Comparison study of the axial length measured using the new swept-source optical coherence tomography ANTERION and the partial coherence interferometry IOL Master

Comparison between spectral-domain optical coherence tomography-based and partial coherence interferometry-based biometry

We compared axial length (AL) measurements using spectral-domain optical coherence tomography (SD-OCT)-based and partial coherence interferometry (PCI)-based biometry in eyes with various chorioretinal diseases. Medical records were retrospectively analyzed in 123 eyes from 73 patients who underwent AL measurements using SD-OCT and PCI. AL values were highly consistent by both measurements (ICC = 0.996 in SD-OCT and 0.995 in PCI-based biometry). The mean difference in AL between the two instruments was - 0.09 ± 0.17 mm, which was significant (P < 0.001). There was a strong correlation between the measurements obtained using the two instruments (r = 0.982, P < 0.001). The 95% limits of agreement were - 0.43 to 0.25 mm, and the agreement of AL in the Bland-Altman analysis showed a difference. The difference in measurements was not associated with the difference in central retinal thickness (r = 0.033, P = 0.720). However, the presence of an epiretinal membrane affected the difference in measurements, unlike in other chorioretinal diseases (P = 0.014). SD-OCT-based biometry showed a good correlation with PCI-based biometry in the measurement of AL; however, the mean AL between the two instruments was significantly different. Therefore, AL measurements made using SD-OCT-based and PCI-based biometry are not interchangeable.

Comparison of measurements and calculated lens power using three biometers: a Scheimpflug tomographer with partial coherence interferometry and two swept source optical coherence tomographers

PURPOSE

To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae.

METHODS

This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula.

RESULTS

The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35-45% of patients recommended the same sphere of IOL power. In another 30-40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power.

CONCLUSIONS

The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35-45% of cases recommended the same sphere IOL power, and in another 30-40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700.

Axial length and keratometry characteristics of patients undergoing cataract surgery in Saudi Arabia

Cataract surgery is one of the most successful surgical procedures, mainly due to the recent developments in surgical instruments and intraocular lens (IOL) measurements. Understanding the nature of axial length (AL) and keratometry readings (K) in patients with cataracts has significant implications for accurate postoperative IOL size selection. This study aimed to measure AL and K in patients undergoing cataract surgery in Saudi Arabia. This retrospective study included patients who underwent cataract surgery in Madinah, Saudi Arabia. The medical records of adult patients between May 2022 and May 2023 were reviewed, and those with a history of retinal detachment, refractive surgery, or trauma were excluded. The AL and K readings were obtained from the patient's IOL master results. A total of 691 eyes from 451 patients were included in the analysis. The mean age was 64.54 years old. Most of the patients were women (55%). The mean AL, K1, and K2 values were 23.27, 43.42, and 44.69, respectively. Linear regression analysis was used to measure the relationship between AL and K, revealing an inverse relationship in our findings. As AL increased by one unit, the mean K was estimated to decrease by 0.548, with a 95% confidence interval. Our results demonstrated an inverse relationship between AL and K, implying that when AL increases, K decreases, or the corneal curvature becomes flat. Further studies are needed to investigate the biomechanical mechanisms underlying this relationship.

Clinical Evaluation of a New Spectral-Domain Optical Coherence Tomography-Based Biometer

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

Total keratometry for toric intraocular lens calculation: comparison from two swept-source optical coherence tomography biometers

Purpose

To compare the astigmatism prediction accuracy of total keratometry (TK) from the IOLMaster 700 and total corneal power (TCP) from Anterion based on swept-source optical coherence tomography (SS-OCT) technology in toric intraocular lens (toric IOL) calculation.

Design

A retrospective observational study.

Methods

Total corneal astigmatism (TCA) were obtained using IOLMaster 700 and Anterion. Z CALC 2.0 was used to calculate the expected postoperative refractive astigmatism in conjunction with TCA. Prediction errors (PE) in refractive outcomes was analyzed 1 month postoperatively using the vector analysis by the Holladay method, including the mean vector PE magnitude, percentage of cases with vector PE in certain intervals, and the centroid PE.

Results

A total of 56 eyes from 56 patients were enrolled in the study with an insertion of an AT TORBI 709 toric IOL. The difference in mean vector PE of postoperative refractive astigmatism between TK and TCP was not statistically significant (0.48D versus 0.46D, P = 0.281). TK and TCP yielded 27.3 and 40.0% of eyes with vector PE ≤ 0.25D, and 58.2 and 63.6% with vector PE ≤ 0.5D (both P > 0.05), respectively. TK and TCP resulted in similar ATR centroid PE of 0.10D@35° ± 0.60D and 0.15D@22° ± 0.57D, respectively, and there were no significant differences between x-PE component and y-PE component.

Conclusion

IOLMaster 700 and Anterion provided comparable astigmatic predictability in toric IOL implantation using total keratometry and Z CALC 2.0.

Biometry-Based Technique for Determining the Anterior Scleral Thickness: Validation Using Optical Coherence Tomography Landmarks

Purpose

Considering the potential role of anterior scleral thickness (AST) in myopia and the ubiquitous use of optical biometers, we applied and validated a biometry-based technique for estimating AST using optical coherence tomography (OCT) landmarks.

Methods

The AST was determined across four meridians in 62 participants (aged 20-37 years) with a swept-source OCT and a noncontact optical biometer at a mean ± SD distance of 3.13 ± 0.88 mm from the limbus. The biometer's graticule was focused and aligned with the anterior scleral reflex, which led to the generation of four prominent A-scan peaks: P1 (anterior bulbar conjunctiva), P2 (anterior episclera), P3 (anterior margin of anterior sclera), and P4 (posterior margin of anterior sclera), which were analyzed and compared with the corresponding OCT landmarks to determine tissue thickness.

Results

The AST measurements between biometer and OCT correlated for all meridians (r ≥ 0.70, overall r = 0.82; coefficient of variation [CV], 9%-12%; P < 0.01). The mean difference ± SD between two instruments for overall AST measures was 3 ± 2.8 µm (range, -18 to +16 µm; lower limits of agreement, -89 to +83 µm; P = 0.23) across all meridians. The mean ± SE AST with both instruments was found to be thickest at the inferior (562 ± 7 µm and 578 ± 7 µm) and thinnest at the superior (451 ± 7 µm and 433 ± 6 µm) meridian. The biometer demonstrated good intrasession (CV, 8.4%-9.6%) and intersession (CV, 7.9%-13.3%) repeatability for AST measurements across all meridians.

Conclusions

The noncontact optical biometer, which is typically used to determine axial length, is capable of accurately estimating AST based on OCT landmarks.

Translational Relevance

The high-resolution optical biometers can demonstrate wider application in the field of myopia research and practice to determine AST.

Clinical applications of anterior segment swept-source optical coherence tomography: A systematic review

Optical coherence tomography (OCT) is a non-invasive method that provides the opportunity to examine tissues by taking cross-sectional images. OCT is increasingly being used to evaluate anterior segment (AS) pathologies. Swept-source (SS) OCT allows greater penetration and achieves better visualization of the internal configuration of AS tissues due to the longer wavelength employed and high scan speeds. We reviewed the utilization of AS SS-OCT in various conditions including glaucoma, ocular surface pathologies, iris tumors, refractive surgery, cataract surgery, and scleral diseases. A systematic literature search was carried out on PubMed, Scopus, and Web of Science databases between January 1, 2008, and September 1, 2022 using the following keywords: AS SS-OCT; dry eye and SS-OCT; ocular surface and SS-OCT; cornea and SS-OCT; dystrophy and SS-OCT; glaucoma and SS-OCT; ocular surface tumors and SS-OCT; conjunctival tumors and SS-OCT; refractive surgery and SS-OCT; cataract and SS-OCT; biometry and SS-OCT; sclera and SS-OCT; iris and SS-OCT; ciliary body and SS-OCT; artificial intelligence and SS-OCT. A total of 221 studies were included in this review. Review of the existing literature shows that SS-OCT offers several advantages in the diagnosis of AS diseases. Exclusive features of SS-OCT including rapid scanning, deeper tissue penetration, and better image quality help improve our understanding of various AS pathologies.

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

PURPOSE

To 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.

DESIGN

An observational, descriptive, cross-sectional study.

METHODS

45 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 (S_w) 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.

RESULTS

The 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.

CONCLUSIONS

Performing biometry with the SS-OCT Anterion is a reliable and reproducible procedure, and it is comparable with the Lenstar LS900.

Evaluation of angle-to-angle and spur-to-spur using swept source optical coherence tomography in different refractive error

PURPOSE

To measure angle-to-angle (ATA) and spur-to-spur (STS) distances along six meridians using swept-source optical coherence tomography (SS-OCT) and compare with horizontal white-to-white (WTW) distance in different refractive error.

METHODS

Overall, 126 eyes were assessed with the Anterion SS-OCT (Heidelberg Engineering, Heidelberg, Germany). ATA and STS distances were obtained using SS-OCT at 0, 30, 60, 90, 120, and 150 degrees. WTW was measured at 0 degree with built-in infrared camera. One way ANOVA test, pearson correlation coefficient, and stepwise multivariate regression analysis were used to compare ATA and STS distances with age, anterior chamber depth (ACD), axial length (AL), and simulated keratometric values (Sim K) in different refractive error groups.

RESULTS

The mean MRSE refraction was +0.05 ± 0.23 D in the emmetropic group (41 eyes), -3.42 ± 3.04 D in the myopic group (44 eyes), and +1.33 ± 0.64 D in the hyperopic group (31 eyes). There was no statistical difference in the WTW of the emmetropic (11.62 ± 0.44 mm), myopic (11.79 ± 0.46 mm), and hyperopic groups (11.80 ± 0.49 mm) using one-way ANOVA (p = 0.007). ATA and STS were vertically oval in all groups. The correlation between ATA, STS and age, ACD, AL, and K values showed different significance for each meridian according to the refractive error. ATA increased as the horizontal WTW, ACD, and AL increased and Sim K decreased. STS shows relatively smaller explanatory power than ATA in the stepwise multivariate regression analysis.

CONCLUSIONS

This study is the first to analyze the relationship between ATA and STS compared to WTW by different refractive error. The difference between the horizontally oval WTW and vertically oval anterior chamber can be large, especially in myopia. ATA showed a greater positive correlation than STS with AL and ACD.

Evaluation of three biometric devices: ocular parameters and calculated intraocular lens power

Cataract surgery is among the most common medical procedures, and accurate ocular biometry measurements are key for successful visual outcome. The current study evaluated data obtained by the Eyestar 900, Anterion, IOLMaster700 biometers and the Pentacam corneal topographer. Compared values were axial length (AL), anterior chamber depth (ACD), steep- and flat-K, cylinder and axis. Clinical impact was assessed by calculating intraocular lens (IOL) power using the mean values of every parameter and the Barrett and Kane formulas, stratified by device and amount of cylinder. IOL was re-calculated for each device substituting Pentacam K-values. This study included 196 eyes (98 participants) of cataract surgery candidates. When comparing the IOLMaster to the Eyestar (157 eyes), no difference was found in mean AL or ACD measurements (P > 0.05). Steep-K measurements differed between these devices and the Pentacam (P = 0.01). AL and ACD measurements differed between the IOLMaster and Anterion (38 eyes; P < 0.05). Strong correlations (range 0.72-0.99) were found between all four devices. Bland-Altman analysis demonstrated excellent agreement between biometry devices other than ACD between the IOLMaster and Eyestar. Calculated IOL power was 0.50-1.00 diopter (D) lower with the IOLMaster. Cylinder power was 0.75D higher in all biometers when Pentacam K-values were substituted.

Comparison of 2 modern swept-source optical biometers—IOLMaster 700 and Anterion

Purpose

To compare biometric measures from 2 modern swept-source OCT biometers (IOLMaster700 (Z, Carl-Zeiss-Meditec) and Anterion (H, Heidelberg Engineering)) and evaluate the effect of measurement differences on the resulting lens power (IOLP).

Methods

Biometric measurements were made on a large study population with both instruments. We compared axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and corneal front and back surface curvature measurements. Corneal curvature was converted to power vectors and total power derived using the Gullstrand formula. A paraxial lens power calculation formula and a prediction for the IOL axial position according to the Castrop formula were used to estimate differences in IOLP targeting for emmetropia.

Results

There were no systematic differences between measurements of AL (− 0.0146 ± 0.0286 mm) and LT (0.0383 ± 0.0595 mm), whereas CCT yielded lower (7.8 ± 6.6 µm) and ACD higher (0.1200 ± 0.0531 mm) values with H. With H, CCT was lower for thicker corneas. The mean corneal front surface radius did not differ (− 0.4 ± 41.6 µm), but the corneal back surface yielded a steeper radius (− 397.0 ± 74.6 µm) with H, giving lower mean total power (− 0.3469 ± 0.2689 dpt). The astigmatic vector components in 0°/90° and 45°/135° were the same between both instruments for the front/back surface or total power.

Conclusion

The biometric measures used in standard formulae (AL, corneal front surface curvature/power) are consistent between instruments. However, modern formulae involving ACD, CCT or corneal back surface curvature may yield differences in IOLP, and therefore, formula constant optimisation customised to the biometer type is required.

Anterior segment characteristics in normal and keratoconus eyes evaluated with a new type of swept-source optical coherence tomography

PURPOSE

This study aimed to evaluate and compare the discriminating ability of corneal elevation maps generated using a swept-source optical coherence tomography (SS-OCT) (SS-OCT ANTERION, Heidelberg Engineering, Heidelberg, Germany), which was estimated with different reference surfaces, to distinguish normal corneas from those with keratoconus and keratoconus suspect.

METHODS

A total of 126 eyes of patients, which comprised 43, 37, and 46 keratoconus, keratoconus suspects, and normal controls, respectively, were included in this study. The anterior and posterior elevations at the thinnest point under the best-fit sphere (BFS) and toric-ellipsoid (BFT), respectively, and other corneal parameters were measured using the SS-OCT. In addition, the receiver operating characteristic (ROC) curve analysis and cut-off value were calculated to evaluate the diagnostic ability of the corneal elevation values in differentiating keratoconus and keratoconus suspects from normal eyes.

RESULTS

The mean total keratometric and corneal elevation values were significantly higher in the keratoconus group than in the other groups. Pachymetric parameters exhibited the lowest values for keratoconus. In addition, ROC curve analyses showed a high accuracy of the thinnest point anterior and posterior BFT for both keratoconus and keratoconus suspects and normal controls (area under the ROC were 0.969 and 0.961, respectively). Furthermore, the optimal cut-off point of the posterior elevation at the thinnest point under BFT was 16.44 μm (sensitivity and specificity of 86% and 98%, respectively) for differentiating keratoconus from normal and keratoconus suspect eyes.

CONCLUSIONS

The elevation map using the BFS and BFT references measured with the anterior segment SS-OCT is considered an effective indicator for keratoconus diagnosis. Therefore, the anterior segment SS-OCT can effectively differentiate keratoconus from suspected keratoconus and normal corneas by measuring parameters such as posterior and anterior elevations, pachymetry, and keratometry.

Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices

Purpose

To evaluate the clinical availability of a multifunctional ocular biometric unit, MR-6000, for simultaneous keratometry, tonometry, topography, and pachymetry evaluation, and compare anterior segment measurements with five other devices: autokeratometer (KR-1), Scheimpflug camera (Pentacam HR), swept-source optical coherence tomography (IOLMaster 700), Placido disk scanning-slit topography (Orbscan II), and noncontact tonometry (FT-1000).

Methods

Thirty eyes from thirty patients who visited Severance Hospital for cataract surgery were examined using MR-6000 and the other devices. The mean keratometry, central corneal thickness (CCT), white-to-white (WTW) distance, and intraocular pressure (IOP) values were compared. Repeated measures analysis of variance, Wilcoxon signed-rank test, intraclass correlation coefficient (ICC), and Bland-Altman plot were used to assess the correlation and agreement between devices.

Results

Thirty eyes of thirty patients were evaluated. Statistically significant differences in mean keratometry between MR-6000, KR-1, Pentacam HR, and IOLMaster 700 were not observed (p > 0.05). All five devices, including Orbscan II, had almost perfect agreement in measuring keratometry (ICC > 0.80, p < 0.05). CCT measured by MR-6000 was significantly different from that of Pentacam HR and Orbscan II measurements (p < 0.05) but correlated with that of Pentacam HR and Orbscan II measurements (ICC > 0.60, p < 0.05). The WTW distance measured by MR-6000 was not significantly different from that measured by IOLMaster 700 but was different from that measured by Orbscan II. IOP measured by MR-6000 was not correlated with FT-1000.

Conclusions

Keratometric values obtained through MR-6000 can be used interchangeably with other devices based on good correlation and agreement. However, the CCT, WTW, and IOP values were not interchangeable with a single multifunctional unit for cataract surgery preoperative examination.

Agreement Between Two Swept-source Optical Coherence Tomography Biometers and A Partial Coherence Interferometer

Purpose

To evaluate the level of agreement between ANTERION (Heidelberg Engineering, Heidelberg, Germany), OA-2000 (Tomey, Nagoya, Japan), and IOLMaster 500 (Carl Zeiss AG, Jena, Germany).

Methods

Fifty-one eyes of 51 patients were included in the study. Flat keratometry (K) and steep K, vector component of astigmatism (Jackson cross-cylinder at 0° and 90° [J₀] and Jackson cross-cylinder at 45° and 135° [J₄₅]), anterior chamber depth, and axial length were compared using the three devices. Repeated measures analysis of variance was conducted to compare the mean values of the biometrics. Pearson correlation test was conducted to analyze the correlations of the measured values, and a Bland-Altman plot was used to assess the agreement between the three devices. The predicted intraocular lens power of each device was compared to the others using the SRK/T, Haigis, Barrett Universal II, and Kane formulas.

Results

All K values measured using ANTERION were flatter than those of other instruments. However, good agreement was observed for flat K (ANTERION - OA-2000; 95% limits of agreement [LoA], 0.86 diopters [D]) and steep K (ANTERION - OA-2000; 95% LoA, 0.93 D) and OA-2000 - IOLMaster 500 (95% LoA, 0.93 D). J₀ and J₄₅ vector components of astigmatism were not statistically different; however, the agreements were poor between the devices (95% LoA ≥1.97 D). Anterior chamber depth values of ANTERION and OA-2000 were interchangeable (95% LoA, 0.15 mm). The axial length showed a high agreement (95% LoA ≤0.17 mm) among the three devices. The predicted intraocular lens powers of the three devices were not interchangeable regardless of formulas (95% LoA ≥1.04 D).

Conclusions

Significant differences in ocular biometrics were observed between ANTERION and the other two devices. This study demonstrated that only axial length showed good agreement among devices.

Dioptric power and refractive behaviour: a review of methods and applications

Myopia is a global healthcare concern and effective analyses of dioptric power are important in evaluating potential treatments involving surgery, orthokeratology, drugs such as low-dose (0.05%) atropine and gene therapy. This paper considers issues of concern when analysing refractive state such as data normality, transformations, outliers and anisometropia. A brief review of methods for analysing and representing dioptric power is included but the emphasis is on the optimal approach to understanding refractive state (and its variation) in addressing pertinent clinical and research questions.

Although there have been significant improvements in the analysis of refractive state, areas for critical consideration remain and the use of power matrices as opposed to power vectors is one such area. Another is effective identification of outliers in refractive data. The type of multivariate distribution present with samples of dioptric power is often not considered. Similarly, transformations of samples (of dioptric power) towards normality and the effects of such transformations are not thoroughly explored. These areas (outliers, normality and transformations) need further investigation for greater efficacy and proper inferences regarding refractive error. Although power vectors are better known, power matrices are accentuated herein due to potential advantages for statistical analyses of dioptric power such as greater simplicity, completeness, and improved facility for quantitative and graphical representation of refractive state.

Evaluation of ocular biometry in primary angle-closure disease with two swept source optical coherence tomography devices

Purpose

To investigate agreement between 2 swept source OCT biometers, IOL Master700 and Anterion, in various ocular biometry and intraocular lens (IOL) calculations of primary angle-closure disease (PACD).

Setting

Rajavithi Hospital, Bangkok, Thailand.

Design

Prospective comparative study.

Methods

This study conducted in a tertiary eye care center involving biometric measurements obtained with 2 devices in phakic eye with diagnosis of PACD. Mean difference and intraclass correlation coefficient (ICC) with confidence limits were assessed, and calculations of estimated residual refraction of the IOL were analysed using Barrett’s formula.

Results

Sixty-nine eyes from 45 PACD patients were enrolled for the study. Excellent agreement of various parameters was revealed, with ICC (confidence limits) of K1 = 0.953 (0.861–0.979), K2 = 0.950 (0.778–0.98), ACD = 0.932 (0.529–0.978), WTW = 0.775 (0.477–0.888), and LT = 0.947 (0.905–0.97). Mean difference of axial length (AL) was -0.01 ± 0.02 mm with ICC of 1.000. IOL calculation was assessed with Barrett’s formula, and Bland-Altman plot showed excellent agreement in the results of the 2 devices for the IOL power and estimated post-operative residual refraction (EPR).

Conclusions

Mean differences of biometric parameters, obtained with IOL Master700 and Anterion, were small, and ICC showed excellent concordance. No clinical relevance in calculation of IOL power was found, and the two devices appeared to be comparably effective in clinical practice.

Comparison Study of the Two Biometers Based on Swept-Source Optical Coherence Tomography Technology

This research aimed to investigate the potential differences in the parameters, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), flat keratometry (Kf), steep keratometry (Ks), mean keratometry (Km), astigmatism, white-to-white (WTW) distance, acquired rate, and intraocular lens (IOL) power, between the two swept-source optical coherence tomography (SS-OCT) biometers, the ANTERION (biometer A) and IOLMaster 700 (biometer B). In a prospective observational comparative case series study, we enrolled 198 eyes undergoing cataract surgery. The AL, CCT, ACD, LT, Kf, Ks, Km, astigmatism, WTW, acquired rate, and IOL power were assessed. McNemar tests compared the acquired rate, and the paired sample t-test compared the quantitative measurement results between the groups. Nineteen eyes were excluded owing to missing AL data for either biometer. Finally, data from 179 eyes were analyzed. Between the two devices, no significant difference was found in AL, astigmatism magnitude, J0, and J45, while significant differences existed in CCT, ACD, LT, Kf, Ks, Km, WTW, astigmatism axis, and IOL power; no statistical significance was found in the AL acquired rate (biometer A, 90.9% and biometer B, 93.9%). Approximately 65.4% of eyes demonstrated ≥0.5-D difference in IOL power between the two biometers. In conclusion, the two biometers showed significant differences in all measurements (CCT, ACD, LT, K, WTW, astigmatism axis, and IOL power), except for AL.

Repeatability of a new swept-source optical coherence tomographer and agreement with other three optical biometers

PURPOSE

To investigate the repeatability of Anterion and compare the agreement of ocular biometric measurements and predicted intraocular lens (IOL) powers with other three optical biometers.

METHODS

Flat keratometry (Kf), steep keratometry (Ks), J0 and 45 vectors, central cornea thickness (CCT), anterior chamber depth (ACD), and axial length (AL) from the Anterion, IOLMaster 700, Lenstar LS 900, and OA-2000 were recorded. The IOL powers were calculated with the Hoffer Q, Holladay 1, SRK/T, and Haigis formulas. The repeatability was evaluated using the within-subject standard deviation (Sw), repeatability coefficient (RC), coefficient of variation (COV), and intraclass correlation coefficient (ICC). Inter-device agreement between the four biometers was assessed with the 95% limits of agreement.

RESULTS

In total, 101 right eyes of 101 participants were enrolled. The Anterion showed good repeatability for all the included biometric parameters with all the CoV ≤ 0.30% and ICC ≥ 0.930 except for J45 with moderate repeatability (ICC was 0.849). Good agreement was found among the four devices for Kf, Ks, J0, J45, ACD, and AL. Generally, wide 95% LoA was found for the predicted IOL powers with the four IOL calculation formulas between the four devices.

CONCLUSIONS

The Anterion showed good repeatability of biometric measurements for most parameters. Good agreement among the four optical biometers was achieved for all the parameters except for CCT and the predicted IOL power. The AL values exhibited the best repeatability with Anterion and the best agreement among the biometers in our study.

Comparison of Anterior Segment Measurements between Scheimpflug-Placido Camera and New Swept-source Optical Coherence Tomography

Purpose: We compared anterior segment measurements obtained using a Scheimpflug-Placido topographer (SIRIUS®, Costruzione Strumenti Oftalmici, Florence, Italy) and a new anterior module for a swept-source optical coherence tomography system (ANTERION®, Heidelberg Engineering Inc., Heidelberg, Germany).Methods: Anterior segment measurements were evaluated in 74 eyes of 101 patients with the two devices. Central corneal thickness (CCT), anterior chamber depth (ACD), corneal refractive power (K), J0 (Jackson cross-cylinder with axes at 180° and 90°), J45 vector (Jackson cross-cylinder with axes at 45° and 135°), and white-to-white corneal diameter (WTW) measurements obtained using the SIRIUS® system and the new anterior segment module of ANTERION® were compared.Results: The mean CCTs measured by SIRIUS® and ANTERION® were 558.69 ± 44.65 and 540.26 ± 36.57 μm, respectively. The difference was statistically significant (p < 0.005), and there were high correlations between the two methods (r = 0.915, p < 0.001). The mean ACD measurements were 3.34 ± 0.53 and 3.34 ± 0.51 mm (p = 0.856), respectively, for SIRIUS® and ANTERION®. The measurements were strongly correlated (r = 0.966, p < 0.001). The measurements of WTW, total mean K, and J0 obtained with the two systems differed significantly (p < 0.005, p = 0.017, and p < 0.005, respectively), with high correlations between the two systems (r = 0.875, r = 0.967, and r = 0.933, respectively; all p < 0.001).Conclusions: There were significant differences in measurements of K, CCT, WTW, and J0 between the two devices. Agreement analysis suggests that SIRIUS® and ANTERION® should not be used interchangeably.

Repeatability of 2 swept-source OCT biometers and 1 optical low-coherence reflectometry biometer

AIM

To compare the repeatability of 2 swept-source optical coherence tomography (SS-OCT) biometers, IOLMaster 700 (biometer A, Carl Zeiss Meditec AG) and ANTERION (biometer B, Heidelberg Engineering GmbH) and 1 optical low-coherence reflectometry (OLCR) device (biometer C, LENSTAR, LS900; Haag-Streit AG).

SETTING

Department of Ophthalmology, Hanusch Hospital, Vienna Institute for Research in Ocular Surgery-Karl Landsteiner Institute, Vienna, Austria.

DESIGN

Prospective study that included patients scheduled for cataract surgery.

METHOD

Three consecutive measurements were performed with 2 SS-OCT devices and 1 OLCR device. The repeatability of the following biometry variables was compared: keratometry, central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), and axial eye length (AL). To assess the repeatability of each parameter, the within-subject SD (Sw) and coefficient of variation (CoV) were calculated.

RESULT

Fifty eyes of 50 patients were included. The CoV values were below 0.5 for all variables, except for ACD and LT for biometer C. The Sw values for mean keratometry were 0.018 for biometer A, 0.083 for biometer B, and 0.137 for biometer C. For the ACD, the Sw values were 0.039 and 0.004 for biometer A and biometer B, respectively, and 0.134 for biometer C. For the AL, the values were 0.006 for biometer A, 0.008 for biometer B, and 0.012 for biometer C.

CONCLUSIONS

All biometry devices included in the analysis presented a high repeatability. The SS-OCT devices showed a higher repeatability performance compared with the OLCR device.

Agreement of IOL power calculation between IOLMaster 700 and Anterion swept source optical coherence tomography-based biometers

PURPOSE

To assess agreement of measurements by two swept source optical coherence tomography (SS-OCT) biometers and to evaluate the prediction error (PE) in intraocular lens (IOL) power calculation with seven formulas.

SETTING

Tertiary public eye hospital.

DESIGN

Consecutive observational.

METHODS

Axial length (AL), keratometry (K), anterior chamber depth (ACD), lens thickness (LT), and corneal diameter (CD) were measured with IOL Master 700 (Biometer A) and Anterion (Biometer B). Agreement was quantified by the limits of agreement (LoAs) and concordance correlation coefficient (CCC). The PE, the median absolute error (MedAE), and the mean absolute error (MAE) of the Barrett Universal II (BUII), EVO 2.0, Haigis, Hoffer Q, Holladay 1, Kane, and SRK/T formulas was inverstigated after constant optimization.

RESULTS

In 78 eyes from 78 patients, excellent agreement was obtained for AL (CCC >0.99), very good agreement for K, ACD, and LT (CCC >0.95), and strong agreement for CD (CCC>0.72). An additive offset of 0.07 mm was measured for ACD and LT whose mean values were higher with Biometer B (p<0.001). No statistically significant difference was found between the PEs and their absolute values when comparing the results of each formula between the two biometers.

CONCLUSION

Agreement of biometric measurements by the two biometers was high, although Biometer B provided higher mean values of ACD and LT by 0.07 mm.In cataract patients with normal eye length, measurements by the two biometers do not lead to different refractive outcomes with the seven formulas investigated.

Comparison of two novel swept-source optical coherence tomography devices to a partial coherence interferometry-based biometer

To evaluate the repeatability and agreement of corneal and biometry measurements obtained with two swept-source optical coherence tomography (SSOCT) and a partial coherence interferometry-based device. This is a cross-sectional study. Forty-eight eyes of 48 patients had three consecutive measurements for ANTERION (Heidelberg Engineering, Germany), CASIAII (Tomey, Japan) and IOLMaster500 (Carl Zeiss Meditec, USA) on the same visit. Mean keratometry (Km), central corneal thickness (CCT), anterior chamber depth (ACD) and axial length (AL) were recorded. Corneal astigmatic measurements were converted into vector components—J0 and J45. Intra-device repeatability and agreements of measurements amongst the devices were evaluated using repeatability coefficients (RCs) and Bland–Altman plots, respectively. All devices demonstrated comparable repeatability for Km (p ≥ 0.138). ANTERION had the lowest RC for J0 amongst the devices (p ≤ 0.039). Systematic difference was found for the Km and J0 obtained with IOLMaster500 compared to either SSOCTs (p ≤ 0.010). The ACD and AL measured by IOLMaster500 showed a higher RC compared with either SSOCTs (p < 0.002). Systematic difference was found in CCT and ACD between the two SSOCTs (p < 0.001), and in AL between ANTERION and IOLMaster500 (p < 0.001), with a mean difference of 1.6 µm, 0.022 mm and 0.021 mm, respectively. Both SSOCTs demonstrated smaller test–retest variability for measuring ACD and AL compared with IOLMaster500. There were significant disagreement in keratometry and AL measurements between the SSOCTs and PCI-based device; their measurements should not be considered as interchangeable.