Evaluation of 6 biometers based on different optical technologies

Repeatability and agreement of three different ocular biometers including single and dual Scheimpflug cameras

CLINICAL RELEVANCE

With a wide range of commercially available biometry devices, direct comparisons for agreement, interchangeability and repeatability are needed to enable correct interpretation of measured values.

BACKGROUND

The purpose of this study was to evaluate the intra-device repeatability and inter-device agreement of three different ocular biometers.

METHODS

This is a prospective, comparative study conducted at the University Hospital, Goethe University, Frankfurt, Germany. Included were eyes with a cataract which showed no other pathology. One eye per patient was randomly selected and 3 consecutive measurements were taken with the IOLMaster 700, Galilei G6, and Pentacam AXL. Repeatability and agreement were evaluated for simulated keratometry (simK), astigmatism (simA) and its axis, total keratometry (TC), axial length (AL), anterior chamber depth (ACD), and pachymetry (CT).

RESULTS

simK, TC, AL, and CT show very high repeatability with an intra-class correlation (ICC) of > 0.9 and a COV < 0.5 each. Means of the measurements were significantly different between the devices for simK, AL, and TC (p < 0.05). ACD and simA also showed a high ICC, but a lower agreement between the devices. Fixed biases shown by Bland-Altman plots for simK seem to indicate that the values are not interchangeable.

CONCLUSION

Even though very high repeatability and agreement for most of the measured variables was observed with all three devices, fixed differences indicate that measured values are not completely interchangeable between the devices.

Agreement in Biometric Parameters Between Swept-Source-Optical Coherence Tomography and Optical Low-Coherence Interferometry: Insights into Clinical Precision

Background/Objectives: Accurate biometric measurements are critical for achieving optimal refractive outcomes in cataract surgery. This study evaluated the agreement of biometric measurements between a swept-source optical coherence tomography (SS-OCT) biometer (Argos®, Movu Inc.) and an optical low-coherence interferometry (OLCI) biometer (Aladdin®, Topcon Corp.). Parameters analyzed included axial length (AL), anterior chamber depth (ACD), lens thickness (LT), keratometry (K1, K2), and white-to-white corneal diameter (WTW). Methods: A total of 170 eyes were examined, and agreement was assessed using Bland-Altman analysis, intraclass correlation coefficients (ICCs), and Pearson correlation coefficients. Results: Excellent agreement was observed for AL (ICC = 0.975), ACD (ICC = 0.960), LT (ICC = 0.951), K1 (ICC = 0.921), and K2 (ICC = 0.927). Moderate agreement was found for astigmatism axis (ICC = 0.655) and cylinder power (ICC = 0.891). Poor agreement was noted for astigmatism-related Jackson cross-cylinder vectors J0 (ICC = 0.334) and J45 (ICC = -0.311), as well as for WTW (ICC = 0.338). Bland-Altman plots demonstrated narrow limits of agreement for most parameters, with mean differences of 0.009 mm for AL and 0.06 mm for ACD. Conclusions: Both devices demonstrated high degrees of agreement for core biometric parameters, supporting their clinical interchangeability. However, the variability in WTW and astigmatism-related measurements highlights the need for caution when precise corrections are required.

A Retrospective Trial Comparing Prediction Accuracy of Three Biometers in Short, Medium, and Long Eyes

Purpose

To assess the non-inferiority of mean absolute prediction error (APE) of the Argos (Movu, a Santec company) compared with the IOL Master 700 (Carl Zeiss Meditec AG) and Lenstar LS900 (Haag-Streit AG) biometers utilizing the Barrett Universal II (BUII) formula for power calculations in short, medium, and long axial length eyes.

Methods

This was a retrospective chart review of prediction error from 3 biometers (Argos, IOLMaster 700, and Lenstar LS900). Biometer measurement order was determined using blocked randomization. Eligible charts were from eyes 50-85 years old, axial length between 20.00 mm and 30.00 mm, and had IOL implantation with the AcrySof IQ monofocal IOL (SN60WF) and AcrySof toric IOL (SN6AT3, SN6AT4). Preoperative planning was done with the BUII formula on all biometers, with a target of plano. The primary outcome measure was the mean absolute prediction error for each biometer using BUII. Specifically, the non-inferiority of Argos compared to the IOLMaster 700 and Lenstar LS900 using a non-inferiority margin of 0.25 D.

Results

The chart review identified 203 eyes from 123 patients. Mean APE for Argos overall and for each axial length group was non-inferior to that of IOLMaster 700 and Lenstar LS900. The overall mean APE was 0.25 ± 0.20 D for Argos compared to 0.25 ± 0.20 D for IOLMaster 700, and 0.25 ± 0.19 D for Lenstar LS900. The differences were not significant (p > 0.05). The percentages of eyes with APE 0.5 D or less were 90% for Argos, 89% for IOLMaster 700, and 89% for Lenstar LS900. The differences were not significant (p > 0.05).

Conclusion

Overall mean APE was not significantly different with the Argos compared to IOLMaster 700 and Lenstar LS900 using the BUII formula, suggesting that the use of any of these devices can achieve good outcomes.

Repeatability and reproducibility of a new spectral-domain optical coherence tomography biometer and agreement with swept-source optical coherence tomography based biometer

BACKGROUND

To assess the repeatability and reproducibility of the Colombo IOL biometer (Moptim, China), which utilizes spectral-domain optical coherence tomography (SD-OCT), in measuring ocular parameters of normal subjects and to compare its agreement with the swept-source optical coherence tomography (SS-OCT)-based IOLMaster 700 biometer (Carl Zeiss Meditec AG, Germany).

METHODS

This prospective study included 91 eyes from 91 normal subjects. The evaluated parameters were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), lens thickness (LT), flattest and steepest meridian keratometry (Kf and Ks), mean keratometry (Km), astigmatism (AST) magnitude, white-to-white (WTW) distance, and pupil diameter (PD). The within-subject standard deviation (Sw), test-retest repeatability (TRT), coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were calculated to determine the repeatability and reproducibility. Paired t-tests and Bland-Altman plots with 95% limits of agreement (LoA) were employed to assess the agreement.

RESULTS

With respect to intraobserver repeatability, the Sw and TRT values of all evaluated parameters were low. Except J45 and PD, the ICCs were all higher than 0.928. The reproducibility Sw and TRT values of Colombo IOL were also low, and ICCs were not lower than 0.900. Comparing Colombo IOL and IOLMaster 700, the 95% LoA of AL, CCT, AQD, ACD, LT, Kf, Ks, Km, AST, J0, J45, WTW and PD ranged from - 0.08 to 0.03 mm, - 21.58 to 5.09 μm, 0.01 to 0.15 mm, - 0.01 to 0.14 mm, - 0.05 to 0.10 mm, - 0.14 to 0.59 D, - 0.31 to 0.40 D, - 0.13 to 0.40 D, - 0.68 to 0.32 D, - 0.09 to 0.34 D, - 0.07 to 0.25 D, 0.11 to 1.47 mm, and - 0.97 to 2.31 mm, respectively.

CONCLUSION

The new SD-OCT-based Colombo IOL biometer demonstrates excellent repeatability and reproducibility. Moreover, it generally agrees well with the SS-OCT-based IOLMaster 700, except for the WTW and PD measurements.

Comparison of Precision, Agreement, and Accuracy of Two Swept-Source Optical Coherence Tomography Biometers

Background/Objectives: This study's aim was to compare the precision, agreement, and accuracy in axial length (AL) measurements of Argos® (Alcon Healthcare, US) and Eyestar 900® (Haag-Streit, Switzerland) swept-source optical coherence tomography (SS-OCT) biometers. Methods: We performed a prospective evaluation of two diagnostic devices. Three consecutive measurements of AL with the Argos® and the Eyestar® 900 SS-OCT biometers were conducted in random order in eyes undergoing cataract surgery in Barcelona, Spain. The main endpoint was the median difference in AL between devices. Secondary endpoints included agreement on Bland-Altman plots and 95% limits of agreement (LoAs), repeatability as measured within-subject standard deviation (SW), percent of failed AL measurements, percent of eyes within ±0.50 D and ±1.00 D one month after surgery, and median and mean prediction error. Results: We included 107 eyes of 107 patients (60.8% females, mean age of 73.1 years). The median difference in AL (Argos®-Eyestar 900®) was -0.01 mm (interquartile range [IQR], 0.06), p = 0.01. The 95% LoAs were -0.11 to +0.08 mm, with a trend towards less extreme measurements with Argos® for very short and long eyes. The median (IQR) Sw was 0.0058 (0.0058) and 0.0000 (0.0058) for Argos® and Eyestar 900®, respectively. There were no failed AL measurements with either device (0%, 95% CI = 0% to 3.4%). Overall, 96.1% of eyes were within ±0.50 D and 100% were within ±1.00 D. Conclusions: Argos® and Eyestar 900® provided statistically different but clinically negligible differences in AL. However, they are not interchangeable in very long or short eyes, due to the different principles used to determine AL.

Comparison of corneal topography maps obtained using the IOLMaster 700® and the Anterion® in candidates for toric IOL implantation

OBJECTIVES

To compare central corneal topography (CT) obtained using the IOLMaster 700® biometer to corneal topography obtained using a Swept-Source OCT-based predicated topographer (PT), in candidates for toric intraocular lens (IOL) implantation.

METHODS

A retrospective comparative study was conducted in consecutive patients undergoing a routine cataract surgery assessment with significant astigmatism on keratometry. Each patient was examined using both the IOLMaster 700® (Carl Zeiss Meditec, Jena, Germany) and the Anterion® (Heidelberg Engineering, Heidelberg, Germany) for routine preoperative measurements. The corneal axial anterior power map obtained with each device was then anonymized and analysed independently by two ophthalmologists using a reading grid. The reading grid assessed the usual parameters describing astigmatism and evaluated if a toric IOL was indicated or a second topography examination was needed to confirm the indication.

RESULTS

In total, 169 eyes of 120 patients were included. The inter-examination agreement for the astigmatism description ranged from 56 to 85% depending on the reader and parameter. The decision to implant a toric IOL based on the axial map was the same in 59-60% of cases depending on the examiner. A second examination was needed in 18-25% and 8-14% of cases after CT and PT, respectively. The IOLMaster 700® central anterior axial map allowed toric IOL implantation in 58-70% of cases with no need for second corneal examination.

CONCLUSION

The agreement between the anterior axial maps obtained using both devices was good. However, in about a quarter of the cases, dedicated topography had to be performed to confirm the surgical indication.

Accuracy of new intraocular lens power calculation formula for short and long eyes using segmental refractive indices

PURPOSE

To evaluate the accuracy of a new intraocular lens power calculation formula using segmental refractive index-based axial length (AL).

SETTING

Chukyo Eye Clinic, Nagoya, Japan.

DESIGN

Retrospective observational study.

METHODS

This study included patients undergoing preoperative examination for cataract surgery with the new Barrett True AL (BTAL) and Emmetropia Verifying Optical (EVO) formulas using segmental refractive index, and conventional Barrett Universal II (BU II) formula using equivalent refractive index. The predicted refractive error of each formula was compared with the postoperative subjective spherical equivalent.

RESULTS

The mean prediction error (MPE) in the short AL group (≤22 mm; 44 eyes) was 0.32 ± 0.40 diopter (D) for BU II, 0.22 ± 0.37 D for BTAL, and 0.10 ± 0.37 D for EVO ( P < .0001). MPE in the long AL group (≥26 mm; 92 eyes) was 0.01 ± 0.32 D for BU II, 0.04 ± 0.32 D for BTAL, and 0.09 ± 0.32 D for EVO ( P < .0001). In patients with an AL ≥ 28 mm, BU II showed a myopic trend in 57.1% of cases, while BTAL and EVO showed a hyperopic trend in 71.4%. The MPE for patients with an AL ≥ 28 mm was -0.16 ± 0.34 D for BU II, 0.18 ± 0.33 D for BTAL, and 0.16 ± 0.32 D for EVO ( P < .0001).

CONCLUSIONS

The new EVO and BTAL formulas showed higher accuracy than BU II in short eyes, whereas there was no difference in long eyes.

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

AIMS

To 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, and to compare them to those obtained by a swept-source optical coherence tomography (SS-OCT)-based biometer.

METHODS

This prospective study consisted of 115 eyes of 115 healthy subjects. The measurements were taken by the two optical biometers in random order. The measured parameters were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), mean keratometry (Km), lens thickness (LT) and corneal diameter (CD). To evaluate the intraobserver repeatability and interobserver reproducibility, the within-subject SD, test-retest variability, coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were adopted. The Bland-Altman plot was drawn to assess the agreement.

RESULTS

The repeatability and reproducibility of all parameters for the new device were excellent (ICC>0.960 and CoV<0.71%). The Bland-Altman plots showed high agreement between the OLCR-based and SS-OCT-based devices for AL, CCT, AQD, ACD, Km and LT, with narrow 95% limit of agreements (LoAs) (-0.08 mm to 0.06 mm, -15.91 µm to -1.01 µm, -0.09 mm to 0.09 mm, -0.09 mm to 0.08 mm, -0.47 D to 0.35 D, -0.05 mm to 0.16 mm, respectively) and moderate agreement for CD (95% LoA: -0.67 mm to -0.01 mm).

CONCLUSIONS

The new Suoer SW-9000 μm Plus biometer showed excellent repeatability and reproducibility. All the parameters obtained by this biometer were similar to those measured by SS-OCT-based biometer.

Current Concepts and Recent Updates of Optical Biometry- A Comprehensive Review

One of the most recent advancements in the field of cataract surgery is optical biometry. With the advent of optical biometry ocular measurements are now simpler, quicker, and more precise. The devices have made intraocular lens (IOL) power calculations easier in difficult situations too, such as in cases with extremes of axial lengths, silicone filled eyes, cataract surgery in post-keratoplasty eyes, post Laser-Assisted in Situ Keratomileusis (LASIK) eyes, etc. The gold standard for IOL power calculation in the present day is by the use of optical biometry devices. The anatomical measurements by these devices are highly precise and because of these measurements and the incorporation of various IOL power calculation formulas the optical biometry devices give the accurate power and the post-operative visual outcome is highly satisfactory among the patients. The growing use of these devices has made cataract the most commonly performed refractive surgical procedure nowadays. In the current scenario, optical biometry has widespread acceptance in almost all countries and has many advantages over ultrasound or immersion biometry. Cataract surgeons can obtain easy and reliable measurements from these devices. Refractive surprises have also decreased considerably with their use. This article will comprehensively review the principles of the various optical biometry devices, the parameters used in each of the devices, the advantages and disadvantages, and add more like what all this article will add.

Impact of segmented optical axial length on the performance of intraocular lens power calculation formulas

PURPOSE

To investigate the difference between the segmented axial length (AL) and the composite AL on a swept-source optical coherence tomography biometer and to evaluate the subsequent effects on artificial intelligence intraocular lens (IOL) power calculations: the Kane and Hill-RBF 3.0 formulas compared with established vergence formulas.

SETTING

National Hospital Organization, Tokyo Medical Center, Japan.

DESIGN

Retrospective case series.

METHODS

Consecutive patients undergoing cataract surgery with a single-piece IOL were reviewed. The prediction accuracy of the Barrett Universal II, Haigis, Hill-RBF 3.0, Hoffer Q, Holladay 1, Kane, and SRK/T formulas based on 2 ALs were compared for each formula. The heteroscedastic test was used with the SD of prediction errors as the endpoint for formula performance.

RESULTS

The study included 145 eyes of 145 patients. The segmented AL (24.83 ± 1.89) was significantly shorter than the composite AL (24.88 ± 1.96, P < .001). Bland-Altman analysis revealed a negative proportional bias for the differences between the segmented AL and the composite AL. The SD values obtained by Hoffer Q, Holladay 1, and SRK/T formulas based on the segmented AL (0.52 diopters [D], 0.54 D, and 0.50 D, respectively) were significantly lower than those based on the composite AL (0.57 D, 0.60 D, and 0.52 D, respectively, P < .01).

CONCLUSIONS

The segmented ALs were longer in short eyes and shorter in long eyes than the composite ALs. The refractive accuracy can be improved in the Hoffer Q, Holladay 1, and SRK/T formulas by changing the composite ALs to the segmented ALs.

Comparison of two swept-source optical coherence tomography devices, a Scheimpflug camera system and a ray-tracing aberrometer in the measurement of corneal power in patients with cataract

PURPOSE

To assess the differences and similarities in the corneal curvature obtained by two swept-source optical coherence tomography (SS-OCT) devices, Scheimpflug imaging system and one ray tracing aberrometer in patients with cataracts. Moreover, this study aimed to compare the differences in posterior corneal (PK), total corneal (TK) and true net power (TNP) measurements among the IOLMaster 700, CASIA2, and Pentacam.

METHODS

A total of 200 eyes of 200 patients (116 female, 58%) were enrolled in this study, with a mean age of 65.9 ± 9.5 years. The flattest (Kf), steepest (Ks), and mean cornal powers (Km), J0, and J45 were obtained using two SS-OCT-based biometric devices, one rotating camera system and one ray-tracing aberrometer. The PK, TK and TNP values were also measured using these devices. To evaluate the differences and similarities between the devicves, the Friedman test, Pearson correlation coefficient (r), intraclass coefficient correlation (ICC) and Bland‒Altman plots with 95% limits of agreement (LoA) were used, and boxplots and stacked histograms were generated to describe the distributions of the data.

RESULTS

There were no significant differences between the IOLMaster 700 and Pentacam for any of the keratometry values. Additionally, there were no significant differences between the IOLMaster 700 and iTrace in evaluating J0 and J45. Bland‒Altman plots revealed relatively wide LoA widths, almost larger than 1 diopter for the keratometry values and almost larger than 0.5 diopter for J0 and J45 values among the four devices. In terms of PK and TK values, significant differences and low ICCs were found among the three devices.

CONCLUSIONS

Although strong correlations and good agreement were found among the IOLMaster700, CASIA2, Pentacam and iTrace for Kf, Ks, Km and J0, J45, it seems that the measurements should not be used interchangeably because of the wide LoA widths and the presence of significant differences among the devices. Similarly, due to significant differences and low ICCs, the PK, TK and TNP values obtained by IOLMaster 700, CASIA2, and Pentacam should not be used interchangeably.

Evaluation of a new dynamic real-time visualization 25 kHz swept-source optical coherence tomography based biometer

BACKGROUND

To evaluate the intraobserver repeatability and interobserver reproducibility of a newly developed dynamic real-time visualization 25 kHz swept-source optical coherence tomography (SS-OCT) based biometer (ZW-30, TowardPi Medical Technology Ltd, China) and compare its agreement with another SS-OCT based biometer (IOLMaster 700, Carl Zeiss Meditec AG, Jena, Germany).

METHODS

Eighty-two healthy right eyes were enrolled in this prospective observational study. Measurements were repeated for three times using the ZW-30 and IOLMaster 700 in a random order. Obtained parameters included axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), lens thickness (LT), mean keratometry (Km), astigmatism magnitude (AST), vector J0, vector J45, and corneal diameter (CD). The within-subject standard deviation (Sw), test-retest (TRT) variability, coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were adopted to assess the intraobserver repeatability and interobserver reproducibility. The double-angle plot was also used to display the distribution of AST. To estimate agreement, Bland-Altman plots were used.

RESULTS

For the intraobserver repeatability and interobserver reproducibility, the Sw, TRT and CoV for all parameters were low. Meanwhile, the ICC values were all close to 1.000, except for the J45 (ICC = 0.887 for the intraobserver repeatability). The double-angle plot showed that the distribution of AST measured by these two devices was similar. For agreement, the Bland-Altman plots showed narrow 95% limits of agreements (LoAs) for AL, CCT, AQD, ACD, LT, Km AST, J0, J45, and CD (- 0.02 mm to 0.02 mm, - 7.49 μm to 8.08 μm, - 0.07 mm to 0.04 mm, - 0.07 mm to 0.04 mm, - 0.07 mm to 0.08 mm, - 0.16 D to 0.30 D, - 0.30 D to 0.29 D, - 0.16 D to 0.16 D, - 0.23 D to 0.13 D, and - 0.39 mm to 0.10 mm, respectively).

CONCLUSIONS

The newly dynamic real-time visualization biometer exhibited excellent intraobserver repeatability and interobserver reproducibility. The two devices both based on the SS-OCT principle had similar ocular parameters measurement values and can be interchanged in clinical practice.

Interchangeability in Automated Corneal Diameter Measurements Across Different Biometric Devices: A Systematic Review of Agreement Studies

PURPOSE

To provide an up-to-date review of the agreement in automated white-to-white (WTW) measurement between the latest topographic and biometric devices.

METHODS

In this systematic review, PubMed, Web of Science, and Scopus databases were searched for articles published between 2017 and 2023, focusing on WTW agreement studies on adult, virgin eyes, with or without cataract and no other ocular comorbidities. Studies evaluating WTW measurements performed with autokeratometers, manual calipers, or manual image analysis were excluded. When available, the following metrics for the agreement of WTW measurements between pairs of devices were included: mean difference ± standard deviation, 95% limits of agreement (LoA), LoA width, 95% confidence interval (95 CI%), and intraclass correlation coefficient (ICC).

RESULTS

Forty-one studies, covering comparisons for 19 devices, were included. Altogether, 81 paired comparisons were performed for 4,595 eyes of 4,002 individuals. The mean difference in WTW measurements between devices ranged from 0.01 mm up to 0.96 mm, with varying CI. The 95% LoA width ranged from 0.31 to 2.45 mm (median: 0.65 mm). The majority of pairwise comparisons reported LoA wider than 0.5 mm, a clinically significant value for phakic intraocular lens sizing.

CONCLUSIONS

Nearly all analyzed studies demonstrated the lack of interchangeability of the WTW parameter. The corneal diameter, assessed by means of grayscale en-face image analysis, tended to demonstrate the lowest agreement among devices compared to other measured biometric parameters. [J Refract Surg. 2024;40(3):e182-e194.].

Biometry challenges in the longest eyes we have encountered to date

Purpose

This report aims to present biometry challenges and solutions for a patient with the longest eyes we have encountered to date.

Observations

A 41-year-old woman with a history of Crouzon syndrome, extreme axial myopia, and posterior segment staphylomas was referred for cataract evaluation. Optical biometry was attempted using two partial coherence interferometry and optical low-coherence reflectometry devices that were available in 2011. Neither device could measure the axial length (AL) of either eye, unfortunately. We were able to measure them by A scan ultrasound, however, with results of 40.59 mm for the right eye and 38.29 mm for the left eye. Shortly thereafter, she underwent uncomplicated phacoemulsification with posterior chamber intraocular lens implantation under topical anesthesia. Twelve years later, she returned for repeat optical biometry with 3 newer generation devices, 2 of which utilized swept-source optical coherence tomography (SS-OCT). Only 1 SS-OCT device, the Argos biometer, was able to obtain AL measurements, and they were 40.54 mm and 40.84 mm for the right and left eyes, respectively.

Conclusions and importance

Biometry measurement using optical biometers on a patient with ALs greater than 40 mm was impossible in 2011 because of the relatively short gate for acceptable readings. Ultrasound biometry can also be challenging due to the presence of posterior staphylomas. However, a newer SS-OCT with a longer AL measurement capability enabled readings to be obtained more recently.

Repeatability and agreement of the MYAH and Lenstar

SIGNIFICANCE

Validation of new biometry instruments against the gold standard and establishing repeatability are important before being utilized for clinical and research applications.

PURPOSE

This study aimed to investigate intersession repeatability of the MYAH optical biometer and corneal topographer and examine agreement with the Lenstar LS900 optical biometer in healthy young adults.

METHODS

Forty participants (mean age, 25.2 ± 3.1 years) presented for two visits, 2 to 4 days apart. At each visit, measurements for right eyes were collected with the MYAH and Lenstar LS 900 and included axial length, corneal power, white-to-white distance, and pupil diameter. Bland-Altman analysis was used to assess the intrasession agreement between the MYAH and Lenstar for each parameter and intersession repeatability for the two devices. For each device, coefficient of variation and intraclass correlation coefficient were calculated, and paired t tests between visits were performed to assess intersession repeatability.

RESULTS

Good agreement (mean difference [95% limits of agreement]) between the MYAH and Lenstar was found for axial length (-0.01 [-0.07 to 0.04] mm), corneal power (-0.02 D [-0.15 to 0.19 d]), white-to-white distance (-0.13 [-0.43 to 0.17] mm), and pupil diameter (-0.27 [-0.79 to 1.33] mm). The limits of agreement, coefficient of variations, and intraclass correlation coefficients for MYAH-measured parameters were -0.04 to 0.04, 0.06%, and >0.99 for axial length; -0.24 to 0.19, 0.18%, and >0.99 for corneal power; -1.05 to 1.15, 0.57%, and 0.96 for white-to-white distance; and -0.17 to 0.21, 7.0%, and 0.76 for pupil diameter, with no significant difference between visits (p>0.05 for all), indicating good intersession repeatability. Similar intersession repeatability was also noted for Lenstar.

CONCLUSIONS

Findings show good intersession repeatability of the MYAH and good agreement with the Lenstar for axial length, corneal power, and white-to-white distance in young adults. Pupil diameter was more variable, likely due to the dynamic nature of the pupil. This study provides validation and supports the use of the MYAH for ocular biometry.

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.

Optimization of biometry for best refractive outcome in cataract surgery

High-precision biometry and accurate intraocular lens (IOL) power calculation have become essential components of cataract surgery. In clinical practice, IOL power calculation involves measuring parameters such as corneal power and axial length and then applying a power calculation formula. The importance of posterior corneal curvature in determining the true power of the cornea is increasingly being recognized, and newer investigative modalities that can estimate both the anterior and posterior corneal power are becoming the standard of care. Optical biometry, especially using swept-source biometers, with an accuracy of 0.01-0.02 mm, has become the state-of-the-art method in biometry. With the evolution of IOL formulas, the ultimate goal of achieving a given target refraction has also moved closer to accuracy. However, despite these technological efforts to standardize and calibrate methods of IOL power calculation, achieving a mean absolute error of zero for every patient undergoing cataract surgery may not be possible. This is due to inherent consistent bias and systematic errors in the measurement devices, IOL formulas, and the individual bias of the surgeon. Optimization and personalization of lens constants allow for the incorporation of these systematic errors as well as individual bias, thereby further improving IOL power prediction accuracy. Our review provides a comprehensive overview of parameters for accurate biometry, along with considerations to enhance IOL power prediction accuracy through optimization and personalization. We conducted a detailed search in PubMed and Google Scholar by using a combination of MeSH terms and specific keywords such as "ocular biometry," "IOL power calculations," "prediction accuracy of refractive outcome in cataract surgery," "effective lens position," "intraocular lens calculation formulas," and "optimization of A-constants" to find relevant literature. We identified and analyzed 121 relevant articles, and their findings were included.

Evaluation of a New All-in-One Optical Biometer and Comparison With a Validated Swept-source OCT Biometer

PURPOSE

To assess agreement between a new all-in-one non-contact optical biometer based on optical low coherence reflectometry (SW-9000 µm Plus; Suoer) and a swept-source optical coherence tomography biometer (OA-2000; Tomey).

METHODS

Each eye was scanned three times in a row by each device at random. The measured ocular parameters included central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), axial length (AL), flat keratometry (Kf), steep keratometry (Ks), mean keratometry (Km), astigmatism, corneal diameter (CD), and pupil diameter (PD). The paired t test was used to show the differences between the SW-9000 and OA-2000. Bland-Altman plots and the 95% limits of agreement (LoA) were applied to assess the consistency of the measurements.

RESULTS

Sixty eyes from 60 healthy participants were examined, with a mean spherical equivalent refraction of -5.58 ± 2.31 diopters and a mean age of 30.40 ± 6.07 years. The Bland-Altman plots showed high agreement for AL, ACD, LT, Kf, Ks, Km, astigmatism, and CD measurements (95% LoA: -0.06 to 0.04 mm, -0.10 to 0.06 mm, -0.12 to 0.11 mm, -0.30 to 0.29 D, -0.35 to 0.38 D, -0.29 to 0.30 D, -0.30 to 0.34 D, and -0.50 to 0.06 mm, respectively), whereas the agreement for CCT and PD were moderate (95% LoA: 7.12 to 20.43 µm, -0.75 to 1.19 mm, respectively).

CONCLUSIONS

The new all-in-one non-contact biometer had high agreement with the OA-2000 biometer on the AL, ACD, LT, Kf, Ks, Km, astigmatism, and CD measurements. For most of the ocular parameters assessed, they were clinically interchangeable. [J Refract Surg. 2023;39(12):825-830.].

Accuracy and Precision of New Optical Biometer Designed for Myopia Management in Measurement of Ocular Biometry

SIGNIFICANCE

This study provides information about the repeatability of Myopia Master (Oculus, Wetzlar, Germany) and its agreement with Lenstar LS900, which might be useful for the practitioners involved in myopia management.

PURPOSE

Myopia Master is a new optical biometer that measures ocular biometry and refractive error. The purpose of this study was to assess its repeatability (intrasession and short-term intersession) and its agreement with Lenstar LS900 for the measurement of axial length and corneal curvature.

METHODS

A total of 304 participants including 254 children (mean ± standard deviation age, 13.7 ± 1.6 years) and 50 adults (24 ± 2.9 years) underwent measurements on Myopia Master and Lenstar LS900 to obtain axial length, flat K, and steep K. On a subset of 30 participants, measurements were obtained with Myopia Master in two sessions that were spread over 10 minutes to assess the short-term intersession repeatability.

RESULTS

The mean standard deviation of Myopia Master in the measurement of axial length in the total sample was 0.01 mm for intrasession, when the best three measurements were considered. The short-term intersession mean standard deviation for axial length, flat K, and steep K was 0.06 mm, 0.15 D, and 0.21 D, respectively. There were statistically significant differences in mean values of axial length (-0.04 ± 0.06 mm), flat K (-0.07 ± 0.15 D), and steep K (-0.24 ± 0.29 D) between Lenstar LS900 and Myopia Master, with the Lenstar providing slightly longer axial length and steeper K values. Adults showed better repeatability with Myopia Master and better agreement between the biometers for axial length measurement than children. Neither axial length nor refractive error influenced the repeatability or agreement.

CONCLUSIONS

Myopia Master is repeatable for the measurement of axial length and corneal curvature. Considering the differences in axial length between the Myopia Master and Lenstar LS900, caution must be applied when these biometers are used interchangeably.

Axial length acquisition success rates and agreement of four optical biometers and one ultrasound biometer in eyes with dense cataracts

BACKGROUND

To evaluate the axial length acquisition success rates and agreement between various biometric parameters obtained with different biometers in dense cataracts.

METHODS

Fifty-one eyes were measured using Anterion®, Argos® and IOLMaster® 700 swept-source optical coherence tomography (SS-OCT) biometers, a Pentacam® AXL partial coherence interferometry (PCI) biometer, and an OcuScan® RxP ultrasound biometer. We measured keratometry (K1, flattest keratometry and K2, steepest keratometry), white-to-white (WTW), anterior chamber depth (ACD), lens thickness (LT) and axial length. Cataracts were classified according to the Lens Opacities Classification System III grading system, the dysfunctional lens index (DLI) and Pentacam® nucleus staging (PNS) metrics. Percentage of acquisition success rate and a Bland-Altman analysis for the agreement between biometers were calculated.

RESULTS

The mean LOCS III score was 3.63 ± 0.92, the mean DLI was 2.95 ± 1.30 and the mean PNS was 2.36 ± 1.20. The acquisition success rates for the Anterion®, Argos®, IOLMaster® 700, Pentacam® AXL and OcuScan® RxP biometers were 94.12%, 100%, 98.04%, 60.78% and 100%, respectively. There were significant differences in the success rates between biometers (P = 0.014). There were statistically significant differences between biometers for all parameters evaluated (P < 0.05). The range of the limit of agreement (LoA) for all comparisons of K1 and K2 were > 1.00 D. The LoA for WTW ranged from 0.095 to 1.050 mm. The LoA for ACD and LT ranged from 0.307 to 0.114 mm and from 0.378 to 0.108 mm, respectively. The LoA for axial length ranged from 0.129 to 2.378 mm.

CONCLUSIONS

Among optical biometers, those based on SS-OCT technology are more successful at measuring axial length in eyes with dense cataracts.

TRIAL REGISTRATION

The study was registered with the National Institutes of Health (clinical trial identifier NCT05239715, http://www.

CLINICALTRIALS

gov ).

Randomized Trial Comparing Prediction Accuracy of Two Swept Source Optical Coherence Tomography Biometers

Purpose

To compare the prediction accuracy of the Argos biometer using standard keratometry to the prediction accuracy of the IOLMaster 700 biometer using Total Keratometry.

Methods

This was a randomized, prospective, single surgeon study of 80 right eyes of 80 patients that had preoperative biometry with both the Argos and IOLMaster 700 devices, followed by cataract surgery and intraocular lens (IOL) implantation. Prediction errors (directional and absolute) for each device were determined from the 1 month postoperative manifest refraction.

Results

The directional prediction error was 0.07 ± 0.32 D for the Argos and 0.08 ± 0.34 D for the IOLMaster 700. The mean of the difference in prediction error (directional) was 0.02 D, which was not statistically significant (p > 0.05). The absolute prediction error was 0.21 ± 0.25 D for the Argos and 0.25 ± 0.24 D for the IOLMaster 700. The mean of the difference in absolute prediction error was 0.04 D, which was statistically significant (p < 0.004) but not clinically significant. The percentage of eyes with absolute prediction error ≤ 0.5 D was 91% (73 eyes) for the Argos and 88% (70 eyes) for the IOLMaster 700. This difference was not statistically significant.

Conclusion

The prediction accuracies were similar between the Argos and IOLMaster 700 in eyes with normal axial length. There was a significant difference in mean absolute prediction error between devices; however, this was not clinically meaningful.

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

Purpose

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.

Methods

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.

Results

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.

Conclusion

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.

Corneal diameter measurements by 3 optical biometers and their effect on phakic intraocular lens sizing

PURPOSE

To compare phakic intraocular lens size calculations based on corneal diameter (CD) measurements by 3 instruments.

SETTING

G.B. Bietti Foundation I.R.C.C.S., Rome, Italy.

DESIGN

Retrospective interventional case series.

METHODS

Preoperatively, CD was measured with the Aladdin, IOLMaster 700, and Pentacam AXL Wave. The simulated ICL size was computed by entering CD measurements into the manufacturer's calculator. Postoperatively, vaulting was measured by anterior segment optical coherence tomography. The optimal ICL size (OIS) was calculated and compared with the commercially available OIS (CAOIS).

RESULTS

54 eyes (29 patients) with the implantable collamer lens (ICL) were enrolled. The mean CD was 12.02 ± 0.36 mm with the Aladdin, 12.35 ± 0.39 mm with the IOLMaster 700, and 12.22 ± 0.41 mm with the Pentacam AXL Wave ( P &amp;lt; .0001), with the closest agreement between the Pentacam AXL Wave and IOLMaster 700 (95% limits of agreement: -0.43 to +0.17 mm). Vaulting (mean: 558 ± 261 μm) was within 251 and 1000 μm in 49 eyes (83.3%). The mean difference between the simulated ICL size and OIS ranged between -0.11 ± 0.35 mm and 0.10 ± 0.30 mm ( P &amp;lt; .0001), with no statistically significant difference between the IOLMaster 700 and Pentacam AXL Wave. The simulated ICL size was equal to CAOIS in 38 eyes (70.37%) with the Aladdin, 37 eyes (68.52%) with the IOLMaster 700, and 39 eyes (72.22%) with the Pentacam AXL Wave, without any statistically significant difference.

CONCLUSIONS

CD measurements by the 3 devices lead to similar percentages of eyes with an ICL size equal to the OIS. Agreement is closer between the IOLMaster 700 and Pentacam AXL Wave.

Comparison of Astigmatism Prediction Accuracy for Toric Lens Implantation from Two Swept-Source Optical Coherence Tomography Devices

Purpose

To compare the astigmatism prediction accuracy for toric intraocular lens (IOL) implantation between two swept-source optical coherence tomography (SS-OCT) devices: Argos (Movu, a Santec Company) and the IOLMaster 700 (Carl Zeiss Meditec).

Methods

This was a retrospective chart review of 59 eyes (44 patients) with corneal astigmatism and cataract that underwent cataract surgery or refractive lens exchange surgery with a toric IOL. Biometry was performed on all patients prior to cataract surgery and the Barrett toric IOL calculator was used. Visual acuity was measured postoperatively. Manifest refraction was measured at 1 month and compared to the predicted postoperative residual refraction. Preoperative K measurements between devices were also compared.

Results

Mean cylinder prediction error was −0.17 ± 0.43 for Argos and 0.12 ± 0.56 for IOLMaster 700. The cylinder prediction error 0.5 D or less was not significantly different between the devices, with 83.1% (49 eyes) for Argos and 76.3% (45 eyes) for IOLMaster 700 (p = 0.206). Spherical equivalent prediction error was 0.13 ± 0.39 for Argos and 0.25 ± 0.50 for IOLMaster 700. The mean spherical equivalent prediction error 0.5 D or less was significantly different between the devices, with 79.7% (47 eyes) for Argos and 61.0% (36 eyes) for IOLMaster 700 (p = 0.016).

Conclusion

The prediction accuracies were similar between the devices, except for spherical equivalent, where a higher percentage of eyes were 0.5 D or less of the prediction with the Argos compared to the IOLMaster.

Axial length measurement failure rates using optical biometry based on swept-source OCT in cataractous eyes

INTRODUCTION

Ocular dimensions measurement is extremely important in cataract procedures and refractive surgery. The use of optical techniques for axial measurements has been developed in recent years.

AREAS COVERED

The purpose was to summarize the outcomes reported when swept-source optical coherence tomography (SS-OCT) optical biometry failed during axial length measurement. A peer-reviewed literature search was carried out to identify publications reporting clinical outcomes for cataractous eyes measured with SS-OCT optical biometers available on the market. A comprehensive analysis of the available data was performed, focusing on parameters such as the sample of eyes evaluated, failure rates, and specifically, the cataract type when the measurement was not possible. 27 studies were included in this review. In general, SS-OCT biometers lead to only small failure rates when measuring axial length (but in some cases up to 38.49%). In the few cases where the measurement was not possible, the cataract type of the eyes was mainly mature white or grade ≥ IV. SS-OCT optical biometers show good outcomes when measuring axial length in eyes with advanced cataracts.

EXPERT OPINION

We believe that the use of SS-OCT technology may be considered the gold standard for measuring axial length in any type of cataract.

Agreement of axial length and anterior segment parameters measured with the MYAH device compared to Pentacam AXL and IOLMaster 700 in myopic children

PURPOSE

To compare the difference and agreement of axial length (AL) and anterior segment parameters obtained from the MYAH device with Pentacam AXL and IOLMaster 700 in myopic children.

METHODS

The study included 60 eyes of 60 myopic children. AL, keratometry (K), and horizontal corneal diameter (CD) were measured with Pentacam AXL, IOLMaster 700, and MYAH, respectively. The Friedman test was used to assess the differences. The Intraclass Correlation Coefficient (ICC) and Bland-Altman plots were used to assess the consistency of measurements.

RESULTS

The mean age was 10.2 ± 1.8 years (7-16 years). No statistically significant difference was determined between the Pentacam AXL, IOLMaster 700, and MYAH devices in terms of mean AL values (23.61 ± 1.42, 23.62 ± 1.45, 23.61 ± 1.42, respectively) (p = 0.06). The difference between devices in the mean steep K, flat K, mean K, and CD was statistically significant but clinically insignificant (steep K; 44.45 ± 1.25, 44.59 ± 1.23, 44.51 ± 1.24, flat K; 43.29 ± 1.28, 43.43 ± 1.29, 43.35 ± 1.30, mean K; 43.85 ± 1.21, 44.00 ± 1.19, 43.94 ± 1.20, and CD; 11.90 ± 0.34, 12.11 ± 0.38, 11.96 ± 0.31, respectively; p < 0.05). ICC and Bland-Altman plot analysis revealed a high correlation between the three devices in AL, steep K, flat K, mean K, and CD measurements.

CONCLUSION

There was a quite good agreement between the MYAH, Pentacam AXL, and IOLMaster 700 devices regarding AL and anterior segment parameters. MYAH provides reliable measurements and will be a good option in the diagnosis of and follow-up with myopic children.

Comparison of the IOLMaster 700 and the Pentacam in the Analysis of the Lens Nuclear Density Before the Cataract Surgery

Purpose: To evaluate the difference of the lens nuclear density measured before and after mydriasis by using the IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany) and the Pentacam Scheimpflug imaging (Pentacam HR, Oculus Incorporation, Wetzlar, Germany) and investigate the relationship between the measurement data and the phacoemulsification parameters.

Methods: Patients with age-related nuclear cataracts diagnosed on the slit-lamp examination were enrolled in the age range of 53–76 years. No patient had a history of ocular surgery, laser treatment, or general disorders affecting vision. The mean optical density (OD) was measured by the IOLMaster 700 by using the Image-Pro^® Plus software before and after mydriasis. The Pentacam nucleus densitometry (PND) was obtained automatically from the Pentacam Scheimpflug imaging and compared with OD. The correlation between OD and effective phacoemulsification time (EPT), PND, and EPT were analyzed, respectively.

Results: In this study, 53 eyes of 52 patients were evaluated. Before and after mydriasis, the mean OD values were 64.34 ± 23.31 and 63.81 ± 23.21 pixel units, respectively; the mean PND values were 28.51 ± 11.42 and 25.41 ± 11.31, respectively; and the mean EPT value was 6.24 ± 3.49. The Bland–Altman analysis showed that the lens nuclear densities of the two devices were highly consistent. There was no significant difference in the OD values (t = 0.455, p > 0.05) before and after mydriasis, but the difference has existed in the PND values (t = 2.509, p < 0.05). The OD and PND values were positively correlated with EPT before and after mydriasis (r_OD−Before = 0.604, r_OD−After = 0.593, r_PND−Before = 0.701, and r_PND−After = 0.891, p < 0.01).

Conclusion: The combination of the IOLMaster 700 and the Image-Pro^® Plus software can quantitatively evaluate the degree of the cataract lens opacification. It has good consistency with the Pentacam and is positively correlated with the phacoemulsification parameters. It is expected to become a new method to predict the phacoemulsification parameters before and during cataract surgery.