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Purpose: To assess the influence of artificial tears of different viscosity on K-readings prior to cataract surgery., Design: Prospective randomized crossover, before-and-after clinical study., Methods: Setting: Department of Ophthalmology, Medical University of Vienna., Patient Population: A total of 123 eyes of 80 patients prior to cataract surgery were assigned to 2 groups based on normal and dry eyes., Intervention: Two native baseline keratometries were followed by instillation of either high- or low-viscosity eye drops. Keratometry was repeated 30 seconds, 2 minutes, and 5 minutes after instillation., Main Outcome Measures: Influence of eye drops of different viscosity in normal and dry eyes on short time K-readings., Results: Repeatability between native baseline measurements was high (standard deviation = 0.02 mm in normal and in dry eyes). In normal and dry eyes, a statistically significant increase in measurement variability after instillation of both low-viscosity and high-viscosity eye drops was observed (P < .01). Measurement variability was most pronounced between baseline measurement and 30 seconds and diminished over time. Variability of K-readings appeared higher in dry eyes compared with normal eyes. Astigmatism changed more than 0.5 diopters in 13.2% of normal eyes and 34.4% in dry eyes using eye drops of high viscosity., Conclusion: Tear film-stabilizing eye drops prior to keratometry measurements influenced K-readings significantly, especially in dry eyes. A time period of more than 5 minutes should be allowed to pass after instillation of eye drops. The higher the viscosity of the eye drops, the stronger the influence and the longer its persistence., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: This study was conducted to evaluate the level of agreement in keratometry measurements between a rotating Scheimpflug imaging-based system (Pentacam) and a handheld auto-refractokeratometer (handheld NIDEK ARK-30)., Method: This analytical cross-sectional study was conducted in the right eyes of 579 subjects. Keratometry measurements were conducted with the Pentacam and the handheld NIDEK ARK-30 systems. The SPSS Software version 22 and MedCalc V3 were applied to estimate descriptive statistics using paired t-test, Pearson correlation coefficient, 95% limits of agreement (LoA), and Bland-Altman plot., Results: In the total sample, the inter-device difference in the mean flat and steep keratometry values was -0.266 diopter (D) (P-value<0.001) and 0.052D (P-value=0.093), respectively. There was a significant difference in mean flat keratometry between the two devices in all groups of refractive errors (paired difference <0.5D and P-value<0.001). The difference in mean steep keratometry was significant only in myopic subjects (P-value=0.046). The 95% LoA between the two devices measurements was 2.51D, 3.98D, and 6.37D for flat keratometry and 2.6D, 3.2D, and 3.9D for steep keratometry in emmetropic, myopic, and hyperopic subjects, respectively., Conclusion: Our study showed relatively wide limits of agreement between handheld NIDEK ARK-30 and Pentacam; therefore, these devices cannot be used interchangeably for measuring corneal curvature., (Copyright © 2019 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.)

Purpose: To determine the agreement and validity of keratometric measurements in children with the Nidek ARK-510A auto-refractokeratometer compared to rotating Scheimpflug imaging with Pentacam and biograph with Lenstar LS 900., Methods: This study was conducted on 5620 schoolchildren aged 6-12 years in Shahroud, Iran. Minimum and maximum keratometry values and corneal astigmatism magnitude were compared by calculation of Paired difference, interclass correlation coefficient, and 95% limits of agreement (LoA) between devices., Results: After applying the exclusion criteria, 4215 right eyes were enrolled into the study. Mean minimum keratometry with Nidek ARK-510A, Pentacam, and Lenstar was 43.13±1.51, 43.14±1.48, and 42.87±1.46 diopters (D), respectively, and mean maximum keratometry was 43.97±1.59, 44.00±1.56, and 43.75±1.54D, respectively. Nidek ARK-510A overestimated minimum and maximum keratometry by 0.25±0.37 and 0.22±0.41, respectively, compared to Penatcam. The LoA between Nidek ARK-510A and Pentacam for minimum and maximum keratometry measurements were -0.98 to 0.47D and -1.02 to 0.57D, respectively. The LoA between Nidek ARK-510A and Lenstar for minimum and maximum keratometry measurements were -0.70 to 0.72D and -0.79 to 0.85D, respectively. The agreement between devices was best in emmetropes, worst in hyperopes. For astigmatic vector components, the agreements between devices were poor but best agreement was between Nidek ARK-510A and Pentacam., Conclusions: Keratometry measurement with Nidek ARK-510A was not significantly different from Pentacam and Lenstar, and this device can be used in screening programs in emmetropes., (Copyright © 2019 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.)

Purpose: To compare keratometry and corneal astigmatism measurements obtained by the Verion Image Guided System to those obtained by automated keratometry (IOLMaster), manual keratometry (YZ38, Suzhou 66 visual Polytron Technologies Inc., China), and Scheimpflug imaging (Pentacam HR) in eyes with cataract., Methods: A total of 149 cataractous eyes of 149 patients were examined and categorized as low astigmatism (<1.0 D, N = 50), moderate astigmatism (1.0-2.0 D, N = 49), and high astigmatism (>2.0 D, N = 50). The flattest and the steepest keratometric values (Kf and Ks), the magnitude of astigmatism (Ast), the orientation of the steepest meridian (Axis), and power vectors J 0 and J 45 were compared., Results: Keratometry readings (Kf, Ks, and Km) obtained by the Verion system showed statistically significant differences as compared to the other three devices. The magnitude of astigmatism (Ast) measured by the Verion (1.50 ± 0.85 D) was similar to that measured by the YZ38 (1.45 ± 0.82 D, P = 0.110) and slightly lower than that by the IOLMaster (1.56 ± 0.87 D, P = 0.014), but much higher than that by the Pentacam (1.36 ± 0.81 D, P = 0.000) significantly. However, no statistically significant differences were observed in the J 0 and J 45 vectors in the whole sample, besides moderate and high astigmatism subgroups. A difference in astigmatism magnitude of 0.50 D or more was detected between the Verion system and other three devices most commonly in moderate astigmatism eyes (16.3-24.5%). The difference in the location of the steep meridian was greater than 10 degrees most frequently in the low astigmatism eyes (26.0-52.0%)., Conclusions: Keratometric and astigmatic results obtained with Verion were not completely interchangeable with those obtained with IOLMaster, manual keratometry, and Pentacam. The individual differences in power and orientation of the corneal cylinder should be considered while selecting the appropriate toric intraocular lens.

Purpose: To compare ocular measurements of three optical biometry devices and their application in intraocular lens (IOL) power calculations., Methods: One hundred and forty eyes which had undergone cataract extraction surgery with preoperative biometry with OA--2000, IOLMaster-500, and Lenstar-LS900 were enrolled. Biometry measurements of the three devices were compared. The deviation of the postoperative refraction from the preoperative refractive target was calculated with different formulas (Barrett Universal II, Hoffer Q, Holladay I, and SRK/T). Errors in the predicted astigmatism using the Barrett toric calculator were calculated for the toric IOLs. Additional 6465 eyes in which the IOLMaster-500 failed to measure axial length (AL) were reviewed. The percentage of successful measurements using the OA-2000 in those eyes was calculated., Results: High agreement was found between the three devices for AL, anterior chamber depth, and average keratometry measurements (interclass correlation confidents: 1.000, 0.970, and 0.998, respectively, P < 0.001). The mean absolute prediction errors were similar using all formulas, ranging from 0.25 to 0.29 D, with no statistical significant difference between the three devices per each formula. The OA-2000 yielded a lower against-the-rule (ATR) centroid error in the predicted astigmatism than the IOLMaster-500 and Lenstar-LS900 (0.06 D ± 0.59 at 13.4° vs. 0.20 D ± 0.61 at 14.8° and 0.16 D ± 0.55 at 21.4°, respectively, P < 0.001, X-axis). Among 301 cases with unsuccessful AL readings using the IOLMaster-500, the OA-2000 had 284 (94.35%) successful measurements., Conclusions: The OA-2000 measurements showed good agreement with those of the IOLMaster-500 and Lenstar-LS900. Our results may suggest a potential advantage of the OA-2000 device in toric IOLs calculations and AL measurement success rate.

Purpose: To provide the first description of posterior corneal astigmatism as measured by the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany) and assess how its characteristics compare to previous measurements from other devices., Methods: A total of 1,098 routine IOLMaster 700 biometric measurements were analyzed to provide magnitudes and orientation of steep and flat axes of anterior and posterior corneal astigmatism. Subgroup analysis was conducted to assess correlation of posterior corneal astigmatism characteristics to anterior corneal astigmatism and describe the distribution of posterior corneal astigmatism with age., Results: Mean posterior corneal astigmatism was 0.24 ± 0.15 diopters (D). The steep axis of posterior corneal astigmatism was vertically oriented in 73.32% of measurements. Correlation between the magnitude of anterior and posterior corneal astigmatism was greatest when the steep axis of the anterior corneal astigmatism was oriented vertically (r = 0.68, P < .0001). Vertical orientation of the steep axis of anterior corneal astigmatism became less common as age increased, whereas for posterior corneal astigmatism it remained by far the most common orientation., Conclusions: This first description of posterior corneal astigmatism measurement by the IOLMaster 700 found the average magnitude of posterior corneal astigmatism and proportion of vertical orientation of steep axis was lower than previous estimates. The IOLMaster 700 appears capable of providing enhanced biometric measurement for individualized surgical planning. [J Refract Surg. 2018;34(5):331-336.]., (Copyright 2018, SLACK Incorporated.)

Purpose: To evaluate the intra-session repeatability of keratometric measurements obtained in healthy eyes with the Verion image-guided system (Alcon Laboratories Inc, Fort Worth, Texas, USA) as well as the interchangeability of such measurements with those obtained with an optical biometer (Aladdin, Topcon, Tokyo, Japan)., Methods: A total of 53 eyes of 53 patients (age 31-67 years) were enrolled in the study. All eyes received a comprehensive ophthalmologic examination including an analysis with the Verion image-guided and Aladdin systems. Three consecutive measurements of keratometry were obtained with the Verion system to assess the intra-session repeatability. Within-subject standard deviation (S w ) and intraobserver precision (± 1.96 × S w ) were calculated. Bland-Altman analysis was used for the interchangeability analysis., Results: Mean S w was 0.26, 0.24 and 0.10 D for the keratometric power in the flattest meridian (K1), keratometric power in the steepest meridian (K2) and astigmatism, respectively. Mean S w was 4.29° for the axis of the flattest corneal meridian (AX1). Statistically significant but clinically acceptable differences were found in K1, K2 and keratometric astigmatism among systems (p < 0.01). In contrast, differences among systems in AX1 were not statistically significant (p = 0.385) but clinically relevant (mean difference: 15.74°; limits of agreement: -30.93 to 62.41°)., Conclusions: The Verion system provides consistent measurements of keratometric parameters, with measurements of AX1 that are not interchangeable with that provided by the optical biometer Aladdin, especially in cases of low and oblique astigmatism., (© 2017 Optometry Australia.)

Purpose: Accurate and reproducible exophthalmometry is mandatory to diagnose and follow-up orbital patients, especially in Graves disease. However, many variations are described among the different commercially available exophthalmometers., Methods: Sixty patients, who underwent a cerebral computed tomography (CT) scan, were included. External prebicanthal segments (EPBCS) for right and left eyes (RE and LE), interorbital distance, and globe axial length were recorded by a first observer (O1), more experienced than a second (O2). Intraobserver and interobserver reproducibility were evaluated, using intraclass correlation coefficient (ICC) and Bland and Altman plots., Results: Concordance between each EPBCS measurement for each eye and CT scan biometry was moderate for the Luedde ruler for the 2 observers. For the Hertel exophthalmometer, concordance was moderate for O1 in the 2 eyes and moderate in RE but good in LE for O2. For the Mourits exophthalmometer, this concordance was very good in RE and good in LE for O1, and good whatever the eye for O2. Intraobserver (ICC varying from 0.75 to 0.95 for the 2 observers) and interobserver (ICC from 0.69 to 0.94) reproducibility were high, especially for the Mourits exophthalmometer. Bland and Altman plots showed underestimations when using the Luedde ruler, overestimations when using the Hertel exophthalmometer, and overestimation of small values and underestimation of high values when using the Mourits exophthalmometer when compared to CT scan biometry., Conclusions: We demonstrated great accuracy to CT scan biometry with 1-prism Mourits exophthalmometer, low accuracy with the Luedde instrument, and intermediate accuracy with the Hertel exophthalmometer, with fair intraobserver and interobserver reproducibility.

Purpose: To assess the precision (repeatability and reproducibility) of ocular parameters measured by the Tomey OA-2000 biometer, and to compare them with those measured by the IOLMaster., Methods: In this prospective study, the right eyes of 108 healthy subjects were included. Three consecutive scans were obtained by 2 observers using the Tomey OA-2000, and in the same session one observer used the IOLMaster (version 5.4.4.0006) for the measurements. About 1 week later, 3 scans were obtained by one observer using the Tomey OA-2000. The axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), keratometer readings, pupil diameter (PD) and corneal diameter (CD) values measured by the Tomey OA-2000 and IOLMaster were analyzed. The coefficient of variation (CoV), intraclass correlation coefficient (ICC), within subject standard deviation (Sw) and 2.77Sw were calculated to assess the repeatability and reproducibility. The paired t test and Bland-Altman plots were used to analyze the differences and agreements of parameters measured by the two devices, respectively., Results: Intraobserver repeatability, and interobserver and intersession reproducibility of the AL, CCT, ACD, LT, Kf, Ks, Km, PD and CD values measured by the Tomey OA-2000 biometer showed a CoV of less than 1% except that for PD, and an ICC of more than 0.97 except that for PD and CD. The AL, Kf, Ks, Km and CD values measured by the Tomey OA-2000 were 0.058 ± 0.094 mm, 0.088± 0.150 diopters (D), 0.163 ± 0.170 D, 0.127 ± 0.117 D and 0.171 ± 0.217 mm lower than those measured by the IOLMaster, respectively (all Ps < 0.05). However, the ACD values from the two devices were comparable (P = 0.169). The 95% linite of agreement (LoA) of the AL, ACD, CD and all keratometer readings were no more than 0.24 mm, 0.14 mm 0.60 mm and 0.5 D, respectively., Conclusion: Except for the PD and CD, the ocular parameters measured by the Tomey OA-2000 were highly repeatable and reproducible. Except for the CD value, there was good agreement of ocular parameters measured by the Tomey OA-2000 and the IOLMaster in healthy eyes.

Purpose: To evaluate the repeatability and comparability of biometry parameters between a Scheimpflug-based topography with axial length measurement (Pentacam AXL, Oculus, Wetzlar, Germany) and a swept-source optical biometry (IOLMaster 700, Carl Zeiss Meditec AG, Jena, Germany)., Methods: A total of 50 eyes from 50 adult subjects had biometry measurements in one session three times using the Pentacam AXL and the IOLMaster 700. Keratometry, anterior chamber depth (ACD) and axial length (AL) values were obtained by both devices. Mean keratometry (K mean ) was calculated and the corneal spherocylinder was converted into power vectors (J0, J45). Repeatability was assessed based on intraclass correlation coefficient (ICC). Agreement was evaluated by linear regression analysis and Bland-Altman analysis by calculating the mean difference and 95% limits of agreement (LoA)., Results: Assessment of intraoperator repeatability by means of ICC showed excellent reproducibility of measurements for both devices and all parameters examined ranging from 0.994 to 1.0. IOLMaster 700 exhibited significantly higher K mean (p<0.001) and AL (p<0.001) values than the Pentacam AXL. Pentacam AXL showed significantly higher ACD (p<0.001) measurements than IOLMaster 700. There was no statistically significant difference of J0 (p=0.115) and J45 (p=0.255) values between Pentacam AXL and IOLMaster 700., Conclusions: Both devices provide high reproducible values for all parameters investigated. J0 and J45 values are statistically and clinically interchangeable between Pentacam AXL and IOLMaster 700. All other parameters are statistically different. In clinical practice, the differences for ACD and AL are to small and the values can be used interchangeable. However, K mean values are clinically and statistically different and cannot be used interchangeable between the two devices., (Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Objective: To assess the repeatability and agreement between the Aladdin and Lenstar biometers., Methods: Three consecutive measurements of the right eye of 102 subjects were acquired by the Aladdin (V.1.1.3) and the Lenstar (V.1.0.3), respectively, with a random order of which biometer to use first. Parameters compared included axial length (AL), anterior chamber depth (ACD), flat keratometry (Kf), steep keratometry (Ks), mean keratometry (Km), J 0 , J 45 and white-to-white (WTW) distance. Intraocular lens (IOL) power formulas included SRK/T (Sanders-Retzlaff-Kraff/Theoretical), Holladay 1, Hoffer Q and Haigis. Repeatability (S r ), repeatability limit (r) and Bland-Altman limits of agreement (LoA) were calculated., Results: S r was marginally better with the Lenstar for AL (0.02 mm), ACD (0.02 mm) and WTW distance (0.07 mm), but S r was marginally better with the Aladdin for Kf (0.10 dioptre (D)), J 0 (0.07 D) and J 45 (0.06 D). In terms of agreement, the mean difference was small and non-statistically significant between the two devices for ACD, Ks and J 45 . The mean difference for Kf, Km, J 0 and WTW distance were all statistically significantly lower with the Aladdin than the Lenstar for the exception of WTW distance. The Bland-Altman LoA displayed narrow ranges implying good agreement with the exception for WTW distance. For IOL formulas, the mean difference was very small and not statistically significantly different. The LoA were narrow (within 0.50 D), implying acceptable use of each device interchangeably., Conclusions: High levels of repeatability and agreement were found between the Aladdin and Lenstar suggesting that the devices may be used interchangeably in normal eyes with refractive error., Competing Interests: Competing interests: None declared., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

The aim of this study was to compare the keratometric measurements of Verion Image Guided System with an optical biometer (Zeiss IOLMaster 500, Carl Zeiss Meditec, Jena, Germany) and an automated keratorefractometer (AKR) (Topcon KR-8900, Topcon, Japan). In this prospective clinical trial, the right eyes of 52 patients with cataract were examined (mean age 62.25 ± 12.16 years). The measurements were taken by the three systems in a random order. Keratometric data, magnitude of astigmatism, and astigmatic axis measurements from all three instruments were compared. The results were evaluated using, intraclass correlation coefficients (ICC), Bland-Altman plots, and paired samples t tests. The mean flat/steep K of Verion, IOLMaster, and AKR were 43.22 ± 1.38D/44.23 ± 1.46D, 43.07 ± 1.26D/44.05 ± 1.34D, and 43.07 ± 1.31D/43.89 ± 1.42D, respectively. Flat K readings of Verion were higher than IOLMaster and AKR (p < 0.05 for both). Steep K readings were different for all three (p < 0.05). The magnitude of astigmatism by Verion and IOLMaster were 0.98 ± 0.65D and 0.98 ± 0.59D (p = 0.88). The mean astigmatism measured by the AKR was 0.82 ± 0.62D, less than the other two instruments (p < 0.001). Astigmatic axis measurements of Verion and AKR differed <10° in 38, between 10° and 20° in 5, and >20° in 9 eyes; the same difference was 30, 11, and 11 eyes, respectively, between Verion and IOLMaster. Although, keratometric and astigmatic results obtained from Verion were not completely interchangeable with IOLMaster and AKR, especially the agreement between Verion and IOLMaster was excellent with ICCs close to one. However, there were pronounced astigmatic axis measurement differences between three instruments.

Objective: To evaluate the repeatability and agreement of a new partial coherence interferometry optical biometer (AL-Scan, Nidek CO, Aichi, Japan) with optical low-coherence reflectometry device (Lenstar LS 900, Haag-Streit AG, Köniz, Switzerland)., Methods: Three consecutive measurements with the 2 devices were performed by the same examiner in 65 eyes of 65 patients with cataract. Patients were divided into 2 groups: axial length (AL) between 22 and 26mm (Group 1) and more than 26mm (Group 2). Comparisons were performed for AL, anterior chamber depth (ACD), keratometry (K, over 2.4mm diameter for AL-Scan and 2.3mm diameter for Lenstar) and corneal diameter (CD). Repeatability was analyzed using the intraclass correlation coefficient (ICC) and the agreement was by the Bland-Altman method., Results: The repeatability of both devices was high for all biometry measurements (ICC over 0.970) in Group 1 and 2. The best repeatability was achieved for AL in each group. In both groups, the differences were statistically significant for all parameters (p<0.05) except for the measurement of AL and CCT (p>0.05). The Bland-Altman analysis showed good agreement between devices for all measurements in both groups. The closest agreement was for the AL measurements (ranged from -0.06 to 0.08mm in Group 1 and -0.05-0.07mm in Group 2)., Conclusions: The new biometer provided excellent repeatability for all ocular biometry. In addition, there was good agreement between AL-Scan and Lenstar biometers for all parameters in cataractous patients with medium and long ALs., (Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

The pupillometer, a cutting-edge biometric device, is a valuable assessment tool that can aid in the early detection and prompt treatment of neurological abnormalities. Pupil assessment is a critical component of the neurological examination, and manual pupil assessment leaves much room for error. Automated pupillometry improves the quality and reliability of pupillary and neurological assessments, ultimately improving patient outcomes., (Copyright 2015, SLACK Incorporated.)

Purpose: To evaluate the lens thickness, anterior cortex space, nucleus thickness, and posterior cortex space in cataractous eyes and compare them with those in eyes of younger patients with clear lenses., Setting: Private practice, Lynwood, California, USA., Design: Retrospective observational study., Methods: The study evaluated a group of cataractous eyes and compared them with a group of eyes of younger patients with clear lenses. All measurements were performed with a biometer (Lenstar LS 900)., Results: The cataractous group (200 eyes) had a greater mean lens thickness (4.65 mm ± 0.41 [SD]) than the control group (80 eyes) (4.09 ± 0.33 mm). The mean measured values for the cataractous groups and control groups were 0.84 ± 0.21 mm and 0.35 ± 0.11 mm for anterior cortex space, 3.31 ± 0.25 mm and 3.27 ± 0.27 mm for mean nucleus thickness, and 0.51 ± 0.16 mm and 0.48 ± 0.13 mm for mean posterior cortex space, respectively. Anterior cortex space, nucleus thickness, and posterior cortex space correlated positively with lens thickness (r = 0.69, r = 0.69, and r = 0.59, respectively). Lens thickness, anterior cortex space, nucleus thickness, and posterior cortex space showed a weak inverse correlation with axial length (r = 0.06, r = 0.08, r = 0.10, and r = 0.10, respectively) and an inverse correlation with anterior chamber depth (r = 0.57, r = 0.43, r = 0.42, and r = 0.22, respectively). Lens thickness showed a positive correlation with age (r = 0.28), as did the anterior cortex space (r = 0.32) and posterior cortex space (r = 0.26), but nucleus thickness did not show a positive correlation (r = 0.02)., Conclusion: Lens thickness increased with age and with cataract formation and was mostly attributable to an increase in the anterior cortex space., Financial Disclosure: Neither author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To analyze the repeatability of keratometric and white-to-white (WTW) distance measurements with the VERION Measurement Module (Alcon Laboratories, Inc., Fort Worth, TX) and to compare the measured data to the results of the IOLMaster (Carl Zeiss Meditec, Jena, Germany)., Methods: Three images were captured with the VERION and the flattest and steepest keratometric data, the astigmatism axis, and the WTW distance were recorded. Subsequently, the axial length, the keratometric data with axis, and the WTW distance were measured with an IOLMaster. The repeatability data of the keratometric value of the VERION System, converted to cross cylinder J0 and J45 vector components, were analyzed. The agreement data for keratometry obtained by the VERION System and the differences regarding keratometric data and WTW distance compared to IOLMaster were calculated., Results: The measurements were conducted in 50 eyes of 50 healthy volunteers (median age: 50.32 years, range: 19.34 to 85.3 years). The flattest and the steepest keratometric data, the diopter of astigmatism, the J0 and J45 vector components, and WTW distance did not differ significantly between devices (P > .05). Intraclass correlation coefficients (range: 0.863 to 0.994) and Cronbach's alpha values (range: 0.950 to 0.998) were high for all parameters measured by the VERION System., Conclusions: The VERION System has high repeatability and agreement with the IOLMaster, making it suitable as an alternative tool in clinical practice., (Copyright 2015, SLACK Incorporated.)

Background: To evaluate the accuracy of predicted refraction using multifocal intraocular lenses (IOLs) with power calculation based on two biometric devices and multiple IOL power calculation formulas., Design: A retrospective study conducted in a private practice ophthalmology clinic., Participants: Seventy-three eyes of 48 patients were evaluated., Methods: Consecutive cases of eyes that had undergone successful cataract surgery with an implantation of a multifocal IOL (SN6AD1, Alcon Laboratories, Inc., Fort Worth, TX, USA) by a single surgeon were enrolled. Patients were meticulously screened for suitability for a multifocal IOL implantation according to our clinic guidelines. Two biometric measurement devices (IOLMaster-500 [Carl Zeiss Meditec AG, Jena, Germany] and Lenstar-LS900 [Haag-Streit AG, Koeniz, Switzerland]) were used under strict validation criteria to evaluate the predicted refraction errors for the Holladay 1, SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II and Olsen formulas., Main Outcome Measures: Predicted refractive sphere equivalent (RSE) errors., Results: The measurements obtained from the two biometric devices were highly correlated. The standard deviation of the error in predicted RSE and the median absolute error were similar for the IOLMaster and the Lenstar devices using all formulas, ranging from 0.27 dioptres (D) to 0.31D and from 0.15D to 0.21D, respectively. A high percentage of eyes had an error in predicted RSE within ±0.5D from target refraction, ranging from 86.3% to 93.2%., Conclusions: High accuracy can be achieved in multifocal IOL power calculations by appropriate patient selection, precise biometry and appropriate IOL calculation formulas., (© 2014 Royal Australian and New Zealand College of Ophthalmologists.)

Purpose: To compare corneal astigmatism measurements obtained using a new optical biometer (AL-Scan) and a standard biometer based on partial coherence interferometry (IOLMaster 500) for toric intraocular lens (IOL) selection., Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand., Design: Prospective comparative study., Methods: Keratometry (K) readings were taken with the 2 biometers in eyes of cataract patients. The corneal astigmatism readings from the 2 devices were compared. The cylinder measurements were transformed into J0 and J45 vector components for analysis, and the devices' values were compared using the paired t test. Correlation coefficients were calculated. The Bland-Altman method was used to evaluate the agreement between the sets of measurements., Results: One hundred thirty-seven eyes (81 patients) were enrolled. The magnitude of astigmatism between the new biometer 2.4 mm zone and the standard biometer was similar (P = .19). There was a statistically significant difference between values from the new biometer 3.3 mm zone and the standard biometer (P < .05). There was good correlation in the overall magnitude of astigmatism between devices. There was a trend of low correlation toward the flat cornea (K <43.0 diopters [D]), low corneal cylinder (<1.0 D), and with-the-rule astigmatism. The IOL toricity calculated from both devices was similar., Conclusions: Corneal astigmatism measurements with the 2 biometers were similar in magnitude, especially in 2.4 mm zone of the new biometer. There was no difference in the toric IOL selections between the devices., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the repeatability and reproducibility of measurements obtained by a new optical biometer (Nidek AL-Scan) in normal eyes and keratoconic eyes., Setting: Department of Ophthalmology, Turgut Özal University, Medical School, Ankara, Turkey., Design: Evaluation of diagnostic technology., Methods: To assess the repeatability and reproducibility of the optical biometer, 2 independent examiners performed 3 consecutive measurements. The following parameters were evaluated: central corneal thickness (CCT), anterior chamber depth, axial length (AL), corneal dioptric power in the flattest meridian (flat keratometry [K]) and in the steepest meridian (steep K), and white-to-white (WTW) distance. Repeatability was assessed using the within-subject standard deviation (S(w)), repeatability, and precision. Reproducibility was evaluated using the 95% limits of agreement proposed by Bland and Altman., Results: Thirty healthy subjects and 27 patients with keratoconus were evaluated. Both examiners achieved high repeatability for all parameters in each group except for the steep K measurement in keratoconic eyes performed by examiner 2 (S(w) = 3.341). The WTW in normal eyes and the CCT and steep K in keratoconic eyes showed less repeatability. In both groups, the smallest range of agreement was in AL measurements whereas the largest was in CCT measurements. In keratoconic eyes, the range of agreement for steep K was also greater (3.766)., Conclusions: The precision of the measurements obtained by the new optical biometer was high., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To present an overview of the measurement errors for various biometric devices, as well as a meta-analysis of the agreement between biometric devices using the Pentacam, Orbscan, and IOL Master as a reference., Design: Meta-analysis of the literature., Methods: The meta-analysis is based on data from 216 articles that compare a total of 24 different devices with the reference devices for the following 9 parameters: mean, steep and flat curvature of the anterior and posterior cornea; central corneal thickness; anterior chamber depth; and axial length. After the weighted average difference between devices has been determined, the "two one-sided t test" was used to test for equivalence between devices within certain thresholds defined by the measurement errors and the influence of these differences on the calculated refraction., Results: In only 17 of the 70 comparisons a device was equivalent with the reference device within the thresholds set by the measurement error. More lenient thresholds, based on a change in calculated refraction of ±0.25 diopter, increased this number to a maximum of 25/50 comparisons (excluding pachymetry). High degrees of inconsistency were seen in the reported results, which could partially explain the low agreement between devices., Conclusion: As a rule, biometry measurements taken by different devices should not be considered equivalent, although several exceptions could be identified. We therefore recommend that clinical studies involving multiple device types treat this as a within-subject variable to avoid bias. The follow-up of individual patients using different devices should be avoided at all times., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: To compare the repeatability and reproducibility of ocular biometry and intraocular lens (IOL) power obtained with a new optical biometer (AL-Scan) and a standard optical biometer (IOLMaster 500)., Setting: Siriraj Hospital, Mahidol University, Bangkok, Thailand., Design: Prospective comparative study., Methods: Two independent operators measured eyes with cataract using both biometers. The keratometry values, axial length, anterior chamber depth, white-to-white (WTW) corneal diameter, and IOL power calculated using the Holladay 1 formula obtained with each device were recorded. Intraoperator repeatability and interoperator reproducibility of both devices were analyzed using the intraclass correlation coefficient (ICC). The agreement in ocular biometry and IOL power between the 2 devices was evaluated by the Bland-Altman method., Results: The study recruited 137 eyes of 81 patients. The repeatability and reproducibility of both devices were high for all ocular biometry measurements (ICC, 0.87-1.00). Except for the WTW corneal diameter (ICC, 0.44), the agreement between the biometers was also high (ICC, 0.98-0.99). The IOL powers calculated by the Holladay 1 formula were similar between the 2 biometers., Conclusion: The new optical biometer provided excellent repeatability and reproducibility for all ocular biometry. Agreement with the standard optical biometer was good except for the WTW corneal diameter., (Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Aim: To assess the accuracy and reproducibility of biometry undertaken with the Aladdin (Topcon, Tokyo, Japan) in comparison with the current gold standard device, the IOLMaster 500 (Zeiss, Jena, Germany)., Setting: University Eye Clinic, Birmingham, UK and Refractive Surgery Centre, Kiel, Germany., Methods: The right eye of 75 patients with cataracts and 22 healthy participants were assessed using the two devices. Measurements of axial length (AL), anterior chamber depth (ACD) and keratometry (K) were undertaken with the Aladdin and IOLMaster 500 in random order by an experienced practitioner. A second practitioner then obtained measurements for each participant using the Aladdin biometer in order to assess interobserver variability., Results: No statistically significant differences (p>0.05) between the two biometers were found for average difference (AL)±95% CI=0.01±0.06 mm), ACD (0.00±0.11 mm) or mean K values (0.08±0.51 D). Furthermore, interobserver variability was very good for each parameter (weighted κ≥0.85). One patient's IOL powers could not be calculated with either biometer measurements, whereas a further three could not be analysed by the IOLMaster 500. The IOL power calculated from the valid measurements was not statistically significantly different between the biometers (p=0.842), with 91% of predictions within±0.25 D., Conclusions: The Aladdin is a quick, easy-to-use biometer that produces valid and reproducible results that are comparable with those obtained with the IOLMaster 500.

Objective: The purpose of the study is to determine the precision of whole globe and cornea measurements acquired using calipers, and to quantify the intraoperator and interoperator variance., Design: Experimental study., Participants: Ten human donor eyes., Methods: Ten human eyes (donor age, 16-54 years) were obtained between 18.5 and 66.5 hours postmortem. The horizontal and vertical diameters and the anteroposterior length of the globe were measured using a digital Vernier caliper. The horizontal and vertical diameters of the cornea were measured using both a digital Vernier caliper and a Castroviejo caliper. The measurements were performed by 3 operators with 5 repeat measurements for each dimension., Results: No significant differences were observed between measurements of globe anteroposterior length, horizontal diameter, and vertical diameter. Horizontal corneal diameter was greater than vertical diameter with all instruments and all operators. Variability of either instrument did not change with measurement object scale, and was similar across all operators. No significant differences were observed between the variabilities of the 2 devices. The mean intraoperator SD was 0.127 ± 0.023 mm with the digital caliper and 0.094 ± 0.056 mm with the Castroviejo caliper., Conclusions: The precision of commercially available calipers in ophthalmic biometry measurements is limited to approximately 0.1 mm., (Copyright © 2013 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare the keratometric (K) readings from the Pentacam-HR (High Resolution) unit with the automated K values from the IOLMaster keratometer (KIOLM), and to evaluate them in the commonly used intraocular lens (IOL) power calculation formulas for routine cataract surgery., Design: Prospective, comparative observational study., Methods: setting: Private practice, Lynwood, California. study population: Fifty cataractous eyes scheduled for surgery between July and August 2012. observation procedure: The K readings from the Pentacam-HR unit taken at the 2-, 3-, 4-, and 5-mm zones and the 2-, 3-, 4-, and 5-mm rings, respectively, from 3 different maps: sagittal corneal front (KF), true net power (KTNP), and total refractive power (KRP) are compared with KIOLM. IOL power calculations were performed with each of the 25 sets of K readings. main outcome measures: The IOL prediction median absolute error (MedAE) obtained with each measurement., Results: KF averaged 0.03-0.13 diopter (D) higher than KIOLM (P > .05), KTNP averaged 1.16-1.21 D lower than KIOLM (P > .001), and KRP averaged 0.23-0.72 D lower than KIOLM (P > .001), with large variations in the measurements. The MedAE obtained with the different Pentacam K readings ranged from 0.44-0.64 D vs 0.52 D obtained with KIOLM (P > .05). MedAE was lower in all categories when the pupil was 3 mm or smaller., Conclusion: The Pentacam KF values were the closest to KIOLM and the KF readings from the 2-mm ring yielded the best results for IOL power calculation., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to compare keratometry and anterior chamber depth (ACD) measurements from the Lenstar LS 900 (Haag-Streit AG, Switzerland) and the Pentacam (Oculus, Weltzar, Germany), and compare the keratometry readings of these two systems to a manual keratometer (MK), (Haag-Streit, Switzerland)., Materials and Methods: In this prospective study, keratometry and ACD measurements were obtained in 50 eyes of 50 normal subjects with the Lenstar and the Pentacam. Keratometry was also measured using a MK. Correlation, comparison, and interdevice agreement was evaluated using intraclass correlation analysis, Wilcoxon test, and Bland-Altman plots., Results: The keratometry and ACD measurements obtained from the Lenstar and the Pentacam showed excellent correlation. The mean interdevice differences in mean keratometry (Km) for the Lenstar and the Pentacam, the Lenstar and the MK, and the Pentacam and the MK were 0.39 D, 0.10 D, and 0.30 D respectively; and the 95% limits of agreement (LoA) for Km were 0.04-0.82 D; -1.90-2.10 D; and -2.30-1.70 D, respectively. The mean interdevice difference in ACD for the Lenstar versus the Pentacam was 0.09 mm, with 95% LoA of 0.23-0.05 mm., Conclusions: The ACD measurements obtained using the Lenstar and the Pentacam seem to be interchangeable, whereas, the keratometry measurements obtained using the Lenstar, Pentacam, and MK differ considerably, and are not interchangeable.

Objective: To examine the change of the axial length measured by IOL Master in adults with high myopia during a 2-year period., Design: Open-label, consecutive, prospective longitudinal case series., Methods: One hundred and eighty-five eyes of 185 consecutive patients with bilateral high myopia (myopia ≤ -6 diopters (D) or axial length ≥ 26.5 mm) were studied. The mean age of the patients was 48.4 ± 12.2 years, with a range of 22 to 84 years. The axial length, the anterior chamber depth, and the radius of curvature of the cornea were measured by IOL Master at the initial examination and at 2 years after the first visit. The significance of the changes in the axial length after the 2-year periods was determined. Multiple regression analyses were performed to identify the factors which were significantly associated with the increase of the axial length., Results: The mean axial length increased significantly from 29.35 ± 1.80 mm to 29.48 ± 1.85 mm in 2 years, a mean increase of 0.13 mm with a range of -0.12 to 1.10 mm. The difference in the increase of the axial length between the patients with and without a posterior staphyloma was not significant. Among the possible explanatory factors, age, axial length, anterior chamber depth, the radius of curvature of the cornea, and intraocular pressure at the initial examination, the increase in the axial length was significantly and positively correlated with the axial length at the initial examination., Conclusions: The measurement by IOL Master in a large population of highly myopic patients clearly showed that the axial length continued to increase in a span of 2 years even in the 4th decade of life. The eyes with longer axial length showed a greater increase of axial length, suggesting the possibility that the more myopic eyes become more myopic with increasing age.

Purpose: To assess the repeatability and accuracy of optical biometry (Lenstar LS900 optical low-coherence reflectometry [OLCR] and IOLMaster partial coherence interferometry [PCI]) and applanation ultrasound biometry in highly myopic eyes., Setting: Division of Preventive Ophthalmology, Zhongshan Ophthalmic Center, Guangzhou, China., Design: Comparative evaluation of diagnostic technology., Methods: Biometric measurements were taken in highly myopic subjects with a spherical equivalent (SE) of -6.00 diopters (D) or higher and an axial length (AL) longer than 25.0 mm. Measurements of AL and anterior chamber depth (ACD) obtained by OLCR were compared with those obtained by PCI and applanation A-scan ultrasound. Right eyes were analyzed. Repeatability was evaluated using the coefficient of variation (CoV) and agreement, using Bland-Altman analyses., Results: The mean SE was -11.20 D ± 4.65 (SD). The CoVs for repeated AL measurements using OLCR, PCI, and applanation ultrasound were 0.06%, 0.07%, and 0.20%, respectively. The limits of agreement (LoA) for AL were 0.11 mm between OLCR and PCI, 1.01 mm between OLCR and applanation ultrasound, and 1.03 mm between PCI and ultrasound. The ACD values were 0.29 mm, 0.53 mm, and 0.51 mm, respectively. These repeatability and agreement results were comparable in eyes with extreme myopia (AL ≥ 27.0 mm) or posterior staphyloma. The mean radius of corneal curvature was similar between OLCR and PCI (7.66 ± 0.24 mm versus 7.64 ± 0.25 mm), with an LoA of 0.12 mm., Conclusion: Optical biometry provided more repeatable and precise measurements of biometric parameters, including AL and ACD, than applanation ultrasound biometry in highly myopic eyes., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare and correlate central corneal thickness (CCT), anterior chamber depth (ACD), and keratometric (flat and steep K) measurements using two anterior segment imaging methods, a Scheimpflug camera system (Oculyzer II [Oculus Optikgeräte GmbH]) and a partial coherence biometry system (WaveLight OB820 [Alcon Laboratories Inc]) in eyes undergoing cataract surgery., Methods: Ninety patients (mean age: 66±13 years [range: 32 to 88 years]) underwent preoperative measurement of CCT, ACD, and keratometric measurements by Scheimpflug tomography (Oculyzer II) and optical low coherence reflectometry (WaveLight OB820). Interdevice agreement and correlation between the two techniques were assessed., Results: All measurements were highly correlated and showed no clinically significant difference between methods. Mean CCT was 554.21±39.07 μm and 546.59±37.75 μm for the Oculyzer II and WaveLight OB820, respectively (R²=0.9268). Mean ACD was 2.63±0.44 mm and 2.63±0.43 mm for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9488). The principal meridian keratometric values were also highly correlated. Mean flat K was 42.88±1.50 diopters (D) and 42.96±1.40 D for the Oculyzer II and WaveLight OB820, respectively (R²=0.8741). Mean steep K was 44.08±1.79 D and 44.26±1.95 D for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9159)., Conclusions: Our data show that the Oculyzer II and WaveLight OB820 provide measurements that are in agreement with published values for CCT and ACD in patients. Excellent agreement for CCT and ACD was found between the two devices, as demonstrated by a high degree of correlation and linearity, in addition to minimal bias. Thus, CCT, ACD, and K measurements by these instruments can both be used in clinical preparation, and their agreement is an ensuring precision factor for cataract and refractive surgeons., (Copyright 2012, SLACK Incorporated.)

Purpose: To compare the accuracy and reliability of intraocular lens (IOL) master and A-scan immersion biometry in silicone oil (SO)-filled eyes., Methods: A prospective, consecutive, nonrandomized study was performed in 34 SO-filled eyes of 34 patients, who underwent a pars plana vitrectomy, with SO removal and cataract surgery, as well as IOL implantation. Both IOL master and immersion A-scan were performed to measure the axial length (AXL) before SO removal. Three months after removal of the SO, AXL measurements using IOL master and refraction was performed. Accuracy of the two techniques was determined by a mean postoperative AXL using an IOL master and reliability was determined by mean actual postoperative refractive error., Results: Preoperative mean AXL was 23.91±0.24 mm (range 21.33-28.61 mm) and 23.71±0.59 mm (range 19.27-36.18 mm) by IOL master and A-scan immersion, respectively. Postoperative mean AXL by IOL master was 23.90±0.23 mm (range 21.58-27.94 mm), which showed a statistically significant difference from the preoperative mean AXL by A-scan immersion (P=0.005). The AXL measurement by IOL master also was more accurate than A-scan immersion by Pearson's correlation (0.966 vs 0.410). For reliability of the two techniques, the predictive postoperative refractive error in A-scan immersion (mean 1.79±1.04 D, range -14.62 to 16.41 D) was greater than that in IOL master (mean 0.60±0.23 D, range -2.74 to 2.33 D), with a statistically significant difference (P=0.049)., Conclusion: IOL master had more accuracy and less deviation in predictive postoperative refractive error than A-scan immersion in SO-filled eyes.

Purpose: To obtain comparable resolution and repeatability data for a selection of anterior segment imaging devices., Methods: A standard letter of request was sent in May 2008 to each device manufacturer requesting resolution and repeatability data for its device to be provided according to specific definitions and protocol; if this was not already published in the peer-reviewed domain, compliant raw data were required. Where applicable, repeatability data were reported for corneal vertex corneal thickness; epithelial and flap thickness; minimum corneal thickness; corneal, epithelial and flap thickness mapping for the central 6-mm diameter; minimum residual stromal thickness; angle-to-angle diameter; sulcus-to-sulcus diameter; and anterior chamber depth. To summarize published repeatability data, a complete review of the peer-reviewed literature waas performed., Results: Nine of the 13 manufacturers contacted agreed to take part and provided the data requested: Pentacam HD (Oculus Optikgeräte GmbH), Galilei (Ziemer), Visante OCT (Carl Zeiss Meditec), SL-OCT (Haag-Streit), RTVue (Optovue), Artemis (ArcScan), Vumax (Sonomed), HiScan (Opticon), and Eye Cubed (Ellex/Innovative). Only one (Carl Zeiss Meditec) of 9 manufacturers was able to provide the data directly upon request, without performing a prospective study. Five of the 9 manufacturers were able to provide a complete set of repeatability data for all parameters measurable with their device; the remaining 4 manufacturers admitted that repeatability of some parameters was unknown., Conclusions: Both literature and manufacturers' data on file were lacking and required the study to be performed. This report provides an imperfect, but most comprehensive to date, resolution and repeatability data review of biometric devices intended for surgical planning., (Copyright 2012, SLACK Incorporated.)

Purpose: To evaluate the agreement between optical low-coherence reflectometry (OLCR) and anterior segment optical coherence tomography (AS-OCT) for biometry of the anterior segment., Setting: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China., Design: Evaluation of diagnostic technology., Methods: A series of OLCR (Lenstar LS 900) and AS-OCT measurements of the anterior segment were taken for consecutive subjects aged 35 years and older in a population-based study. The differences and correlations between the 2 methods of ocular biometry were assessed. Agreement was calculated as the 95% limits of agreement (LoA)., Results: The mean age of the 776 subjects was 55.2 years ± 12.0 (SD); 54.6% were women. The mean central corneal thickness (CCT) was smaller with OLCR than with AS-OCT (537.84 ± 31.46 μm versus 559.39 ± 32.02 μm) as was anterior chamber depth (ACD) (2.60 ± 0.37 mm versus 2.72 ± 0.37 mm) and anterior chamber width (ACW) (11.76 ± 0.47 mm versus 12.04 ± 0.55 mm) (all P<.001). The 95% LoA between the 2 instruments were -44.80 to 1.71 μm for CCT, -0.17 to -0.06 mm for ACD, and -1.28 to 0.72 mm for ACW., Conclusion: Optical low-coherence reflectometry and AS-OCT yielded potentially interchangeable ACD measurements, while the CCT and ACW measurements acquired by the 2 devices showed clinically significant differences., (Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between normal eyes and eyes with keratoconus correcting for the effect of central corneal thickness (CCT) and to estimate keratoconus detection sensitivity and specificity of these parameters., Methods: Observational case series of 102 normal eyes (control group) and 77 eyes with keratoconus (keratoconus group). Examination included corneal topography, tomography, and biomechanical testing with the Ocular Response Analyzer (Reichert Technologies). The confounding effect of CCT was controlled by stratification (20-μm CCT intervals) and linear transformation. Receiver operating characteristic curves were used to identify optimal CH and CRF cutoff points for keratoconus detection. Main outcome measures were CCT, CH, CRF, and diagnostic performance of CH and CRF., Results: Corneal hysteresis and CRF were positively correlated to CCT in both groups. In the control versus keratoconus group, CH was 9.79 ± 1.51 vs 8.49 ± 1.48 (P<.0001) and CRF was 9.55 ± 1.64 vs 7.24 ± 1.43 (P<.0001), respectively. Only CRF remained significantly lower in eyes with keratoconus after CCT stratification in 20-μm intervals, and keratoconus grade influenced CH and CRF. Transformed CH and CRF data confirmed these results. Sensitivity and specificity of CRF cutoff points ranged between 83% and 94% and 69% and 83%, respectively. True positive rate for CRF in eyes with keratoconus with normal topography was 84%., Conclusions: Corneal resistance factor was better than CH for detecting keratoconic corneas once the effect of CCT on ORA measurements was considered, even for topographically unaffected fellow eyes of patients with keratoconus. The CCT-corrected CRF cutoff values and transformed indices may be of clinical use., (Copyright 2012, SLACK Incorporated.)

Purpose: To evaluate the intraobserver repeatability and validity of biometric measurements with a newly developed auxiliary A-scan ultrasound apparatus at a rural clinic., Setting: Rural county hospital in China., Design: Evaluation of diagnostic technology., Methods: Patients awaiting surgery for age-related cataract were consecutively enrolled for preoperative A-scan biometric measurements. The applanation A-scan was performed by 2 experienced nurses, with 1 using the conventional handheld method and the other using the new method with the auxiliary desktop apparatus. Two consecutive measurements were performed with each method. The 95% limits of agreement (LoA) and Bland-Altman plot were used to assess and compare the intersession measurement repeatability between the 2 methods., Results: Data for 75 eyes of 75 consecutive patients were available for analysis. The mean age of the patients was 74.3 years ± 7.4 (SD); 40.0% were men. The desktop method had a smaller standard deviation and coefficient of variance than the conventional handheld method for both measurement sessions. For intersession repeatability, the desktop method had a narrower 95% LoA range than the handheld method for all the biometry parameters. The axial length (AL) obtained with the desktop method was significantly longer than that with the handheld method (23.32 mm versus 23.14 mm; P<.01)., Conclusion: The newly developed auxiliary device had better intraobserver repeatability and more accurate AL measurements than the conventional handheld method, making it a better option for preoperative biometric measurement of cataract patients., (Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: The new Lenstar biometry device was compared in a typical clinical setting to the IOL-Master and Visante-OCT., Methods: Fifty-one eyes of 51 patients with age-related cataract were examined with Lenstar LS900 (Haag Streit AG) biometer, IOL-Master V.5 (Carl Zeiss Meditec AG) and Visante-OCT (Carl Zeiss Meditec AG) before cataract surgery. Central corneal thickness (CCT), anterior chamber depth (ACD), keratometry readings of flattest and steepest meridian (K), corneal radius (R) and axial length (AL) values were correlated. Cataracts were graded according to the Lens Opacities Classification System III (LOCS) regarding nuclear colour (NC), nuclear opalescence (NO), cortical (C) and posterior subcapsular (P) cataract., Results: Mean values and standard deviations for AL, K and R was 23.66 ± 1.23 mm and 23.67 ± 1.26 mm, 43.24 ± 1.69 dpt and 43.16 ± 1.71 dpt, 7.68 ± 0.29 mm and 7.70 ± 0.28 mm with the IOL-Master and with the LS900, respectively (r = 0.99 and p = 0.76, r = 0.99 and p = 0.029, r = 0.89 and p = 0.14, respectively). Visante-OCT demonstrated highest values of three devices regarding to ACD followed by Lenstar LS900 and IOLMaster. Axial length measurements were unfeasible in 10% of the cases (five patients) and this significantly correlated with the presence of posterior subcapsular cataract of LOCS III grade 4.0 or higher., Conclusions: IOL-Master, Lenstar LS900 and AC–OCT proved to be excellent non-contact measurement methods in eyes with age-related cataract. Nevertheless, ultrasound biometry is still required for cases with dense posterior subcapsular cataract., (© 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.)

Purpose: To evaluate the reproducibility of Lenstar in the pediatric population., Methods: Three consecutive measurements per eye by 2 ophthalmologists with a total of 6 measurements per eye were performed using Lenstar. Axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and corneal curvatures (K1 and K2) were measured for right and left eyes in 154 school-age children. Right and left eyes were analyzed separately. Each optical parameter obtained by 2 examiners was compared by paired samples t test. Intraobserver and interobserver correlation coefficients (r) were calculated for each variable. Significance was attributed when p<0.05., Results: Measurements could be performed in 152 of the children included. The mean measurements were not different statistically except for left AL (23.22±0.81 vs 23.21±0.82 mm; p=0.014), left CCT (548.5±32.3 vs 548.0±32.7 µm; p=0.013), and right ACD (3.19±0.25 vs 3.19±0.25 mm; p=0.033). Intraobserver r values were all above 0.957 except for left LT (r=0.786) for examiner 2. Interobserver r values were all above 0.979., Conclusions: Although statistical significance was obtained in some variables, they were clinically negligible. The intraobserver and interobserver relation coefficients were very high for all optical parameters including the r value for left LT for examiner 2 (r=0.786). Lenstar is a highly reproducible, user independent, and tolerable instrument for ocular biometry in the pediatric population, with no anesthesia or discomfort.

Purpose: To compare 2 new optical biometry devices with the present gold standard biometer., Setting: Vienna Institute for Research in Ocular Surgery, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria., Design: Evaluation of diagnostic test or technology., Methods: In patients scheduled for cataract surgery, measurements performed with the current gold standard optical biometer (IOLMaster) were compared with those of 2 new optical biometers, the Lenstar LS 900 (optical low-coherence reflectometry [OLCR] device; substudy 1) and the IOLMaster 500 (partial coherence interferometry [PCI] device; substudy 2). The duration of patient data entry and of the actual measurement process and the time from intraocular lens power calculation to printout were calculated., Results: The mean difference in axial length measurements was 0.01 mm ± 0.05 (SD) between the gold standard device and the new OLCR device and 0.01 ± 0.02 mm between the gold standard device and the new PCI device (P=.12 and P < .001, respectively). Measurements with the new OLCR device took significantly longer than with the gold standard device (mean difference 209 ± 127 seconds), and measurements with the gold standard device took significantly longer than with the new PCI device (mean difference 82 ± 46 seconds) (both P < .001)., Conclusions: All 3 devices were easy to use for biometry before cataract surgery. Measurements with the new PCI device took half as long as those with the gold standard device. Measurements with the new OLCR device took twice as long as those with the gold standard device., (Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Introduction: Non-contact biometers have many advantages including the delegation of tasks to orthoptists. This study analyses the reliability of measurements comparing contact and non-contacts techniques., Patients and Methods: Comparative measurements were taken on 86 eyes of 45 patients (mean age: 74 years; 44.4 % males) in preoperative phacoemulsification by three orthoptists with experience in this task. Each patient had non-contact measurements (Lenstar LS 900, Haag-Streit) and contact measurements (corneal biometry and ultrasound pachymetry with OcuScan RXP, Alcon) and a keratometry refractometer (TONOREF II, Nidek). The axial length data, pachymetry, power of the intraocular lens (SRK/T formula), anterior chamber depth, and the average keratometry were analyzed by paired comparisons., Results: The non-contact biometer was ineffective in 5.8 % of cases (Parkinson's disease, two cases; dense posterior subcapsular cataracts, three cases). The non-contact pachymetry was statistically significantly higher (546.4 μm vs. 538.6 μm; p<0.001). The axial length was significantly longer for the non-contact measurement (23.21 mm vs. 23.05 mm; p<0.0001). In 25.9 % of patients, this difference was greater than or equal to 0.3mm and affected the power of the implant chosen. The anterior chamber depth measured on non-contact biometry was statistically greater (3.33 mm vs. 3.03 mm; p<0.0001). However, there was no significant difference regarding the average keratometry (43.82 D vs. 43.78 D; p=0327)., Conclusion: Besides the infectious benefit for patients, absence of cleaning and decontamination of biometric probes, non-contact measurements using Lenstar are an example of a safe activity that can be delegated to assistants. This technique has been used to optimize the refractive outcome of 25.9 % of our patients undergoing refractive cataract surgery., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Background: The purpose of the study was to assess intraobserver and interobserver repeatability of eight ocular components measurement in cataract eyes using the optical low-coherence reflectometer Lenstar LS 900®., Methods: Five consecutive measurements of ocular components were taken by two examiners using the Lenstar. Components analyzed were: central corneal thickness, lens thickness, anterior chamber depth, axial length, retinal thickness, keratometry, white-to-white distance, and pupillometry. Within-subject standard deviation and the coefficient of variation were calculated for evaluation of intraobserver repeatability. Bland-Altman analysis was used for assessment of interobserver repeatability., Results: Thirty-two eyes of 22 patients were included. For both observers, the smallest intraobserver coefficient of variation was obtained for axial length, while the largest was found for corneal steepest meridian position. Interobserver repeatability demonstrated less repeatable results for white-to-white distance and corneal steepest meridian position. Considering axial length and anterior chamber depth values, predicted refractive error was 0 ± 0.05 D and 0.02 ± 0.19 D respectively in 95% of observations., Conclusion: The Lenstar LS 900® evidenced excellent repeatability and observers´ independent results of all components analyzed except white-to-white distance and corneal steepest meridian position measurements. To the best of our knowledge, this is the first study on interobserver repeatability of optical low-coherence reflectometry in cataract eyes.

Background: The aim of the study was to determine whether the innovative non-contact optical low-coherence reflectometry method utilized by the Lenstar LS 900® agrees sufficiently with applanation ultrasound A-scan technique in routine biometric measurement and intraocular lens power calculation to replace it., Methods: Twenty-two patients hospitalized at our eye clinic undergoing cataract surgery were assigned to have five consecutive measurements of axial length by two examiners in a single session using applanation ultrasound and the Lenstar. The applanation ultrasound intraocular lens power calculation was based on automated keratometry and applanation ultrasound axial length measurements. The Lenstar intraocular lens power calculation was based on its measurement of keratometry and axial length. Bland-Altman analysis was used to assess interobserver repeatability of applanation ultrasound and the Lenstar as well as agreement between the Lenstar and applanation ultrasound for axial length measurement and intraocular lens power calculation., Results: Thirty-two eyes of 22 patients were analyzed. In 95% of the observations, predicted refractive error corresponded to -0.26 ± 0.62 D and 0.01 ± 0.20 D obtained with applanation ultrasound and the Lenstar, respectively., Conclusions: Based on excellent repeatability of the Lenstar and acceptable repeatability of applanation ultrasound, two techniques may be used interchangeably. The predicted refractive error of ± 0.20 D in 95% of the observations has never been achieved. Optical low-coherence reflectometry might become a new standard method for biometric measurement needed for intraocular lens-power calculation in patients with cataract.

Purpose: To evaluate a new high-resolution noncontact biometer (Lenstar; Haag-Streit AG, Koeniz, Switzerland) using optical low-coherence reflectometry and to compare the clinical measurements with those obtained from the IOLMaster (Carl Zeiss, Jena, Germany) and the Pachmumeter (Haag-Streit AG)., Design: Exploratory evaluation of diagnostic technology and nonrandomized, prospective clinical trial., Participants: Eighty subjects (144 eyes) aged 20 to 90 years with cataractous, pseudophakic, aphakic, silicon oil-filled, or normal eyes., Methods: Measurements of axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), corneal radius (R1 [flattest radius of corneal curvature] and R2 [steep radius, 90 degrees apart from R1]), and axis of the flattest radius (Ax1) obtained with the Lenstar were compared with those obtained with the IOLMaster or Pachmumeter. The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t test, and its correlation was evaluated by Pearson coefficient., Main Outcome Measures: Axial length, CCT, ACD, R1, R2, and Ax1., Results: The overall mean AL measured with the Lenstar and the IOLMaster was 24.1 mm (r = 0.999). Anterior chamber depth was 3.19 mm (Lenstar) and 3.17 mm (IOLMaster; r = 0.875). Excellent correlations also were found for the corneal radius and the axis of flattest radius (R1, r = 0.927; R2, r = 0.929; and Ax1, r = 0.938). Mean CCT was 0.557 mm (r = 0.978) for both Lenstar and Pachmumeter., Conclusions: Measurements with the new Lenstar correlated well with those with the IOLMaster and Pachmumeter in cataractous, pseudophakic, aphakic, silicon oil-filled, and normal eyes. It is an accurate, fast instrument that provides additional information of interest to any cataract or refractive surgeon.

Aims: Precise biometry is an essential preoperative measurement for refractive surgery as well as cataract surgery. A new device based on partial coherence interferometry technology was tested and evaluated for accuracy of measurements., Methods: In a prospective study 200 eyes of 100 healthy phakic volunteers were examined with a functional prototype of the new ALLEGRO BioGraph (Wavelight AG)/LENSTAR LS 900 (Haag Streit AG) biometer and with the IOLMaster V.5 (Carl Zeiss Meditec AG). As recommended by the manufacturers, repeated measurements were performed with both devices and the results compared using Spearman correlation calculations (WinSTAT)., Results: Spearman correlation showed high correlations for axial length and keratometry measurements between the two devices tested. Anterior chamber depth, however, had a lower correlation between the two biometry devices. In addition, the mean values of the anterior chamber depth differed (IOLMaster 3.48 (SD 0.42) mm versus BioGraph/LENSTAR 3.64 (SD 0.26) mm); however, this difference was not statistically different (p>0.05, t test)., Conclusion: The new biometer provided results that correlated very well with those of the IOLMaster. The ALLEGRO BioGraph/LENSTAR LS 900 is a precise device containing additional features that will be helpful tools for any cataract or refractive surgeon.

Purpose: To assess the performance of a partial coherence interferometry (PCI)-based device for the determination of anterior segment biometry., Setting: Clinica Centrofama, Cartagena, Murcia, Spain., Methods: Central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) were measured with the ACMaster PCI anterior segment biometer and an Echoscan US-1800 ultrasound (US) biometer/pachymeter with and without cycloplegia. To determine the precision of the instruments, the same examiner took 30 consecutive CCT, ACD, and LT measurements in a single subject under the same conditions and with and without cycloplegia. The same measurements were performed in additional subjects., Results: Twenty-one eyes (16 subjects) were evaluated. Repeated measurements of the single subject yielded a standard deviation of 4.0 microm for CCT, 106.0 microm for ACD, and 323.0 microm for LT; there were many peaks, mainly in the last 10 readings. There was a high correlation between CCT measurements with both systems with and without cycloplegia (r(2)>0.93), with the US system giving higher values. Differences were significant (P< .001), but not consistent, throughout the range of corneal thicknesses and were greater for thicker corneas. Differences in ACD and LT measurements were similar. Agreement between systems in ACD and LT measurements was considerably lower than for CCT measurements., Conclusions: The PCI biometer provided precise CCT measurements. The ACD and LT measurements had a higher variance. Differences in CCT measurements between the 2 systems were greater for thicker corneas, with higher values with the US system.

Purpose: Corneal radii (R1, R2) and anterior chamber depth are important parameters for biometry and refractive surgery. This study aimed to investigate whether the IOLMaster, a biometric device, and the Pentacam, a rotating Scheimpflug camera, provide comparable results., Methods: In this prospective study, corneal radii and anterior chamber depth were analyzed in 82 eyes of 41 phakic patients (median age 72 years) using the IOLMaster and Pentacam. Normal distribution was confirmed using the Kolmogorov-Smirnov test. A paired t test was used for statistical analysis., Results: No statistically significant difference was noted for R2 using the Pentacam versus the IOLMaster (P = .40). There was a small statistical difference of 0.03 mm (P < .01) for R1 (corresponding to 0.08 diopters [D]). The IOLMaster measured a mean R1 of 7.87 mm and R2 of 7.67 mm. The Pentacam measured mean R1 of 7.90 mm and R2 of 7.69 mm. For anterior chamber depth values, a small statistically significant difference of 0.05 mm (P < .001) was found (corresponding to 0.01 D). Mean anterior chamber depth measured from the epithelium was 3.20 mm for the IOLMaster and 3.25 mm for the Pentacam. The Bland-Altman plot showed no distorting trends for either variable., Conclusions: Keratometry and anterior chamber depth were comparable for the two devices. If the axial length is known, the Pentacam can be used as a biometric device.

Purpose: To compare corneal thickness measurements using Orbscan II (OII) and ultrasonic (US) pachymetry in normal and in keratoconic eyes., Setting: Eye Department, Heartlands and Solihull NHS Trust, Birmingham, United Kingdom., Methods: Central corneal thickness (CCT) was measured by means of OII and US pachymetry in 1 eye of 72 normal subjects and 36 keratoconus patients. The apical corneal thickness (ACT) in keratoconus patients was also evaluated using each method. The mean of the difference, standard deviation (SD), and 95% limits of agreement (LoA = mean +/- 2 SD), with and without applying the default linear correction factor (LCF), were determined for each sample. The Student t test was used to identify significant differences between methods, and the correlation between methods was determined using the Pearson bivariate correlation. Bland-Altman analysis was performed to confirm that the results of the 2 instruments were clinically comparable., Results: In normal eyes, the mean difference (+/- 95% LoA) in CCT was 1.04 microm +/- 68.52 (SD) (P>.05; r = 0.71) when the LCF was used and 46.73 +/- 75.40 microm (P =.0001; r = 0.71) without the LCF. In keratoconus patients, the mean difference (+/- 95% LoA) in CCT between methods was 42.46 +/- 66.56 microm (P<.0001: r = 0.85) with the LCF, and 2.51 +/- 73.00 microm (P>.05: r = 0.85) without the LCF. The mean difference (+/- 95% LoA) in ACT for this group was 49.24 +/- 60.88 microm (P<.0001: r = 0.89) with the LCF and 12.71 +/- 68.14 microm (P =.0077; r = 0.89) when the LCF was not used., Conclusions: This study suggests that OII and US pachymetry provide similar readings for CCT in normal subjects when an LCF is used. In keratoconus patients, OII provides a valid clinical tool for the noninvasive assessment of CCT when the LCF is not applied.

Purpose: To assess the degree of agreement of anterior chamber depth (ACD) measurements by 2 optical devices (Orbscan II and IOLMaster) and compare them with contact ultrasound A-scan., Setting: Department of Ophthalmology at Hull Royal Infirmary, England. methods: In this prospective study of 81 eyes of 41 consecutive patients, ACD estimation was done by 3 methods-scanning slit topography (Orbscan II), partial coherence interferometry (IOLMaster), and contact ultrasound A-scan in that order. The same observer performed all measurements. Repeated measures Analysis of Variance (ANOVA) was used to analyze difference between ACD measurements by the 3 methods. Difference in measurements between methods was assessed using the paired t test., Results: The mean ACD (+/-SD) by the 3 methods was 3.32 mm (0.60), 3.33 mm (0.61), and 2.87 mm (0.55), respectively. There was a statistically significant difference between measurements recorded by the 3 methods (P<.01). Mean contact A-scan measurements were 0.40 mm and 0.43 mm lower than by Orbscan II and IOLMaster respectively (P<.01)., Conclusion: Applanation ultrasound gives consistently lower measurements for ACD compared to Orbscan II and IOLMaster. Although a high degree of agreement between Orbscan II and IOLMaster was noted, further studies are needed to assess the interchangeability of measurements in clinical practice.