Axial Error Research Articles

Placement accuracy of the second electrode in bilateral deep brain stimulation surgery

Purpose Due to brain shift during bilateral deep brain stimulation (DBS) surgery, placement of the second electrode may be subjected to more error than that of the first electrode. The authors aimed to investigate the accuracy of second electrode placement in this setting. Materials and methods Fifty-five patients with Parkinson’s disease who underwent bilateral DBS surgery (110 electrodes) were retrospectively evaluated. The targets were subthalamic nucleus (STN) and globus pallidus interna (GPi) in 40 and 15 cases, respectively. Preoperative planning and postoperative electrode images were co-registered to compare the error margin between the two sides. Results There is a statistically significant difference in the directional axis error along the y axis only when comparing each laterality (posterior 0.04 ± 1.21 mm vs anterior 0.41 ± 1.07 mm, p = 0.006). There is no significant difference of other error parameters, final track location, and number of microelectrode recording passes between the two sides. In a subgroup analysis, there is a significant difference in directional axis error along the y axis only in the STN subgroup (posterior 0.40 ± 1.05 mm vs anterior 0.18 ± 1.04 mm, p = 0.003). Conclusion Although a statistically significant difference in directional axis error along the y axis was found between first and second electrode placements in the STN group but not in the GPi group, its magnitude is well below the clinically significant threshold.

New correlations between ocular parameters and disease severity in Spanish patients with Gaucher's disease Type I.

BackgroundGaucher’s disease is associated with a high variety of structural and functional abnormalities in the eye, which do not always affect visual acuity. The purpose of this study was to analyse ocular features in Spanish patients with Gaucher’s disease type I, and to investigate their possible correlation with phenotypic and burden parameters of this entity.MethodsThis cross-sectional observational study compared parameters belonging to 18 eyes from 9 Spanish patients with Gaucher’s disease Type I with 80 eyes from 40 healthy controls. Complete ophthalmological examination included choroidal and retinal thickness maps with swept source optical coherence tomography. Systemic analysis included genotype, plasmatic biomarkers, [ferritin, chemokine ligand 18 (CCL18) and chitotriosidase (ChT)] and severity scoring systems results [“Gaucher Disease Severity Score Index Type I" (GauSSI-I) and “Gaucher disease severity scoring system” (GD-DS3)].ResultsNine subjects (18 eyes) were cases (female: 55.5%, mean age 45 years; male: 44.5%, mean age 36 years) and 40 subjects (80 eyes) were controls (female: 49%, mean age 50 years; male: 51%, mean age 55 years). There were no statistically significant differences when comparing ocular parameters (visual acuity; axial length, refractive errors, corneal parameters, lens, retinal and choroidal thickness) between case and control subjects (p>0.05). A statistically significant moderate correlation was observed between lower retinal thickness and choroidal quadrants thickness and greater disease severity scores. A lower central retinal thickness also correlates with higher biological plasmatic levels, and has a statistically significant association with the most affected patient with genotype N370S/Del 55pb. Conversely, higher pachymetry involves a more severe plasmatic concentration of biomarkers.ConclusionsOur results suggest that pachymetry, and retinal and choroidal thickness, are associated with burden biomarkers and disease severity index scores in Spanish patients with Gaucher’s disease Type I.

Flatness on-machine measurement system of chemical mechanical polishing process for large-caliber tin plates

In planar optics machining, surface flatness is a critical requirement for making high-quality optical devices. Chemical mechanical polishing (CMP) is an important process of smoothing surfaces for hard and brittle planar optics. Thus, there are growing interests in developing high-precision flatness on-machine measurement system for tin plate CMP process. However, the traditional evaluation measurement cannot meet the measurement accuracy requirement of approximate 2 μm. In this study, we propose an effective on-machine measuring system for the large-caliber optical tin plate, which consists of linear guideway, rotary table, and measuring sensor. In the system, the straightness error of the guideway and the axial runout error of the rotary table are compensated using a spiral method and the Keyence LK-G5000 measuring sensor. First, the spiral measuring path is formed by the movement of the line guideway and rotary table, which can prevent from multiple calibration. Then, the 3D flatness error of the dressing process is measured by linear movement of the LK-G5000 and the rotation of the tin plate. After the primary measurement process, the obtained 3D flatness error is compensated for straightness and axial runout error in sequence. To verify the accuracy of the flatness measurement, the tin plate is dressed by the natural diamond tool according to the measured 3D flatness error. After the dressing process, the peak-valley value of the remeasured flatness error can achieve 2.12 μm through a single-step dressing. The experimental results provide the accuracy and reliability of the high-precision on-machine flatness measurement system for the large-caliber tin plate.

Influences of tracking and installation errors on the optical performance of a parabolic trough collector with heat pipe evacuated tube

In this study, the parabolic trough collector with heat pipe evacuated tube is used as the research object. Using the ray tracing method, this study analyzes the effect of tracking error of azimuth-elevation axis and receiver installation error on the optical performance of the collector. A test bench for the azimuth-elevation axis manual tracking device of the parabolic trough concentrator was designed and built, and the heat flux distribution at the focal plane was measured. The optical simulation results were compared with the test results to verify their accuracy, and the maximum relative error was 2.69%. The simulation results were compared with those calculated in the literature, and the maximum error was 16.23%. Simulation results show that the circumferential heat flux of the receiver is still symmetrically distributed when longitudinal incidence angles and vertical installation errors were found. The symmetry disappeared when transverse incidence angles and horizontal installation errors were found. As the tracking error of the elevation axis increases, the optical efficiency of the collector decreases, and the length of the end loss increases. For the collector in this study, the azimuth axis tracking error is less than 1.5° and the elevation axis tracking error is less than 6°, which can ensure high optical efficiency. The vertical installation error of the receiver was |Δz| <17 mm, the horizontal installation error was |Δx| < 20 mm, and the optical efficiency of the collector remained unchanged. The calculation method and results in this study can provide theoretical support for selecting an automatic tracking system with reasonable tracking accuracy and determining the allowable installation errors for the parabolic trough collector with heat pipe evacuated tube, and can also provide detailed thermal boundary conditions for the subsequent research of heat transfer performance of the receiver, which has great theoretical value.

RNA-Seq Analysis Reveals an Essential Role of the Tyrosine Metabolic Pathway and Inflammation in Myopia-Induced Retinal Degeneration in Guinea Pigs.

Background: Myopia is the second leading cause of visual impairment globally. Myopia can induce sight-threatening retinal degeneration and the underlying mechanism remains poorly defined. We generated a model of myopia-induced early-stage retinal degeneration in guinea pigs and investigated the mechanism of action. Methods: The form-deprivation-induced myopia (FDM) was induced in the right eyes of 2~3-week-old guinea pigs using a translucent balloon for 15 weeks. The left eye remained untreated and served as a self-control. Another group of untreated age-matched animals was used as naïve controls. The refractive error and ocular biometrics were measured at 3, 7, 9, 12 and 15 weeks post-FDM induction. Visual function was evaluated by electroretinography. Retinal neurons and synaptic structures were examined by confocal microscopy of immunolabelled retinal sections. The total RNAs were extracted from the retinas and processed for RNA sequencing analysis. Results: The FDM eyes presented a progressive axial length elongation and refractive error development. After 15 weeks of intervention, the average refractive power was −3.40 ± 1.85 D in the FDM eyes, +2.94 ± 0.59 D and +2.69 ± 0.56 D in the self-control and naïve control eyes, respectively. The a-wave amplitude was significantly lower in FDM eyes and these eyes had a significantly lower number of rods, secretagogin+ bipolar cells, and GABAergic amacrine cells in selected retinal areas. RNA-seq analysis showed that 288 genes were upregulated and 119 genes were downregulated in FDM retinas compared to naïve control retinas. In addition, 152 genes were upregulated and 12 were downregulated in FDM retinas compared to self-control retinas. The KEGG enrichment analysis showed that tyrosine metabolism, ABC transporters and inflammatory pathways were upregulated, whereas tight junction, lipid and glycosaminoglycan biosynthesis were downregulated in FDM eyes. Conclusions: The long-term (15-week) FDM in the guinea pig models induced an early-stage retinal degeneration. The dysregulation of the tyrosine metabolism and inflammatory pathways may contribute to the pathogenesis of myopia-induced retinal degeneration.

Research on control technology of tip-tilt mirror system in adaptive optics

In order to solve the control problem of the tip-tilt mirror under the unknown disturbance, a nonlinear disturbance observer with adaptive ability based on the sliding mode control is designed.Firstly, the sliding mode control method of the tip-tilt mirror system is established with Lyapunov functions. Secondly, an adaptive nonlinear disturbance observer is developed on a basis of observer model. Finally, the proposed sliding mode control method is combined with a nonlinear observer with adaptive capability to achieve the goal of improving the control accuracy of the system, while also reducing the chattering caused by the system. The experiment proves that this method is achievable. The experimental results show that the tracking error of the azimuth axis is reduced from 1.637μrad to 1.083μrad, and the accuracy is improved by about 51.2%. The tracking error of the pitch axis is reduced from 1.966μrad to 1.614μrad, and the accuracy is improved by about 21.8%. This method can greatly weaken the inherent chattering and external disturbance of the system, and improve the stability of the tip-tilt mirror system.

Study on improved droop control strategy of MMC-MTDC system based on novel sliding mode control

In view of the strong coupling, nonlinearity and uncertainty of HVDC system, and the poor consistency when the MMC control policy adopts the traditional PI double closed-loop control, an improved droop control policy with the novel sliding pattern controlling is given herein. The controller brings to the dual closed loop control structure, the internal loop takes current error in the dq axis as the sliding mode surface. A sliding mode controller with the novel exponential approach law is designed, which improves the convergence speed of the traditional exponential approach law and eliminates the chattering phenomena. Then the consistency of the system is identified by Lyapunov method. The outer-loop adopts a modified sag control policy. After comparing with the voltage reference value, the droop factor is proposed. Finally, an emulation model including MMC-MTDC with four terminal is constructed on the PSCAD/EMTDC, which is emulated and validated under stable and transient conditions. The consequences reveal that the given control policy not only has a good convergence effect, but also improves the kinematic respond speed. It can also reduce the direct current voltage deviation, and enhances the stability and reliability of the system.

Simultaneous calibration of probe parameters and location errors of rotary axes on multi-axis CNC machines by using a sphere

On-machine measurement (OMM) systems with touch-triggered probes are efficacious in productivity improvement. Machine motion errors impose major limitations on their accuracy for any OMM systems, especially when rotary axes motions are involved. This research proposes a precise measurement method to address this problem by simultaneously identifying the probe parameters and the location errors of rotary axes, using a touch-triggered probe to sample a sphere. This method is suitable for both periodic machine checks and OMM system recalibrations. The method formulates a mathematical model based on machine kinematics to represent errors between the theoretical probed data and the actual recorded data, minimizing which can solve for necessary parameters. Two proposed probing patterns simplify the solution to the model. Experiment results demonstrate that the method is effective and accurate. Monte Carlo simulations were carried out to prove the robustness of the method.

Accuracy improvement for RLLLR five-axis machine tools: A posture and position compensation method for geometric errors

Compensating geometric errors on machine tools requires further improvement for the purpose of high accuracy, because most current methods only focus on positions of cutting points, while ignoring vector errors of the rotary axes' postures; and they usually use the calculated compensation values to directly modify NC commands or axial movements, without considering the errors that the compensated movements themselves would create. This paper proposes a novel compensation method that includes both position and posture errors of the tool center point of a RLLLR five-axis machine tool. First, the position and posture errors are modeled through the multi-body system kinematics of the five-axis machine. Second, both kinds of errors are compensated in an off-line way that compares the coordinates and angles point by point through iterations, thus the extra errors that compensated results generate can be eliminated. The iteration process is terminated under control of the allowable error range. Posture errors are first compensated through correcting the angles of the rotary axes, and then position errors are corrected by modifying TCP's coordinates. Third, a program that incorporates the error molding and the compensation algorithms are developed. It can automatically complete the process of calculating error matrices, identifying parameters and outputting commands. Finally, the comparison experiments were conducted on the linear axes' linear and arc movements, as well as the rotary axes' rotating movements, and the results validated that the proposed method could effectively improve geometric accuracy.

Measurement of cemented carbide-PCD microdrill geometry error based on computer vision algorithm

Microdrill machining is in high demand and is widely applied in various industries where the structural design and material properties of the microdrill are critical components in machining. A composite microdrill composed of cemented carbide and polycrystalline diamond balances the wear resistance, toughness, and hardness properties of the cutting tool. Nevertheless, the tool geometry error must be examined because of complex technique involved in the tool fabrication process. The investigated microdrill is fabricated through a brazing technique that connects the shank and drill body of different material compositions. A computer vision algorithm was developed specifically for measuring the axial straightness error and radial runout of the microdrill. Accordingly, the ability of the developed measurement techniques to perform precise and accurate tool geometry error measurements is evaluated in this study.

Association of Myopia With Microvascular Alterations in Patients With Type 2 Diabetes: An Optical Coherence Tomography Angiography Study.

Purpose: To determine the association of myopia with peripapillary and macular microvasculature in eyes with type 2 diabetes using optical coherence tomography angiography (OCTA).Methods: Diabetic patients with and without diabetic retinopathy (DR) were recruited and grouped according to myopic status in this cross-sectional study. Axial length, refractive error, and OCTA parameters were measured. OCTA parameters were analyzed with adjustment of confounding factors and further Bonferroni analysis was performed to determine the differences in multiple group comparisons.Results: Compared with the diabetic eyes without myopia, those with myopia had lower rate of DR (21.82 vs. 35.90%, χ2 = 6.190, P = 0.013), longer axial lengths (24.94 ± 0.75 vs. 23.16 ± 0.64, F = 311.055, P < 0.001) and reduced whole vessel density (VD) of optic nerve head (ONH) (45.89 ± 5.76 vs. 49.14 ± 4.33, F = 19.052, P < 0.001), peripapillary VD (48.75 ± 6.56 vs. 50.76 ± 4.51, F = 7.600, P = 0.006), and reduced thickness of the retinal nerve fiber layer (RNFL) (95.50 ± 12.35 vs. 100.67 ± 13.68, F = 5.020, P = 0.026). In eyes without myopia, the superficial vessel density (SVD) (46.58 ± 4.90 vs. 43.01 ± 4.25; 95% CI, 1.80–4.61; P < 0.001), deep vessel density (DVD) (45.64 ± 6.34 vs. 42.15 ± 6.31; 95% CI, 1.07–5.00; P < 0.001), and FD300 area density (50.31 ± 5.74 vs. 44.95 ± 6.96; 95% CI, 2.88–7.27; P < 0.001) were significant reduced in eyes with DR(DR eyes) comparing to those without DR (NoDR eyes). In eyes with myopia, only SVD were significantly reduced in DR eyes comparing to NoDR eyes (41.68 ± 3.34 vs. 45.99 ± 4.17; 95% CI, 1.10–7.22; P = 0.002). In NoDR eyes, both whole VD of ONH and Peripapillary VD demonstrated a significant decrease in eyes with myopia comparing to those without myopia (49.91 ± 4.36 vs. 45.61 ± 6.32; 95% CI, 1.95–6.27; P < 0.001 and 51.36 ± 4.24 vs. 48.52 ± 6.99; 95% CI, 0.56–5.11; P = 0.006, respectively).Conclusions: In diabetic patients, myopic eyes exhibited lower prevalence of DR and thinner thickness of RNFL. The refractive status could possibly impact the retinal microvascular changes from NoDR to DR stage.

Bricklaying Robot Lifting and Levelling System

The article presents the concept of building and controlling a Bricklaying Robotic System (BRS). The research presents the design process and how to control a four-cylinder electro-hydraulic servo drive system. The article presents a mathematical model and optimizes the process of aligning the mobile support platform of the masonry robot. The lifting mechanism was presented and its kinematic analysis performed. The mathematical model of the hydraulic system was described. The control system, designed for the masonry robot lifting platform, includes position errors for a single drive axis and synchronization errors between the axes.

Parallel Calculation Method of Patch Area Landscape Art Index Based on Surface Coverage Data

Aiming at the problem of slow convergence in the parallel calculation of patch area landscape art index, a parallel calculation method of patch area landscape art index based on land cover data was proposed. Firstly, patch type area index, patch connectivity index, patch number index, and fragmentation index were selected as patch area landscape art spatial staggered pattern indexes to conduct characteristic analysis and establish a 3D visual reconstruction model with actual colors. Then, the coordinate points of the landscape space staggered pattern are transformed into three-dimensional visual coordinate points to realize the reconstruction of landscape art space staggered pattern in patch area. The aerial landscape image of patch area is preprocessed and input into GPU to build a Gaussian difference pyramid model. The feature points of the patch area in the aerial landscape image are calculated by the parallel computing process, and the patch boundary in the aerial landscape image is determined. The landscape perimeter of the patch area was calculated according to the boundary. The experimental results show that the complete convergence time of the horizontal axis error and the vertical axis error is 2.13 s and 1.81 s, respectively, and the absolute error and relative error of the perimeter measurement are controlled below 0.60 m and 1.00%, respectively.

A novel error equivalence model on the kinematic error of the linear axis of high-end machine tool

The kinematic errors of the linear axis play a key role in machining precision of high-end CNC (computer numerical control) machine tool. The quantification of error relationship is still an urgent problem to be solved in the assembly process of the linear axis, especially considering the effect of the elastic deformation of rollers. In order to obtain the kinematic errors of the linear axis of machine tool, a systematic error equivalence model of slider is proposed. The linear axis contains the base, the linear guide rail, and carriage. Firstly, the geometric errors of assembly surface of linear guide rail are represented by small displacement torsor. Then, according to the theory of different motion of robots, the error equivalence model of a single slider is established, namely the geometric errors of assembly surface of linear guide rail and the pose error of slider are equivalent to the elastic deformation of roller. Based on the principle of vector summation, the kinematic error of a single slider is mapped to the carriage, and the kinematic error of the linear axis is obtained. At the same time, experiments validation of kinematic error model of the linear axis is carried out. It is indicated that the proposed model is accurate and feasible. The analysis of key design parameters shows that the proposed model can provide an accurate guidance for the manufacturing and operation performance of the linear axis in quantification, and a more effective reference for the engineers at the design and assembly stage.

Swept-source OCT reduces the risk of axial length measurement errors in eyes with cataract and epiretinal membranes.

AimsTo compare the biometric data from partial coherence interferometry (PCI) and swept-source OCT (SS-OCT) in patients with age-related cataract and epiretinal membrane (ERM): ERM, ERM with foveoschisis and macular pseudohole.Methods49 eyes of 49 subjects including 36 ERM, 9 ERM foveoschisis and 4 macular pseudohole were analysed to evaluate the axial length (AL) measurements and the presence of AL measurement errors, defined basing on the shape of the biometric output graphs and on the concordance of AL values between instruments. Eyes with ERM were divided in four stages according to OCT features (i.e. presence/absence of the foveal pit, presence of ectopic inner foveal layers, disrupted retinal layers).ResultsThe devices provided similar mean AL measurements in all subgroups, with differences <0.1 mm in 41/49 cases (83.6%). AL measurement errors were observed in ERM stages 3 and 4, characterized by ectopic inner foveal layers, and were significantly more frequent with the PCI (8/17, 47%) as compared with the SS-OCT device (2/17, 12%), p = 0.02. The refractive prediction error in cases with AL measurement errors was significantly greater using the PCI compared to the SS-OCT device (p<0.05).ConclusionBoth devices provide reliable biometric data in the majority of patients and can be used in the preoperative assessment of patients with age-related cataract and ERM. In eyes with ectopic inner foveal layers, attention should be paid as AL measurement and refractive prediction errors may occur, more frequently with the PCI device.

Dynamic reliability of thermally deduced positioning precision of ball screw systems based on random moving difference method

The positioning precision of a half-closed-loop feed system of machine tools is usually affected by the frictional heat of the system. The axial thermal errors of the working table exceeding the axial allowed tolerance is a type of failure mode of the ball screw system in positioning precision. At present, thermal error prediction and compensation methods have poor accuracy retention because they do not consider the randomness of the parameters. In order to solve the problem, we present a new random moving difference method of studying a tree-like heat transfer with thermally excited moving branches. Furthermore, based on the random moving difference method, a dynamic reliability prediction model (DRPM) of thermally deduced positioning precision is proposed, which was used in the study for predicting the dynamic variation performance of the heat boundaries in the ball screw feed drive system and the dynamic reliability of positioning precision of the system. Finally, the prediction performance of the presented method is verified under a CNC lathe. Our method provides the theoretical and practical foundation for a real-time monitoring positioning precision reliability index while describing the positioning precision accurately because it effectively takes into account the random parameters.

Contour error modeling and compensation of CNC machining based on deep learning and reinforcement learning

Contour error compensation of the computer numerical control (CNC) machine tool is a vital technology that can improve machining accuracy and quality. To achieve this goal, the tracking error of a feeding axis, which is a dominant issue incurring the contour error, should be firstly modeled and then a proper compensation strategy should be determined. However, building the precise tracking error prediction model is a challenging task because of the nonlinear issues like backlash and friction involved in the feeding axis; besides, the optimal compensation parameter is also difficult to determine because it is sensitive to the machining tool path. In this paper, a set of novel approaches for contour error prediction and compensation is presented based on the technologies of deep learning and reinforcement learning. By utilizing the internal data of the CNC system, the tracking error of the feeding axis is modeled as a Nonlinear Auto-Regressive Long-Short-Term Memory (NAR-LSTM) network, considering all the nonlinear issues of the feeding axis. Given the contour error as calculated based on the predicted tracking error of each feeding axis, a compensation strategy is presented with its parameters identified efficiently by a Time-Series Deep Q-Network (TS-DQN) as designed in our work. To validate the feasibility and advantage of the proposed approaches, extensive experiments are conducted, testifying that our approaches can predict the tracking error and contour error with very good precision (better than about 99% and 90% respectively), and the contour error compensated based on the predicted results and our compensation strategy is significantly reduced (about 60~85% reduction) with the machining quality improved drastically (machining error reduced about 50%).

Evaluation of Kinematic and Compliance Calibration of Serial Articulated Industrial Manipulators

As long as industrial robots are programmed by teach programming, their positioning accuracy is unimportant. With a wider implementation of offline programming and new applications such as machining, ensuring a higher positioning accuracy of industrial robots over the entire working space has become very important. In this paper, we first review the measurement schemes of end effector poses. We then outline kinematic models of serial articulated industrial manipulators to quantify the positioning accuracy with a focus on the extension of the classical Denavit-Hartenberg (DH) models to include rotary axis error motions. Subsequently, we expand the discussion on kinematic models to compliant robot models. The review highlights compliance models that are applied to calculate the elastic deformation produced by forces, namely gravity and external loads. Model-based numerical compensation plays an important role in machine tool control. This paper aims to present state-of-the-art technical issues and future research directions for the implementation of model-based numerical compensation schemes for industrial robots.

A Novel Method for Approximating Object Location Error in Bounding Box Detection Algorithms Using a Monocular Camera

Many autonomous vehicles and advanced driver-assistance systems are equipped with front-facing cameras that detect and track objects using deep-learning-based algorithms. However, the localization capability of monocular cameras is often overlooked. In this paper, a novel method for estimating the pixel-wise error in a detected object's location versus its ground truth is proposed. As the object moves away from the camera, the pixel errors are shown to be normally distributed with unique spreads along the image's vertical axis (y-pixel). The pixel error appears to be smaller as objects get farther away, while at the same distance range, objects have similar error distribution across the camera's horizontal view. The horizontal axis (x-pixel) error appears to be smaller while the distance moves further away. However, the x-pixel location along a constant y-pixel row has no impact on the error distribution. The estimated x and y-pixel error distributions can in turn be used to form a spatial error distribution for finding the location of a detected object within a certain confidence interval. The spatial errors are then projected onto the world coordinate system using a camera transformation matrix to give a more realistic sense of what this error means. The results show that location estimation using monocular cameras generates an elliptical error distribution around the object with a larger error in the y-pixel direction compared to the x-pixel direction. This error distribution can be important to fuse information from multiple range-detecting sensors as well as multi-vehicle and multi-object tracking. The uncertainty characterization for position measurement, as demonstrated in this paper is an essential element of tracking and, is sensor and algorithm dependent.

Effect Of Trabeculectomy On Ocular Biometry And Refractive Errors In Pediatric Glaucoma

Background: Pediatric glaucoma triggers refractive errors by modifying the biometry of the eye. This study was conducted with the objective of estimating the short-term biometric and refractive changes prior to and post trabeculectomy in pediatric glaucoma. Material and Methods: A 12-month, descriptive, cross-sectional study was carried out from January to December 2019, using patients operated on for pediatric glaucoma. Pre- and post-operative biometric and refraction measurements were noted. Visual acuity, axial length, corneal diameter and refraction were obtained. All ethical requirements (anonymity, free, informed, and continuous consent) were satisfied. Data analysis was done using SPSS 20.0. Results: In the present study, 47 eyes of 27 patients were surgically operated upon, from January 2019 to December 2019 at CHU-IOTA. The predominant sex was male (17 patients) at 63%, giving a sex ratio (M / F) of 1.7. The mean age was 5.04 ± 4.24. Preoperatively, the mean corneal diameter, and D90 were respectively 13.83 ± 1.51 and 12.55 ± 0.99. Preoperatively, the mean axial length, and D90, were 23.87 ± 1.29 and 22.28 ± 1.07, respectively. Preoperatively and at three month, the mean myopia (n = 36), were respectively -3.13 ± 1.83 and -1.59 ± 0.97. The mean preoperative astigmatism (n = 47) and D90 were respectively, -1.59 ± 0.77 and -1.23 ± 0.57. A statistically significant relationship (p &lt;0.05) was found to exist between the preoperative and postoperative data of the axial length, corneal diameter, and refractive errors. Conclusions: Trabeculectomy significantly exerts a short-term positive impact on the biometrics and refraction by modifying the initial measurements and diopters.