Correction Of Residual Errors Research Articles

FemtoLASIK clinical case of laser visual correction of residual myopia in the eye with IOL by using MEL-90 and VisuMax 500

The authors describe their experience of successful laser additional correction of residual myopic refractive error (Vis OD = 0.04; Sph –5.75 D, Cyl –2.00 D, ax 25° = 0.4) using the FemtoLASIK method with the MEL-90 excimer laser and the VISUMAX femtosecond laser (Carl Zeiss Meditec) in a 15-year-old patient on a pseudophakic eye (Acrysof® Natural, model SN60AT), with moderate glistening and refractive amblyopia after phacoemulsification of congenital posterior capsular cataract with IOL implantation performed at the age of 7 years. Moreover, the very next day after present surgery, the patient’s maximum distance visual acuity without correction increased to 0.5, but she still had the ability to read ordinary magazine text at close distance. Thus, the described clinical case confirms that FemtoLASIK technology can be successfully used as the second stage of bioptics (laser correction of myopia in pseudophakic eyes) in young patients.

Changes of Gait Patterns after Correction of Refractive Error in the Elderly with Cataracts

The aim of this study was to verify whether providing older adults with actual corrected glasses for refractive errors would have a positive impact on their gait patterns. This study included 30 subjects with an average age of 78.77 ± 7.27 years. The measurement of gait patterns was performed using the Optogait analysis system, and a comparative analysis was performed to compare the patients before and after they wore correction glasses. Step length, stride length, and width showed significant increases after the patients wore correction glasses, and cadence showed a decrease compared to before they wore correction glasses (p < 0.05). A strong positive correlation was observed between step length and stride length (r = 0.779, p < 0.001), and a decrease in cadence (r = −0.686, p < 0.001) was observed with increasing step length. In addition, a proportional increase in speed with increasing step length was observed after the patients wore correction glasses (r = 0.416, p < 0.05). The correction of residual refractive errors in order to provide optimal visual information can have a positive effect on gait patterns. Therefore, efforts by optometry professionals to provide the accurate correction of refractive errors in elderly patients can contribute to the prevention of falls, and collaboration with other experts is needed.

Correction of residual errors in configuration interaction electronic structure calculations.

Methods for correcting residual energy errors of configuration interaction (CI) calculations of molecules and other electronic systems are discussed based on the assumption that the energy defect can be mapped onto atomic regions. The methods do not consider the detailed nature of excitations but instead define a defect energy per electron that is unique to a specific atom. Defect energy contributions are determined from calculations on diatomic and hydride molecules and then applied to other systems. Calculated energies are compared with experimental thermodynamic and spectroscopic data for a set of 41 mainly organic molecules representing a wide range of bonding environments. The most stringent test is based on a severely truncated virtual space in which higher spherical harmonic basis functions are removed. The errors of the initial CI calculations are large, but in each case, including defect corrections brings calculated CI energies into agreement with experimental values. The method is also applied to a NIST compilation of coupled cluster calculations that employ a larger basis set and no truncation of the virtual space. The corrections show excellent consistency with total energies in very good agreement with experimental values. An extension of the method is applied to dmsn states of Sc, Ti, V, Mn, Cr, Fe, Co, Ni, and Cu, significantly improving the agreement of calculated transition energies with spectroscopic values.

Refractive surgery after deep anterior lamellar keratoplasty: a review of the literature.

The main objective of this work is to present an updated review of the different surgical procedures for the correction of residual refractive errors following deep anterior lamellar keratoplasty (DALK) surgery. A review of the literature was conducted using PubMed, Web of Science, and Scopus databases. The search was conducted in January 2022 and was limited to articles published in peer-reviewed journals. The information extracted from each publication included sample size, mean follow-up time, pre- and post-operative uncorrected (UDVA) and corrected distance visual acuity (CDVA), pre- and post-operative refraction and spherical equivalent (SE), safety and efficacy indexes and complications. Residual ametropias, mainly high astigmatism and myopia, and the resulting anisometropia are likely to occur following DALK. They become a limiting factor and may lead to unsatisfactory visual restoration, therefore affecting patients' quality of vision and life. Alternative surgical interventions may be required to treat this residual ametropia, such as corneal refractive surgery or intraocular lens implantation. A total of 47 relevant articles were studied in detail. Different refractive surgery techniques have been shown to be effective and safe for the correction of ametropia following the DALK procedure and to improve the patient's quality of vision, although more research is needed to confirm long-term results. The final refractive technique will depend on different factors, such as the amount of ametropia, the condition of the cornea or the patient's individual needs, economics, and occupational demands.

Changes in Postural Control Ability after Wearing Corrective Glasses for Distance in Older Adults and Their Causes.

Deterioration of postural control in older adults is unavoidable due to age-associated degeneration of the visual system. Our study objective was therefore to verify whether there is a positive effect on postural control ability after providing older adults, whose postural control function had deteriorated, with corrective glasses to correct refractive errors. Twenty-seven participants, 66 to 90 years of age, were included in this study. Stability index, synchronization index, and sway power index were measured by using the TETRAX balance system and comparatively analyzed before and after wearing the corrective glasses for distance. The stability index after wearing corrective glasses significantly decreased compared to before wearing them (p < 0.05). Four synchronization areas, among six, showed a significant increase in the synchronization index after wearing corrective glasses compared to before wearing them (p < 0.05). The sway power index significantly decreased in the mid–high and the high frequency after wearing the corrective glasses (p < 0.05). Optimal visual information can be obtained through the correction of residual refractive errors, eliciting a positive effect on the overall posture control by improving the sensory integration ability with the somatic nervous system responsible for posture control, maximizing the lower extremity motor function of the elderly.

Influence of Residual Amplitude and Phase Error for GF-3 Quad-Polarization SAR on Wind Vector Retrieval

High-resolution wind vector is important to investigate local winds’ variability over the global ocean. Quad-polarization Synthetic Aperture Radar (SAR) can provide wind vector independently without any external wind direction inputs. Although quad-polarization SAR wind retrieval algorithms have been widely studied, improvements are still required. The amplitude and phase imbalance of polarization channel cannot be neglected for improving the wind vector retrieval precision. In this study, rainforest was performed to remove the amplitude and phase imbalance of polarization channel of GF-3 SAR. To explore the applicability of this method for sea surface measurement, the influence of residual amplitude and phase error for GF-3 quad-polarization SAR on wind vector retrieval was assessed. Variation of amplitude and phase imbalance of sea surface for transmit and receive channel were assessed against collocated wind speed and incidence angle. Considering the polarization difference of VV channel relative to HH channel, the residual amplitude and phase error was found to be closely related to wind speed and polarization isolation. Correction of residual amplitude and phase error were employed to improve the retrieval precision of wind vector. It is revealed that the wind speed retrieval precision of VV polarization improved with correction of residual amplitude error. In addition, the influence of residual amplitude and phase error on wind direction retrieval can be neglected. Thus, it is concluded that correction of amplitude and phase error has the potential to improve wind vector retrievals from GF-3 quad-polarization SAR.

Research on Ship Motion Prediction Algorithm Based on Dual-Pass Long Short-Term Memory Neural Network

When forecasting ship movements, the random errors of the inertial navigation system (INS) seriously affect the accuracy of general prediction methods. In actual measurement, the main causes of the random errors are electrostatic bias and micro-electric disturbance. In response to this problem, a novel type of dual-pass Long Short-Term Memory (LSTM) neural network architecture is developed, on the basis of regular LSTM neural network. In the designed dual-pass LSTM neural network, the random drift and the noise residual of the INS are regarded as a autoregressive moving average (ARMA) and generalized autoregressive conditional heteroskedasticity (GARCH) model. Through dual-pass layers, the prediction of drift and the correction of residual errors are realized respectively in the same time. The simulation of ship heave motion was carried out on the ship motion simulation platform, and the real-time datas which are measured by the INS are inputted to the trained dual-pass LSTM netural network. The experiment proved that, when training the same source datas offline, the average Root Mean Squared Error (RMSE) percentage of conventional LSTM network was 3.94%, but when training different source datas or training online, the prediction accuracy obvious decline. In contrast, the average RMSE percentage of the dual-pass LSTM neural network was 1.05% when training offline and 1.12% when training online. Compared with conventional LSTM networks, the dual-pass LSTM network is more targeted and has better adaptability in the field of ship-motion prediction, and this network restores the motion prediction to the actual trajectory of a ship more accurately.

An Extended Two Step Approach to High-Resolution Airborne and Spaceborne SAR Full-Aperture Processing

The processing of synthetic aperture radar (SAR) echoes collected during radar antenna beam steering, such as in the staring spotlight, sliding spotlight, and TOPS operating modes, requires additional efforts due to the limited pulse repetition frequency (PRF). Subaperture processing is mostly used in these cases, but the complexity arising from subaperture dividing and recombination is preferably avoided. The two-step approach (TSA) is an elegant solution to full-aperture processing. Nevertheless, for high-resolution airborne and spaceborne SAR processing, the TSA is still faced with a number of difficulties, which does not occur, however, in subaperture processing. For instance, the high range bandwidth induces Doppler spectrum aliasing during the spectral analysis (SPECAN) stage of the original TSA. Moreover, the Doppler spectrum obtained in TSA, when inverse Fourier transformed back to the slow time domain, might also suffer from aliasing, which precludes the estimation and correction of the unknown residual motion error or tropospheric disturbance. In this article, we extend the TSA to address these problems and present a full-aperture processing framework to precisely focus the high-resolution airborne and spaceborne SAR data. Simulation of X-band spaceborne SAR echoes with transmission signal bandwidth of 3.6 GHz and coherent integration angle of 12.5° has validated the extended TSA (ETSA). Meanwhile, experimental X-band airborne SAR data with the same range and azimuth resolution are also processed using the ETSA, where the conventional autofocusing techniques have been smoothly incorporated.

Refractive enhancements for residual refractive error after cataract surgery.

Advances in cataract surgery have allowed surgeons to achieve superior refractive outcomes but have also led to higher patient expectations. Despite ever-evolving technology, residual refractive errors still occur. Postcataract refractive enhancements may be required to deliver satisfactory visual outcomes. This review aims to discuss the potential causes of residual refractive errors and the various enhancement modalities to correct them. A thorough preoperative workup to detect and address underlying pathologic causes of impaired vision should be performed prior to enhancement or corrective procedures. Corneal-based procedures are the safest and most accurate methods of correcting mild cases of residual refractive error. Hyperopic, high myopic, and high astigmatic errors are best managed with lens-based enhancements. Piggyback intraocular lenses (IOLs) are safer and more effective compared with IOL exchange. Toric IOL rotation and IOL exchange are ideally performed in the early postoperative period. A multitude of options exist for effective correction of residual refractive errors. The choice on how to best manage these patients depends on many factors such as the cause of refractive error, type of IOL used, ocular comorbidities, and patient preference.

Implantable collamer lens with a central hole for residual refractive error correction after corneal refractive surgery.

The present study aimed to assess the visual and refractive outcomes of an implantable collamer lens with a central hole (ICL V4c) for residual refractive error correction after corneal refractive surgery in individuals with myopia. A total of 16 eyes of eight consecutive patients with myopia undergoing ICL V4c implantation after corneal refractive surgery were investigated. The uncorrected visual acuity (VA) and best-corrected VA were examined prior to surgery and at 1, 3 and 6 months after surgery. The post-operative values of the modulation transfer function (MTF) cutoff frequency, Strehl ratio (SR), objective scattering index (OSI) and Optical Quality Analysis System (OQAS) values (OVs) were quantitatively assessed using an OQAS. At 6 months after surgery, the mean uncorrected LogMAR VA was 0.06±0.10 and the values had improved in 100% of the eyes. The mean MTF cutoff frequency, SR, OSI, OV 100%, OV 20% and OV 9%, were 31.294±4.321 cycles/degree, 0.187±0.039, 1.399±0.274, 1.066±0.261, 0.748±0.287 and 0.509±0.229, respectively. In conclusion, ICL V4c implantation for the correction of residual refractive error after corneal refractive surgery appeared feasible and safe and also had an excellent optical performance. However, long-term changes in visual quality require further investigation.

This Issue of Acta

This Issue of Acta

Enhancement-procedure outcomes in patients implanted with the Precisight multicomponent intraocular lens.

PurposeEyes that have undergone phacoemulsification with implantation of a multicomponent intraocular lens (MCIOL) may further undergo an enhancement procedure for correction of residual refractive errors. The enhancement procedure is accomplished by exchanging the front lens used in the primary surgery with another lens containing the correct dioptric power. We evaluated the efficacy and safety of enhancement procedures among eyes that received an MCIOL.MethodsA total of 25 eyes that had undergone phacoemulsification with implantation of an MCIOL were found to have a residual error of refraction (spherical equivalent ≥0.75 D) 3 months after primary cataract surgery, and underwent further enhancement surgery. The main study outcomes were uncorrected and corrected distance visual acuity, subjective refraction, anterior-chamber depth, pachymetry, and endothelial cell count.ResultsThere was a statistically significant improvement in uncorrected distance visual acuity of approximately two lines after enhancement surgery (0.20±0.20–0.02±0.08 logMAR, P<0.001) and a significant decrease in residual spherical equivalent from 1.3±1.1 D to 0±0.38 D (P<0.001). There were no statistically significant changes in pre- and postenhancement corrected distance visual acuity, anterior-chamber depth, pachymetry, or keratometry. There was a statistically significant decrease (2.6%) in endothelial cell count (P<0.01), which could have been endothelial equilibration from the primary procedure. All enhancement surgeries were uneventful, and no major complications were observed.ConclusionThe MCIOL-enhancement procedure demonstrates statistical and clinical improvement in uncorrected distance visual acuity and correction of postoperative refractive errors. The Precisight IOL may be a useful choice for patients with high risk of having significant residual refractive errors after primary cataract surgery.

Implantable Collamer Lens ® for Management of Pseudophakic Ametropia in Eyes With a Spectrum of Previous Corneal Surgery

To assess the visual outcomes, predictability, and safety of the Implantable Collamer Lens (ICL) (STAAR Surgical, Inc., Monrovia, CA) for the management of residual pseudophakic refractive error. Forty-nine pseudophakic eyes of 40 patients in which myopic, hyperopic, or toric ICLs were implanted were retrospectively analyzed. Twenty-nine eyes had been implanted with a monofocal intraocular lens (IOL) and 20 eyes had a multifocal IOL. All IOLs were implanted in the capsular bag. Of the 49 eyes included, 6 had residual refractive error after phacoemulsification without corneal pathology or surgical alteration (virgin cornea group), 12 had LASIK or photorefractive keratectomy (PRK) (excimer laser group), 8 had radial keratotomy, 5 had intrastromal corneal ring segments (ICRS) implantation, 11 had penetrating keratoplasty, and 7 had deep anterior lamellar keratoplasty (DALK). Uncorrected and corrected (CDVA) distance visual acuity and manifest refraction were evaluated. The efficacy/safety indices were 0.92/1.10, 0.98/1.13, 1.04/1.11, 0.90/1.13, 0.79/1.17, and 0.71/1.23 for the virgin cornea, excimer laser, radial keratotomy, ICRS, penetrating keratoplasty, and DALK groups, respectively. No eye lost one or more lines of CDVA. The virgin cornea, excimer laser, and radial keratotomy groups showed better predictability and accuracy, with 96.2% spherical equivalent within ±1.00 diopters (D). The ICRS, penetrating keratoplasty, and DALK groups demonstrated approximately 50% spherical equivalent within ±1.00 D. There were no intraoperative or postoperative complications. Good refractive outcomes and a strong safety record support the use of the ICL for the correction of residual refractive error in pseudophakic eyes with previous corneal surgery. [J Refract Surg. 2018;34(10):654-663.].

Применение метода Femto-Lasik для коррекции остаточных рефракционных ошибок после хирургии катаракты

Применение метода Femto-Lasik для коррекции остаточных рефракционных ошибок после хирургии катаракты

Correction of patient motion in cone-beam CT using 3D–2D registration

Cone-beam CT (CBCT) is increasingly common in guidance of interventional procedures, but can be subject to artifacts arising from patient motion during fairly long (~5–60 s) scan times. We present a fiducial-free method to mitigate motion artifacts using 3D–2D image registration that simultaneously corrects residual errors in the intrinsic and extrinsic parameters of geometric calibration. The 3D–2D registration process registers each projection to a prior 3D image by maximizing gradient orientation using the covariance matrix adaptation-evolution strategy optimizer. The resulting rigid transforms are applied to the system projection matrices, and a 3D image is reconstructed via model-based iterative reconstruction. Phantom experiments were conducted using a Zeego robotic C-arm to image a head phantom undergoing 5–15 cm translations and 5–15° rotations. To further test the algorithm, clinical images were acquired with a CBCT head scanner in which long scan times were susceptible to significant patient motion. CBCT images were reconstructed using a penalized likelihood objective function. For phantom studies the structural similarity (SSIM) between motion-free and motion-corrected images was >0.995, with significant improvement (p < 0.001) compared to the SSIM values of uncorrected images. Additionally, motion-corrected images exhibited a point-spread function with full-width at half maximum comparable to that of the motion-free reference image. Qualitative comparison of the motion-corrupted and motion-corrected clinical images demonstrated a significant improvement in image quality after motion correction. This indicates that the 3D–2D registration method could provide a useful approach to motion artifact correction under assumptions of local rigidity, as in the head, pelvis, and extremities. The method is highly parallelizable, and the automatic correction of residual geometric calibration errors provides added benefit that could be valuable in routine use.

A review of results after implantation of a secondary intraocular lens to correct residual refractive error after cataract surgery.

PurposeThe purpose of this study was to provide clinical outcomes data related to secondary intraocular lens (IOL) implantation for the correction of residual refractive error after cataract surgery.Patients and methodsA chart review was conducted to identify all eyes implanted with the monofocal spherical or toric AddOn® secondary IOL. Data were collated from charts where uncomplicated initial cataract surgery was completed. Measures of interest included the original IOL implanted, the postoperative refractive error (before secondary IOL implantation) and the associated corrected and uncorrected visual acuities (VAs). Postoperative data of interest included the residual refractive error, the best-corrected visual acuity (BCVA) and uncorrected visual acuity (UCVA).ResultsRefractive and VA data from 1 week to 3 months post-surgery were available for 46 of 70 eyes implanted with a secondary IOL by one surgeon at one practice between 4/15 and 3/17. There was a statistically significant improvement in UCVA of about 2 lines after surgery (p<0.01), with no change in BCVA (p=0.94). No eyes lost a line of BCVA. There was a statistically significant reduction in the absolute magnitude of the residual spherical equivalent refractive error (p<0.01). In the 10 cases with a toric secondary IOL, there was a statistically significant reduction in refractive cylinder (p<0.01).ConclusionThe secondary IOL studied here appears to be a viable surgical option to correct residual refractive error after primary IOL implantation.

Improvements on Calibration and Image Reconstruction of SMOS for Salinity Retrievals in Coastal Regions

Estimating sea surface salinity by European Space Agency's soil moisture and ocean salinity (SMOS) mission in coastal regions is still a challenging task. The brightness temperature measured by the SMOS interferometric radiometer is biased at coastal areas by the presence of land–sea contamination and other variable sources of error, mainly human-induced radio frequency interferences (RFI). In this paper, we will discuss on the benefits for retrieving salinity maps in coastal regions of applying two correction techniques that enhance the quality of brightness temperatures: the correction of residual multiplicative errors at calibration level (for the mitigation of systematic biases close to landmasses) and the nodal sampling at imaging level (for the reduction of Gibbs-like contamination). The joint application of both techniques leads to significant improvements in salinity retrievals not only in open ocean, but also in strongly contaminated coastal regions. Comparisons of SMOS salinity observations with in situ measurements show that biases of salinity differences are lower and standard deviations are significantly reduced with respect to those obtained from the current SMOS brightness temperatures.

Management of Residual Refractive Error after Cataract Phacoemulsification. Part 1. Keratorefractive Approaches

The review presents an analysis of the literature data on the methods of surgical correction of residual refractive error after cataract phacoemulsification. Keratorefractive and intraocular approaches are considered in details. A comparison of the efficacy and safety of different groups of methods on the example of comparative studies is given. Historically earlier keratorefractive methods (laser vision correction with LASIK and PRK techniques on intact eyes, LASIK after implantation of multifocal IOLs and arcuate keratotomy after phaco) are indicated for the correction of astigmatic refractive error and a small spherical refractive error. Intraocular methods, including the replacement of the IOL and “piggyback” IOLs implantation are used to correct a large spherical refractive error. The introduction of new technology, the implantation of light-adjustable IOLs, will expand the existing evidence and provide greater predictability and efficiency of the method of correction of residual refractive error.

Clinical Outcomes of an Optimized Prolate Ablation Procedure for Correcting Residual Refractive Errors Following Laser Surgery.

PurposeThe purpose of this study was to investigate the clinical efficacy of an optimized prolate ablation procedure for correcting residual refractive errors following laser surgery.MethodsWe analyzed 24 eyes of 15 patients who underwent an optimized prolate ablation procedure for the correction of residual refractive errors following laser in situ keratomileusis, laser-assisted subepithelial keratectomy, or photorefractive keratectomy surgeries. Preoperative ophthalmic examinations were performed, and uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction values (sphere, cylinder, and spherical equivalent), point spread function, modulation transfer function, corneal asphericity (Q value), ocular aberrations, and corneal haze measurements were obtained postoperatively at 1, 3, and 6 months.ResultsUncorrected distance visual acuity improved and refractive errors decreased significantly at 1, 3, and 6 months postoperatively. Total coma aberration increased at 3 and 6 months postoperatively, while changes in all other aberrations were not statistically significant. Similarly, no significant changes in point spread function were detected, but modulation transfer function increased significantly at the postoperative time points measured.ConclusionsThe optimized prolate ablation procedure was effective in terms of improving visual acuity and objective visual performance for the correction of persistent refractive errors following laser surgery.

Prevention and correction of residual refractive errors after cataract surgery

Cataract surgery today has become more of a refractive surgery with high patient expectations and demand for independence from glasses. With advances in biometry, precise intraocular lens (IOL) power calculation is the most important step in achieving desired target refraction. Noncontact optical biometry has become the gold standard worldwide with a few exceptions where contact ultrasound biometry still needs to be performed. Although there is no single formula for IOL power calculation suitable for all eyes, our understanding of which formulae to use in specific situations is much better. Despite advances in biometry and cataract surgery techniques, unsatisfactory visual and refractive outcomes occur occasionally. Enhancement after cataract surgery is required in these cases. The common methods to treat such cases are corneal-based laser refractive surgery or lens-based procedures such as piggyback IOL and lens exchange.