The comparison of white-to-white via triple person-times caliper measuring and machine-measuring in V4c implantable collamer lens implantation.

This study aimed to compare the differences and characteristics of white-to-white (WTW) values obtained before V4c implantation using triple person-times caliper, IOL-Master 700, Pentacam HR, and UBM, and to assess their correlation with vaulting. A total of 930 myopia patients (1842 eyes) who were interested in undergoing ICL surgery were assessed before the procedure using various instruments. The WTW measurements were obtained using a triple person-times caliper, Pentacam HR, and IOL-Master 700, whereas the angle-to-angle (ATA) measurements were obtained using UBM. The size of the ICL was subsequently calculated using triple person-times caliper measurements. The vault of the ICL was assessed using Pentacam HR three months after the surgery. The WTW was determined to be 11.30 ± 0.29 mm, 11.43 ± 0.29 mm, and11.86 ± 0.38 mm, respectively, using the triple person-times caliper, Pentacam HR, and IOL-Master 700. The measurement of ATA was 11.57 ± 0.51 mm, as done by UBM. The ICL vault was measured to be 400.97 ± 198.46 µm when examined with Pentacam HR three monthsafter the procedure. The linear regression analyses of ICL size and WTW of triple person-times caliper, ICL vault and WTW were (R = 0.703, p < 0.001; R = 0.0969, p < 0.001) respectively. The highest correlation was found between IOL-Master and Pentacam HR (r = 0.766, p = 0.000). The lowest correlation was found between UBM and Pentacam HR (r = 0.358, p = 0.002). Bland-Altman analysis showed that the 95% limits of agreement (LoA) were the triple person-times caliper and Pentacam HR (- 0.573, 0.298) and the triple person-times caliper and UBM (- 1.15, - 0.605). This indicated a strong agreement between the triple person-times caliper and Pentacam HR and a lack of agreement between the triple person-times caliper and UBM. Triple person-times caliper measurements offer excellent maneuverability, practicality, and reliable outcomes for determining ICL vaults. Measurements obtained using the triple-person caliper were less differece than those obtained using the Pentacam HR.

Total and simulated keratometry measurements using IOLMaster 700 and Pentacam AXL after small incision lenticule extraction.

PURPOSE: Calculating the intraocular lens (IOL) in patients after corneal refractive surgery presents a challenge. Because an overestimation of corneal power in cases undergone this surgery leading to a subsequent under-correction of IOL power. However, recent advancements in technology have eliable measurement of total corneal power. The aim of this research was to assess the agreement in simulated keratometry (SimK) and total keratometry (TK) values between IOLMaster 700 and Pentacam AXL. METHODS: The study involved 99 patients (99 eyes) undergone small incision lenticule extraction (SMILE) surgery. Each patient underwent scans using IOL Master 700 and Pentacam AXL. The following parameters were recorded: SimK1, SimK2, Total K1 (TK1), and Total K2 (TK2) for IOLMaster 700; and SimK1, SimK2, True Net Power (TNP) K1, TNPK2, Total Corneal Refractive Power (TCRP) K1, and TCRP K2 for Pentacam AXL. Agreement between the two devices was evaluated using Bland-Altman plot, while paired t-test was utilized to compare any differences in the same parameter by both instruments. RESULTS: The results revealed a strong correlation between the two devices.Noticeable comparability was identified for all SimK variables. However, there were noticeable differences in TK measurements as well as TK1-TNPK1, TK2-TNP K2, TK1-TCRP K1, and TK2-TCRP K2 parameters when comparing the two devices. The IOLMaster 700 consistently measured steeper values than the Pentacam AXL, with significant and clinically relevant differences of 1.34, 1.37, 0.87, and 0.95 diopters, respectively. CONCLUSION: While there was a noticeable correlation between the IOLMaster 700 and Pentacam AXL in SimK measurements, a marked difference was noted in TK values. The two devices cannot be used interchangeably when quantifying TK values.

Measurement of in vivo lens shapes using IOLMaster 700 B-scan images: Comparison with phakometry.

PURPOSE: This study compared in vivo crystalline lens shape measurements using B-scan images from the IOLMaster 700 with phakometry. METHODS: Twenty-four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1% cyclopentolate). The IOLMaster 700 generated B-scan images along six meridians in 30° increments, which were analysed using custom MATLAB software to determine lens surface radii of curvature. Phakometry measurements were obtained using Purkinje images reflected from the lens surfaces. RESULTS: The IOLMaster 700 image analysis method yielded a lower mean anterior lens surface spherical equivalent power (+6.20 D) than phakometry (+7.55 D); however, the two measurements were strongly correlated (R(21) = 0.97, p < 0.0001). The astigmatic power vectors (J0 and J45) for the anterior lens surface were significantly higher for the IOLMaster 700 measurements, with only J0 showing a significant moderate positive correlation (R(21) = 0.57, p = 0.005). For the posterior lens surface, the IOLMaster 700 measurements had a higher mean spherical power (+14.28 D) compared to phakometry (+13.70 D); however, a strong positive correlation (R(21) = 0.90, p < 0.0001) was observed. No significant correlations were noted for posterior lens surface astigmatic vectors (J0 and J45). The IOLMaster 700 estimates for the equivalent lens mean spherical power were slightly lower than those for phakometry, with a mean difference of -0.72 D, and both methods were positively correlated (R(21) = 0.94, p < 0.0001). CONCLUSIONS: The findings demonstrate that IOLMaster 700 B-scan image analysis technique provides similar estimates of lens surface powers to phakometry. These results highlight the potential of the IOLMaster 700 to provide measurements of lens shape, informing future research and clinical use.

Comparison of corneal measurements in keratoconus eyes with two swept-source-optical coherence tomography devices and a Scheimpflug device.

PURPOSE: To assess the feasibility and reliability of biometric measurements taken with the Eyestar 900 device in keratoconus eyes in comparison with those taken with the Pentacam HR and IOLMaster 700. METHODS: Seventy-five eyes of 75 patients with keratoconus were included. The central corneal thickness (CCT), thinnest point of corneal thickness (TCT), axial length (AL), flat (K1) and steep (K2) anterior and posterior (Kp1, Kp2) keratometry, maximal keratometry (KMax) and anterior chamber depth (ACD) were compared between the Eyestar 900, Pentacam HR and IOLMaster 700. Reliability parameters such as the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated. Pearson's r was determined to assess the correlation between devices. RESULTS: A high repeatability (CoV < 1%) and intraclass correlation (ICC > 0.9) was found for all devices, led by AL, TCT, K1 and K2 (CoV 0.01-0.36%; ICC 0.994-1.00). The largest correlation between devices was found for AL (Eyestar vs. IOLMaster, r = 1.0), K1 (Eyestar vs. IOLMaster, r = 0.997) and ACD (Eyestar vs. IOLMaster, r = 0.995; Pentacam vs. IOLMaster, r = 0.987; Eyestar vs. Pentacam, r = 0.983), but there were significant differences in measured values between devices (p < 0.001), whereas the correlation was only slightly lower (r = 0.947 to 0.994) for KMax, CCT, TCT, K2, Kp1 and Kp2. CONCLUSION: Keratometric and axial length measurements with the Eyestar 900 were feasible and revealed a high repeatability and a good correlation to the other devices in eyes with keratoconus.

Angle Kappa and angle Alpha agreement between Pentacam Scheimpflug system, swept source optical coherence tomography and ray-tracing aberrometry.

PURPOSE: To compare the consistency of Pentacam Scheimpflug system (Pentacam® HR), ray-tracing aberrometry (iTrace), and swept source optical coherence tomography (IOLMaster 700) measurements for Angle Kappa and angle Alpha. METHODS: A prospective randomized cohort study. 86 individuals (86 eyes) aged 19-45 years with best corrected vision of 4.9 or better were randomly selected from January 2022 to December 2022 in a tertiary-level hospital. Angle Kappa and angle Alpha were measured or calculated using Pentacam, iTrace, and IOLMaster 700, respectively. RESULTS: The mean difference of angle Kappa between any two instruments was not statistically significant, but the mean difference of angle Alpha between both Pentacam and iTrace, Pentacam and IOLMaster 700, and iTrace and IOLMaster 700 was statistically significant (p value <0.001, 0.003, <0.001). The highest consistency of angle Kappa and the narrowest 95% LoA (-0.20 to 0.21) were found between Pentacam and iTrace according to Bland Altman plots, but between Pentacam and IOLMaster 700 according to Mountain plots. Both Bland Altman plots and Mountain plots showed the highest consistency of angle Alpha and the narrowest 95% LoA (-0.14 to 0.24) between Pentacam and iTrace. CONCLUSION: The mean angle Kappa among Pentacam® HR, iTrace, and IOLMaster 700 had good agreement, and the value of angle Kappa could be output directly, making it more convenient for clinical application. The measured or calculated angle Alpha had poor agreement, and ophthalmologists could refer to measurements from multiple instruments.

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.

Accuracy of the VRF and VRF-G Intraocular Lens Power Calculation Formulas Using Swept-Source Optical Coherence Tomography Biometry.

Purpose: To collate the accuracy of two recently introduced intraocular lens (IOL) formulas (VRF and VRF-G) in cataract patients using a swept-source optical coherence tomography (SS-OCT) biometry (IOL Master 700, Carl Zeiss Meditec AG, Jena, Germany). Patients and Methods: Data records of 295 eyes from 295 patients were included in this scrutiny. The IOLMaster 700 SS-OCT biometer was used for biometric measurements. The VRF and VRF-G formulas were compared with seven 3rd and 4th generation thin and thick-lens formulas: Haigis, Hoffer Q, Holladay 1, Holladay 2, SRK/T, T2, and Barrett Universal II. With optimized lens constants, the mean prediction error (PE) and its standard deviation (SD), the median absolute error (MedAE), the mean absolute error (MAE), and the percentage of eyes with PEs within ±0.25 D, ±0.50 D, ±0.75 D, ±1.00 D, and <±2.00 D were analyzed. Results: Statistically significant differences were found between formulas in the whole group (Friedman test, P = 0.000). The VRF-G and Haigis formulas showed the lowest SD values (0.464 D and 0.466 D respectively). The VRF and Barrett Universal II formulas were less predictable (SD 0.471 D and SD 0.474 D respectively). The biggest proportion of eyes within ±0.50 D was found with VRF-G (76.27%), Haigis (75.59%), VRF (74.92%), and Barrett Universal II (74.92%) formulas. Conclusion: Based on data achieved from the SS-OCT biometry, the VRF-G and Haigis methods were the more precise predictors of postoperative refraction with the biggest proportion of eyes within ±0.50 D.

The effect of sustained eye rotation upon eye length in healthy myopic adults.

AIM: The aim of the study was to determine whether ocular movement can affect the shape of the globe and lead to measurable change in axial and peripheral eye length. METHODS: Ten subjects aged 18-30 years (6 M/4 F) participated with informed consent. The mean spherical equivalent refractive error was ≤-1.00 DS with cylindrical refraction <-1.25 DC. One drop of tropicamide hydrochloride 1% was instilled 20 min before measurement to induce mydriasis and mild cycloplegia. Using IOLMaster, eye length was measured centrally and temporally (25° off-axis) in four different positions. Subjects then rotated their eyes 25° in the temporal direction to fixate on a target for 10 min. After that, the same measurements were repeated. RESULTS: Before rotation, the group mean peripheral eye length was significantly shorter than the central eye length (P < 0.05). There was no significant variation in central or peripheral eye length due to off-axis fixation, either after the initial eye rotation or after fixation for 10 min at the off-axis point. The difference between central and peripheral eye lengths was maintained after 10 min of temporal fixation (P < 0.05). CONCLUSION: Peripheral eye length was shorter than central eye length showing the prolate shape associated with myopia. The action of the extraocular muscles on the globe has no significant effect upon the retinal shape assessed by off-axis eye length measurement in myopic subjects.

Impact of age on measurement variability for axial length in myopic children.

CLINICAL RELEVANCE: Axial length is a primary outcome in the management of progressive myopia. However, young children may have difficulty fixating during these measurements compared to older children, which can result in higher measurement variability. This may affect perceived axial length progression, leading to inappropriate management. BACKGROUND: This study assessed the impact of patient age on measurement variability for axial length measurements taken with the IOLMaster 700 and IOLMaster 500 in myopic children. METHODS: A retrospective review of records was undertaken at a university optometry clinic. Five axial length measurements captured at the same visit were collected with the IOLMaster 700 and IOLMaster 500 for myopic patients ≤16 years. The within-subject standard deviation and R2 were calculated for each instrument to examine the effects of age on instrument variability. RESULTS: Data was collected for 51 patients (30 female and 21 male), and the mean age was 10.98 ± 2.77 years. Mean axial length measured with the IOLMaster 700 was longer compared to the IOLMaster 500 (difference -0.02 ± 0.02 mm; p < 0.001). There was no effect of age on within-person variability for the measurement of axial lengths with either instrument, with R2 values of 0.021 (p = 0.305) and 0.13 (p = 0.420) for the IOLMaster 700 and IOLMaster 500, respectively. The within-subject variability of axial measurements with the IOLMaster 700 was significantly lower than that with the IOLMaster 500 (p < 0.001). CONCLUSION: Measurement variability of axial length measurements with the IOLMaster 700 and IOLMaster 500 was not dependent on age. However, axial length measurements captured with the IOLMaster 700 were significantly longer and less variable than those with the IOLMaster 500. Eye health care practitioners should be aware of the differences between the two instruments and refrain from using them interchangeably, especially for myopia control where small changes in axial length can affect patient management.

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.

Accuracy of refractive outcomes using standard or total keratometry for intraocular lens power formulas in conventional cataract surgery.

PURPOSE: To evaluate if total keratometry (TK) is better than standard keratometry (K) for predicting an accurate intraocular lens (IOL) refractive outcome in virgin eyes using four IOL power calculation formulas. METHODS: 447 eyes that underwent monofocal intraocular lens implantation were enrolled in this study. IOLMaster 700 (Carl Zeiss Meditech, Jena, Germany) was used for optical biometry. Prediction error (PE), mean absolute prediction error (MAE), median absolute prediction error (MedAE), proportions of eyes within ± 0.25 diopters (D), ± 0.50 D, ± 0.75 D, ± 1.00 D, ± 2.00 D prediction error, and formula performance index (FPI) were calculated for each K- and TK-based formula. RESULTS: Overall, the accuracy of each TK and K formula was comparable. The MAEs and MedAEs showed no difference between most of the K-based and the TK-based formula; only the MAE of TK was significantly higher than that of K using the Haigis. The percent of eyes within ± 0.25 D PE for TK was not significantly different from that for K. The analysis of PE across various optical dimensions revealed that TK had no effect on the refractive results in eyes with different preoperative axial length, anterior chamber depth, keratometry, and lens thickness. The K-based Barrett Universal II formula performed excellently, showed the leading FPI score, and had the best refractive prediction outcomes among the four formulas. CONCLUSION: TK and K can be used for IOL power calculation in monofocal IOL implantation cataract surgery in virgin eyes, as both are comparable. In all investigated formulas, the predictive accuracy of TK-based formulas is not superior to that of standard K-based formulas.

Agreement of Corneal Diameter and Anterior Chamber Depth Measurements with the IOLMaster 500 and the IOLMaster 700 Optical Biometers in Myopic Eyes.

Purpose: To assess the agreement in automated corneal diameter (CD) and anterior chamber depth (ACD, measured from corneal epithelium to lens) distances measurements between the IOLMaster 500 and 700 optical biometers in myopic eyes. Methods: One hundred and sixteen eyes of 116 myopic patients aged between 21 to 60 years were included in this study. Measurements of CD and ACD distances were taken with each biometer for all patients in the same session. A t-test and a p-value less than 0.05 was considered statistically significant when the measurements were compared. The agreement between biometers was studied by applying a Bland-Altman analysis. Results: The mean CD values obtained using the IOLMaster 500 and 700 biometers were 12.26±0.35 mm and 12.13±0.34 mm, respectively. The mean ACD distance values were 3.61±0.29 mm and 3.62±0.31, for the IOLMaster 500 and 700 biometers, respectively. There were statistically significant differences between the two devices only for CD measurements (p<0.001), but not for ACD measurements (p=0.26). The limits of agreement obtained were wide in both types of measurements, being 0.422 mm for the CD distance and 0.389 mm for the ACD distance. Conclusion: There were statistically significant differences between the IOLMaster 500 and 700 biometers regarding CD but not in ACD measurements in healthy myopic eyes. These differences could be clinically significant in some cases. According to these results, medical judgement should be used to assess whether the two devices could be used interchangeably for CD and ACD measurements during the clinical practice.

Evaluating Changes in Apparent Chord Mu after Pharmacological Pupil Dilatation.

INTRODUCTION: Preoperative measurements of apparent chord mu length above 0.6 mm have been associated with higher risks for photic phenomena after cataract surgery with multifocal intraocular lenses (MFIOLs). METHODS: This retrospective study evaluated patients scheduled for elective cataract surgery at a single tertiary medical center between 2021 and 2022. Pupil diameter and apparent chord mu length were analyzed for eyes with biometry measurements from IOLMaster 700 (Carl Zeiss Meditec, AG) under photopic light conditions, before and after pharmacological pupil dilatation. Exclusion criteria were visual acuity worse than 20/100, prior intraocular surgery, refractive surgery, iris-related procedures, or pupil abnormalities affecting dilatation. Apparent chord mu lengths before and after pupil dilatation were compared. In addition, multivariate linear regression analysis, using a stepwise method, was conducted to assess possible predictors of apparent chord values. RESULTS: Included were 87 eyes of 87 patients. Mean chord mu length increased after pupillary dilatation from 0.32 ± 0.17 mm to 0.41 ± 0.17 mm for right eyes (p < 0.001) and from 0.29 ± 0.16 mm to 0.40 ± 0.22 mm for left eyes (p < 0.001). Seven eyes (8.0%) had an apparent chord mu of 0.6 mm and above pre-dilatation. Fourteen eyes (16.1%) with an apparent chord mu under 0.6 mm pre-dilatation had apparent chord mu of 0.6 mm or above post-dilatation. CONCLUSION: Apparent chord mu length significantly increases after pharmacological pupillary dilatation. Pupil size and dilatation status should always be considered during patient selection for a planned MFIOL using apparent chord mu length as a reference marker.

Comparison of the prediction accuracy of 13 formulas in long eyes.

PURPOSE: To investigate the accuracy of modern intraocular lens (IOL) power calculation formulas in eyes with axial length (AL) ≥ 26.00 mm. METHODS: A total of 193 eyes with one type of lens were analysed. An IOL Master 700 (Carl Zeiss Meditec, Jena, Germany) was used for optical biometry. Thirteen formulas and their modifications were evaluated: Barrett Universal II, Haigis, Hoffer QST, Holladay 1 MWK, Holladay 1 NLR, Holladay 2 NLR, Kane, Naeser 2, SRK/T, SRK/T MWK, T2, VRF and VRF-G. The User Group for Laser Interference Biometry lens constants were used for IOL power calculation. The mean prediction error (PE) and its standard deviation (SD), the median absolute error (MedAE), the mean absolute error (MAE) and the percentage of eyes with PEs within ± 0.25 D, ± 0.50 D and < ± 1.00 D were calculated. RESULTS: The modern formulas (Barrett Universal II, Hoffer QST, Kane, Naeser 2 and VRF-G) produced the smallest MedAE among all methods (0.30 D, 0.30 D, 0.30 D, 0.29 D and 0.28 D, respectively). The percentage of eyes with a PE within ± 0.50 D ranged from 67.48% to 74.85% for SRK/T and Hoffer QST, Naeser 2 and VRF-G, respectively. CONCLUSIONS: Dunn's post hoc test of the absolute errors revealed statistically significant differences (P < 0.05) between some of the newer formulas (Naeser 2 and VRF-G) and the remaining ones. From a clinical perspective the Hoffer QST, Naeser 2 and VRF-G formulas were more accurate predictors of postoperative refraction with the largest proportion of eyes within ± 0.50 D.

Intra-operative aberrometry versus conventional biometry for intraocular lens power calculation: A prospective observational study from a tertiary referral center.

Purpose: To evaluate the per operative intra-ocular lens (IOL) power calculation using intra-operative aberrometry (ORA) and its comparison with conventional methods. Methods: Patients with cataract planned for phacoemulsification by a single surgeon under topical anesthesia were enrolled in this prospective observational study in this prospective observational study. All patients underwent pre-operative biometry (Manual SRK-II and IOLMaster® 500) to determine the intra-ocular lens (IOL) power. Intra-operative aberrometry using ORA was also performed; however, IOL was inserted according to IOLMaster® (SRK/T). Spherical equivalent (SE) was recorded on post-operative days 1, 7, and 30. Patients were divided into three groups based on axial lengths for analysis. Comparative analysis was performed for the calculated IOL powers and prediction errors of ORA with conventional methods. Adjusted IOL power to calculate the emmetropic IOL using the LiHue formula was also determined and was compared with existing methods. A P-value less than 0.05 was considered statistically significant. Results: A total of 115 eyes from 113 patients were included, with a median age of 54.90 ± 14.3 years. The mean axial length was found to be 23.94 ± 2.3 mm. There was good agreement (87%) between ORA and IOLMaster® for calculated IOL powers with a mean difference of 0.047 ± 0.5D between the two (P = 0.33). A positive correlation was found between IOL power calculated using ORA, IOLMaster®, SRK-II, and adjusted IOL. Conclusion: The use of intra-operative aberrometry (ORA) to calculate IOL power in patients undergoing uncomplicated phacoemulsification is non-inferior relative to standard pre-operative measurement and planning.

Comparing ocular biometry and autorefraction measurements from the Myopia Master with the IOLMaster 700 and the Huvitz HRK-8000A autorefractor.

PURPOSE: To compare axial length (AL) and corneal radius (CR) measured with the Oculus Myopia Master and the Zeiss IOLMaster 700, and cycloplegic refractive error measured with the Myopia Master and the Huvitz Auto Ref/Keratometer (HRK-8000A). METHODS: The study included both eyes of 74 participants (16 male), with a mean (SD) age of 22.8 (3.7) years. The parameters indicated were measured under cycloplegia with these instruments: Myopia Master (AL, CR and refractive error), IOLMaster 700 (AL and CR) and HRK-8000A (refractive error and CR). Bland-Altman plots with mixed effects 95% limits of agreement (LoA) and corresponding 95% confidence intervals were used to assess the agreement in ocular biometry between the Myopia Master and the IOLMaster 700, and for refractive error between the Myopia Master and the HRK-8000A. RESULTS: The analysis included 139 eyes, of which 52 were myopic (spherical equivalent refractive error, SER ≤ -0.50 D), 32 emmetropic and 55 hyperopic (SER ≥ 0.50 D). The 95% LoA for AL between the Myopia Master and IOLMaster 700 was -0.097 to 0.089 mm. There was no mean difference in AL [mean (SD) = -0.004 (0.047) mm, p = 0.34]. There was a significant difference in mean CR, with that measured with the Myopia Master being flatter than that found with the IOLMaster 700 [0.035 (0.028) mm, p < 0.001]. The 95% LoA for CR was -0.02 to 0.09 mm. Compared with HRK-8000A, the Myopia Master measured a significantly more negative SER [-0.19 (0.33) D, p < 0.001], with 95% LoA of -0.86 to 0.46 D. CONCLUSION: The LoA for measurements of SER, CR and AL when comparing the Myopia Master with the HRK-8000A and the IOLMaster 700 were wider than deemed acceptable for making direct comparisons. This indicates that the instruments cannot be used interchangeably in clinical practice or research.

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.

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.

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

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

Effect of pupil dilation on biometry measurements and intraocular lens power in eyes with high myopia.

Purpose: The present study sought to evaluate the effects of pupil dilation on ocular parameter measurements and intraocular lens (IOL) power calculation using IOLMaster in highly myopic cataract patients. Materials and methods: A total of 233 eyes were included in this prospective study and assigned to four groups based on range of axial length (AL) as follows: group A:26-28 mm, group B:28-30 mm, group C:30-32 mm, and group D:32-36 mm. Flattest and steepest keratometry (K1 and K2), AL, anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WtW) were determined using IOLMaster before and after administration of topical tropicamide. The corresponding IOL powers were calculated using Sanders-Retzlaff-Kraff/theoretical (SRK/T), Haigis, and Barrett Universal II formulas. Results: Variations in AL, K1 and K2 following dilation were not significant (P > 0.05 in all groups). The results showed that ACD increased significantly after dilation (P = 0.000 in all groups), whereas LT decreased significantly after dilation (P = 0.000, 0.000, 0.001, and 0.003). Post-dilation WtW increased significantly in Group A, B, and C (P = 0.001, 0.001, and 0.025) but not in Group D. When IOL power was calculated as a discrete variable, significant differences were observed between pre- and post-dilation IOL power. Conclusion: Pupil dilation in cataract eyes with high myopia does not cause significant changes in AL and K. However, it significantly increases ACD as well as WtW values and significantly decreases the LT value. Surgeons should evaluate the effect of pupil dilation on IOL power prediction as the present findings show extreme cases. Notably, Barrett Universal II formula had the best concordance between different pupil conditions in long eyes.