Fog Method Research Articles

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

Dengue Infection Survey on Prevention and Control Strategies Among Community in Malaysia

Dengue is a vector-borne disease caused by a rapidly spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards prevention and control measures of Dengue infection. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: i) respondent profile ii) knowledge about prevention of Dengue Fever and insecticide use for mosquito control iii) knowledge about biological control.Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and Abate® (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel biocontrol and successful community programmes is significantly influenced by the perception of prevention and control measures for mosquitoes.

Visualization of a jet stream group influencing the noise increase phenomena in generated by airflow through a perforated metal plate

The perforated plate is made by a punching process. Because of this manufacturing process, the cross section of holes in a perforated plate varies in the direction of the thickness of the plate. When an airflow passes through a group of holes in a perforated plate, the noise characteristics change depending on the direction of passage. In the case where the cross-sectional area of holes increases in the downstream direction, the aerodynamic noise generated by airflow through holes in perforated plates increases. The cause of the noise increase is considered to be the lock-in phenomenon between the vibration of the plates and the outflow of the vortex. For this to occur, at least seven closely spaced groups of holes are required. In this study, flow visualization using the fog method was performed to clarify the behavior of the jet stream group during the noise increase. The results showed that the vortex outflows at each hole were in opposite phase when the lock-in phenomenon did not occur, but that the vortex outflows at adjacent holes were synchronized when the lock-in phenomenon occurred.

Long-term changes as oil palm plantation age simplify the structure of host-parasitoid food webs.

Understanding host-parasitoid food webs, as well as the factors affecting species interactions, is important for developing pest management strategies in an agroecosystem. This research aimed to study how the long-term change in oil palm plantations, specifically the tree age, affect the structure of host-parasitoid food webs. The field research was conducted on an oil palm plantation located in Central Kalimantan and Jambi Province, Indonesia. In Central Kalimantan, we conducted observations of lepidopteran larvae and parasitoid wasps at different tree ages, ranging from 3 to 18 years old. For tree ages from 3 to 10 years, observations of host-parasitoid food webs were conducted by collecting the lepidopteran larvae using a hand-collection method in each oil palm tree within a hundred trees and they were later reared in the laboratory for observing the emerging parasitoids. The fogging method was applied for trees aged 12 to 18 years because the tree height was too high, and hand-collection was difficult to perform. To compare host-parasitoid food webs between different regions, we also conducted a hand-collection method in Jambi, but only for trees aged 3 years old. The food-web structure that was analyzed included the species number of lepidopteran larvae and parasitoid wasps, linkage density, and interaction diversity. We found 32 species of lepidopteran pests and 16 species of associated parasitoids in Central Kalimantan and 12 species of lepidopteran pests, and 11 species of parasitoids in Jambi. Based on the GLM analysis, tree age had a negative relationship with the species number of lepidopteran larvae and parasitoids as well as linkage density and interaction diversity. Different geographical regions showed different host-parasitoid food web structures, especially the species number of lepidopteran larvae and interaction diversity, which were higher in Central Kalimantan than in Jambi. However, some parasitoids can be found across different tree ages. For example, Fornicia sp (Hymenoptera: Braconidae) was recorded in all ages of oil palm sampled. Results of the GLM analysis showed that the abundance of Fornicia sp and its host (lepidopteran larvae abundance) were not affected by the tree age of the oil palm. In conclusion, the long-term change in oil palm plantations simplifies the structure of host-parasitoid food webs. This highlights the importance of long-term studies across geographical regions for a better understanding of the consequences that wide monoculture oil palm plantations have on biological control services.

Effect of the Freezing Step on Primary Drying Experiments and Simulation of Lyophilization Processes

Lyophilization is a widely used preservation method for thermosensitive products. It consists of three process steps: freezing, primary and secondary drying. One of the major drawbacks is the long processing time. The main optimization effort was put into the primary drying phase since it is usually the longest phase. However, the freezing step is of immense importance for process efficiency and product quality. The lack of control during freezing comprises a challenge for process design and tech transfer. In this study, four different freezing steps (shelf-ramped freezing with and without holding step, precooled shelves and an ice fog method for controlled nucleation) are used and their impact on primary drying experiments and simulations is shown. Only the ice fog method is able to control the nucleation temperature leading to low dry layer resistances with low deviations. During the primary drying simulations, the control of the nucleation temperature drastically increases the precision and accuracy of the product temperature prediction. For optimal primary drying design and model predictive control, the nucleation temperature is strongly recommended to be controlled inside a Process Analytical Technology (PAT) concept to achieve reliable and reproducible process conditions.

Accommodative spasm and its different treatment approaches: A systematic review.

This article is about the accommodation spasm. The primary rule for near vision is ciliary muscle constriction, synchronised convergence of both eyes, and pupil constriction. Any weaknesses in these components could result in an accommodative spasm. Variable retinoscopic reflex, unstable refractive error, and lead of accommodation in near retinoscopy are common causes of spasm. We conducted a thorough literature search in the PubMed and Google Scholar databases for published journals prior to June 2022, with no data limitations. This review contains twenty-eight case reports, six cohort studies, four book references, four review articles, and two comparative studies after applying the inclusion and exclusion criteria. The majority of studies looked at accommodative spasm, near reflex spasm, and pseudomyopia. The most common causes of accommodative spasm are excessive close work, emotional distress, head injury, and strabismus. Despite side effects or an insufficient regimen, cycloplegic drops are effective in diagnosing accommodation spasm. The modified optical fogging technique is also effective and may be an option for treating accommodative spasm symptoms. Bifocals for near work, manifest refraction, base-in prisms, and vision therapy are some of the other management options. As a result, it requires a comprehensive clinical treatment strategy. This review aims to investigate the various aetiology and treatments responsible for accommodative spasm and proposes widely implementing the modified optical fogging method and vision therapy in clinics as comprehensive management to reduce the future upward trend of accommodative spasm.

Diversity and species composition of ants at coffee agroforestry systems in East Java, Indonesia: Effect of habitat condition and landscape composition

Abstract. Muhammad FN, Rizali A, Rahardjo BT. 2022. Diversity and species composition of ants at coffee agroforestry systems in East Java, Indonesia: Effect of habitat condition and landscape composition. Biodiversitas 23: 3313-3321. Habitat condition and landscape composition are the main factors that shape biodiversity in agroecosystems. However, information on the effect of habitat conditions and landscape composition on biodiversity in agroforestry systems is lacking. Agroforestry systems possess habitats that are characterized by a high diversity of vegetation, that can support biodiversity both on the field or landscape scale. This research aimed to study the diversity and species composition of ants in coffee (Coffea spp.) agroforestry systems, and to investigate the effects of habitat conditions and landscape composition on ant communities. Field research was conducted in twelve coffee agroforestry systems in East Java, Indonesia. Ants were sampled with the fogging method for canopy ants and pitfall traps for ground-dwelling ants in 40 m x 30 m plots. In each location, habitat conditions aspects (such as cultural technique and tree age) were identified by interviews with farmers and vegetation observation. Meanwhile, landscape composition was characterized by ground checking and mapping the land-use type within a 500 m radius from plot centers. This research recorded 35 species and 4,622 individuals of ants from all coffee plantations. Dolichoderus thoracicus was the most dominant canopy ant, while Pheidole sp.2 was the most dominant ground-dwelling ant in all plantations. Based on the GLM analysis, different responses were found between canopy and ground-dwelling ants in relation to habitat conditions and landscape composition. Canopy and ground-dwelling ants were affected by habitat conditions (such as tree age and canopy cover). The species composition of ground-dwelling ants was also affected by habitat conditions. In conclusion, habitats in coffee plantations can affect ant communities with ground-dwelling ants being more sensitive than canopy ants. Meanwhile, landscape composition can affect the species richness of all ants and not affect each stratum (canopy and ground-dwelling ants).

Clarity method of fog and dust image in fully mechanized mining face

At present, the abnormal state of equipment and surrounding rocks in the fully mechanized mining face is mainly detected by visual methods. However, the vision sensor works in a low-light environment and it is affected by factors such as water fog and dust, which lead to blurred images. The defogging algorithm of image based on boundary constraint and context regularization has a good effect on image restoration in the daily environment, but the recovery quality is poor in low illumination environment. Therefore, a method based on boundary constraint and nonlinear context regularization is proposed. The model of fog and dust image is established, and the transmittance function is roughly estimated by boundary constraint method. Then, the nonlinear context regularization method based on logarithmic transformation is used to estimate and optimize the scene transmission model to improve the brightness of the image, and the low illumination fog and dust image is restored by the optimized transmittance function. The logarithmic transformation multiple is selected according to the peak value of image brightness. In order to highlight the effectiveness of our method, the widely used and improved Dark Channel Prior or other methods are used for comparison. The experiment results indicate that our method can effectively remove fog and dust and improve the brightness of the image of the fully mechanized face. It is of great significance to ensure safe production and safety of workers and equipment in coal mine.

Effect of cold fog disinfection on Escherichia coli affecting commercial egg layer flocks

On a field level among poultry flocks a study was conducted to estimate the efficacy of the most common disinfectants against E. coli (APEC isolates) was determined. The selected disinfectants were; Formalin, Phenol, QAC, Halamid, Virkon" S and Micro Sept M against E. coli isolates of commercial egg- layer flocks in Egyptian farms. The recovered results showed that: (1) the incidence of E. coli in the observed commercial egg-layer flocks; the isolation of E. coli (APEC of rfbO157 gene ) from 4 commercial egg-layer flocks (26.7 %) out of 15 flocks, the mortalities rates at the end of 78 weeks of age was 20% and also, the current egg-production, average egg weight, hen housed day, hen housed egg and percent peak of egg-production were: 69.2%,58.3 gm, 70%,326,78% and 69%,respectivel. (2) Formalin, Micro Sept M and Virkon'S treatment demonstrated a significant reduction in E. coli populations especially by cold fogging method.

A Study on the Construction Method of Airflow Fan and Fog Combined System for the Cooling of the Greenhouse Facility

A Study on the Construction Method of Airflow Fan and Fog Combined System for the Cooling of the Greenhouse Facility

Deep reinforcement learning for computation offloading in mobile edge computing environment

Recently, in order to distribute computing, networking resources, services, near terminals, mobile fog is gradually becoming the mobile edge computing (MEC) paradigm. In a mobile fog environment, the quality of service affected by offloading speeds and the fog processing, however the traditional fog method to solve the problem of computation resources allocation is difficult because of the complex network states distribution environment (that is, F-AP states, AP states, mobile device states and code block states). In this paper, to improve the fog resource provisioning performance of mobile devices, the learning-based mobile fog scheme with deep deterministic policy gradient (DDPG) algorithm is proposed. An offloading block pulsating discrete event system is modeled as a Markov Decision Processes (MDPs), which can realize the offloading computing without knowing the transition probabilities among different network states. Furthermore, the DDPG algorithm is used to solve the issue of state spaces explosion and learn an optimal offloading policy on distributed mobile fog computing. The simulation results show that our proposed scheme achieves 20%, 37%, 46% improvement on related performance compared with the policy gradient (PG), deterministic policy gradient (DPG) and actor–critic (AC) methods. Besides, compared with the traditional fog provisioning scheme, our scheme shows better cost performance of fog resource provisioning under different locations number and different task arrival rates.

Minimizing Energy Consumption and SLA Violation in Fog Computing Using Artificial Neural Network

With the fast development of cloud computing methods, exponential growth is faced by several users. It is complicated for traditional data centers to perform several jobs in real-time because of inadequate bandwidth resources. Therefore, the method of fog computing is recommended for supporting and providing fast cloud services. It is not a substitute but is a powerful complement to cloud computing. The reduction of energy consumption through the notion of fog computing has certainly been a challenge for current researchers, industries, and communities. Various industries, including finance and healthcare, require a rich resource-based platform for processing large amounts of data with cloud computing across fog architecture. The consumption of energy across fog servers relies on allocating techniques for services (user requests). It facilitates processing at the edge with the probability of interacting with the cloud. This article proposed energy-aware scheduling by using Artificial Neural Network (ANN) and Modified Multiobjective Job Scheduling (MMJS) techniques. The emphasis of the work is on the reduction of energy consumption rate with less Service Level Agreement (SLA) violation in fog computing for data centers. The result shows that there is a 3.9% reduction in SLA violation when a multiobjective function with Artificial Neural Network is applied.

Application with initiative to replace common insect fuel for fogging system with biodiesel

The project addressed the application of biodiesel as a fuel in replacing the petroleum-based liquid carrier in common fogging system. In controlling the population of larvae and adult mosquito using chemical pesticide spraying through fogging method, the dilution rate based on the efficient mixing of pesticide and biodiesel is yet to be investigated. A simulation field trial was conducted indoor in a visible container with the designed dimension of 50 cm × 50 cm × 50 cm with the method of fogging was adapted from the principle of thermal fogger. The biodiesel was produced through the transesterification reaction of palm oil with methanol using hydrotalcite as catalysts. To evaluate the larvicidal and adulticidal mortality, dilution of pesticide which is Sumithion L-40 into biodiesel as liquid carrier is varied. The 5 ml pesticide-carrier mixture with the dilution ratio of 1:9, 3:7 and 5:5 were used and dispersed into the ambient in the form of fog. After several tests, it can be deduced that the most effective dilution ratio for against larvae is 1:9 and adult mosquito is 5:5. The larvae mortality rate achieved 100% at the duration of 117 min due to effective settlement of the spraying droplet of formulation mixture on exposed water. The result also proven that, biodiesel as liquid carrier capable to overcome the solubility problem encountered by the conventional petroleum-based carrier. The adult mosquito needs shorter knockdown time with the higher dosage of pesticide. Sumithion L-40 consists of two active ingredients which are tetramethrin and fenitrothion that provide quick knockdown and residual effect especially to adult mosquito.

Sensitivity and specificity in methods for examination of the eye astigmatism.

We usually use objective and subjective methods for examination of the eye astigmatism in optometry, respectively ophthalmology. Objective methods enable to measure sphere-cylindrical refraction of the eye. If we want to prescribe new glasses or contact lenses we usually use subjective methods. The aim of this study was to measure sensitivity and specificity of some subjective and objective methods for examination of the eye astigmatism. We supposed that automatic objective refraction will be the most exact method so we choose this method as the reference method. For comparison we chose subjective methods Jackson crossed cylinders (JCC), fogging method (FM) and objective method Spot Vision Screener (SVS, WelschAllyn). We had in total 30 subjects with average age 23 years (SD 1 year) in our study. We made each measurement per eye separately and it was independent measurement so we could use measurement from each eye (n = 60). Each eye was firstly measured by subjective method FM, followed by JCC method and finally was use objective method Spot Vision Screener (SVS, WelschAllyn). Measurement with objective instrument TRK-1P (TOPCON) was use as reference measurement. The significance level was set at p = 0.05. In variable FM we measured sensitivity 76.2 % and specificity 66.7 %. Criterion for positive finding was -0.25 D. Result was statistically significant on level p < 0.001. In variable JCC we measured sensitivity 95.2 % and specificity 66.7 %. Criterion for positive finding was -0.25 D. Result was statistically significant on level p < 0.001. In variable SVS we measured sensitivity 47.6 % and specificity 94.4 %. Criterion for positive finding was -0.75 D. Result was statistically significant on level p < 0.001. Direct comparison of all methods showed statistically important difference between techniques JCC and FM (p = 0.0095). In other method we did not find statistically important difference (FM vs. SVS, p = 0.526 and JCC vs. SVS, p = 0.105). All subjective and objective techniques were statistically significant in detection of eye astigmatism. Comparison of ROC curves showed statistically significant difference between FM and JCC technique. The JCC method showed the highest sensitivity, whereas SVS highest specificity.

An investigation on professional performance of optometric refraction in spectacles stores in Anyang city of Henan Province

Objective: To investigate the methods of optometric refraction adopted for adolescents in spectacles stores in Anyang city of Henan Province and the professional performance of optometric refraction. Methods: Cross-sectional study. Maps and yellow pages were used to collect the information of 131 spectacles stores in Anyang city. A questionnaire was used to investigate spectacles stores that had optometry equipment and can provide refraction prescription and spectacles in this city. The questionnaire covered (1) the process of optometric refraction, including whether cycloplegic refraction was conducted for adolescents and children if it was their first-time optometry and the type of cycloplegics,and (2) the opticians' knowledge on optometric refraction for adolescents and children, such as necessity of cycloplegic refraction for adolescents and children and age cut-offs. According to whether they used a comprehensive refractometer, the optometry methods were divided into conventional optometry and medical optometry. Results: Of 131 spectacles stores in Anyang city, 127 were enrolled. A total of 127 questionnaires were distributed and returned with an effective rate of 100%. Conventional optometric refraction was performed in 53 stores (41.73%), and medical optometric refraction was performed in 74 stores (58.27%). Cycloplegic refraction was conducted in only 4 spectacles stores (3.15%) for adolescents and children upon their first-time optometry. The fogging method of refraction was adopted in 31 stores (24.41%), while optometric refraction was directly conducted in 92 stores (72.44%) without controlling accommodation. As for the use of cycloplegia at initial optometric refraction of children, cycloplegia was objected to in 4 stores,and thought to be no need in 28 stores including 6 stores in which the fogging method was used to replace cycloplegia. In 68 stores, cycloplegia was performed if wanted, or children could go to a hospital for it. In 12 stores, the use of cycloplegics was determined by children's vision and diopters. In 5 stores, children were suggested to go to a hospital for cycloplegic refraction. Cycloplegic refraction was required in only 4 stores. As to the age cut-offs of cycloplegic refraction, 6 years old, 12 years old, and 18 years old were considered as the boundary in 7 stores, 33 stores, and 9 stores, respectively.In 11 stores, age was only considered for amblyopia and hyperopia, and in 67 stores, it was not realized. Conclusions: Cycloplegic refraction was found to be conducted for adolescents and children in only 3% of the spectacles stores in Anyang city. Moreover, most of the spectacles store opticians did not support to use cycloplegia before optometric refraction for adolescents and children and lacked knowledge on the age cut-offs of cycloplegic refraction.Standardized training of cycloplegic refraction should be further strengthened. (Chin J Ophthalmol, 2019, 55: 576-581).

Comparison of ice fog methods and monitoring of controlled nucleation success after freeze-drying

Improving freeze-drying processes regarding drying time and batch homogeneity is subject of ongoing research work. In this context, controlled nucleation raised great expectations. However, practically we face some challenges, e.g. how to non-destructively monitor successfully performed controlled nucleation. The question if different controlled nucleation methods lead to comparable products, as not every method can easily be implemented in lab and production scale equipment, is also of high interest. Additionally, the optimal nucleation temperature for controlled nucleation is an open question. In our study, we addressed these challenges. We successfully evaluated frequency modulated spectroscopy as a fast and non-destructive method to monitor controlled nucleation success and batch homogeneity. We found that the better homogeneity generated by controlled nucleation during the freezing step did not sustain in the dried product. Lyophilizates produced by three different ice fog methods for controlled nucleation were characterized by comparable specific surface areas but differed in residual moisture content. To investigate the impact of the ice nucleation temperature (TN) on the resulting specific surface area, we performed controlled nucleation at −3 °C and −10 °C. We concluded that TN is not the only specific surface area determining factor and a high TN does not necessarily lead to larger pores but poses a higher risk of not-nucleating vials.

Fogging and water spray velocity to reduce dust cement widespread

Climate change as the global issue should be analysed from mitigating especially in the cement industrial. This industry contributes up to 6% to the global warming. Cement plants must already take over management of the cement dust arising mainly on the production. However, there are still many who are exposed to cement dust into the surrounding environment, due to the dust cement contributes to air pollutant and give impact to climate change. This research aims to study the various strategies to catch a smooth dust using fogging methods with variable water speed. In such a device, as media dust catcher is mist generated from water which is converted into mist by sprayer. The dust catcher instrument installed at the location after the end of the cement factory chimneys. Of course, in order not to complicate the technical implementation in the chimney is curved downward so it is easier to install dust extraction tool such fogging method. The tool optimal conditions occur in the water velocity 110 ml per min with an efficiency of 63.60%. In the water velocity 110 ml per min it will form a mist with the optimal amount, if the water velocity is greater than 110 ml per min will tend to form droplets, on the contrary if the water velocity is less than 110 ml per min of the amount of haze formed is not maximized.

Alternating Current Discharge Characteristics and Simulation Analysis of Rod-Plane Short Air Gaps under Salt Fog Conditions

In this paper, smog meteorological conditions in the natural environment is simulated by the salt fog method. The study of the alternating current (AC) discharge characteristics of rod-plane short air gaps in salt fog environments has important guiding significance for how to strengthen the external insulation strength of ultra-high voltage (UHV) transmission lines and electrical equipment in smog environments. The rod-plane short air gap is selected as the model to simulate the extremely uneven electric field. The AC discharge test is carried out in the salt fog environment with different conductivity, and the finite element method (FEM) is used to simulate the distribution of electric field in air gap under salt fog environment conditions. The results show that under clean fog conditions the AC discharge voltage in the air gap increased by 15.1% to 35.5% compared to that under dry conditions. With the increased conductivity of salt fog, the AC discharge voltage in air gap decreased by 4.1% to 9.2% compared to that under clean fog conditions, and the reduction is within 10%. The distortion of the electric field and the adsorption of free electrons in the gap by droplets lead to the decrease of the electric field intensity in the air gap. With the increase of the conductivity, the electric field intensity in the air gap increases slightly. Meanwhile, the influence of salt fog and its conductivity on the AC discharge voltage of rod-plane short air gap is examined, becoming saturated with the increase of the gap distance and the conductivity of salt fog.

Amplitude of Accommodation in Schoolchildren

ABSTRACTPurpose: Hofstetter’s equations are based on studies of Amplitude of Accommodation (AA) with methodological limitations, particularly in the case of children younger than 10 years of age. The aim of this study is to evaluate AA by age, gender, economic status, and time of day as well as accommodative insufficiency prevalence.Methods: A cross-sectional study was conducted with 867 schoolchildren aged 6–16 years attending two public schools in the urban area of the South Brazilian city of Pelotas. Subjective refraction was performed using a monocular fogging method to standard end point of maximum plus for best visual acuity (20/25). AA was assessed using the push-up method.Results: The median AA value was 14.3D (P25 13.3–P75 16.7) among children aged 6–16 years, being 15.5D (P25 14.3D–P75 16.7) among children aged 6–10 years, 14.2D (P25 12.5D–P75 15.4) among 11–13-year-olds, 13.3D (P25 12.5D–P75 15.4) among children aged 14–15 and 12.9D (P25 11.1D–P75 14.3) among those aged 16. AA variability was 2.4D in those aged 6–8, 3.4D in children aged 9–12, and 2.9D in those aged 13–16. There was no significant difference in median AA according to gender, time of examination, or economic status; 2.8% of children showed AA of less than 2D lower than Hofstetter’s minimum reference value.Conclusions: This study reports AA in a large sample of children and therefore may contribute to current knowledge on AA norms. In order to avoid the impact of outliers, it proposes the use of the median and percentiles to define AA standards by specific age. A set of studies using precise AA measurement and large sample size are needed to determine clinical standards for AA.