Effect Of Tilt Research Articles

Effects of head-down tilt on optic nerve sheath diameter in healthy subjects.

Intracranial pressure increases in head-down tilt (HDT) body posture. This study evaluated the effect of HDT on the optic nerve sheath diameter (ONSD) in normal subjects. Twenty six healthy adults (age 28 [4.7] years) participated in seated and 6° HDT visits. For each visit, subjects presented at 11:00 h for baseline seated scans and then maintained a seated or 6° HDT posture from 12:00 to 15:00 h. Three horizontal axial and three vertical axial scans were obtained at 11:00, 12:00 and 15:00 h with a 10 MHz ultrasonography probe on the same eye, randomly chosen per subject. At each time point, horizontal and vertical ONSD (mm) were quantified by averaging three measures taken 3 mm behind the globe. In the seated visit, ONSDs were similar across time (p > 0.05), with an overall mean (standard deviation) of 4.71 (0.48) horizontally and 5.08 (0.44) vertically. ONSD was larger vertically than horizontally at each time point (p < 0.001). In the HDT visit, ONSD was significantly enlarged from baseline at 12:00 and 15:00 h (p < 0.001 horizontal and p < 0.05 vertical). Mean (standard error) horizontal ONSD change from baseline was 0.37 (0.07) HDT versus 0.10 (0.05) seated at 12:00 h (p = 0.002) and 0.41 (0.09) HDT versus 0.12 (0.06) seated at 15:00 h (p = 0.002); mean vertical ONSD change was 0.14 (0.07) HDT versus -0.07 (0.04) seated at 12:00 h (p = 0.02) and 0.19 (0.06) HDT versus -0.03 (0.04) seated at 15:00 h (p = 0.01). ONSD change in HDT was similar between 12:00 and 15:00 h (p ≥ 0.30). Changes at 12:00 h correlated with those at 15:00 h for horizontal (r = 0.78, p < 0.001) and vertical ONSD (r = 0.73, p < 0.001). The ONSD increased when body posture transitioned from seated to HDT position without any further change at the end of the 3 h in HDT.

Laboratory Evaluation of Optical Performance of Aspheric Monofocal Intraocular Lenses With Various Anti-misalignment Designs Under the Influence of Decentration and Tilt.

To assess the effectiveness and characteristics of aspheric monofocal intraocular lenses (IOLs) with different anti-misalignment designs. Three types of anti-misalignment IOLs (with aspheric balance curve design, ZO optic design, and high-order optical aspheric surface design) and no anti-misalignment IOLs were involved. From each type of these IOLs, +8.00, +17.00, and +26.00 diopter (D) lenses were used for detection at the 3- and 4.5-mm apertures. The modulation transfer function (MTF) and 50% of the maximum value of the MTF (MTF50) were measured while IOLs were centered, decentered by 0.3, 0.5, and 0.7 mm, and tilted by 3, 5, and 7 degrees. Within the average clinical range of IOL malpositions (0.3-mm decentration or 3.00-D tilt), the anti-misalignment design slightly reduced the negative effect of decentration and tilt (P = .1845 and .6495, t test) on the optical performance of IOLs. Beyond the average range, the anti-misalignment design narrowed the reductions of MTF50 from 23.18% to 8.60% for decentration and from 40.31% to 27.96% for tilt (P = .0010, two-factor analysis of variance). The optical performance varied in anti-misalignment IOLs with different diopters, types, and degrees of malpositions at different aperture sizes. In both photopic and mesopic conditions and all probable misalignments, from the perspective of MTF50, better sharpness generally may be achieved with the 8.00-D ZO optic designed lens and 17.00-D high-order optical aspheric surface designed lens. For 26.00-D IOLs with different misalignments, the ABC design was more resistant to decentrations, whereas the high-order optical aspheric surface design was more resistant to tilts. Aspheric monofocal IOLs with an anti-misalignment design can effectively resist decentration and tilt. Anti-misalignment IOLs for complicated cataract could be selected according to diopter of IOL and types and degrees of probable IOL malpositions. [J Refract Surg. 2023;39(7):446-455.].

Northern and Southern Hemisphere Polar Cap Indices: To What Extent Do They Agree and to What Extent Should They Agree?

AbstractThe IAGA‐endorsed Polar Cap Indices for the northern and southern hemispheres, PCN and PCS, are compared for 1998–2018, inclusive. Potential effects of the slightly different, and changing, magnetic coordinates of the two magnetic stations employed, Thule (Qaanaaq) in Greenland and Vostok in Antarctica, are investigated. It is shown that the agreement in overall behavior of the two indices is very close indeed but that PCS consistently correlates slightly better with solar wind parameters than PCN. Optimum lags for these correlations are 19 min for 1‐min data and 37 min for hourly averages. The correlations are significantly highest for the predicted magnetopause reconnection voltage, which is a linear predictor of PCN and PCS for all 1‐hr data and for all but the largest 0.1% of 1‐min values. The indices show lower correlation and marked non‐linearity (tending to saturation) at all levels with the estimated magnetopause reconnection electric field or the estimated power input into the magnetosphere. The PCN index is shown to correlate closely with the transpolar voltage measured by the northern‐hemisphere SuperDARN radar network and both PCN and PCS clearly show the Russell‐McPherron effect of dipole tilt and the Y‐component of the interplanetary magnetic field. However the patterns in time‐of‐year and Universal Time (UT) are complicated by lobe reconnection during northward‐IMF, the effect of which on the indices is shown to be predominantly a summer hemisphere phenomenon and gives a UT dependence on the IMF Y‐component that is predicted theoretically.

Effect of tablet tilt positioning on ergonomic risks and respiratory function

The static posture associated with continuous tablet use can lead to musculoskeletal disorders of the neck and upper extremities as well as respiratory function disorders. We hypothesized that 0-degree tablet placement (flat on a table) would affect ergonomic risks and respiratory function. Eighteen undergraduate students were divided into two groups (n = 9 per group). In the first group, the tablet was placed at a 0-degree angle, whereas in the second group, it was placed at a 40- to 55-degree angle on a student learning chair. The tablet was used continuously for 2 h for writing and internet use. Rapid upper-limb assessment (RULA), craniovertebral angle, and respiratory function were assessed. There was no significant difference in respiratory function, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC, between the groups (p = 0.09) or within groups. However, there was a statistically significant between-group difference in RULA (p = 0.001), with the 0-degree group having a greater ergonomic risk. There were also significant within-group differences between pre- and posttest. The CV angle differed significantly between groups (p = 0.03), whereby the 0-degree group had poor posture, as well as within the 0-degree group (p = 0.039), though not within the 40- to 55-degree group (p = 0.067). Undergraduate students who place their tablets at a 0-degree angle face increased ergonomic risks and higher potential for developing musculoskeletal disorders and poor posture. Thus, elevating the tablet and instituting rest intervals may prevent or decrease the ergonomic risks among tablet users.

Investigation of Electromagnetic Scattering Mechanisms from Dynamic Oil Spill–Covered Sea Surface

The electromagnetic (EM) scattering mechanism of dynamic oil spill–covered sea surface area is studied in this manuscript. Utilizing the theory of oil film diffusion combined with oil spill volume, a three–dimensional (3D) geometric model of dynamic oil spill–covered sea surface area is established. The changes of the geometric structure and statistical characteristics of the sea surface area under the influence of the oil film are also analyzed. The thinner the oil spill thickness, the more sensitive it is to the sea surface slope and wave height. The facet-based hybrid model and the multilayer dielectric scattering method are combined to measure the EM scattering on the sea surface when covered by dynamic oil spills. In addition, the hydrodynamic and tilt effect are discussed. The EM scattering mechanism of the dynamic oil spill–covered sea surface area is revealed, and the tilt modulation is greater than the hydrodynamic effect in the dynamic process of an oil spill. It provides an important reference for the remote sensing monitoring of oil.

The influence of scene tilt on saccade directions is amplitude dependent

When exploring a visual scene, humans make more saccades in the horizontal direction than any other direction. While many have shown that the horizontal saccade bias rotates in response to scene tilt, it is unclear whether this effect depends on saccade amplitude. We addressed this question by examining the effect of image tilt on the saccade direction distributions recorded during freely viewing natural scenes. Participants (n = 20) viewed scenes tilted at −30°, 0°, and 30°. Saccade distributions during free viewing rotated by an angle of 12.1° ± 6.7° (t(19) = 8.04, p < 0.001) in the direction of the image tilt. When we partitioned the saccades according to their amplitude we found that small amplitude saccades occurred most in the horizontal direction while large amplitude saccades were more oriented to the scene tilt (p < 0.001). To further study the characteristics of small saccades and how they are affected by scene tilt, we looked at the effect of image tilt on small fixational saccades made while fixating a central target amidst a larger scene and found that fixational saccade distributions did not rotate with scene tilt (−0.3° ±1.7° degrees; t(19) = −0.8, p = 0.39). These results suggest a combined effect of two reference frames in saccade generation: one egocentric reference frame that dominates for small saccades, biases them horizontally, and may be common for different tasks, and another allocentric reference frame that biases larger saccades along the orientation of an image during free viewing.

Rotational Doppler Velocimetry of a Surface at Larger Tilt Angles

Here, we experimentally demonstrate a straightforward-to-implement scheme that enables the rotating velocimetry of a noncooperative target at large deflection angles. This scheme is based upon the combination of digital modal decomposition with the rotational Doppler effect of orbital angular momentum (OAM)-carried light modes. To achieve this, we first theoretically analyzed the tilt effect of a rotating surface on the OAM complex spectra and rotational Doppler spectrum. Our findings validate that the tilted surface causes not only the broadening of OAM power and phase spectra, but also the broadening of the scattered Doppler spectrum. Furthermore, we introduce a compensation phase for tilted OAM light that effectively suppresses the sidebands of the OAM power spectrum, thereby restraining the sideband amplitudes of the Doppler spectrum. As a consequence, the rotating velocimetry can be extended to cover larger tilt angles (as large as 70 degrees) than those of existing systems. Our outcomes have the advantages of providing, in addition to profound insight into the interaction between OAM-carrying light and object motion, potential opportunities for noncontact optical metrology and the telemetry of angular speeds, particularly in meteorological applications.

Aeolian dust distribution, elemental concentration, characteristics and its effects on the conversion efficiency of crystalline silicon solar cells

Exposure of PV modules to ambient environmental conditions like dust deposits, has some deleterious effects on peak power (Pmax) and overall conversion efficiency (η). This study investigates the effect of module height, tilt, and orientation on the rate of dust deposition on the surfaces of PV modules. Consequently, the effect of different dust categories on Pmax and η are investigated. North facing module surfaces are observed to exhibit higher deposition rates in southerly winds. A significant decrease in conversion efficiency of 1.30%, 1.74%, 4.05%, 2.74% and 1.38% after a fortnight are observed in modules installed in five randomly selected study sites. A higher decrease in efficiency on average after a fortnight is observed in sites having traces of anthropogenic particles on dust samples collected from the PV surfaces with minimal effects observed in sites having biogenic and geogenic particles. Abundance of anthropogenic dust particles coupled with mild tilt and leeward orientation led to a higher maximum power and efficiency degradation rate.

Magnetic Tilt Effect on Externally Driven Electromagnetic Ion Cyclotron (EMIC) Waves

AbstractWe examine coupling of fluctuations in the solar wind with electromagnetic ion cyclotron (EMIC) waves in the magnetosphere using an advanced full‐wave simulation code, Petra‐M. Dipole tilt dramatically affects the coupling process. While very little wave power can reach the inner magnetosphere without tilt effects, a tilted dipole field dramatically increases the efficiency of the coupling process. Solar wind fluctuations incident at high magnetic latitude effectively reaches the ground along the field line and mode‐convert to linearly polarized field‐aligned propagating waves at the Alfvén and IIH resonances. Therefore, solar wind compressions efficiently drive linearly polarized EMIC waves when the dipole angle is tilted toward or away from the Sun‐Earth direction.

Detection of peanut seed vigor based on hyperspectral imaging and chemometrics.

Rapid nondestructive testing of peanut seed vigor is of great significance in current research. Before seeds are sown, effective screening of high-quality seeds for planting is crucial to improve the quality of crop yield, and seed vitality is one of the important indicators to evaluate seed quality, which can represent the potential ability of seeds to germinate quickly and whole and grow into normal seedlings or plants. Meanwhile, the advantage of nondestructive testing technology is that the seeds themselves will not be damaged. In this study, hyperspectral technology and superoxide dismutase activity were used to detect peanut seed vigor. To investigate peanut seed vigor and predict superoxide dismutase activity, spectral characteristics of peanut seeds in the wavelength range of 400-1000 nm were analyzed. The spectral data are processed by a variety of hot spot algorithms. Spectral data were preprocessed with Savitzky-Golay (SG), multivariate scatter correction (MSC), and median filtering (MF), which can effectively to reduce the effects of baseline drift and tilt. CatBoost and Gradient Boosted Decision Tree were used for feature band extraction, the top five weights of the characteristic bands of peanut seed vigor classification are 425.48nm, 930.8nm, 965.32nm, 984.0nm, and 994.7nm. XGBoost, LightGBM, Support Vector Machine and Random Forest were used for modeling of seed vitality classification. XGBoost and partial least squares regression were used to establish superoxide dismutase activity value regression model. The results indicated that MF-CatBoost-LightGBM was the best model for peanut seed vigor classification, and the accuracy result was 90.83%. MSC-CatBoost-PLSR was the optimal regression model of superoxide dismutase activity value. The results show that the R2 was 0.9787 and the RMSE value was 0.0566. The results suggested that hyperspectral technology could correlate the external manifestation of effective peanut seed vigor.

Optic disc tilt and rotation effects on positions of superotemporal and inferotemporal retinal nerve fibre layer peaks in myopic Caucasians

ABSTRACT Clinical relevance In myopic eyes, the optic disc may become tilted and rotated, making glaucoma diagnosis more difficult. Background To determine the presence of tilted optic disc, the degree of optic disc rotation, and their effects on the angular location of superotemporal and inferotemporal retinal nerve fibre layer (RNFL) peaks in healthy myopic Caucasians. Methods Non-glaucomatous healthy myopic Caucasian eyes with an axial length > 24 mm were evaluated. ImageJ was used to quantify optic disc tilt and torsion on red-free fundus photography. The RNFL was scanned using spectral-domain optical coherence tomography. The angle of the superotemporal and inferotemporal peaks with the vertical-horizontal meridian was measured. Results Fifty-four eyes of 54 individuals were evaluated. The axial length was correlated with the angular location for both the superotemporal (r = −0.549, p < 0.001) and inferotemporal (r = −0.415, p = 0.002) RNFL peaks; they were placed more temporally in eyes with higher axial lengths. For each 1 mm increase in axial length, the angle between the superotemporal peak and the temporal horizontal meridian decreased by 3.976°, and the angle between the inferotemporal apex and the temporal horizontal meridian decreased by 3.028°. The angle between the inferotemporal peak and the temporal horizontal meridian decreased by 0.231° for each 1° increase in optical disc torsion (R2 = 0.09 Regression coefficient = −0.231, p = 0.027). Conclusions The temporal shift of superior and inferior peaks, the thickening of temporal and nasal RNFL, the presence of tilted optic disc, and optic disc rotation may cause misinterpretation of the RNFL in myopic Caucasians. When evaluating peripapillary RNFL thickness in myopic individuals, it would be better to consider these to avoid misinterpretation.

Effects of Contralateral Trunk Tilt on Shoulder and Elbow Injury Risk and Pitching Biomechanics in Professional Baseball Pitchers

Background: Baseball pitchers employ various contralateral trunk tilt (CTT) positions when pitching depending on if they have an overhand, three-quarter, or sidearm delivery. There are no known studies that have examined how pitching biomechanics are significantly different in professional pitchers with varying amounts of CTT, which may provide insight into shoulder and elbow injury risk among pitchers with different CTT. Purpose: To assess differences in shoulder and elbow forces and torques and baseball pitching biomechanics in professional pitchers with maximum 30° to 40° CTT (MaxCTT), moderate 15° to 25° CTT (ModCTT), and minimum 0° to 10° CTT (MinCTT). Study Design: Controlled laboratory study. Methods: In total, 215 pitchers were examined, including 46 pitchers with MaxCTT, 126 pitchers with ModCTT, and 43 pitchers with MinCTT. All pitchers were tested using a 240-Hz, 10-camera motion analysis system, and 37 kinematic and kinetic parameters were calculated. Differences in kinematic and kinetic variables among the 3 CTT groups were assessed with a 1-way analysis of variance (P < .01). Results: Maximum shoulder anterior force and maximum elbow proximal force were significantly greater in ModCTT (403 ± 79 N) than MaxCTT (369 ± 75 N) and MinCTT (364 ± 70 N), while maximum elbow flexion torque and shoulder proximal force, respectively, were significantly greater in ModCTT (69 ± 11 N·m and 1176 ± 152 N, respectively) than MaxCTT (62 ± 12 N·m and 1085 ± 119 N, respectively). During arm cocking, maximum pelvis angular velocity was greater in MinCTT than MaxCTT and ModCTT, and maximum upper trunk angular velocity was greater in MaxCTT and ModCTT than MinCTT. At ball release, trunk forward tilt was greater in MaxCTT and ModCTT than MinCTT and greater in MaxCTT than ModCTT, while arm slot angle was less in MaxCTT and ModCTT than MinCTT and less in MaxCTT than ModCTT. Conclusion: The greatest shoulder and elbow peak forces occurred in ModCTT, which occurs in pitchers who throw with a three-quarter arm slot. More research is needed to assess if pitchers with ModCTT are at a higher risk of shoulder and elbow injury compared with pitchers with MaxCTT (overhand arm slot) and MinCTT (sidearm arm slot), although in the pitching literature, excessive elbow and shoulder forces and torques have been shown to correlate with elbow and shoulder injuries. Clinical Relevance: The results from the current study will help clinicians better understand if differences in kinematic and kinetic measures differ with pitching, or if differences in force, torque, and arm position occur at different arm slots.

Universal Time variations in the magnetosphere

We study the dependencies of Earth’s magnetosphere on Universal Time, UT. These are introduced because Earth’s magnetic axis is not aligned with the rotational axis and complicated because it is eccentric, which makes the offset of the magnetic and rotation poles considerably greater in the Southern hemisphere and the longitudinal separation of the magnetic poles less than 180°: hence consequent UT variations in the two hemispheres are not in equal in amplitude nor in exact antiphase and do not cancel, as they would for a geocentric dipole. We use long series of a variety of geomagnetic data to demonstrate the inductive effect of motions of the polar caps in a “geocentric-solar” frame, which is phase-locked to the Russell-McPherron (R-M) effect on solar-wind magnetosphere coupling. This makes the response of the magnetosphere-ionosphere system different for the two polarities of the Y-component of the Interplanetary Magnetic Field in the GSEQ reference frame, explaining the difference in response to the March and September equinox peaks in solar wind forcing. The sunward/antisunward pole-motion effect is detected directly in satellite transpolar voltage data and is shown to have a greater effect on the geomagnetic data than the full dipole tilt effect which generates the equinoctial pattern, the potential origins of which are discussed in terms of the dipole tilt effect on ionospheric conductivities and the stability of the near-Earth tail. Persistent UT variations in Region-1 and Region-2 field-aligned currents and in partial ring current indices are presented: their explanation is an important challenge for numerical modelling of the magnetosphere-ionosphere-thermosphere system which we need to quantify the relative contributions of the various mechanisms and to give understanding of the effect of arrival time on the response of the system to large, geoeffective disturbances in interplanetary space.Plain language summary: The effect on terrestrial space weather of Earth’s magnetic axis not being aligned with the rotational axis is investigated. It is complex because not only do these two axes not align in direction (the “dipole tilt”), the magnetic axis does not pass through the centre of the Earth, which sets a requirement for an “eccentric” model of the field and not the commonly-used “geocentric” one. For many years, it has been known that the dipole tilt gives a peak in geomagnetic activity at the equinoxes (the semi-annual variation) through the “Russell-McPherron” (R-M) effect. However, although the variation with Universal Time is consistent with the R-M effect for the September equinox, it is not for the March equinox. We here solve this long-standing puzzle by investigating the effects of the motions of the two poles in a frame fixed with respect to both the Earth and the Sun for an eccentric dipole model. But solving one puzzle generates many others. We present observations of the Universal Time variations that these mechanisms combine to generate, which set an important challenge to the numerical modelling of the near-Earth space environment.

RADIATION DOSE OF THE EYE LENS IN CT EXAMINATIONS OF THE BRAIN IN CLINICAL PRACTICE-THE EFFECT OF RADIOGRAPHER TRAINING TO OPTIMISE GANTRY TILT AND SCAN LENGTH.

Lenses are always exposed to radiation in brain computed tomography (CT) scans. However, the lens dose can be reduced by excluding lens from scanning area by optimising gantry tilt and scan length. The object of this study is to retrospectively analyse if the optimisation by gantry tilt and scan length have been adequate in the CT scan of the brain, and to prospectively analyse the effect of radiographer training to the quality of the CT examinations. This study was conducted in two parts. In all, 329 brain CTs performed in the Tampere University Hospital from 2017 to 2019 were revised retrospectively. The prospective part included 51 brain CT studies conducted in October 2021. Dose to the eye of the lens was modelled using CT-Expo using zero-degree beam angle and scan lengths to expose the lens either to the primary or scattered radiation. Non-zero gantry tilt had been used in a large proportion of the CT examinations in the retrospective setting, 84.8%. However, the lenses were successfully excluded from the scan area in only 1.8% of the examinations. In the prospective part, the gantry tilt was used in 98% of the studies and the proportion of successful examinations rose from 1.8 to 11.8%. The lens dose decreased significantly when the eyes were excluded from the imaging area. The modelled lens dose in the large retrospective part was 25.9mGy (17.8-49.2mGy) when the eyes were included and 1.5mGy (0.4-1.9mGy) when the eyes were excluded. The lens dose was similar in the small prospective part. Despite the gantry tilt is widely used, unnecessary lens irradiation occurs extensively because of suboptimal gantry tilt and scan length. The training of radiographers reduces the radiation exposure to the lens by more optimal gantry tilt and scan length.

Classification and adulteration of mengding mountain green tea varieties based on fluorescence hyperspectral image method

For rapid nondestructive detection of classification and adulteration of Mengding Mountain green tea, an experimental method combining Fluorescence hyperspectral imaging technology and machine learning modeling method was proposed. Spectral data were preprocessed with Median Filtering (MF) and Multiplicative Scatter Correction (MSC), which can effectively reduce the effects of baseline drift and tilt. Xgboost (XGB) and Logistic Regression (LGR) were used for feature band extraction. Light Gradient Boosting Machine (LightGBM), Random Forest (RF), and CatBoost were used to build predictive models. The results show that the MF-LGR-RF algorithm model is the best model for the classification of Mengshan green tea, and its accuracy is 100%. The MF-XGB-CatBoost algorithm model is the best model for the quantitative analysis of the doping of Laochuan tea tree Ganlu. The R2 of the test set is 0.959 and the RMSE is 0.065. In order to further improve the model performance, a multi-model stacking ensemble learning model was designed to quantitatively analyze the adulteration of Laochuan tea tree Ganlu. The R2 of the test set was increased to 0.968 and the RMSE was reduced to 0.058.

Scheimpflug imaging for evaluation of intraocular lens position in modified flanged scleral fixated intraocular lens.

Scleral fixation of intraocular lens (IOLs) is the most preferred technique for the management of aphakia and the techniques have evolved over the years. These methods have their advantages and disadvantages, however, the major concern being the position of the intraocular lens, its stability and complications. The final IOL position is the major determinant of the final visual acuity, and various imaging modalities have been used to quantify the IOL tilt. Use of Scheimpflug imaging to evaluate the IOL tilt in modified flanged scleral-fixated intraocular lens (MFSIOL). Retrospective chart review of 41 consecutive patients who underwent MFIOL. We conducted a retrospective chart review of 41 consecutive patients who underwent MFIOL. The baseline and final best-corrected visual acuity (BCVA), refractive error, and clinical examination findings were recorded. The vertical and horizontal tilts of the IOLs were calculated using the Scheimpflug image. The IOL tilt (in degrees) in the vertical and horizontal axes was the primary outcome and the BCVA, residual refractive error, intraocular pressure, and surgical complications were secondary outcome measures. The mean baseline BCVA was logMAR 0.49, which improved to logMAR 0.356 (p < .005) after the surgery. The mean IOL tilt in the vertical axis was 3.40° (range of 0.0°-8.5°, interquartile range: 1.21-5.66) and in the horizontal axis was 1.35° (range of 0.60°-4.620°, interquartile range: 0.44-1.86), respectively. There was no correlation between angle of IOL tilt and UCVA (r = 0.089, p = 0.580), BCVA (r = 0.109, p = 0.498), final spherical error (r = 0.081, p = 0.615), cylindrical error (r = 0.207, p = 0.195), axial length (r = 0.105, p = 0.514), and IOL power (r = -0.139, p = 0.388). Modified flanged IOL (MFIOL) is an alternative technique for intrascleral fixation of IOL resulting in good lens stability. The IOL tilt achieved by this technique is minimal and did not influence the final visual outcome or spectacle correction. Scheimpflug imaging is simple and non-invasive method to measure the IOL tilt. This study on 41 eyes was aimed to analyze the lens tilt using Scheimpflug imaging in cases of modified flanged scleral fixation of intraocular lens (MFSFIOL), which is a novel technique to minimize the complications and simplify the procedure. The intraocular lens (IOL) remained stable with an acceptable range of vertical and horizontal tilt. There was no significant effect of IOL tilt on the final best-corrected visual acuity (BCVA) or spectacle correction. Scheimpflug imaging is an accurate and non-invasive technique for assessment of lens position in the patients with intrascleral fixation of IOL.

Effect of Pelvic Sagittal Tilt and Axial Rotation on Functional Acetabular Orientation.

Accurate and reproducible acetabular component positioning is among the most important technical factors affecting outcomes of total hip arthroplasty. Although several studies have investigated the influence of pelvic tilt and obliquity on functional acetabular anteversion, the effect of pelvic axial rotation has not yet been established. We analyzed a generic simulated pelvis created using preoperative full-body standing and sitting radiographs. A virtual acetabulum was placed in 144 different scenarios of acetabular anteversion and abduction angles. In each scenario, the effects of pelvic tilt and pelvic axial rotation on different combinations of acetabular orientations were assessed. The change in acetabular anteversion was 0.75° for each 1° of pelvic tilt and was most linear in abduction angles of 40°±45°. The change in acetabular anteversion was 0.8° for each 1° of pelvic axial rotation. Surgeons may consider adjusting acetabular anteversion in fixed axial pelvic deformities when the degree of deformity affects functional acetabular positioning, assessed from preoperative standing and sitting weight-bearing radiographs. [Orthopedics. 2023;46(1):e27-e30.].

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye. Methods: Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: in their designed position and flipped with respect to the planned position (IOL is implanted upside down). The theoretical model eye used was the Atchison model eye. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA, and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the modulation transfer function (MTF) was used, together with the Zernike wavefront aberration coefficients of defocus, astigmatism, and primary coma. Results: Off-centring and tilting the IOL reduced overall MTF values and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag, the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt, in terms of MTF and wavefront aberrations. Conclusion: The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Comparative Assessment of the Influence of the IOL Position on the Aberrometry Parameters after Suture Fixation of the IOL-Capsule Bag Complex to the Iris

Relevance. Suture fixation of dislocated IOL capsule-sac complexes to the iris is widely used at present. Violation of the correct position of the IOL affects the decrease in contrast sensitivity, the appearance of dysphotopsias and aberrations. Determining the dependence of the parameters of the IOL position on the quantitative characteristics of wave front aberrations in the delayed period will allow us to consider the applied methods of surgical treatment from the position of influencing the quality of vision.Purpose: to conduct a comparative assessment of the effect of IOL tilt and decentration on aberrometry indicators in the delayed postoperative period in patients with suture fixation of the IOL capsular-bag complex to the iris.Patients and methods. The main group consisted of 46 eyes operated on in 2014–2016 for the dislocation of capsule-bag complex by suture fixation to the iris for 2 arches. Comparison group — 30 eyes with articulation without suture fixation, having high uncorrected visual acuity (0.8–1.0). According to the study design, the indicators of both groups were determined at least 5 years after the operation. All patients had spherical IOLs. The determination of the IOL position (tilt and decentration) was carried out on RTVue OCT (Optovue, USA). Aberrometry was carried out on the OPD-Scan III, a comparative assessment of the wavefront indicators was performed: the mean square error of the total wavefront (Total RMS), general internal aberrations, tilt aberrations — “tilt”, total high-order aberrations “high”, oblique ray aberrations “Coma”.Results. Indicators of the IOL position. The main group. The average value of the angle of inclination in the horizontal meridian of the IOL was 3.07 ± 0.35°, in the vertical meridian 2.35 ± 0.25°. The decentration relative to the center of the pupil was 387.0 ± 3.4 mkm in the horizontal meridian, 443.0 ± 4.3 mkm in the vertical meridian. The comparison group. The average value of the angle of inclination in the horizontal meridian of the IOL was 3.04 ± 0.35°, in the vertical meridian 1.43 ± 0.13°. The decentration relative to the center of the pupil was 190.0 ± 2.8 mkm in the horizontal meridian, 259.0 ± 3.4 mkm in the vertical meridian. Aberrometry indicators. The main group: total RMS 0.52 ± 0.04, total internal aberrations 0.96 ± 0.04, tilt aberrations — “tilt” 0.31 ± 0.02, total high-order aberrations “high” 0.29 ± 0.01, oblique ray aberrations “Coma” 0.201 ± 0.010. The comparison group: total RMS 0.29 ± 0.03, total internal aberrations 0.66 ± 0.08, tilt aberrations — ““tilt” 0.202 ± 0.02, total high-order aberrations “high” 0.19 ± 0.07, oblique ray aberrations “Coma” 0.088 ± 0.010.The differences in the compared groups were significant (p &lt; 0.05).The calculation of the correlation coefficient, when comparing the parameters of IOL decentration and the quantitative characteristics of aberrations, revealed a weak positive dependence, which indicates a slight influence of the obtained IOL decentration parameters on both internal aberrations and the RMS integral indicator.Conclusion. Thus, a comparative assessment of the indicators of the IOL position (tilt / decentration) and the number of wave front aberrations did not reveal a significant correlation. The correct central position of the IOL reduces wavefront aberrations and ensures high quality of vision. The method of suture fixation of the capsule-bag complexes to the iris provides a high functional and qualitative result in a delayed period.

Stability Analysis of a Real Life Tilted RCC Over Head Reservoir (Tank) considering Soil-Structure and Fluid-Structure Interaction

Tilt and settlement of RCC structures with foundations over alluvial soil of greater Kolkata and surrounding Ganges Flood Basin is a frequent problem with respect to the stability of these structures. The tilt and subsequent distress have a significant effect on the overall stability of the Over Head Reservoirs (Tanks); which also depend on the nature of the supporting soil, Fluid Structure Interaction (FSI). Various NDTs can be performed to assess the condition of the concrete members, but this piecewise assessments may not adequately address the overall stability of the OHRs subjected to various loadings including lateral seismic forces, particularly for a tilted one. Thus, numerical analysis of the tilted OHR is significantly important to assess its overall stability considering its global behaviour. The present numerical study aims to evaluate the effect of the tilt on the overall stability of a real life existing RCC OHR supported on frame staging. The increase in design reinforcement demand and lateral displacement at crown top level are compared to assess the effect of tilt from the Limit State of Collapse and Limit State of Serviceability points of view. The global effect of the tilt is studied based on the changes of its fundamental period of vibrations of the OHR. Subsequently, Pushover analysis is also performed to evaluate the effect of the tilt on the various parameters e.g. base shear capacity, inelastic displacement at crown top level, global ductility. The vulnerability index based on the pushover analysis results are also compared to ascertain the effect of the tilt. Soil-Structure Interaction and Fluid-Structure Interaction have been duly considered in the Finite Element models on SAP2000 platform to study the effect of tilt on the OHR stability. It is found that the tilt plays a great role on the overall stability and safety of the frame staging OHR, which further get aggravated due to softer supporting soil and considering Fluid-Structure Interactions. The proposed stability analysis of this case study seems to have a great potential for its practical application in safety evaluation and retrofit of existing OHRs subjected to tilt.