White-to-white Distance Research Articles

Peripheral Iridectomy in Intrascleral Intraocular Lens Fixation: Preventing Reverse Pupillary Block

To compare clinical outcomes, reverse pupillary block (RPB) findings, and anterior segment parameters in patients with and without intraoperative peripheral iridectomy during sutureless flattened flange intrascleral intraocular lens (IOL) fixation. Retrospective comparative case series. This study included 94 eyes of 82 patients who underwent IOL explantation due to vitreous-dislocated IOL at our clinic between March 2020 and September 2023, followed by flattened haptic-tipped IOL intrascleral fixation combined with pars plana vitrectomy. The patients were divided into two groups: Group 1 (n = 54) underwent peripheral iridectomy during surgery, while Group 2 (n = 40) did not undergo surgical peripheral iridectomy. Anterior chamber depth (ACD), anterior chamber angle (ACA), and white-to-white distance were measured with Scheimpflug imaging. Visual outcomes, ACD, ACA, spherical equivalent (SE), intraocular pressure (IOP), complications, and secondary interventions were evaluated. There was no significant difference between the two groups preoperatively in terms of IOP, ACD, ACA, white-to-white distance, and axial length (P > .05). Postoperatively, the mean ACD was significantly less in Group 1 (3.79 ± 0.67 mm) than in Group 2 (4.11 ± 0.75 mm) (P = .03). Postoperative IOP was 15.51 ± 2.48 mm Hg in group 1 and 18.20 ± 4.51 mm Hg in group 2 (P < .001). The postoperative ACA was statistically significantly shallower in Group 1 (41.72 ± 3.47 degrees) than in Group 2 (52.45 ± 17.93 degrees) (P < .001). Postoperatively, RPB developed in 10 eyes (25.0%) in Group 2, while it was not observed in any patient in Group 1 (P < .001). In Group 2, pupillary capture developed in 4 cases (10%) in addition to RPB. Laser peripheral iridotomy (LPI) was performed in cases with RPB. After LPI, mean IOP, mean ACA, and ACD also decreased significantly (P < .001). Intraoperative peripheral iridectomy during scleral fixation surgery combined with pars plana vitrectomy leads to significantly less RPB, a more stable anterior chamber, and fewer complications. LPI was very useful in managing RPB that developed in the postoperative period.

A comparison of white-to-white measurements obtained by Anterion AS-OCT versus three optical devices in refractive surgery candidates.

To assess the agreement between Anterion AS-OCT and three optical devices in measuring the white-to-white (WTW) diameter in candidates for refractive surgery. In this cross-sectional prospective study, 129 right eyes of 129 normal individuals underwent consecutive scans with the Anterion, the Pentacam AXL, the IOLMaster 700, and the Orbscan IIz. Mean difference (MD), 95% limits of agreement (LoA), and concordance correlation coefficient (CCC) were calculated to assess agreement and interchangeability. The mean age of participants was 30.4 ± 5.9 (range: 21-47) years. The mean WTW distance measured by the different instruments was as follows: 12.00 ± 0.42 mm (range, 10.57 to 13.05) using the Anterion, 11.87 ± 0.34 (11.10 to 12.80) using the Pentacam, 12.12 ± 0.44 (11.00 to 13.30) using the IOLMaster, and 11.73 ± 0.37 (11.00 to 13.10) using the Orbscan. The MD and 95% LoA for Anterion vs. Pentacam, IOLMaster, or Orbscan were [0.11; -0.31 to 0.54 mm], [-0.13; -0.93 to 0.66], and [0.25; -0.28 to 0.78], respectively. The corresponding CCCs were 0.803, 0.514, and 0.631. This study found weak agreement between Anterion and Pentacam AXL, IOLMaster 700, and Orbscan IIz devices regarding WTW distance measurements in refractive surgery candidates. Therefore, it is not recommended to use Anterion's WTW measurements interchangeably with the other three devices, particularly for phakic intraocular lens sizing.

Correlations of Corneal Endothelial Morphology and Corneal Thickness With Anterior Segment Parameters in Healthy Individuals.

The purpose of this study was to investigate the associations between central corneal endothelial cell density (ECD), endothelial morphology, and corneal thickness (central corneal thickness) with the anterior chamber depth, corneal volume (CV), white-to-white (WTW) distance, mean anterior chamber angle (CAmean), and gender in healthy individuals. This observational study included 136 healthy volunteers. The ECD, coefficient of variation of cell area, and hexagonal cell appearance ratio (%Hex) were measured by means of specular microscopy. The central corneal thickness, anterior chamber depth, CV, WTW distance, and the angle width of 12 points were taken by the Pentacam HR Scheimpflug anterior segment imaging. The arithmetical mean of the 12 points was considered as the CAmean. We used mixed effect linear regression model for the statistical analysis of the data. ECD was positively correlated with CV ( P = 0.028), while after adjusting for age, it was negatively correlated with age ( P < 0.001). Coefficient of variation of cell area was positively correlated with CAmean ( P = 0.036), while after adjusting for age, it was positively correlated with age ( P < 0.001) and CAmean ( P = 0.005). Hex was negatively correlated with WTW ( P = 0.023) and CAmean ( P = 0.025), and after adjusting for age, this correlation remained the same ( P = 0.029 when correlated with WTW and P = 0.035 with CAmean). There were significant changes in the morphology of the corneal endothelial cells in eyes with wider anterior chamber angle. Greater pleomorphism and polymegethism of the corneal endothelium was observed in healthy patients with wider CAmean. Deepening of the anterior chamber as myopia progresses could render the corneal endothelium more fragile and susceptible to mechanical stress, which is an area worthy of further study.

Comparison of keratometric values and anterior segment parameters measured using Scheimpflug Sirius topography and Lenstar biometry.

This study aimed to evaluate the consistency of preoperative keratometric values, anterior segment, and intraocular lens (IOL) power measurements in patients with cataract and no comorbidities using the Sirius topography device (CSO, Italy) and Lenstar LS 900 (Haag-Streit AG, Köeniz, Switzerland). Patients with grade 2 and 3 cataracts who applied to Ophthalmology Clinic of Dışkapı Yıldırım Beyazıt Education and Research Hospital, University of Health Sciences and planned for cataract surgery were included the study. Forty eyes with cataract from 40 patients were taken in the study. All patients underwent preoperative assessment using a combined Scheimpflug-Placido disc-based tomography device (Sirius) and Lenstar before cataract surgery. Keratometric measurements, such as flat keratometry (K1), steep keratometry (K2), and maximum keratometry (Kmax), and anterior segment parameters, white-to-white (WTW) distance, IOL power, astigmatism (AST), anterior chamber depth (ACD), aqueous depth (AD), and central cornea thickness (CCT), were recorded. There were significant differences between K1Lenstar and K1Sirius, K2Lenstar and K2Sirius, KmaxLenstar and KmaxSirius, WTWLenstar and WTWSirius, and IOL powerLenstar versus IOL powerSirius. However, there were insignificant differences between ASTLenstar and ASTSirius, ACDLenstar versus ACDSirius, ADLenstar and ADSirius, and CCTLenstar and CCTSirius variables. Furthermore, it was found that Sirius measured significantly higher than Lenstar, especially in terms of IOL power. Significant differences were observed between Lenstar and Sirius in terms of keratometric values, WTW distance, and IOL power. The IOL power value measured with Sirius was found to be higher than the IOL power value measured with Lenstar.

Evaluation of Ocular Diameter Parameters Using Swept-Source Optical Coherence Tomography.

Purpose: To investigate the iridocorneal angle-to-angle (ATA), sclera spur-to-sclera spur (STS), and white-to-white (WTW) ocular diameters and their potential influence on anterior chamber intraocular lens (ACIOL) and implantable collamer lens (ICL) sizing in Chinese subjects by using a swept-source optical coherence tomography system (SS-OCT). Design: A retrospective, observational, cross-sectional study. Methods: In 60 right eyes (60 subjects), the ATA, STS, and WTW were measured in six axes (0°-180°, 30°-210°, 60°-240°, 90°-270°, 120°-300°, and 150°-330°) using SS-OCT. The ACIOL and ICL sizes were calculated based on horizontal and vertical axes anterior segment data. A paired sample t-test was used to test the differences in each parameter across the six axes, the potential difference between each pair of parameters in a given axis, and the artificial lens size difference between the horizontal and vertical directions. Pearson's correlation analysis was used to determine the potential correlation between age and AL, WTW, STS, and ATA distances. Results: ATA and STS were the longest on the vertical and shortest on the horizontal axis, while WTW was similar on both axes. These three parameters differed only in the vertical axis (F = 4.910, p = 0.008). ATA and STS were by 0.23 ± 0.08 mm (p = 0.005) and 0.21 ± 0.08 mm wider (p = 0.010) than WTW, respectively. ICL size was 0.27 ± 0.23 mm smaller when based on the horizontal than on the vertical axis parameters (p < 0.001), while ACIOL remained similar (p = 0.709). Age correlated negatively and axial length positively with all measured values. ATA, STS, and WTW correlated positively in the same axis (all p < 0.001). Conclusions: ATA and STS were longer in the vertical than in the horizontal direction, while WTW measurements remained similar. ATA and STS diameters more accurately depicted anatomic relationships for phakic IOL sizing than WTW.

Clinical Validation of a New Optical Biometer for Myopia Control in a Healthy Pediatric Population.

To assess the clinical validation of the Myah device in a pediatric population by evaluating the repeatability of biometric evaluations and analyzing its agreement with the Myopia Master system. A total of 51 children (51 eyes) were enrolled. Repeated measurements of flat (K1) and steep (K2) corneal radius, white-to-white (WTW) distance and axial length (AL) were performed with the Myah device. The same parameters were obtained from a subgroup (30 eyes) with the Myopia Master for the agreement analysis. The repeatability was assessed using the intrasubject standard deviation (Sw) and the intraclass correlation coefficient (ICC). The agreement was analyzed using the Bland−Altman method and the paired Student t-test. The Sw was 0.018 D, 0.021 D, 0.071 mm and 0.017 mm for K1, K2, WTW and AL, respectively (ICC ≥ 0.971). The mean difference and limits of agreement when comparing instruments were −0.013 (−0.102/0.077) for K1 (p = 0.16), −0.058 (−0.127/0.012) for K2 (p < 0.001), 0.151 (−0.370/0.673) for WTW (p < 0.001) and 0.030 (−0.091/0.151) for AL (p = 0.009). In conclusion, the Myah device provides consistent measurements of corneal radius, WTW distance and AL in a healthy pediatric population, validating their usefulness in clinical practice. These measurements could be used interchangeably with those provided by the Myopia Master device, although with some caution.

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

PurposeTo evaluate the clinical availability of a multifunctional ocular biometric unit, MR-6000, for simultaneous keratometry, tonometry, topography, and pachymetry evaluation, and compare anterior segment measurements with five other devices: autokeratometer (KR-1), Scheimpflug camera (Pentacam HR), swept-source optical coherence tomography (IOLMaster 700), Placido disk scanning-slit topography (Orbscan II), and noncontact tonometry (FT-1000).MethodsThirty eyes from thirty patients who visited Severance Hospital for cataract surgery were examined using MR-6000 and the other devices. The mean keratometry, central corneal thickness (CCT), white-to-white (WTW) distance, and intraocular pressure (IOP) values were compared. Repeated measures analysis of variance, Wilcoxon signed-rank test, intraclass correlation coefficient (ICC), and Bland-Altman plot were used to assess the correlation and agreement between devices.ResultsThirty eyes of thirty patients were evaluated. Statistically significant differences in mean keratometry between MR-6000, KR-1, Pentacam HR, and IOLMaster 700 were not observed (p > 0.05). All five devices, including Orbscan II, had almost perfect agreement in measuring keratometry (ICC > 0.80, p < 0.05). CCT measured by MR-6000 was significantly different from that of Pentacam HR and Orbscan II measurements (p < 0.05) but correlated with that of Pentacam HR and Orbscan II measurements (ICC > 0.60, p < 0.05). The WTW distance measured by MR-6000 was not significantly different from that measured by IOLMaster 700 but was different from that measured by Orbscan II. IOP measured by MR-6000 was not correlated with FT-1000.ConclusionsKeratometric values obtained through MR-6000 can be used interchangeably with other devices based on good correlation and agreement. However, the CCT, WTW, and IOP values were not interchangeable with a single multifunctional unit for cataract surgery preoperative examination.

Predicted Refraction Variability Due to Reliability of Nine Optical Biometers for Intraocular Lens Power Calculation.

To assess the influence of reliability (repeatability and reproducibility) of eye parameter measurements on the prediction refraction by using the outcomes of nine optical biometers reported in the literature. A search was conducted in PubMed focused on the outcomes from original studies regarding reliability. The mean population of within-subject standard deviation (Sw) was estimated from the mean samples reported in the included studies. Repeatability coefficients (R) for the mean population were computed as 2.77 × Sw. The influence of reliability on the prediction refraction for eye biometric parameters, such as mean corneal power in diopters (D) (Km), anterior chamber depth (ACD), and axial length (AXL), were evaluated using a thick lens formula. The lens thickness (LT), central corneal thickness (CCT), and white-to-white (WTW) distance were also evaluated. The repeatability of optical biometers ranged from 0.19 to 0.42 D for Km, from 0.04 to 0.13 mm for ACD, from 0.03 to 0.22 mm for AXL, from 0.06 to 0.13 mm for LT, from 5.5 to 17.7 µm for CCT, and from 0.18 to 0.48 mm for WTW distance. Total prediction refraction due to repeatability ranged from 0.21 to 0.61 D, with Km the variable that caused the major part of total prediction refraction variability, followed by AXL and ACD. Reproducibility for the evaluated variables was generally inside the repeatability ranges. New optical biometers are equally reliable as earlier technologies. Special attention should be focused on Km and AXL, which explain the major part of prediction refraction variability. [J Refract Surg. 2022;38(2):120-127.].

Agreement in anterior segment measurements between swept-source and Scheimpflug-based optical biometries in keratoconic eyes: a pilot study.

Background:Cataract surgery in keratoconic patients is challenging because of the corneal distortion, which can lead to inaccurate keratometry readings. This study is a comparison of the accuracy of keratometry readings by two types of devices in a tertiary hospital.Purpose:To evaluate the comparability of corneal power measurements, anterior chamber depth (ACD), and white-to-white (WTW) distance between Scheimpflug-based tomography (Pentacam AXL; OCULUS GmbH, Wetzlar, Germany) and swept-source optical biometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) in patients with keratoconus.Methods:This pilot, prospective, interinstrument reliability study included 30 keratoconic eyes of 15 individuals who had not undergone any kind of corneal surgery. Standard K and total refractive power (TK®) of the flattest and steepest axes of the IOLMaster 700 were compared with the standard keratometry (SimK), true net power (TNP), equivalent keratometer readings (EKR), and total corneal refractive power (TCRP) of the Pentacam. The Bland–Altman analysis was used to evaluate the agreement between the measurements of both devices. The paired-samples t-test and the Wilcoxon signed-rank test were performed to compare the mean values of the variables obtained with the devices.Results:The K1 value of the IOLMaster 700 was significantly higher from EKR K1 along the 3-mm (mean difference: 0.79 diopters, p = 0.01), 4-mm (mean difference: 1.01 D, p = 0.01), and 4.5-mm zones (mean difference: 1.20 D, p = 0.01) and TNP K1 along the 3-mm (mean difference: 0.88 D, p < 0.001) and 4-mm zones (mean difference: 0.97 D, p < 0.001). The TK1 value was significantly higher from EKR K1 along the 2-mm (mean difference: 0.42 D, p = 0.04), 3-mm (mean difference: 0.83 D, p = 0.003), 4-mm (mean difference: 1.05 D, p = 0.004), and 4.5-mm zones (mean difference: 1.24 D, p = 0.005) and TNP K1 along the 3-mm (mean difference: 0.92 D, p < 0.001) and 4-mm zones (mean difference: 1.01 D, p < 0.001). The K2 value of the IOLMaster 700 was significantly higher from TK2 (mean difference: 0.11 D, p = 0.04) and all the corresponding variables of the Pentacam device. The TK2 value was significantly higher from all the corresponding variables of the Pentacam device. The Pentacam also yielded significantly lower values for the WTW distance (mean difference: 0.31 mm, p < 0.001) and no significant difference in terms of ACD values (p = 0.9).Conclusion:The IOLMaster measured significantly greater keratometry readings in the steep axis for all the variables studied. The keratometry and WTW measurements of the investigated devices cannot be used interchangeably in keratoconus.

Associations between anterior segment parameters and rotational stability of a plate-haptic toric intraocular lens.

To evaluate the associations between anterior segment parameters and the rotational stability of a plate-haptic toric intraocular lens (IOL). Eye and Ear, Nose, Throat Hospital of Fudan University. Retrospective case series. Patients who underwent uneventful phacoemulsification and plate-haptic toric IOL (AT TORBI 709M IOL) implantation were included. Preoperative axial length (AL) and anterior segment parameters, including the white-to-white (WTW) distance, anterior chamber depth (ACD), lens thickness (LT), and anterior segment length (ASL; the sum of ACD and LT) were recorded. IOL rotation, residual astigmatism (RAS), and visual acuity were evaluated 1 month postoperatively. The associations between the anterior segment parameters and IOL rotation were evaluated. A total of 102 eyes of 102 patients were included. The mean AL was 26.43 ± 2.65 mm (range 21.71-34.60 mm). The mean IOL rotation was 4.59 ± 3.18 degrees, and RAS was 0.62 ± 0.39 D postoperatively. No correlation was detected between AL, ACD, or LT and the rotation of the plate-haptic toric IOL (all P > .05). However, its rotation correlated positively with the WTW distance (r = 0.250, P = .011) and ASL (r = 0.214, P = .030). Backward stepwise multiple linear regression revealed that the WTW distance (β = 2.142, P = .014) and ASL (β = 2.060, P = .037) were independent predictors of plate-haptic toric IOL rotation. Plate-haptic toric IOLs rotate more in eyes with larger WTW distances and longer ASLs; therefore, toric IOL implantation should be performed with caution in eyes with these characteristics.

Impact of correlation of angle α with ocular biometry variables.

To analyze the association between angle α and ocular biometry in the general population at a third-level ophthalmology hospital. Anterior Segment Surgery Department, Asociación para Evitar la Ceguera en México I.A.P., Mexico City, Mexico. Prospective, cross-sectional study. Healthy subjects who attended the hospital for a comprehensive ophthalmological evaluation were examined, and general data were collected. A complete ophthalmological assessment and biomicroscopy evaluation were performed and biometry and clinical data were obtained, including visual acuity, axial length (AL), keratometry (K), white-to-white (WTW) measurement. An OPD-Scan III analyzer was used to assess both the angle α distance and biometry parameters. 74 eyes from the same number of patients were included; 43 (58.10%) were women. A statistically significant inverse correlation was found between the angle α and the AL (r = -0.585; P < .0001) and between the WTW distance and the mean K (r = 0.557; P < .0001). A significant correlation was found between the mean K and the angle α (r = 0.271; P = .019). A significant inverse correlation was observed regarding the WTW distance and angle α (r = -0.359; P = .001). By contrast, a direct correlation was evidenced between the WTW and the AL (r = 0.385; P = .0007). There was a significant inverse correlation between the AL and the angle α magnitude. Hyperopic patients demonstrated significantly higher angle α values when compared with those of myopic patients. In addition, hyperopic eyes with steeper mean K and lesser WTW distance were associated with an increased angle α.

Comparison of Clinical Outcomes and Visual Quality Using a Medium Versus Small Contact Glass in Patients Undergoing SMILE With Large Corneal Diameters.

To compare the clinical outcomes and visual quality using a small (S) versus medium (M) size contact glass in eyes with large white-to-white (WTW) distance undergoing bilateral small incision lenticule extraction (SMILE) for myopia correction. This contralateral eye study involved 60 eyes of 30 patients (mean age: 27.20 years) undergoing bilateral SMILE for myopia/myopic astigmatism with a WTW distance of 12 mm or greater in both eyes, which were randomized to receive treatment with an S-contact glass in one eye and an M-contact glass in the fellow eye. Opaque bubble layer (OBL) was graded using a new grading system. On postoperative 1 day, 2 weeks, and 3 months, UDVA, CDVA, contrast sensitivity, Objective Scatter Index, and modulation transfer function cut-off values were compared between the two groups. The mean OBL score was significantly lower in the S-contact glass group (28.18%) compared to the M-contact glass group (67.13%) (P < .01). At 1 day postoperatively, the UDVA, Objective Scatter Index score, and contrast sensitivity values for all spatial frequencies were significantly better in eyes treated with the S-contact glass compared to the M-contact glass (P ⩽ .05). At 3 months postoperatively, however, the UDVA, Objective Scatter Index score, modulation transfer function cut-off, and contrast sensitivity values were comparable for both groups. No eye in either group had intraoperative complications such as suction loss, incision/lenticule tears, or lenticule retention. In corneas with a WTW distance of 12 mm or greater, docking with the S-contact glass resulted in significantly better immediate visual results due to less OBL formation and smoother tissue dissection compared to the M-contact glass. [J Refract Surg. 2021;37(3):150-157.].

Evaluation and comparison of a novel Scheimpflug‑based optical biometer with standard partial coherence interferometry for biometry and intraocular lens power calculation

In the present study, the axial length (AL), corneal curvature, anterior chamber depth (ACD) and white-to-white (WTW) distance were assessed using the Pentacam AXL (Oculus Optikgeraete GmbH), a novel Scheimpflug-based optical biometer with standard partial coherence interferometry (PCI). The Pentacam AXL and PCI biometer (IOLMaster 500; Carl Zeiss AG) were compared in terms of their intraocular lens (IOL) power calculations. The medical records of patients (eyes, n=190) who underwent cataract surgery were retrospectively reviewed. Biometry measurements involved the eyes of patients with cataract and were performed by the same examiner with the Pentacam AXL biometer and the IOLMaster 500 device. Following determination of the AL, mean keratometry (Km), ACD and WTW distance, the IOL power calculation was compared between the two devices using the Sanders, Retzlaff and Kraff theoretical (SRK/T) and Haigis formulas. The AL, Km and WTW values for the Pentacam AXL group were significantly lower compared with those of the IOLMaster 500 group. The difference was -0.02±0.04 mm, -0.20±0.28 D and -0.10±0.20 mm, respectively (P<0.001). The ACD for the Pentacam AXL group was higher compared with that of the IOLMaster 500 group with a difference of 0.02±0.13 mm (P=0.13). The IOL power calculated using the SRK/T and Haigis formulas exhibited significant differences between the two devices (t=11.48 and 10.97, respectively; P<0.001). In conclusion, the AL, ACD, WTW measurement and IOL power indicated optimal agreement and strong correlations between the two devices. However, constant optimization may be necessary for the novel biometer Pentacam AXL.

Inter-device measurement variability of vital data parameters for keratorefractive and cataract refractive surgery.

Introduction:The measurements of corneal white-to-white (WTW) diameter and pupil size are critical for decision making in refractive surgery. Currently, automatic measurement of keratometry, corneal WTW, and pupil size are implemented in several ocular devices. The purpose of this study was to examine the agreement between two commonly used devices, an autorefractor and an optical biometer, for these parameters.Methods:Measurements were performed with both a Lenstar LS-900 and Nidek ARK-1 by an experienced examiner in random order. The devices were placed in close proximity within the same dimly lit room.Results:The measurements of 65 right eyes were analyzed. The results of the flat, steep, and mean keratometric reading were not significantly different (p = 0.96, p = 0.90, p = 0.93, respectively). Corneal WTW distances showed only moderate agreement between devices and were found to be significantly different (r = 0.8071; p < 0.01). Pupil diameters showed poor agreement between devices and were significantly different (r = 0.4890; p < 0.01). Agreement between implantable contact lens sizing, based on the measurements obtained by the two devices, was achieved for 19 of the 51 eyes (37.3%).Conclusion:We found a significant difference in WTW and pupil size measurements between ARK-1 and Lenstar. Results for both of the devices cannot be considered interchangeable for these data parameters.

Assessment of anterior segment measurements using a high-resolution imaging device

ABSTRACT Purpose To assess the repeatability of several anterior segment parameters obtained with swept-source optical coherence tomography (SS-OCT). Methods We measured 5-times consequently several parameters in 69 eyes using the ANTERION SS-OCT. White-to-white (WTW), angle-to-angle (ATA), spur-to-spur (STS), and lens vault distances were measured in the horizontal- and vertical-meridian. Anterior-chamber-angle (ACA), scleral-spur-angle (SSA), angle-opening-distance (AOD), and trabecular-iris-space-area (TISA) were measured at 500 and 750 μm for the superior-, nasal-,inferior-, and temporal-quadrants. Intrasubject standard deviation (Sw),coefficient of variation (CoV), coefficient of repeatability (CoR), and intraclass-correlation-coefficient (ICC) were calculated for each parameter. Bland-Altman analysis was done. Results We have not found statistically significant differences between repeated measurements (p > 0.05). Repeatability was good for the different parameters evaluated. Sw values in distances and areas were low and ranged from 0.01 to 0.07. CoR values showed a similar pattern being larger for those metrics measuring angles. The same happened with CoV values, being very small for WTW,ATA, and STS distances (0.16–0.57%). ICC values for all parameters analyzed were > 0.97. Bland-Altman plots evidenced the narrow limits of agreement for all parameters. Conclusions The ANTERION SS-OCT demonstrated high repeatability measuring different distances, angles, and areas of the anterior segment of the eye.

Agreement of white-to-white measurements with swept-source OCT, Scheimpflug and color LED devices.

To assess the interchangeability of different devices for measuring white-to-white (WTW) distance. WTW distance was measured in 53 eyes of 53 patients using Anterion swept-source optical coherence topographer (SS-OCT), IOLMaster 700 SS-OCT, Pentacam HR Scheimpflug and Cassini color LED. Statistical analysis was done by means of the Friedman test and the post hoc Tukey test. The Bland-Altman analysis was applied to carry out pairwise comparisons with the average difference, 95% confidence interval of the average difference and limits of agreement 95% (LoA). WTW values obtained by the Anterion, IOLMaster 700, Pentacam HR and Cassini were: 11.84 ± 0.41mm, 11.96 ± 0.41mm, 11.68 ± 0.38mm and 12.65 ± 0.52mm, respectively. Statistically significant differences were found in all pairwise comparison (p < 0.001). The lowest mean difference was found between the Anterion and IOLMaster 700 (- 0.11mm) and the highest between the Pentacam HR and Cassini (- 0.96mm). The widest LoA ranges were those that compared any device with the Cassini. LoA ranges when the other three devices were compared among them were similar: Anterion versus IOLMaster 700, Anterion versus Pentacam HR and IOLMaster versus Pentacam HR (about 0.2mm). Our results show that there were statistically significant differences in WTW measurement among the four devices, but under a clinical point of view, we believe that Anterion and IOLMaster 700 may be considered interchangeable and so Anterion and Pentacam HR, however, IOLMaster 700 and Pentacam HR may not and neither is Cassini with any of the other three devices.

Corneal topography, anterior segment and high-order aberration assessments in children with ≥ 2 diopter astigmatism.

To assess topographic findings, anterior segment parameters and high-order aberrations (HOAs) by using corneal tomography in children with 2diopters (dp) or more astigmatism. Children with 2dp or more astigmatism (study group) and children with astigmatism less than 1dp (control group) were recruited. Corneal astigmatism, mean, steep, flat keratometry (K) findings, anterior and posterior K results and anterior segment parameters including anterior chamber depth, kappa distance, horizontal corneal diameter, mean, central, middle, peripheral corneal thicknesses (CT), white-to-white (WTW) distance and pupil diameter were measured by Galilei G4 Dual Scheimpflug corneal tomography. HOAs were also assessed and compared between groups. Fifty-eight eyes of 37 children in the study group and 37 eyes of 37 children in the control group were enrolled. The mean ages of groups were 9.7 ± 2.4years and 9.3 ± 1.6years in study and control groups, respectively. The mean astigmatism was 3.3 ± 1.1dp and 0.5 ± 0.3dp in study and control groups, respectively (p < 0.05). Total corneal astigmatism was 3.3 ± 0.84dp and 1.14 ± 0.47dp in study and control groups, respectively (p < 0.05). There was a significant difference between groups in terms of posterior steep K and posterior astigmatism values. Among anterior segment parameters, mean CT and WTW values were statistically different between groups. HOAs were found to be statistically different between groups. Higher posterior corneal astigmatism, thinner mean CT and lower WTW distance were found in children with 2dp or more astigmatism. Besides, HOAs were much more in these astigmatic children.

Repeatability and Agreement of a Swept-Source Optical Coherence Tomography-Based Biometer IOLMaster 700 Versus a Scheimpflug Imaging-Based Biometer AL-Scan in Cataract Patients.

To compare the repeatability and agreement between a swept-source biometer and a Scheimpflug biometer in cataract patients. Three consecutive measurements were obtained using a swept-source biometer (IOLMaster 700) and a Scheimpflug biometer (AL-Scan) in 52 eyes of 52 patients. Keratometry, central corneal thickness (CCT), anterior chamber depth (ACD), axial length, and white-to-white (WTW) distance were recorded. Astigmatism values were transformed into vector components of J0 and J45. Intraoperator repeatability was analyzed using intraclass correlation coefficients (ICCs) and reproducibility coefficients (RCs). Agreement of measurements between the two devices was evaluated using the Bland-Altman method. The IOLMaster 700 showed higher ICCs and lower RCs for the mean keratometry (Km) (P≤0.018), CCT (P≤0.027), and ACD (P≤0.001) measurements, whereas the AL-Scan showed higher ICC and lower RC for the J45 vector component of astigmatism at the 2.4-mm zone (P≤0.034). Both the devices had excellent repeatability (ICC=0.999) in axial length measurement. Systematic differences were found in Km, CCT, ACD, and WTW (P≤0.018) between the devices. The mean difference for Km was -0.196 and -0.144 D measured at the 2.4-mm zone and 3.3-mm zone, respectively. The corresponding mean difference for CCT, ACD, and WTW distance was 14.92 μm, -0.017 mm, and 0.283 mm, respectively. These differences led to a statistically significant but clinically insignificant difference in the prediction of intraocular lens power. This study showed significant differences in anterior segment measurement repeatability and agreement between a swept-source biometer and a Scheimpflug biometer in eyes with cataract.

Effects of steep-axis incision on corneal curvature in one-handed phacoemulsification.

To examine the effects of one-handed phacoemulsification with steep-axis incision on corneal curvature and analyze surgically induced astigmatism (SIA) on the true net power, anterior and posterior corneal surfaces. Patients with cataracts underwent one-handed phacoemulsification with a 2.4-mm steep-axis of clear corneal incision (CCI) based on true net power. CCI was created under the guidance of Verion. Central corneal thickness (CCT), keratometry readings of the true net power and anterior and posterior corneal surface were obtained using Pentacam. Biometry, such as axial length, anterior chamber depth (ACD) and white-to-white (WTW) were performed using Lenstar pre- and 3mo post-operatively. The study evaluated 68 eyes of 65 patients. The mean age was 65.93±9.40y; CCT was 529.21±37.40 µm; WTW was 11.59±0.35 mm. Regarding true net power, keratometric value at the flattest corneal meridian for the 3-mm central zone (Ks) was significantly decreased postoperatively (P=0.031). Keratometric value at the steepest corneal meridian for the 3-mm central zone (Kf) was increased postoperatively (P>0.05). Astigmatism of true net power was 1.21±0.56 D preoperatively and significantly decreased to 1.02±0.58 D postoperatively (P=0.021). On the anterior corneal surface, no significant difference in Ks and Kf was noted pre- versus postoperatively. Anterior corneal astigmatism was 1.08±0.51 D preoperatively and significantly decreased to 0.87±0.46 D postoperatively (P=0.002). On the posterior corneal surface, Ks and Kf were significantly increased postoperatively (all P<0.05), and posterior corneal astigmatism also increased (P=0.008). The SIA values of true net power and the anterior and posterior corneal surfaces at 3mo postoperatively were 1.26±0.63 D (range: 0.11 to 2.80 D), 1.05±0.54 D (range: 0.23 to 2.40 D), and 0.21±0.17 D (range: 0.01 to 0.07 D), respectively. One-handed phacoemulsification with steep-axis incision can effectively decrease astigmatism of true net power and anterior corneal astigmatism. In the same surgery, the difference in personal SIA potentially originated from a difference in personal corneal thickness and diameter, both CCT and WTW distance should always be measured preoperatively when planning steep-axis phacoemulsification.

Agreement of ocular biometry measurements between 2 biometers

To establish the agreement of routine measurements taken before cataract surgery between the Aladdin biometer, which is based on optical low-coherence interferometry (OLCI), and the Lenstar biometer, which is based on optical low-coherence reflectometry (OLCR). Virginia Eye Consultants, Norfolk, Virginia, USA. Prospective case series. Biometry parameters in the same eye were measured using the OLCI biometer and the OLCR biometer at separate preoperative visits. Measured parameters included axial length (AL), anterior chamber depth (ACD), keratometry (K) values (flat K, steep K, steep K axis), lens thickness, central corneal thickness (CCT), and the white-to-white (WTW) distance. Adverse events were monitored. Data were collected for 101 eyes (65 right eyes) of 101 patients (mean age 67.9years±7.2 [SD]). The mean values measured by the OLCI biometer and OLCR biometer, respectively, were as follows: AL, 23.88±1.23mm and 23.89±1.23mm; ACD, 3.24±0.36mm and 3.25±0.37mm; flat K, 43.63±1.65 diopters (D) and 43.61±1.67 D; steep K, 44.59±1.76 D and 44.61±1.77 D; lens thickness, 4.61±0.39mm and 4.45±0.45mm; CCT, 0.55±0.04mm and 0.55±0.04mm; and WTW distance, 11.63±0.41 and 12.03±0.49mm. There was a high correlation between all parameter measurements obtained by the 2 devices. No adverse events occurred. The measurements of the OLCI biometer were as reliable and reproducible as those of a leading biometer on the market, with the former having the advantage of an incorporated full corneal topographer.