Understanding post-operative refractive outcome in pediatrics after IOL implementation: factors and predictors.

BACKGROUND: In pediatric ophthalmology, calculating intra-ocular lens (IOL) power can be challenging. It is important to predict if the post-surgery refractive error (RE) will meet the intended refractive goal. In this study, we aimed to investigate the factors and predictors influencing RE outcomes in children undergoing IOL implantation. METHODS: This was a retrospective cross-sectional cohort study that involved 47 eyes with congenital cataracts underwent IOL implantation. Each patient underwent follow-up visits at two months and two years' post-surgery. The IOL power calculations were conducted using the Holladay 1 formula, and both the prediction error (PE) and absolute prediction error (APE) were calculated. RESULTS: The mean age was 6.52 ± 4.61 years, with an age range of 1-15 years. The mean IOL power was 20.31 ± 6.57 D, and the mean post-operative refraction was 1.31 ± 2.65 D. The mean of PE and APE were 0.67 ± 1.77 and 1.55 ± 1.06 D, respectively. Whereas PE was correlated to axial length with an R-value of - 0.29 (P = 0.04). The calculation method had a significant negative relationship with APE and PE, with coefficients of - 1.05 (P = 0.009) and - 1.81 (P = 0.009), respectively. CONCLUSION: High astigmatism was associated with greater errors in the refractive outcome. The calculation methods had the most considerable impact on the post-operative RE. The customization of surgical approaches to accommodate individual characteristics is crucial. Further research with diverse subgroups is needed to comprehensively understand the influence of each factor.

Macula Characteristics in Young Saudi Male Patients with Myopia: A Comparative Hospital-Based Study.

BACKGROUND: Myopia is associated with changes in the posterior segment of the eye, including the macula, which may contribute to potential blindness. Therefore, the study aims to evaluate the macula integrity in young myopic patients through optical coherence tomography (OCT). METHODS: A cross-sectional study was conducted at Qassim University optometry clinics from January to June 2024, involving 30 healthy young males with myopia and 30 with emmetropia. Clinical examination and OCT imaging were used to gather data on macular volume and thickness. The results were analyzed using descriptive statistics and correlation analysis. RESULTS: The study included 60 myopic eyes and 60 emmetropic eyes. The participants' mean age was 22.10 ± 1.65 years (p = 0.135). A significant difference was found between myopic and emmetropic eyes in fovea, parafovea, perifovea, and total macula thickness and volume (P < 0.05). Additionally, the study showed a significant positive correlation between the magnitude of myopia and fovea thickness (r = 0.297, p = 0.011) and negative correlations with perifovea thickness (r = -0.418, p < 0.001), total macula thickness (r = -0.353, p = 0.003), and total macula volume (r = -0.352, p = 0.003). However, parafoveal thickness had no significant correlation with the severity of myopia (r= -0.107; p=0.207). Fovea thickness was higher in high myopia (255.40 ± 23.51 µm) compared to low (238.69 ± 15.98 µm) and moderate (248.15 ± 8.70 µm) myopia. Perifovea thickness, macula thickness, and macula volume were significantly lower in high myopia (p ˃ 0.05). CONCLUSION: Myopia influences macular parameters compared to emmetropia. It increases fovea thickness and decreases total macula thickness and volume as well as perifovea thickness. High myopia has more alterations in macula parameters.

Childhood visual impairment causes and barriers to accessing eye care: A suggested approach for Africa.

BACKGROUND:  Childhood vision impairment (VI) has a significantly harmful effect on both health and social outcomes. AIM:  To assess the causes of childhood VI, to determine obstacles to accessing eye care services and to develop a strategy for the childhood eye care system in African nations. METHOD:  This systematic review was conducted by searching several online databases, including; Scopus, PubMed, ProQuest, Web of Science, Google Scholar, Ebsco and Medline. They focussed on articles available between 2003 and 2023. These studies were conducted to evaluate the causes of childhood VI and to assess obstacles to accessing eye care services in African countries. RESULTS:  The main causes of childhood VI in African nations can be avoided with timely diagnosis and an appropriate management strategy. The leading obstacles to accessing childhood eye care services were a lack of availability, accessibility and affordability. In addition to these barriers, we found that there are concerns with quality of services, primary health care system, geographic barriers, incorrect health beliefs, inappropriate parental perception, a lack of knowledge, attitudes and inadequate practices related to paediatric eye care. CONCLUSION:  The main causes of childhood VI were uncorrected refractive error (RE), amblyopia, cataract and corneal opacities that can be avoided with timely diagnosis and an appropriate management strategy. While the main obstacles to accessing childhood eye care services were a lack of availability, accessibility, affordability and healthcare system.Contribution: The recommended strategy for childhood eye-care services includes models for delivery and training.

Refractive error and abnormal stereopsis association with road traffic accidents in Saudi Arabian truck drivers.

PURPOSE: To investigate the visual functions of truck drivers of the Kingdom of Saudi Arabia (KSA) in the region of Qassim and Dammam and to see if is there any association between these visual functions and self-reported road traffic accidents (RTA). METHODS: It is a cross-sectional, descriptive study. LogMAR visual acuity, refractive error, color vision, stereopsis, and confrontation visual fields were measured in 300 truck drivers in the Qassim and Dammam regions of KSA. Driving-related history and incidence of RTA from the past 3 years, systemic history, and general eye compliance history were collected through a self-reporting questionnaire. RESULTS: Among 300 truck drivers examined, 54 (18.4%) subjects have a refractive error, 14 (4.7%) subjects have color vision deficiency, 37 (12.2%) subjects have abnormal stereo acuity, and none of them have confrontation visual field defect. RTA was reported in 25 (8.3%) subjects. The current study has found RTA is significantly associated with refractive error (P = 0.01) and abnormal stereopsis (P < 0.01). Systemic history revealed that 11% of the subjects had diabetes mellitus. CONCLUSION: The current study is the first to report on the visual functions of KSA truck drivers. Hence, the current study has found a significant association between visual functions and RTA among truck drivers, we recommend a comprehensive examination need to be part of issuing driver's licenses in KSA. More studies with larger samples from different regions of KSA are needed to extrapolate these findings.

Pyrimido[5,4-c]quinolines: Synthesis from 3,4-Di-functionallized Quinoline, Reactivity and Biological Activities.

Quinoline and pyrimidine moieties are ubiquitous components in both natural and synthetic compounds, showcasing diverse applications. The fusion of these well-known structures into hybrid molecules has garnered attention due to their intriguing biological properties. Particularly in the field of medicinal chemistry, numerous studies in the last decade have focused on pyrimido[5,4-c]quinoline ring systems (PyQs5,4-c). This review elucidates the synthesis of PyQs5,4-c and their derivatives using 3,4-difunctionalized quinoline as a key starting material. The preparation of PyQs5,4-c involves a series of chemical transformations, including the Friedländer, Ullmann and Biginelli reaction, Vilsmeier-Haack formylation, Suzuki coupling, and a one-pot three-component reaction. These synthetic routes not only offer access to diverse PyQs5,4-c derivatives.

Design of three-bit binary to gray converter based on metal-insulator-metal plasmonic waveguides.

Using the finite element method and COMSOL version 5.5, a three-bit binary to gray converter with three plasmonic substructures and five input and three output ports was designed. Using a 520n m×200n m metal-insulator-metal plasmonic structure, the plasmonic converter was developed. In this configuration, the transmission threshold (T t h r e s h o l d ) is set to 45% at an operating wavelength of 1310 nm. Utilizing the modulation depth, contrast ratio (CR), and insertion loss criteria, the effectiveness of the plasmonic converter is evaluated. For the first, second, and third output terminals, the CR has respective values of 40.1 dB, 9.3 dB, and 9.2 dB.

Realization of an optical nanostructure 4×1 multiplexer based on metal-insulator-metal plasmonic waveguides.

The optical multiplexer was created at a nanoscale plasmonic structure utilizing the finite element method (FEM) with COMSOL version 5.5 software to enable maximum light confinement, high-speed optical systems, and a tiny structure. The metal-insulator-metal technology at a nanoscale dimension is used for creating the 4×1 multiplexer. In this design, the transmission threshold (T t h r e s h o l d ) is selected to be 100% for separating between logic "1" and logic "0" at a 1310 nm operating wavelength. The modulation depth (MD), contrast ratio (CR), and insertion loss (IL) characteristics were explained to evaluate the performance of the multiplexer. The CR has 3.48 dB, the MD offers an ideal performance with 95.28 %, and the IL has 3.31 dB.

Cooling of a PVT System Using an Underground Heat Exchanger: An Experimental Study.

In the recent decades, the researchers have been focused on the use of photovoltaic thermal (PVT) systems that provide the best performance and cooling for the photovoltaic panels. In this study, a PVT system consisting of a monocrystalline PV panel and a spiral heat exchanger was connected to an underground heat exchanger that is buried at a depth of 4 m below the surface of the earth. The procedure of the current study can be considered the first of its kind in the Middle East and North Africa region (based on the researchers' knowledge). The study was carried out on agricultural land in Baghdad-Iraq during months of July and August-2022, which are considered the harshest weather conditions for this city. The heat exchanger consists of a copper tube with a length of 21 m and formed in the shape of 3U, and it was buried in the earth and connected with a PVT system. The results of the study showed that the site chosen to bury the heat exchanger (4 m deep) has a stable soil temperature at 22.5 °C. From various volumetric flow rates, a flow rate of 0.18 l/s was selected which is considered the highest flow rate that can show vibration in the PVT system which may harm the system. The practical measurements showed that the largest difference in the surface temperatures of standalone PV and PVT was around 20 °C in favor of the latter. The electrical efficiency of the studied PVT system also increased to outperform the standalone PV system by 127.3%. By comparing the results of the current study with studies of water-cooled PVT systems from the literature, it is clear that the proposed system is feasible and has an acceptable efficiency in such harsh weather conditions tested during the experiment.

Unequal channel spacing 8×5 Gbps optical system utilizing different signal representations.

Data representations are important to communication networks; they convert the data bits into a signal form, which affects the system capacity, maximum bit rate, transmission distance, and different linear and nonlinear impairments. In this paper, we propose non-return-to-zero (NRZ), chirped NRZ, duobinary, and duobinary return-to-zero (DRZ) data representations with eight dense wavelength division multiplexing channels for transmitting a 5 Gbps data rate through a 250 km fiber length. The results of the simulation design are calculated at different equal and unequal channel spacings, and the quality factor is measured over a wide range of optical power. For equal channel spacing, the DRZ has a preferable performance with a 28.40 quality factor at 18 dBm threshold power, and the chirped NRZ has a preferable performance with a 26.06 quality factor at 12 dBm threshold power. For unequal channel spacing, the DRZ has a 25.76 quality factor at 17 dBm threshold power, and the NRZ has a 25.06 quality factor at 10 dBm threshold power.

5 × 5 Gbps DWDM optical system with DCF and cascaded repeaters techniques.

Dispersion and attenuation problems are the most important factors that limit dense wavelength division multiplexing (DWDM) system performance. Dispersion causes pulse broadening of the optical spectrum, and the attenuation degrades the optical signal. In this paper, dispersion compensation fiber (DCF) and cascaded repeaters techniques have been proposed to reduce linear and nonlinear problems by using two different modulation formats (carrier-suppressed return zero [CSRZ] and optical modulator) and two various channel spacings (100 and 50 GHz). The cascaded repeater offers the best performance at 100 GHz channel spacing with 37 quality factors for CSRZ and optical modulation schemes; however, the DCF network design is more compatible with the CSRZ modulation format with 27 quality factors. For 50 GHz channel spacing, the cascaded repeater offers the best performance with 31 quality factors for CSRZ and optical modulator techniques; the DCF technique comes in next with 27 quality factors for CSRZ and 19 for optical modulators.

Multiple-input hybrid plasmonic OR logic gate with a nanostructure.

A multiple-input hybrid plasmonic OR logic gate has been constructed, analyzed, and simulated utilizing the finite element method by using the COMSOL software package version 5.5. To realize the suggested three- and four-input hybrid plasmonic OR gate, constructive and destructive interference has been standard among the input ports and control port. The factors used to evaluate the functionality of the nanoscale gate are the contrast ratio, modulation depth (MD), and insertion losses (ILs). In contrast, the optical power ratio at the output port, known as the transmission value (T value), has been measured and used to distinguish between logic 1 (ON-state) and logic 0 (OFF-state). The transmission threshold value in this article was 25%, and the wavelength range considered to display the result was from 1000 to 2000 nm. The three-input hybrid OR gate occupied a size of 500n m×400n m with transmission amplification results from the best T value of 216.5 % with 98.85% as a MD. In comparison, the four-input OR gate comes with a size of 600n m×400n m at the best T value of 301.5%, supported by a 99.33% as the MD. The IL values for the three-input and four-input designs are -4.07 and -5.4d B, respectively. The system resonance wavelength is 1310 nm.

Structure of 4 × 2 optical encoder based on hybrid plasmonic waveguides.

The optical 4×2 encoder is organized with a structure of dimensions 920n m×400n m, a resonance wavelength of 1310 nm, and a transmission threshold value of 30%. Based on the finite element method with the COMSOL software package, the proposed hybrid plasmonic encoder has been suggested, analyzed, and simulated, standing on the fundamentals of the constructive and destructive interferences between the light waves. The results were delivered in graphs containing the transmission values versus a wavelength range from 800 to 2000 nm, magnetic field distribution, contrast ratio, modulation depth, and insertion losses. The maximum transmission value reached was 68.4%; the modulation depth was 92.34%; and the contrast ratio was 11.1 dB.

Parents' Awareness of and Perspectives on Childhood Refractive Error and Spectacle Wear in Saudi Arabia.

Objectives: This study aimed to assess parents' awareness of and perspectives on childhood refractive errors in Saudi Arabia. Methods: This cross-sectional study was conducted between October and November 2020 in public schools across different regions of Saudi Arabia. Data were collected using an online questionnaire that assessed parents' knowledge and perceptions of childhood refractive errors and spectacle wear. Results: A total of 358 parents from different regions of Saudi Arabia completed the questionnaire and were obtained in this study (response rate: 85%). Approximately one third (38.3%) of the parents reported that they had never heard of refractive errors and one-third (33.8%) mentioned that uncorrected refractive errors did not lead to visual impairment. The majority (74.0%) cited using eyeglasses as an effective way to manage childhood refractive errors. Two-thirds (63.7%) stated that they did not receive any information about paediatric eye care. Better knowledge was associated with a higher educational level, female gender and older age (P <0.001, P = 0.008 and P = 0.024, respectively). Regarding parents' perspective on spectacle wear, 13.7% felt that using eyeglasses affected their children's chances of learning. However, 82.7% supposed that eyeglasses did not affect their children's employment opportunities. Almost a quarter of the sample (22.1%) thought that using eyeglasses would decrease the eye's power, resulting in childhood visual impairment. Conclusion: The level of awareness and perceptions regarding childhood refractive errors and spectacle wear was low among parents. Therefore, a policy is needed to improve the awareness and perception of the key stakeholders in this issue, including parents and teachers.

All-optical design for multiplexer and comparator utilizing hybrid plasmonic waveguides.

Two optical combinational logic circuits, namely a 2×1 multiplexer and a comparator utilized by hybrid plasmonic waveguides, have been designed, analyzed, and simulated standing on the finite element method (FEM) with a COMSOL software package version 5.5. Transmission at the output port versus a wavelength range from 800 to 2000 nm, the contrast ratio, the modulation depth, and the insertion loss are the aspects used to estimate the circuits' functionality. The realization of these circuits was based on the fundamentals of the constructive and destructive interferences among the input and the biasing ports. The multiplexer circuits require a single substructure with a measurement of 400×400nm and delivers the best transmission of 202.3% and 99.75% as a modulation depth, while the comparator performed by three substructures with a 1300×400nm overall size offers a 202.6% as the best transmission and 99.99% modulation depth in the Equality situation. The operating wavelength and the magnitude of the transmission threshold are 1310 nm and 0.3, respectively.

Antibiotic resistance genes in the gut microbiota of mothers and linked neonates with or without sepsis from low- and middle-income countries.

Early development of the microbiome has been shown to affect general health and physical development of the infant and, although some studies have been undertaken in high-income countries, there are few studies from low- and middle-income countries. As part of the BARNARDS study, we examined the rectal microbiota of 2,931 neonates (term used up to 60 d) with clinical signs of sepsis and of 15,217 mothers screening for blaCTX-M-15, blaNDM, blaKPC and blaOXA-48-like genes, which were detected in 56.1%, 18.5%, 0% and 4.1% of neonates' rectal swabs and 47.1%, 4.6%, 0% and 1.6% of mothers' rectal swabs, respectively. Carbapenemase-positive bacteria were identified by MALDI-TOF MS and showed a high diversity of bacterial species (57 distinct species/genera) which exhibited resistance to most of the antibiotics tested. Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae/E. cloacae complex, the most commonly found isolates, were subjected to whole-genome sequencing analysis and revealed close relationships between isolates from different samples, suggesting transmission of bacteria between neonates, and between neonates and mothers. Associations between the carriage of antimicrobial resistance genes (ARGs) and healthcare/environmental factors were identified, and the presence of ARGs was a predictor of neonatal sepsis and adverse birth outcomes.

The Clinical Characteristics of Amblyopia in Children Under 17 Years of Age in Qassim Region, Saudi Arabia.

Purpose: To provide the clinical characteristics of amblyopia in children under 17 years of age in Qassim Region, Saudi Arabia. Patients and Methods: The study was a cross-sectional hospital-based, included 121 children with amblyopia aged between 3 and 17 years, referred from 6 hospitals in Qassim region to the paediatric optometry clinic at Qassim University medical city. Demographics and comprehensive ocular examination including visual acuity (VA), assessment of anterior and posterior segment, cycloplegic refraction (RE), angle of deviation, and cause of amblyopia were collected. Results: The mean age at diagnosis of amblyopia was 8.93 ± 3.67 years. The leading cause of amblyopia was strabismus and anisometropia shared the same percentage at 29.75%, and the combined-mechanism at 18.18%. Amblyopia was more common in males 57.85%, particularly strabismic amblyopia in 66.67% and anisometropic amblyopia in 61.11%, p = 0.408. Amblyopia was more predominant in the age group 6- to 9-year-old, particularly, strabismic amblyopia 44.44%, and amblyopia due to a combined mechanism of 36.36%, p = 0.066. The degree of hyperopia was not varied by the cause of amblyopia (P = 0.401), with slightly high hyperopia found in ametropic and strabismic amblyopia. Conversely, hyperopic astigmatism was significantly associated with amblyopia P = 0.020, with a high degree of hyperopic astigmatism found in meridional amblyopia and ametropic amblyopia. Conclusion: The commonest types of amblyopia in children were attributed to strabismus and anisometropia. Causes of amblyopia differed by age group with strabismus, anisometropia, and combined mechanism accounting for most children aged 6- to 9-years and strabismus for children aged less than 6 years. Hyperopic and myopic astigmatism were significantly associated with anisometropia and meridional amblyopia. Therefore, efforts should be made for early diagnosis and management of childhood amblyopia and uncorrected refractive errors to avoid their impact on quality of life.

Interlayer Defect Detection in Intra-Ply Hybrid Composite Material (GF/CF) Using a Capacitance-Based Sensor.

Combining two types of reinforcement fiber in a common matrix may lead to different failure modes such as micro-cracks between the layers when the structure is subjected to lower stress levels. Real-time damage detection should be integrated into the hybrid composite structure to provide structural integrity and mitigate this problem. This paper outlines the working mechanisms and the fabrication of an integrated capacitive sensor in an intra-ply hybrid composite (2 × 2 twill weave). Uniaxial tensile and flexural tests were conducted to characterize the proposed sensor and provide self-sensing functionality (smart structure). The sensitivity and repeatability of the capacitive sensor were measured to be around 1.3 and 185 µΔC/Co, respectively. The results illustrate that onset of damage between layers can be detected by in situ monitoring. It can be seen that the initial damage was detected at the turning point where the relative change in capacitance begins to reduce while the load increases. Finite element modeling was also constructed to analyze the test results and explain the reasons behind the turning point. It was shown that the carbon yarns experienced high transverse shear stress (τxz) in the crimp region, leading to inter-fiber cracks.

Fracture resistance and failure mode of layered translucent zirconia with different crown designs.

This study investigated the impact of different veneering design on the fracture resistance and failure mode of layered translucent zirconia crowns, compared to the full monolithic zirconia crowns. Ninety crowns with different designs were divided into six groups (n=15); one fully contoured monolithic crown (FMC), one fully veneered with porcelain (FVC), or four partially veneered designs. All crowns were thermo-cycled, and then loaded to failure in a universal testing machine. The fracture resistance (N) and fracture modes were assessed. One-way ANOVA was performed followed by Tukey's multiple comparison (α<0.05). Results demonstrated that all the tested partially veneered designs exhibited enhanced fracture resistances and were comparable to that of the full-contour monolithic translucent zirconia crowns.

Effects of Cyclopentolate Hydrochloride Dosage on Anterior Segment Parameters in Young Adults (Measured with Pentacam).

PURPOSE: To assess the effects of 0.5% and 1% cyclopentolate on the main parameters of the anterior segment (central corneal thickness (CCT), anterior chamber angle (ACA), depth (ACD) and volume (ACV)) in low/moderate myopia and hyperopia along with the effect on IOP. PATIENTS AND METHODS: Both eyes of 30 subjects (15 myopic and 15 hyperopic) with mean age±standard deviation of 21.4±3.6 years were enrolled. Each participant was administered two drops of cyclopentolate 1% in the right eye and two drops of cyclopentolate 0.5% in the left eye, 15 minutes apart. All participants underwent intraocular pressure (IOP) measurement using noncontact tonometry, and anterior chamber parameter measurement using Pentacam. RESULTS: Following the use of 0.5% and 1% cyclopentolate among the hyperopic group, there was a statistically significant increase in ACD for 1% (pre 2.762±0.28 mm and post 2.89±0.25 mm) and 0.5% (pre 2.71±0.28 and post 2.86±0.27 mm) and ACV for 1% (pre 141.40±20.59 mm3 and post 154.35±19.69 mm3) and 0.5% (pre 137.40±20.48 mm3 and post 152.93±20.50 mm3). In contrast, ACA decreased with both doses 1% and 0.5%, but was not statistically significant (p for both >0.05%). With 0.5% and 1% cyclopentolate among the myopia group, there was a significant increase in ACD following cyclopentolate 1% (pre 3.18±0.22 mm and post 3.25±0.21 mm) and 0.5% (pre 3.200±0.22 mm and post 3.26±0.05 mm), p˂0.05. The ACV was significantly increased following 1% cyclopentolate, p˂0.001. The ACA showed a statistically significant decrease following cyclopentolate 1%, P=0.01, but not a significant decrease after cyclopentolate 0.5%, P=0.170. There was a significant increase in the IOP after 1%, p˂0.001, while a decrease with 0.5%, p=0.008. CONCLUSION: A topical dosage of cyclopentolate 1% showed significant changes in ACA and ACV among the hyperopia and myopic groups compared to 0.5%. Therefore, it is important to consider the use of a 0.5% cyclopentolate dosage to minimize changes to anterior chamber parameters.

Building consensus for the development of child eye care services in South Darfur State of Sudan using the Delphi technique.

BACKGROUND:  Global estimates suggest there are almost 19 million visually impaired children worldwide, most of whom reside in poor countries, with the major cause being treatable. AIM:  To determine the barriers to accessing childhood eye care services and to develop an eye care plan for children in South Darfur State, Sudan. SETTING:  The study took place in South Darfur State, Sudan. METHODS:  The classical Delphi technique was used to build consensus on a list of statements, which were generated based on the themes established by the experts, as well as on an extensive literature review. RESULTS:  Response rates ranged from 90% in the first round (n = 18), 100% in the second round (n = 18) to 89% in the third and final round (n = 16). The total number of statements recommended by the Delphi panellists for development of the paediatric eye care plan, was 60 based on a consensus level of 80% agreement or more. The expert's consensus on the following key elements for promotion and improvement of child eye care: The main barriers to accessing child eye care were high poverty rate, unavailability of child eye services and a lack of community awareness. The challenges facing visually impaired children were an absence of paediatric ophthalmologists, low vision and orthoptic services. CONCLUSION:  The main barriers to accessing child eye care services were financial, clinical access and lack of knowledge. There should be greater collaboration between the Ministries of Health, Education and non-governmental organisations (NGOs), to work together in addressing these barriers.