Partial Coherence Interferometry Research Articles

Choroidal thickness as a biomarker for axial length change

Aims/Purpose: Assessing axial eye growth is a key component in myopia management; however, access to biometry is limited in primary eye care settings. This study evaluated choroidal thickness, compared to spherical equivalent refraction, as a potential biomarker of axial elongation.Methods: The Myopia Outcome Study of Atropine in Children (MOSAIC) is a double‐blind, randomized controlled trial of 0.01% atropine eye drops. Irish myopic participants aged 6–16 years used either 0.01% atropine or placebo eye drops nightly for 2 years. Spherical equivalent refraction (SER) was measured by cycloplegic autorefraction, axial length (AL) by partial coherence interferometry and choroidal thickness (ChT) by Swept Source‐OCT. The respective 12‐month changes in both eyes were included in mixed linear regression analysis, while controlling for treatment group and within‐subject correlation. ROC analysis was conducted to assess the ability of ChT and/or SER to identify eyes in the top 25% (fast progressors) of AL change.Results: Of the 250 participants enrolled in MOSAIC (mean age 11.8 years, 62% female), 217 (87%) completed the 12‐month visit. Mean 12‐month change in AL, ChT and SER were 0.268 ± 0.19 mm, −3.62 ± 33.3 um and −0.437 ± 0.346 DS respectively. Analysis revealed a significant association between change in ChT and AL (−0.01 ± 0.002 mm per 10 μm; p < 0.001) and change in SER and AL (−0.28 ± 0.02 mm per 1D; p < 0.001). When both SER and ChT were combined in a single model, a 1D myopic change in SER and a 10um decrease in ChT were associated with a 0.27 mm (p < 0.001) and 0.007 mm increase in AL (p = 0.002), respectively. ROC analysis revealed that change in ChT was a stronger predictor of fast AL progression (AUC = 0.77) compared to SER change (AUC = 0.72), with the combined model performing better than either variable alone (AUC = 0.80).Conclusions: ChT change was significantly associated with AL change over 12 months and better than SER alone at identifying fast AL progressors, with a combined SER and ChT model achieving the best results.

Comparison of Anterior Segment Measurements Between Swept-source Optical Coherence Tomography and Schiempflug Coherence Interferometer

Purpose: To assess the agreement between anterior segment measurements obtained using swept-source optical coherence tomography (Anterion<sup>®</sup>, Heidelberg Engineering Inc., Heidelberg, Germany) and Scheimpflug partial coherence interferometry (Pentacam HR<sup>®</sup>, OCULUS, Wetzlar, Germany).Methods: We analyzed the anterior and posterior corneal keratometry, Cartesian astigmatism (J0), oblique astigmatism (J45), anterior chamber depth (ACD), and central corneal thickness (CCT) measurements obtained using the two devices in 65 eyes of 43 subjects.Results: The mean differences between the anterior flat K, anterior steep K, anterior mean K, anterior J0, anterior J45, posterior flat K, posterior steep K, posterior mean K, posterior J0, posterior J45, ACD, and CCT measurements were -0.13 ± 0.34, -0.02 ± 0.33, -0.05 ± 0.31, -0.03 ± 0.39, -0.06 ± 0.35, 0.12 ± 0.09, 0.07 ± 0.08, 0.10 ± 0.06, -0.02 ± 0.14, 0.01 ± 0.16, 0.04 ± 0.06, and -3.51 ± 7.42, respectively. All measurements except posterior J0 and J45 had interclass correlation coefficients greater than 0.75.Conclusions: The mean differences and 95% limits of agreement in this study are consistent with previously reported values. There was a high level of agreement between Anterion<sup>®</sup> and Pentacam HR<sup>®</sup>. However, considering the statistically significant differences and limits of agreement for certain measurements, caution should be exercised when assuming interchangeability between these devices.

Repeatability and agreement of AOCT-1000 M, RTVue XR and IOL master 500 in measuring corneal thickness mapping and axial length applying principle of optical coherence tomography

PurposeTo evaluate the repeatability and agreement of Fourier-domain optical coherence tomography (AOCT-1000 M and RTVue XR) and partial coherence interferometry biometer (IOL Master 500) in measuring corneal thickness mapping and axial length respectively.MethodsCorneal thickness was measured by AOCT-1000 M and RTVue XR. Axial lengths were measured by AOCT-1000 M and IOL Master 500. The repeatability and agreement of corneal thickness and axial length were calculated in two groups of devices. The intraclass correlation coefficient (ICC) was used to verify the repeatability of the device. The 95% confidence interval of the difference compared to the set cut-off value was used to verify the agreement between the two devices.ResultsA total of 60 subjects with 58 eyes were included. The central corneal thickness measured by AOCT-1000 M and RTVue XR were 504.46 ± 42.53 μm and 504.43 ± 42.89 μm respectively. The average difference between groups was 0.03 ± 4.58 μm, and the 95% confidence interval was (-1.17, 1.24), which was far less than the set threshold value of 15 μm (P < 0.001). Both RTVue XR and AOCT-1000 M had very good ICC values of central corneal thickness (0.998 and 0.994, respectively). The average axial lengths measured by AOCT-1000 M and IOL Master 500 were 24.28 ± 1.25 mm and 24.29 ± 1.26 mm respectively and the 95% confidence interval was (-0.02, 0.01), which was less than the set threshold value of 0.15 mm (P < 0.001). The ICC for both devices were 1.000.ConclusionGood repeatability and agreement were seen in measurements of central corneal thickness and axial length by AOCT-1000 M.

Differences in Axial Length and Anterior Chamber Depth among Keratoconic, Myopic and Emmetropic Eyes

Purpose: To report variation of the axial length (AL) and anterior chamber depth (ACD) among keratoconic (KC) eyes compared to myopic and emmetropic eyes in an African population sample. Study Design: Cross sectional observational. Place and Duration of Study: Al-Faisal Eye Hospital at Khartoum state of Sudanfrom January 2022 to September 2022. Methods: One-hundred and twenty-four eyes of 62 patients were divided into KC group (n =17, eyes=34), myopic group (n=28, eyes=56), and an age/gender matched emmetropic group (n=17, eyes =34). Central corneal thickness (CCT) was measured using ultrasonic pachymeter, AL, ACD and keratometry readings (K-reading) were recorded for each patient using non-contact partial coherence interferometry with an IOL Master. Results: Mean age of the sample population was 22.27± 6.05 (range; 10 – 40 years). KC patients had the highest spherical equivalent of refraction (SER) (-6.19±3.91 dioptres), highest k-reading (48.98±5.68 dioptres) and the thinnest CCT. Myopic participants had a longer AL compared to other refractive error groups (AL=24.99±2.39, p&lt;0.001). KC patients exhibited a larger ACD in comparison to emmetropes and myopes (ACD=3.6?9±0.26, p&lt;0.001). Among all participants, SER exhibited the highest correlation with AL (r=-0.71, p&lt;0.001) followed by a weaker correlation with ACD (r=-0.26, p=0.003). However, among KC patients, SER exhibited a weaker correlation with AL compared to myopes (r=-0.55, p=0.001), and a higher correlation with ACD compared to myopes (r=-0.38, p=0.03). Conclusion: ACD and corneal curvature were the most significantly detrimental parameters in KC. KC participants demonstrated a lower correlation between SER and AL and higher correlation between SER and ACD.

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

BackgroundTo evaluate the axial length acquisition success rates and agreement between various biometric parameters obtained with different biometers in dense cataracts.MethodsFifty-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.ResultsThe 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.ConclusionsAmong 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).

Comparison of Accuracy of 6 Modern Intraocular Lens Power Calculation Formulas.

To compare the accuracy of modern intraocular lens (IOL) power calculation formulas in predicting refractive outcomes after standard cataract surgery. The medical records of 203 eyes of 203 patients that received phacoemulsification and IOL implantation were retrospectively reviewed. Partial coherence interferometry was used to obtain the biometric values. The refractive outcomes of Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) 2.0, Hill-RBF 3.0, Hoffer QST, Kane, and PEARL-DGS formulas were evaluated. Axial length subgroup analysis was done separately. The correlations between the prediction error calculated by each formula and axial length (AL) and corneal power were also analyzed. Overall, there was no significant difference between the absolute prediction errors predicted by the six formulas after adjusting the mean prediction error (p = 0.058). AL subgroup analysis of absolute error also showed that there is no significant difference between the formulas. The BUII and Hill-RBF 3.0 formulas showed a higher percentage of eyes with PE within ±0.50 D compared to the Hoffer QST formula (p = 0.022 and p = 0.035). However, there was no significant difference after Bonferroni correction was applied. The BUII formula showed the highest IOL Formula Performance Index (FPI) and therefore the highest accuracy, followed by PEARL-DGS, EVO 2.0, Kane, Hill-RBF 3.0 and Hoffer QST formulas. Out of the six formulas, the prediction error calculated by the Hoffer QST was significantly correlated with the AL (p = 0.011). None of the prediction errors calculated by the six formulas showed correlation to the corneal power. Analysis of the prediction error showed that the 6 modern IOL power calculation formulas have comparable accuracy overall and across different ranges of axial length.

Correlation Between Corneal Keratometry, Central Corneal Thickness and Anterior Chamber Depth as Measured by Wavelight OB 820 Biometer and Wavelight Oculyzer II in Preoperative Cataract Surgery Patients.

To compare and correlate corneal keratometry (K), central corneal thickness (CCT), and anterior chamber depth (ACD) using a partial coherence interferometry device and a Scheimpflug camera system device in patients planned for cataract surgery. Comparative cross-sectional study. Place and Duration of the Study: Armed Forces Institute of Ophthalmology, from December 2021 to June 2022. Patients planned for cataract surgery underwent measurement of central corneal thickness (CCT), anterior chamber depth (ACD), and keratometric values (K) by Wavelight OB 820 biometer and Allergo Oculyzer II, preoperatively. Correlation and inter-device agreement were assessed between two devices. There were 115 patients with a mean age of 64.23 ± 9.26 years. All anterior segment parameters showed excellent agreement and high degree of correlation between the two optical devices. Correlation coefficient (r) for central corneal thickness was r = 0.958 (p<0.001) while correlation coefficient for anterior chamber depth was r = 0.965 (p<0.001), r = 0.966 (p<0.001) for flat K, and r = .0969 (p<0.001) for steep keratometry, respectively. Ophthalmic parameters assessed by both devices were comparable and are recommended to be used in the clinical practice of keratorefractive and cataract surgeries interchangeably. ACD, CCT, Keratometry, Cataract, OB 820 biometer, Oculyzer II.

Reliability and Agreement of Keratometry Measurements Obtained With Eye Surface Profilometry and Partial Coherence Interferometry.

The aim of this study was to assess the repeatability of keratometry parameters obtained using the Eye Surface Profiler (ESP) system and their agreement with the IOL Master 500 device. Seventy-one eyes of 71 healthy participants were evaluated. Three repeated measurements were performed using the ESP system. Simulated keratometry in the flat (SimKf) and steep (SimKs) meridians, astigmatism, and axis were obtained. The same parameters were measured using the IOL Master 500 device. The J0 and J45 vector components of the astigmatism were calculated. The intrasession repeatability was analyzed using within-subject SD (Sw) and intraclass correlation coefficient (ICC). Agreement was assessed using paired statistical tests and the Bland-Altman method. The Sw was 0.07 mm, 0.04 mm, 0.51 D, 0.33 D, and 0.22 D, and the ICC was 0.96, 0.98, 0.74, 0.61, and 0.55 for SimKf, SimKs, astigmatism, J0, and J45, respectively. The mean difference and limits of agreement when comparing the ESP system with the IOL Master 500 device were 0.37 mm (0.08/0.66) for SimKf ( P < 0.001), 0.18 mm (0.00/0.35) for SimKs ( P < 0.001), -0.93 D (-2.42/0.56) for astigmatism ( P < 0.001), 0.51 D (-0.22/1.24) for J0 ( P < 0.001), and 0.06 D (-0.48/0.60) for J45 ( P = 0.09). The ESP system provides consistent values for simulated keratometry, showing moderate consistency for astigmatism parameters. Contact lens practitioners should be aware that the ESP system and IOL Master 500 device provide different simulated keratometry from a clinically viewpoint.

Comment on- "Comparison of axial length measurements in silicone oil-filled eyes using SS-OCT and partial coherence interferometry".

Comment on- "Comparison of axial length measurements in silicone oil-filled eyes using SS-OCT and partial coherence interferometry".

SubFoveal Choroidal Imaging in High Myopic Nepalese Cohort.

Evidence suggests that choroid is thinner in myopes as compared to nonmyopes. However, choroidal thickness varies with the refractive error, age, axial length, and ethnicity. The purpose of this study was to determine the subfoveal choroidal thickness (SFCT) in high myopic Nepalese subjects and to investigate its association with the mean spherical equivalent refractive error (MSE), axial length, and age. Ninety-two eyes of 92 high myopic subjects (MSE ≤ -6 diopters) and 83 eyes of 83 emmetropic subjects (MSE: 0.00 Diopters) were included in the study. SFCT was assessed using spectral domain optical coherence tomography, and the axial length was measured using partial coherence interferometry. SFCT was measured manually using the inbuilt tool within the imaging software. SFCT in the high myopic subjects was significantly thinner (mean ± SD: 224.17 ± 68.91 μm) as compared to the emmetropic subjects (353.24 ± 65.63 μm) (mean difference, 127.76 ± 130.80 μm, and p < 0.001). In high myopic subjects, there was a significant negative correlation of choroidal thickness with the axial length (rho = -0.75; p < 0.001) and MSE (rho = -0.404; p < 0.01). Regression analysis demonstrated a decrease of choroidal thickness by 40.32 μm (p < 0.001) for every 1 millimeter increase in the axial length and by 11.65 μm (p < 0.001) for every 1 diopter increase in the MSE. High myopic Nepalese subjects had significantly thinner choroid as compared to emmetropes. The MSE and axial length were inversely correlated with the SFCT. Age had no effect on SFCT in this study. These findings may have implications in interpreting choroidal thickness values in clinical and epidemiological studies in myopes, especially in the south Asian population.

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

PurposePrecise ocular measurements are fundamental for achieving excellent target refraction following both cataract surgery and refractive lens exchange. Biometry devices with swept-source optical coherence tomography (SS-OCT) employ longer wavelengths (1055–1300 nm) in order to have better penetration through opaque lenses than those with partial coherence interferometry (PCI) or low-coherence optical reflectometry (LCOR) methods. However, to date a pooled analysis showing the technical failure rate (TFR) between the methods has not been published. The aim of this study was to compare the TFR in SS-OCT and in PCI/LCOR biometry.MethodsPubMed and Scopus were used to search the medical literature as of Feb 1, 2022. The following keywords were used in various combinations: optical biometry, partial coherence interferometry, low-coherence optical reflectometry, swept-source optical coherence tomography. Only clinical studies referring to patients undergoing routine cataract surgery, and employing at least two (PCI or LCOR vs. SS-OCT) optical methods for optical biometry in the same cohort of patients were included.ResultsFourteen studies were included in the final analysis, which presented results of 2,459 eyes of at least 1,853 patients. The overall TFR of all included studies was 5.47% (95% confidence interval [CI]: 3.66–8.08%; overall I2 = 91.49%). The TFR was significantly different among the three methods (p < 0.001): 15.72% for PCI (95% CI: 10.73–22.46%; I2 = 99.62%), 6.88% for LCOR (95% CI: 3.26–13.92%; I2 = 86.44%), and 1.51% for SS-OCT (95% CI: 0.94–2.41%; I2 = 24.64%). The pooled TFR for infrared methods (PCI and LCOR) was 11.12% (95% CI: 8.45–14.52%; I2 = 78.28%), and was also significantly different to that of SS-OCT: 1.51% (95% CI: 0.94–2.41%; I2 = 24.64%; p < 0.001).ConclusionsA meta-analysis of the TFR of different biometry methods highlighted that SS-OCT biometry resulted in significantly decreased TFR compared to PCI/LCOR devices.

Reply: Comparison of axial length measurements in silicone oil-filled eyes using swept-source OCT and partial coherence interferometry.

Zhang, Jiaqing MD*; Han, Xiaotong MD, PhD*; Zhang, Miao MD*; Tan, Xuhua MD, PhD†; Luo, Lixia MD, PhD† Author Information

Comparison of the accuracy of nine intraocular lens power calculation formulas using partial coherence interferometry.

Cataract surgery is the most performed procedure in the world. To achieve the target refraction, several intraocular lens (IOL) power calculation formulas have been developed to improve the accuracy of IOL power predictions. We compared the accuracy of 9 IOL power calculation formulas (SRK/T, Hoffer Q, Holladay 1, Haigis, Barrett Universal II, Kane, EVO 2.0, Ladas Super formula and Hill-RBF 3.0) using partial coherence interferometry (PCI). We collected data from patients who underwent uncomplicated cataract surgery with implantation of 1 of 3 IOL types currently used in our center. All preoperative biometric measurements were performed using PCI. Prediction errors (PE) were deduced from refractive outcomes evaluated 3 months after surgery. The mean prediction error (ME), mean absolute prediction error (MAE), median absolute prediction error (MedAE), and standard deviation of prediction error (SD) were calculated, as well as the percentage of eyes with a PE within ±0.25, ±0.50, ±0.75 and ±1.00D for each formula. We included 126 eyes of 126 patients. Kane achieved the lowest MAE and SD across the entire sample as well as the highest percentage of PE within ±0.50D and was shown to be more accurate than Haigis and Hoffer Q (P<001). For an axial length of more than 26.0mm, EVO 2.0 and Barrett obtained the lowest MAEs, with EVO 2.0 and Kane showing a higher percentage of prediction at ±0.50D compared to old generation formulas except for SRK/T (P=04). All investigated formulas achieved good results; there was a tendency toward better outcomes with new generation formulas, especially in atypical eyes.

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.

Agreements' profile of Scheimpflug-based optical biometer with gold standard partial coherence interferometry.

To determine the agreement of ocular biometric indices including axial length, keratometric readings, anterior chamber depth, and horizontal corneal diameter between the Pentacam AXL and IOL Master 500. The study was a large cross-sectional population-based study (Tehran Geriatric Eye Study) conducted from Jan 2019 to Jan 2020. A total of 160 clusters were randomly selected proportional to size (each cluster contained 20 individuals) from 22 strata of Tehran city. All people aged 60y and above were invited to participate in the study. For all participants, preliminary ocular examinations were performed including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, anterior and posterior segment examinations. All participants underwent an ocular biometry using the Pentacam AXL and IOL Master 500. The 95% limits of agreement (LoA) between the two devices were -0.13 to 0.19, -0.15 to 0.17, and -0.13 to 0.19 in normal, pseudophakic, and cataractous eyes, respectively. With increasing the axial length, the difference between the two devices significantly increased in all three groups of normal, pseudophakic, and cataractous eyes (P<0.001). The 95% LoAs between the two devices regarding the mean keratometry shows that the best LoAs were seen in cataractous (-0.33 to 0.81) and followed by normal eyes (-0.36 to 0.86) and the pseudophakic eyes (-0.48 to 0.90) had the widest LoA. The 95% LoAs for horizontal corneal diameter measurements were -0.08 to 0.86, -0.03 to 0.83, and -0.07 to 0.87 in normal, pseudophakic, and cataractous eyes, respectively. The 95% LoAs of anterior chamber depth measurements between the two devices was -0.39 to 0.19 and -0.37 to 0.13 in normal eyes and cataractous, respectively. The Pentacam AXL has excellent agreement with the gold standard, IOL Master 500 in measuring axial length. In eyes with cataracts, the difference between the two devices is more scattered. With the increasing of axial length, the difference between the two devices increased, which should be considered when using Pentacam AXL.

Repeatability and agreement of swept-source optical coherence tomography and partial coherence interferometry biometers in myopes

ABSTRACT Clinical relevance Biometric measurements in the context of myopia are fundamental to detect eyes at risk of developing myopia and during the follow-up of patients with myopia control treatment. Thus, the accuracy of biometers has high clinical relevance. Background The Myopia Master is a new biometer based on partial coherence interferometry especially dedicated to the follow-up of myopic patients. This study aims to assess the repeatability of the Myopia Master and evaluate its agreement with a swept-source optical coherence interferometry biometer (IOL Master 700). Methods This cross-sectional prospective study assessed the biometric parameters of two groups of myopes (age range: 8–16 years old), spectacle corrected (n = 60) and orthokeratology contact lens wearers (n = 60). One senior optometrist performed two consecutive measurements per instrument, which included axial length, mean keratometry and horizontal visible iris diameter (HVID). The repeatability of each device and the agreement between devices were assessed by the dispersion of the measurement differences, for AL, mean keratometry, corneal astigmatism and HVID. Results The two biometers measured approximately the same value in both measurements. Test–retest repeatability tended to be lower than clinical significant thresholds, in particular, for AL and mean keratometry. Corneal-related parameters tended to have lower repeatability in the orthokeratology group, especially mean keratometry. The agreement between instruments revealed statistically significant differences between devices with the SS-OCT measuring longer eyes, steeper corneas and larger HVID. Conclusions In a paediatric population, the Myopia Master showed clinically acceptable repeatability levels, but the IOL Master 700 demonstrated superior repeatability. Eyes treated with orthokeratology may compromise the repeatability of the corneal-related parameters. The Myopia Master and the IOL Master 700 are repeatable devices appropriate for monitoring myopia progression, but the differences observed do not allow their use interchangeably.

The effect of implantable collamer Lens V4c on ocular biometric measurements and intraocular lens power calculation based on Pentacam-AXL and IOLMaster 500

BackgroundTo investigate the possible effect of implantable collamer lens (ICL) V4c on ocular biometric measurements by a new biometer Pentacam-AXL and partial coherence interferometry (PCI)-based IOLMaster 500 and intraocular lens power calculation using fourth-generation formula.MethodsWe retrospectively enrolled patients who underwent ICL (EVO-V4c, STAAR Surgical Co. Nidau, Switzerland) implantation surgery from September 2020 to November 2021. The Pentacam-AXL and IOLMaster 500 biometers were used to measure axial length (AL), anterior chamber depth (ACD), keratometry (K), white to white (WTW), and central corneal thickness (CCT) values before and at least 2 months after ICL V4c implantation. The IOL power was calculated using the Barrett Universal II formula.ResultsThe study included 45 eyes in 28 patients. There was a significant increase in ALs (average 0.03 ± 0.07 mm, p = 0.01) and a significant decrease of ACDs (average 0.19 ± 0.17 mm, p < 0.001) based on Pentacam-AXL. Similar changes in ALs and ACDs were also found in IOLMaster 500. In addition, the difference in WTWs in the two devices and that of CCTs in Pentacam-AXL were statistically significant. However, the preoperative and postoperative K1 and K2 were separately comparable using either device. The IOL power calculated by the Barrett Universal II formula did not change significantly either by the software built in Pentacam-AXL or by manually putting the parameters of the IOLMaster 500 into the formula manually (p = 0.058, p = 0.675, respectively).ConclusionsOcular parameters including ALs, ACDs, WTWs, and CCTs using a new Pentacam-AXL and standard PCI-based IOLMaster 500 changed significantly before and after the ICL V4c implantation, while IOL power prediction using the Barrett Universal II formula was little affected.

Comparison of optical low coherence interferometry and Scheimpflug imaging combined with partial coherence interferometry biometers in cataract eyes.

PURPOSE:The purpose of the study was to evaluate the agreement between measurements by optical low-coherence interferometry (OLCI, Aladdin) and those by Scheimpflug imaging combined with partial coherence interferometry (Scheimpflug-PCI, Pentacam AXL) in cataract patients.METHODS:This was a retrospective comparative study conducted in the United Arab Emirates. Axial length (AL), corneal power (keratometry, K), anterior chamber depth (ACD), and corneal astigmatism in patients with cataracts were measured with both devices. Difference and correlation were evaluated with paired t-test (p) and Pearson's correlation coefficient®, respectively.RESULTS:A total of 164 eyes of 95 patients were analyzed (164 eyes for K, 155 for ACD, and 112 for AL). The mean AL taken by OLCI was longer than that by Scheimpflug-PCI (23.25 mm vs. 23.23 mm, P ≤ 0.0001), showing an excellent correlation between the two (r = 0.9990). ACD measured by OLCI was 0.08 mm shallower than that by Scheimpflug-PCI (P = 0.0003, r = 0.7386). Corneal power measured by OLCI was lower than that by Scheimpflug-PCI (differences in mean K, flat K, and steep K were 0.05 diopters (D), 0.08 D, and 0.02 D, respectively), showing very strong correlations between the two devices (r = 0.9614, 0.9445, and 0.9535, respectively). Only flat K values measured with the two devices were significantly different (P = 0.0428). There were no statistically significant differences in the magnitude of astigmatism or J45 vector between the two devices (P = 0.1441 and P = 0.4147, respectively). However, J0 vector values were significantly different (P = 0.0087).CONCLUSION:Although OCLI and Scheimpflug-PCI showed strong correlations for measurements of AL, K, ACD, and corneal astigmatism in cataract patients, there were small but statistically significant differences in AL, ACD, flat K, and J0 vector. Thus, these two devices are not interchangeable for calculating intraocular lens power.

Comparison of Accuracy in Keratometries Measured by Different Camera Devices for Predicting the Intraocular Lens Power in Lens-Dislocated Patients

Introduction: This is a cross-sectional cohort study focused on assessing the influence of ocular biometric parameters of different camera devices for accurately predicting the intraocular lens (IOL) power in congenital ectopia lentis (EL) patients. Methods: This study includes a total of 91 eyes of 60 patients with congenital EL from June 2018 to April 2021. All patients underwent lens subluxation surgery with Cionni modified capsular tension rings implantation. Ocular parameters measured by partial coherence interferometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) and rotating Scheimpflug camera (Pentacam HR system; Oculus Optikgeräte GmbH, Wetzlar, Germany) were acquired from the database. The authenticity of the different keratometries (Ks) was analyzed by comparing the prediction error in spherical equivalent under controlled formula SRK/T, Haigis, and after Wang-Koch (WK) adjustment. Results: We observed significant greater K values were obtained in IOLMaster than Pentacam, resulting in more significant hyperopia error while calculating SRK/T. The IOL power calculated with the total corneal refractive power (TCRP) from Pentacam revealed the highest prediction accuracy, indicating that TCRP is the closest to the actual refractive power of the cornea. However, in an exceptional case for long eye patients, total K from IOLMaster was better recommended when using formula Haigis with WK adjustment. Conclusions: For most instances, TCRP is the best-recommended source of K value while calculating IOL power for EL patients. However, the total K from IOLMaster preferably fits for long eye patients, who require WK adjustment for Haigis formula.

Comparison of axial length measurements in silicone oil-filled eyes using SS-OCT and partial coherence interferometry.

To compare axial length (AL) measurements in silicone oil (SO)-filled eyes using swept-source optical coherence tomography (SS-OCT) (the IOLMaster 700 and OA2000) and partial coherence interferometry (the IOLMaster 500). Zhongshan Ophthalmic Center, Guangzhou, China. Cross-sectional study. We enrolled phakic patients who underwent SO removal surgery. The AL measurements by the IOLMaster 500, IOLMaster 700, and OA2000, both before and after SO removal, were compared. Multiple regression analysis was performed to identify risk factors for the differences between preoperative and postoperative AL measurements. 68 patients (68 eyes) with a mean age of 46.43 ± 13.24 years were included. No statistically significant difference was observed in the preoperative AL measurements between the IOLMaster 500 and IOLMaster 700 (25.48 ± 2.51 mm vs 25.49 ± 2.46 mm; P = .63), whereas the OA2000 yielded shorter AL (25.34 ± 2.36 mm) (both P < .001). After SO removal, the AL measurements showed no statistically significant differences among the 3 devices. In reference to the postoperative AL, the IOLMaster 500 and IOLMaster 700 tended to overestimate the AL in SO-filled eyes (both P < .001), and this measurement error increased with longer AL (β = 0.08 and 0.05, respectively; both P < .001). No statistically significant difference was observed between preoperative and postoperative AL measurements by the OA2000 ( P = .18). The OA2000 is the preferred biometer for AL measurement in SO-filled eyes, whereas the IOLMaster 500 and IOLMaster 700 overestimate the AL especially for long eyes, which needs adjustment in clinical use.