed. We characterized the scanning performance and specifications for two spinning mirror tilt angles, and compared them to those of the standard, more expensive FD-ODL implementation, employing a galvanometric scanner for group delay generation. A prototype of the low-cost FD-ODL with a 1.5 deg tilt angle, resulting in an axial scan range of 6.61 mm and an A-scan rate of 10 Hz was experimentally implemented and integrated in a dual sample beam optical low-coherence reflectometry (OLCR) setup with a detour unit to replicate the measurement window around the anterior segment and the retina. The intraocular distances of a model eye were measured with the proposed low-cost biometer and found to be in good agreement with those acquired by a custom swept-source optical coherence tomography (SS-OCT) system and two commercial biometers, validating our novel design.

Comparing Predictive Accuracy of a Swept Source Optical Coherence Tomography Biometer and an Optical Low Coherence Reflectometry Biometer.

To compare the refractive accuracy resulting from calculations based on measurements with a swept-source optical coherence tomography (SS-OCT) biometer compared to calculations based on measurements with an optical low coherence reflectometry (OLCR) biometer at one month postoperatively. This was a retrospective comparative non-interventional study of preoperative biometry and postoperative refraction and visual acuity of 200 eyes. All eyes had preoperative biometry with both the Argos (Movu, a Santec company) and Lenstar LS900 (Haag-Streit AG) devices. Data were collected for mean postoperative prediction error (directional and absolute), preoperative mean K, delta K (corneal astigmatism), axial length, and anterior chamber depth. The mean directional prediction error was -0.15 ± 0.47 D for Argos and -0.31 ± 0.50 D for Lenstar LS900, and there was a statistically significant mean of the differences (0.16 ± 0.24 D; p < 0.001). The mean absolute prediction error was 0.35 ± 0.34 D for Argos and 0.42 ± 0.41 D for Lenstar LS900, and there was a statistically significant mean of the differences (-0.07 ± 0.24 D; p < 0.001). Neither the differences in directional prediction error nor the differences in absolute prediction error were clinically significant. The directional and absolute prediction accuracies were statistically significant, but not clinically different between the Argos and Lenstar LS900 devices. In addition, differences between preoperative K, AL, and ACD measurements were not clinically significant.

Pump-enhanced evaluation scheme of Rayleigh backscattering coefficient distribution of EDF based on optical low-coherence domain reflectometry

We propose a pump-enhanced evaluation scheme of Rayleigh backscattering (RBS) coefficient distribution along the erbium-doped fiber (EDF) based on optical low-coherence domain reflectometry (OLCR). The scattering coefficient distribution in meters-long EDF with micron spatial resolution is demonstrated for the first time. A systematic model is established correspondingly, and the RBS signal can be recovered from the amplified signal (the conventional gain distribution). The detection capability for the weak RBS is improved by the amplification of EDF itself and the low coherence length of the broadband light source. The RBS coefficient distribution of 2 m EDF is compared with standard single-mode fiber to prove its feasibility. The strong variation of the RBS distribution in commercialized EDF is demonstrated clearly, which is useful for the background loss and noise analysis of EDF-based amplifiers and lasers.

Repeatability of a fully automated swept-source optical coherence tomography biometer and agreement with a low coherence reflectometry biometer

BackgroundTo evaluate the repeatability of a fully automated swept-source optical coherence tomography (SS-OCT) and its agreement with an optical low coherence reflectometry (OLCR) for several biometric parameters.MethodsIn this study, 74 eyes of 74 patients were measured using the Eyestar 900 SS-OCT and Lenstar LS 900 OLCR. Flat keratometry (K1) and steep keratometry (K2), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were measured three times with each device. The repeatability was analyzed with the intrasubject standard deviation, coefficient of variability (CoV), and coefficient of repeatability (CoR) for each instrument. The agreement between the instruments was evaluated with Bland-Altman analysis.ResultsK1, K2 and CCT CoV values were < 0.2%, < 0.4% and < 0.55%, respectively. Higher CoV values were found for ACD and LT ranging from 0.56% to 1.74%. The lowest CoV values were found for the AL measurements (0.03% and 0.06% for the Eyestar 900 and the Lenstar LS 900, respectively). AL measurements provided the highest repeatability, measured with both CoV and CoR values, and the CCT was the parameter with the lowest repeatability. The CCT and LT measurements were statistically significant between the two biometers (P < 0.001). The interval of the limits of agreement was < 0.6 D for K1 and K2, 15.78 µm for CCT, 0.21 mm for ACD, 0.34 mm for LT, and 0.08 mm for AL.ConclusionsBoth biometers provide repeatable measurements for the different parameters analyzed and can be used interchangeably.

Repeatability and reproducibility of a new fully automatic measurement optical low coherence reflectometry biometer and agreement with swept-source optical coherence tomography-based biometer

AimsTo assess the repeatability and reproducibility of the ocular measurements obtained with the Suoer SW-9000 μm Plus, a new fully automatic biometer based on optical low coherence reflectometry (OLCR) biometer,...

Refractive Predictability and Biometry Agreement of a Combined Swept Source Optical Coherence and Reflectometry Biometer Compared to an Optical Low Coherence Reflectometry Biometer and an SS-OCT Biometer.

To evaluate the agreement of refractive predictability of a swept-source optical coherence tomography (SS-OCT) biometer, which uses segmental AL calculation, with another SS-OCT biometer, and an optical low coherence reflectometry (OLCR) biometer. The secondary objective was to describe the refractive outcomes, visual acuities, and the agreement of different preoperative biometric parameters. The study was a retrospective one-arm study of refractive and visual outcomes after successful cataract surgery. Preoperative biometric data were collected with two different SS-OCT device (Argos, Alcon Laboratories and Anterion, Heidelberg Engineering) and an OLCR device (Lenstar 900, Haag-Streit). The Barrett Universal II formula was used to calculate IOL power for all three devices. Follow-up examination was 1-2 months after surgery. The main outcome measure, refractive prediction error (RPE), was calculated as the achieved postoperative refraction minus the predicted refraction for each device. Absolute error (AE) was calculated by reducing the mean error to zero. The study included 129 eyes of 129 patients. The mean RPE was 0.06, -0.14 and 0.17 D for the Argos, Anterion and Lenstar, respectively (p < 0.01). The Argos also had the lowest absolute RPE, while the Lenstar had the lowest median AE, but this was not statistically significant (p > 0.2). The percentages of eyes with RPE within ±0.5 was 76%, 71%, and 78% for the Argos, Anterion, and Lenstar, respectively. The percentages of eyes with AE within 0.5 D was 79%, 84%, and 82% for the Argos, Anterion and Lenstar, respectively. None of these percentages were statistically significantly different (p > 0.2). All three biometers showed good refractive predictability with no statistically significant differences in AE or percentages of eyes within ± 0.5 D of RPE or AE. The lowest arithmetic RPE was found with the Argos biometer.

Relationship between the main components of the crystalline lens and the anterior chamber depth after cataract formation

PurposeTo assess the relationship between anterior chamber depth (ACD) and lens thickness (LT), as well as its three main components (anterior and posterior cortex and nucleus thickness), in cataractous and non-cataractous eyes, depending on the axial length (AxL).MethodsAnterior and posterior cortex and nucleus thickness of the crystalline lens, ACD, and AxL were measured using optical low-coherence reflectometry in cataractous and non-cataractous eyes. They were also classified into hyperopia, emmetropia, myopia, and high myopia, depending on AxL; thus, eight subgroups were created. A minimum sample size of 44 eyes (of 44 patients) for each group was recruited. Linear models were fitted for the whole sample and each AxL subgroup to assess if there were differences in the relationships between the crystalline lens variables and ACD, including age as a covariate.ResultsThree hundred seventy cataract patients (237 females, 133 males) and 250 non-cataract controls (180 females, 70 males), aged 70.5 ± 9.4 and 41.9 ± 15.5 years, respectively, were recruited. The mean AxL, ACD, and LT for the cataractous and non-cataractous eyes were 23.90 ± 2.05, 24.11 ± 2.11, 2.64 ± 0.45, and 2.91 ± 0.49, 4.51 ± 0.38, 3.93 ± 0.44 mm, respectively. The inverse relationship of LT, anterior and posterior cortex, and nucleus thickness with ACD was not significantly (p ≥ 0.26) different between cataractous and non-cataractous eyes. Further subclassification of the sample depending on AxL showed that the inverse relationship between the posterior cortex and ACD was no longer significant (p > 0.05) for any non-cataractous AxL group. LT, anterior and posterior cortex, and nucleus thickness was not significantly (p ≥ 0.43) different between cataractous and non-cataractous eyes for the whole sample, and all AxL groups after adjusting for age.ConclusionsThe presence of cataracts does not modify the inverse relationship of the LT, anterior and posterior cortex, and nucleus with ACD. And this relationship does not seem to depend importantly on AxL. Besides, the possible differences in LT, anterior and posterior cortex, and nucleus between cataractous and non-cataractous eyes may not be caused by lens opacification, but possibly by the progressive lens growth due to aging.

The Effect of Cycloplegia on the Biometer for Optical Low-coherence Reflectometry.

The aim of this study was to compare the biometric measurements and different formulas for calculating intraocular lens (IOL) power by using the Lenstar LS900 biometer for optical low-coherence reflectometry before and after induction of cycloplegia in the adult population. In this cross-sectional study, 168 eyes of 168 healthy volunteers aged 40 - 86 years (59.22 ± 11.57) were included. Biometric measurements, including axial length (AL), anterior chamber depth (ACD), keratometry (K1 and K2), and white-to-white (WTW) were compared using a Lenstar LS900 optical biometer before and after induction of cycloplegia with 1% cyclopentolate. The IOL power was also compared using six different formulas (Barrett Universal II, Haigis, SRK/T, Hoffer Q, Holladay, and SRK-II) for the AcrySof MA60AC IOL before and after induction of cycloplegia. There were no statistically significant differences in AL, K1 and K2, or WTW measurements before and after induction of cycloplegia. There was a significant increase only in ACD from the biometric parameters after the induction of cycloplegia (p < 0.05). Despite this change, there were no significant changes in IOL power calculations using the six different formulas before and after induction of cycloplegia. This study demonstrated that IOL power measurements using the Lenstar LS900 can be performed after cycloplegia.

Agreement between a new optical low coherence reflectometry biometer and an anterior segment optical coherence tomographer

BackgroundTo assess agreement of measurements between a new optical low coherence reflectometry (OLCR) biometer (SW-9000, Suoer, Tianjin, China) and a spectral-domain optical coherence tomographer (SD-OCT)/Placido topographer (MS-39, CSO, Florence, Italy) in healthy subjects.MethodsA total of 66 right eyes from 66 healthy subjects were enrolled in this prospective study. Three consecutive measurements were randomly obtained with both devices by the same experienced operator to assess agreement. Bland-Altman plots and 95% limits of agreement (LoA) were used to verify the agreement between the devices. Results are presented as mean ± standard deviation (SD).ResultsThe SD-OCT/Placido tomographer showed high agreement with the OLCR biometer for all parameters included in this study. The mean differences of central corneal thickness (CCT), anterior chamber depth (ACD), aqueous depth (AQD), mean keratometry (Km) and corneal diameter (CD) were 2.21 ± 2.67 μm (P < 0.001), − 0.10 ± 0.03 mm (P < 0.001), − 0.10 ± 0.04 mm (P < 0.001), − 0.01 ± 0.22 D (P = 0.773) and 0.20 ± 0.16 mm (P < 0.001), respectively. This implies that the inter-device difference in Km was not statistically significant, while the differences in CCT, ACD, AQD, CD were statistically but not clinically significant. The 95% LoAs of CCT, ACD, AQD, Km and CD were − 3.01 to 7.44 μm, − 0.16 to − 0.05 mm, − 0.18 to − 0.03 mm, − 0.45 to 0.43 D, and − 0.12 to 0.51 mm, respectively.ConclusionsFor CCT, ACD, AQD, Km, and CD in healthy subjects, the new OLCR biometer has high agreement with the SD-OCT/Placido tomographer and can be used interchangeably due to the narrow range of 95% LoAs.

Agreement between a Spectral-Domain Ocular Coherence Tomography Biometer with a Swept-Source Ocular Coherence Tomography Biometer and an Optical Low-Coherence Reflectometry Biometer in Eyes with Cataract.

To assess the agreement between biometric parameters measured by a spectral-domain optical coherence tomography optical biometer device (Optopol Revo NX) with a validated swept-source biometer (IOLMaster 700) and a validated optical low-coherence reflectometry biometer (Lenstar LS 900), in cataract surgery candidates. In this prospective comparative study, 100 patients (100 eyes) who were eligible for cataract surgery were involved. Bland-Altman plots were used to assess agreement between devices for biometric parameters including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). AL measurements were successful in 82 eyes (82.0%) with Revo NX, in 91 eyes (91.0%) with Lenstar LS 900, and in 97 eyes (97.0%) with IOLMaster 700. When Revo NX was compared to IOL Master 700 and Lenstar LS 900, the mean differences were as follows: -0.02 ± 0.02 mm and -0.02 ± 0.03 mm (P = 0.313, P = 0.525) for AL, 0.01 ± 0.03 mm and 0.10 ± 0.03 mm (P = 0.691, P = 0.002) for ACD, -0.15 ± 0.03 mm and 0.001 ± 0.04 mm (P < 0.001, P = 0.95) for LT, and -2.29 ± 0.92 μm, and 0.73 ± 1.43 μm (P = 0.015, P = 0.612) for CCT. Three devices were highly correlated for AL, ACD, LT, and CCT (interclass correlation coefficient > 0.75). Bland-Altman plots showed a narrower 95% limit of agreement (-0.35 to 0.31) between Revo NX and IOLMaster 700 in measuring AL. Despite the higher measurement failure rate in eyes with cataract, the Revo NX showed very good agreement with the IOLMaster 700 and Lenstar LS 900 optical biometers in measuring AL, ACD, LT, and CCT. However, ACD and LT measurements cannot be considered interchangeable between these devices.

Impact of a Swept Source-Optical Coherence Tomography Device on Efficiency in Cataract Evaluation and Surgery: A Time-and-Motion Study

This study aims to assess the time impact of ARGOS® (image-guided swept-source optical coherence tomography biometer integrated with operating room (OR) technologies (SS-OCT w/ORT)) compared to LENSTAR LS 900 (optical low-coherence reflectometry (OLCR)), IOLMaster 500 (partial coherence interferometry (PCI)), and IOLMaster 700 (SS-OCT) on efficiency in the cataract evaluation and surgery. Data from 212 patients (two study sites) who underwent evaluation and/or cataract surgery were collected. The primary objective was to compare the performance of four biometers; statistical analyses were conducted to compare 1) biometer measurement times for all patients (ANOVA w/post-hoc Dunnett's test) and stratified by cataract density (ANOVA) and 2) rate of biometer acquisition failure (Chi-square test w/post-hoc Bonferroni correction). Real-world observational data collected were then used to develop a practice-based time-efficiency model to demonstrate the combined effect that adopting an SS-OCT w/ORT has on a practice's cataract workflow. Real-world data inputs included assessment of patient's eyes' cataract grade density, time taken for optical biometry, Manual A-scan (ultrasound biometer) when acquisition failed, and measurement times associated with other devices used in cataract evaluation and surgery. For 208 patients (56% non-dense, 44% dense), the SS-OCT w/ORT biometer had a 0% acquisition failure (SS-OCT: 3% (p = 0.05); OLCR: 5% (p = 0.004); PCI: 15% (p < 0.0001)) and an average time savings of 30 seconds/patient compared to the other biometers in this study (p < 0.05). When acquisition failed, ultrasound biometry resulted in an additional 2.5 minutes/patient. For a cohort of 1000 patients, an SS-OCT w/ORT and an image-guidance system adopted at a practice using an SS-OCT, femtosecond laser, and intraoperative aberrometer offer up to 58% efficiency gain across the cataract workflow. Results from this study demonstrate an SS-OCT w/ORT's efficiencies in cataract evaluation and surgery driven by faster measurement times, reducing the need for ultrasound biometry, and its integration benefits with other devices.

The ripple-curry amplifier in photonic applications

This paper discusses the new design of a amplifier for the miniature MEMS-type spectrometer. The application problem of the new amplifier was the correct conditioning of the sensor's photoelectric pulses. The processed signal was a sequence of pulses that had variable both frequency and amplitude value. Thus, such a broadband amplifier should have the functionality of automatic gain control. This paper describes the concept of the new circuit, develops its detailed application, and then performs validation tests. Measurement results of the new circuit are discussed in the final section of the paper. Full Text: PDF ReferencesC. Ortolani, Flow Cytometry Today. Detectors and Electronics, (Springer 2022). pp. 97-119, CrossRef D. Maes, L. Reis, S. Poelman, E. Vissers, V. Avramovic, M. Zaknoune, G. Roelkens, S. Lemey, E. Peytavit, B. Kuyken, "High-Speed Photodiodes on Silicon Nitride with a Bandwidth beyond 100 GHz", Conference on Lasers and Electro-Optics, Optica Publishing Group, (2022). CrossRef R. Das, Y. Xie, A.P. Knights, "All-Silicon Low Noise Photonic Frontend For LIDAR Applications", 2022 IEEE Photonics Conference (IPC), IEEE Xplore (2022). CrossRef FEMTO Messtechnik GmbH, Variable Gain Photoreceiver - Fast Optical Power Meter Series OE-200, DirectLink M. Nehir, C. Frank, S. Aßmann, E.P. Achterberg, "Improving Optical Measurements: Non-Linearity Compensation of Compact Charge-Coupled Device (CCD) Spectrometers", Sensors 19(12), 2833 (2019). CrossRef F. Thomas,; R. Petzold, C. Becker, U. Werban, "Application of Low-Cost MEMS Spectrometers for Forest Topsoil Properties Prediction", Sensors 21(11), 3927 (2021). CrossRef M. Muhiyudin, D. Hutson, D. Gibson, E. Waddell, S. Song, S. Ahmadzadeh, "Miniaturised Infrared Spectrophotometer for Low Power Consumption Multi-Gas Sensing", Sensors 20(14), 3843 (2020). CrossRef S. Maruyama, T Hizawa, K. Takahashi, K. Sawada, "Optical-Interferometry-Based CMOS-MEMS Sensor Transduced by Stress-Induced Nanomechanical Deflection", Sensors 18(1), 138 (2018). CrossRef S. Merlo, P. Poma, E. Crisà, D. Faralli, M. Soldo, "Testing of Piezo-Actuated Glass Micro-Membranes by Optical Low-Coherence Reflectometry", Sensors 17(3), 8 (2017). CrossRef M.S. Wei, F. Xing, B. Li, Z. You, "Investigation of Digital Sun Sensor Technology with an N-Shaped Slit Mask", Sensors 11(10), 9764 (2011). CrossRef Z. Yang, T. Albrow-Owen, W. Cai, T. Hasan, "Miniaturization of optical spectrometers", Science 371, 6528 (2021). CrossRef Hamamatsu Photonics K.K. Fingertip size, ultra-compact spectrometer head integrating MEMS and image sensor technologies. DirectLink Microchip Technology Inc, MCP6291/1R/2/3/4/5 1.0 mA 10 MHz Rail-to-Rail Op Amp, CrossRef Microchip Technology Inc. MCP6021/1R/2/3/4 Rail-to-Rail Input/Output 10 MHz Op Amps, CrossRef

Repeatability and comparability of a new swept-source optical coherence tomographer in optical biometry

PurposeTo evaluate the reproducibility in the measurement of ocular biometric parameters using a new swept-source optical coherence tomographer and its comparability with an optical low coherence reflectometry biometer. DesignAn observational, descriptive, cross-sectional study. Methods45 right eyes of 45 patients diagnosed with cataract were included. Three successive biometric measurements with Anterion and one with Lenstar LS900 were performed on each patient. The following variables were collected: axial length (AXL), anterior chamber depth (ACD), flat K (K1), steep K (K2), central corneal thickness (CCT), lens thickness (LT) and white-to-white distance (WTW). The intrasubject standard deviation (Sw) and the coefficient of Pearson “R” were calculated in order to assess the repeatability. The intraclass correlation coefficient (ICC) and the concordance correlation coefficient (CCC) were obtained to evaluate the comparability between devices. A Bland-Altman plot was performed for each variable. ResultsThe coefficient of Pearson was excellent and statistically significant in the evaluation of the repeatability in all the variables. The highest values were 0.987 (AXL), 0.983 (CCT) and 0.942 (ACD). There were no statically significant differences between repeated measurements with Anterion in all the parameters. The ICC and CCC were excellent in the evaluation of AXL, CCT and ACD, and were also good in regard to K1, K2, LT and WTW. ConclusionsPerforming biometry with the SS-OCT Anterion is a reliable and reproducible procedure, and it is comparable with the Lenstar LS900.

Comparison of central corneal thickness measurements with different non-contact devices in healthy children

PurposeTo investigate the agreement of the Combined Scheimpflug-Placido Disk System (Sirius), specular microscopy (Tomey EM-4000), non-contact tono-pachymetry (Canon TX-20P), and optical low-coherence reflectometry (Lenstar LS 900) devices in the measurement of central corneal thickness (CCT) in healthy children. MethodEighty-three eyes from 83 healthy children were included in the study. The mean age of the children was 11.1 ± 2.8 (range, 7–17) years. CCT was measured using the Sirius topography, Tomey specular microscopy, Canon TX-20P, and Lenstar LS 900 devices. To examine the agreement among these devices, 95% limits of agreement (LoA) and intraclass correlation coefficients (ICC) were determined. ResultsThe mean CCT values obtained using the Sirius topography, Tomey SM, Canon TX-20 P, and Lenstar 900 devices were 555.9 ± 37 µm, 553.5 ± 39 µm, 569.3 ± 33 µm, and 559.7 ± 38 µm, respectively. With the ICC method, the agreement rates were determined as 0.875 between Canon TX-20P and Sirius topography, 0.903 between Canon TX-20P and Lenstar LS 900, 0.842 between Canon TX-20P and Tomey EM-4000, 0.979 between Sirius Topography and Lenstar LS 900, 0.978 between Sirius topography and Tomey EM-4000, and 0.969 between Lenstar LS 900 and Tomey EM-4000. ConclusionThe devices with the closest results to each other were the Sirius and Tomey EM-4000 devices, with a statistically strong agreement. There was also a strong agreement between Sirius and Lenstar LS 900, although there was a 3.7-unit difference between them. Nevertheless, despite the strong agreements among these devices, because their CCT values varied statistically significantly, these devices should not be used interchangeably in clinical practice.

Repetibilidad y comparabilidad de un nuevo tomógrafo con tecnología SS-OCT en biometría óptica

PurposeTo evaluate the reproducibility in the measurement of ocular biometric parameters using a new swept-source optical coherence tomographer and its comparability with an optical low coherence reflectometry biometer. DesignAn observational, descriptive, cross-sectional study. Methods45 right eyes of 45 patients diagnosed with cataract were included. Three successive biometric measurements with Anterion and one with Lenstar LS900 were performed on each patient. The following variables were collected: axial length (AXL), anterior chamber depth (ACD), flat K (K1), steep K (K2), central corneal thickness (CCT), lens thickness (LT) and white-to-white distance (WTW). The intrasubject standard deviation (Sw) and the coefficient of Pearson «R» were calculated in order to assess the repeatability. The intraclass correlation coefficient (ICC) and the concordance correlation coefficient (CCC) were obtained to evaluate the comparability between devices. A Bland–Altman plot was performed for each variable. ResultsThe coefficient of Pearson was excellent and statistically significant in the evaluation of the repeatability in all the variables. The highest values were 0.987 (AXL), 0.983 (CCT) and 0.942 (ACD). There were no statically significant differences between repeated measurements with Anterion in all the parameters. The ICC and CCC were excellent in the evaluation of AXL, CCT and ACD, and were also good in regard to K1, K2, LT and WTW. ConclusionsPerforming biometry with the SS-OCT Anterion is a reliable and reproducible procedure, and it is comparable with the Lenstar LS900.

Erratum to: Repeatability of 2 swept-source OCT biometers and 1 optical low-coherence reflectometry biometer. Andreea D. Fişuş, MD, Nino D. Hirnschall, MD, PhD, Manuel Ruiss, MSc, Caroline Pilwachs, Orthoptist, Stefan Georgiev, MD, Oliver Findl, MD, MBA, FEBO. J Cataract Refract Surg 2021; 47:1302–1307.

Erratum to: Repeatability of 2 swept-source OCT biometers and 1 optical low-coherence reflectometry biometer. Andreea D. Fişuş, MD, Nino D. Hirnschall, MD, PhD, Manuel Ruiss, MSc, Caroline Pilwachs, Orthoptist, Stefan Georgiev, MD, Oliver Findl, MD, MBA, FEBO. J Cataract Refract Surg 2021; 47:1302–1307.

Comparison of preoperative angle kappa measurements in the eyes of cataract patients obtained from Pentacam Scheimpflug system, optical low-coherence reflectometry, and ray-tracing aberrometry

BackgroundAngle kappa plays a vital role in the implantation of multifocal intraocular lens (MIOL). Large angle kappa is related to a higher risk of postoperative photic phenomena. This study aims to compare preoperative angle kappa in the eyes of cataract patients obtained from the Pentacam Scheimpflug system (Pentacam), optical low-coherence reflectometry (Lenstar), and ray-tracing aberrometry (iTrace).MethodsOne hundred thirteen eyes of 113 patients with cataracts were included. Each eye was examined 3 times using all devices to obtain angle kappa and pupil diameter. When considering dependent eyes for one individual, angle kappa in both right eyes and left eyes should be analysed separately. The repeatability and reproducibility were evaluated using the within-subject standard deviation (Sw), repeatability (2.77 Sw), and intraclass correlation coefficient (ICC). The difference, correlation, and agreement between devices were evaluated by paired t-tests, Pearson tests, and Bland-Altman analysis, respectively.ResultsIntraoperator repeatability and interoperator and intersession reproducibility of angle kappa showed an Sw of less than 0.05 mm, a 2.77 Sw of 0.14 mm or less, and an ICC of more than 0.96. Angle kappa was not significantly different between Pentacam and Lenstar (P > 0.05), while angle kappa was significantly different between Pentacam and iTrace and between Lenstar and iTrace (P < 0.05). There was a strong correlation between Pentacam and Lenstar for angle kappa (r =0.907 to 0.918) and a weak or moderate correlation between Pentacam and iTrace and between Lenstar and iTrace (r =0.292 to 0.618). There were narrow 95% limits of agreement (LoA) between Pentacam and Lenstar for angle kappa and wide 95% LoA between Pentacam and iTrace and between Lenstar and iTrace. No significant differences in pupil diameter were found between Pentacam and Lenstar in either eye (P > 0.05). Positive angle kappa (nasal light reflex) was found in most cataract patients (79.25% to 84.91%) through 3 different devices in both eyes.ConclusionsThe 3 devices provided high intraoperator repeatability and interoperator and intersession reproducibility for angle kappa measurements. The measurement of preoperative angle kappa in the eyes of patients with cataracts by Pentacam and Lenstar has good agreement.

Choroidal Morphologic and Vascular Features in Patients With Myopic Choroidal Neovascularization and Different Levels of Myopia Based on Image Binarization of Optical Coherence Tomography.

Purpose: To characterize the choroidal morphologic and vascular features in different levels of myopes and patients with myopic choroidal neovascularization (mCNV).Methods: A total of 148 subjects were enrolled in this cross-sectional study, including 78 low-to-moderate myopes (LMM), 53 high myopes (HM), and 17 high myopic patients with mCNV. Ocular biometrics were measured using an optical low-coherence reflectometry device. Retinal and choroidal imaging was performed using enhanced depth imaging (EDI) spectral domain optical coherence tomography (OCT). Retinal parameters including retinal thickness and retinal volume were obtained from a built-in software. Binarization technique was adopted to investigate choroidal parameters including choroidal thickness (CT), vascular area, stromal area, and choroidal vascularity index (CVI). Choroidal parameters were measured at five locations to cover as much area of choroid as possible, and their patterns of distribution were further analyzed.Results: Patients with mCNV had an atrophic retina of comparable thickness to HM (273.65 ± 17.28 vs. 276.49 ± 13.29 μm, p = 0.47), but the choroid was thinner than that of HM (153.94 ± 15.12 vs. 236.09 ± 38.51 μm, p < 0.001). Subfoveal CVI was greatest in the mCNV eyes (0.651 ± 0.009), followed by HM (0.645 ± 0.012) and LMM eyes (0.636 ± 0.012). Similar to CT, CVI was also found significantly different among these three groups at all five locations (p for trend < 0.001 for all locations). Axial length (AL) was negatively correlated with retinal volume (r = −0.236, p = 0.009), which is the only significant finding in associations between ocular factors and retinal parameters. Strong, negative correlations were identified between AL and subfoveal choroidal thickness (SFCT, r = −0.820, p < 0.001). However, AL was positively correlated with subfoveal CVI (r = 0.668, p < 0.001). CVI was greater in myopic eyes with thinner choroid (r = −0.578, p < 0.001). BCVA exhibited no significant association with CVI (r = 0.139, p = 0.092), but was negatively correlated with SFCT (r = −0.386, p < 0.001) and positively correlated with AL (r = 0.351, p < 0.001).Conclusion: Choroid in patients with mCNV was thinner yet more vascularized than that in HM and LMM subjects. CVI increased with a longer AL which was associated with a smaller SFCT, choroidal vascular area (VA), and total choroidal area (TCA). Better BCVA was achieved in subjects with thicker SFCT and shorter AL.