AIM： To determine the main visual symptoms in a Brazilian population sample, associated to refractive errors（REs） and spectacle need to suggest priorities in preventive programs.METHODS： A cross-sectional study wa...AIM： To determine the main visual symptoms in a Brazilian population sample, associated to refractive errors（REs） and spectacle need to suggest priorities in preventive programs.METHODS： A cross-sectional study was conducted in nine counties of the southeast region of Brazil, using a systematic sampling of households, between March 2004 and July 2005. The population was defined as individuals aged between 1 and 96 y, inhabitants of 3600 residences to be evaluated and 3012 households were included,corresponding to 8010 subjects considered for participation in the survey, of whom 7654 underwent ophthalmic examinations. The individuals were evaluated according their demographic data, eye complaints and eye examination including the RE and the need to prescribe spectacles according to age. Statistical analysis was performed using SPSS software package and descriptive analysis using 95% confidence intervals（P〈0.05）. RESULTS： The main symptom detected was asthenopia, most frequent in the 2ndand 3rddecades of life, with a significant decline after the 4thdecade.Astigmatism was the RE most associated with asthenopia. Reduced near vision sight was more frequent in those ≥40y with a progressive decline thereafter.Spectacles were most frequently required in subjects of≥40 years of age.CONCLUSION： The main symptom related to the vision was asthenopia and was associated to astigmatism. The greatest need for spectacles prescription occurred after40＇s, mainly to correct near vision. Subjects of ≥40years old were determined to be at high risk of uncorrected REs. These observations can guide intervention programs for the Brazilian population.展开更多
This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However,...This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However, it depends highly on the accuracy of model. Model errors between the virtual and real environment exist inevitably. The existing way to deal with the problem is by means of either model matching or robot compliance control. As distinct from the existing methods, this article tries to combine m...展开更多
AIM：To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness. METHODS：A sample of 1466 yo...AIM：To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness. METHODS：A sample of 1466 young subjects（ranging from 3 to 22 years old）,with a mean age of 11.21±3.63 years old,were examined to assess their distance visual acuity（VA）and refractive error. The first screening examination performed by trained volunteers,included visual acuity testing,autokeratometry and non-cycloplegic autorefraction. Inclusion criteria for a second complete cycloplegic eye examination by an optometrist were VA 〈20/25（0.10 log MAR or 0.8 decimal）and/or corneal astigmatism ≥1.50 D. RESULTS：An uncorrected distance VA of 0 log MAR（1.0decimal）was found in 89.2% of children. VA 〈20/25 and/or corneal astigmatism ≥1.50 D was found in 3.9% of children（n=57）,with a prevalence of hyperopia of 5.2%（0.2%of the total）in this specific group. Furthermore,myopia（spherical equivalent ≤-0.5 D）was found in 37.7% of the refracted children（0.5% of the total）. The prevalence of refractive astigmatism（cylinder ≤-1.50 D）was 15.8%（0.6% of the total）. Visual impairment（VI）（0.05≤VA≤0.3）was found in 12/114（0.4%）of the refracted eyes. Main causes for VI were refractive error（58%）,retinal problems（17%,2/12）,albinism（17%,2/12）and unknown（8%,1/12）.CONCLUSION：A low prevalence of refractive error has been found in this rural area of Paraguay,with higher prevalence of myopia than of hyperopia.展开更多
Uncorrected refractive error（URE） is a major health problem among school children. This study was aimed to determine the frequency and patterns of URE across 4 gradients of residential densities（urban, exurban, sub...Uncorrected refractive error（URE） is a major health problem among school children. This study was aimed to determine the frequency and patterns of URE across 4 gradients of residential densities（urban, exurban, suburban and rural）. This was a cross-sectional study of school children from 3 districts in Yogyakarta and 1 district near Yogyakarta, Indonesia. The information regarding age, sex, school and school grader were recorded. The Snellen＇s chart was used to measure the visual acuity and to perform the subjective refraction. The district was then divided into urban, suburban, exurban and rural area based on their location and population. In total, 410 school children were included in the analyses（urban=79, exurban=73, suburban=160 and rural=98 school children）. Urban school children revealed the worst visual acuity（P〈0.001） and it was significant when compared with exurban and rural. The proportion of URE among urban, suburban, exurban and rural area were 10.1%, 12.3%, 3.8%, and 1%, respectively, and it was significant when compared to the proportion of ametropia and corrected refractive error across residential densities（P=0.003）. The risk of URE development in urban, suburban, exurban, and rural were 2.218（95%CI： 0.914-5.385）, 3.019（95%CI： 1.266-7.197）, 0.502（95%CI： 0.195-1.293）, and 0.130（95%CI：0.017-0.972）, respectively. Urban school children showed the worst visual acuity. The school children in urban and suburban residential area had 2 and 3 times higher risk of developing the URE.展开更多
AIM： To report the prevalence and causes of unilateral visual impairment（UVI） in rural population of all ages in rural Andhra Pradesh, India.·METHODS： A population-based cross sectional study using a multi-st...AIM： To report the prevalence and causes of unilateral visual impairment（UVI） in rural population of all ages in rural Andhra Pradesh, India.·METHODS： A population-based cross sectional study using a multi-stage cluster sampling methodology was carried out in West Godavari, Adilabad and Mahbubnagar districts in south India. A comprehensive eye examination that included presenting and best corrected visual acuity and dilated fundus examination was conducted by trained professionals. UVI is defined as presenting visual acuity 6/18 in one eye but ≥6/18 in other eye. Multiple logistic regression analysis was used to test association of UVI with socio-demographic risk factors.· RESULTS： Data were analyzed for 6634/7771 participants after excluding those with bilateral visual impairment. The mean age of the participants was 27.4y（Standard deviation： 17.9y）, 51.9% were women and49.1% were educated. The prevalence of UVI was 7.8%（95% CI： 7.2%- 8.5%）. Uncorrected refractive error（60.8%）, cataract（17.4%） and retinal causes（6.6%） were the leading causes of UVI. On multiple logistic regression analyses, older age, not having education, living in welloff district had significantly higher odds of being associated with UVI. UVI was not associated with gender.·CONCLUSION： UVI is common in rural south India.Most of it is due to cataract and refractive errors, both of which can be addressed at primary and secondary levelsof eye care. Burden of UVI should also be considered in planning eye care services.展开更多
In visual cryptography, many shares are generated which are illogical containing certain message within themselves. When all shares are piled jointly, they tend to expose the secret of the image. The notion of visual ...In visual cryptography, many shares are generated which are illogical containing certain message within themselves. When all shares are piled jointly, they tend to expose the secret of the image. The notion of visual secret sharing scheme is to encrypt a secret image into n illogical share images. It is unable to reveal any data on the original image if at least one of the shares is not achieved. The original image, in fact, is realized by overlapping the entire shares directly, in order that the human visual system is competent to identify the collective secret image without employing any complicated computational tools. Therefore, they are communicated steadily as number of shares. The elliptic curve cryptography approach, in turn, is employed to augment the privacy and safety of the image. The new.fangled technique is utilized to generate the multiple shares which are subjected to encryption and decryption by means of the elliptic curve cryptography technique. The test outcomes have revealed the fact that the peak signal to noise ratio is 58.0025, Mean square error value is 0.1164 and the correlation coefficient is 1 for the decrypted image without any sort of distortion of the original image.展开更多
Introduction: WHO estimated that uncorrected refractive errors are the leading cause of visual impairment and second leading cause of blindness globally. University students are prone to developing refractive errors d...Introduction: WHO estimated that uncorrected refractive errors are the leading cause of visual impairment and second leading cause of blindness globally. University students are prone to developing refractive errors due to their curriculum that requires a lot of near work affecting their performance and quality of life unknowingly. Genetic and environmental factors are thought to play a role in the development of refractive errors. This study addresses the paucity of knowledge about refractive errors among university students in East Africa, providing a foundation for further research. Objectives: To determine the prevalence and factors associated with refractive errors among students in the Faculty of Medicine at Mbarara University of Science and Technology. Methodology: This was a cross-sectional descriptive and analytical study in which 368 undergraduate students selected using random sampling were assessed for refractive errors from March 2021-July 2021. Eligible participants were recruited and their VA assessment done after answering a questionnaire. Students whose VA improved on pin hole had subjective retinoscopy and results were compiled and imported to STATA 14 for analysis. Results: The prevalence of refractive errors was 26.36% with (95% CI) among university students especially myopia. Myopia is most predominant at 60%, followed by 37% Astigmatism and hyperopia of 3% among medical students. Astigmatism consisted of largely myopic astigmatism 72% (26) and 28% (10) compound/mixed astigmatism only. Student positive family history of refractive error was found to have a statistically significant relationship with refractive errors with AOR 1.68 (1.04 - 2.72) (95% CI) and P (0.032). Conclusion: The prevalence of refractive errors among university students, especially myopia, was found to be high and family history was associated with students having refractive errors.展开更多
文摘AIM： To determine the main visual symptoms in a Brazilian population sample, associated to refractive errors（REs） and spectacle need to suggest priorities in preventive programs.METHODS： A cross-sectional study was conducted in nine counties of the southeast region of Brazil, using a systematic sampling of households, between March 2004 and July 2005. The population was defined as individuals aged between 1 and 96 y, inhabitants of 3600 residences to be evaluated and 3012 households were included,corresponding to 8010 subjects considered for participation in the survey, of whom 7654 underwent ophthalmic examinations. The individuals were evaluated according their demographic data, eye complaints and eye examination including the RE and the need to prescribe spectacles according to age. Statistical analysis was performed using SPSS software package and descriptive analysis using 95% confidence intervals（P〈0.05）. RESULTS： The main symptom detected was asthenopia, most frequent in the 2ndand 3rddecades of life, with a significant decline after the 4thdecade.Astigmatism was the RE most associated with asthenopia. Reduced near vision sight was more frequent in those ≥40y with a progressive decline thereafter.Spectacles were most frequently required in subjects of≥40 years of age.CONCLUSION： The main symptom related to the vision was asthenopia and was associated to astigmatism. The greatest need for spectacles prescription occurred after40＇s, mainly to correct near vision. Subjects of ≥40years old were determined to be at high risk of uncorrected REs. These observations can guide intervention programs for the Brazilian population.
基金National Natural Science Foundation of China (60675054)National High-Tech Research and Development Program (2006AA04Z228)"111" Project (B07018)
文摘This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However, it depends highly on the accuracy of model. Model errors between the virtual and real environment exist inevitably. The existing way to deal with the problem is by means of either model matching or robot compliance control. As distinct from the existing methods, this article tries to combine m...
文摘AIM：To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness. METHODS：A sample of 1466 young subjects（ranging from 3 to 22 years old）,with a mean age of 11.21±3.63 years old,were examined to assess their distance visual acuity（VA）and refractive error. The first screening examination performed by trained volunteers,included visual acuity testing,autokeratometry and non-cycloplegic autorefraction. Inclusion criteria for a second complete cycloplegic eye examination by an optometrist were VA 〈20/25（0.10 log MAR or 0.8 decimal）and/or corneal astigmatism ≥1.50 D. RESULTS：An uncorrected distance VA of 0 log MAR（1.0decimal）was found in 89.2% of children. VA 〈20/25 and/or corneal astigmatism ≥1.50 D was found in 3.9% of children（n=57）,with a prevalence of hyperopia of 5.2%（0.2%of the total）in this specific group. Furthermore,myopia（spherical equivalent ≤-0.5 D）was found in 37.7% of the refracted children（0.5% of the total）. The prevalence of refractive astigmatism（cylinder ≤-1.50 D）was 15.8%（0.6% of the total）. Visual impairment（VI）（0.05≤VA≤0.3）was found in 12/114（0.4%）of the refracted eyes. Main causes for VI were refractive error（58%）,retinal problems（17%,2/12）,albinism（17%,2/12）and unknown（8%,1/12）.CONCLUSION：A low prevalence of refractive error has been found in this rural area of Paraguay,with higher prevalence of myopia than of hyperopia.
基金Supported by Department of Ophthalmology, Faculty of Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
文摘Uncorrected refractive error（URE） is a major health problem among school children. This study was aimed to determine the frequency and patterns of URE across 4 gradients of residential densities（urban, exurban, suburban and rural）. This was a cross-sectional study of school children from 3 districts in Yogyakarta and 1 district near Yogyakarta, Indonesia. The information regarding age, sex, school and school grader were recorded. The Snellen＇s chart was used to measure the visual acuity and to perform the subjective refraction. The district was then divided into urban, suburban, exurban and rural area based on their location and population. In total, 410 school children were included in the analyses（urban=79, exurban=73, suburban=160 and rural=98 school children）. Urban school children revealed the worst visual acuity（P〈0.001） and it was significant when compared with exurban and rural. The proportion of URE among urban, suburban, exurban and rural area were 10.1%, 12.3%, 3.8%, and 1%, respectively, and it was significant when compared to the proportion of ametropia and corrected refractive error across residential densities（P=0.003）. The risk of URE development in urban, suburban, exurban, and rural were 2.218（95%CI： 0.914-5.385）, 3.019（95%CI： 1.266-7.197）, 0.502（95%CI： 0.195-1.293）, and 0.130（95%CI：0.017-0.972）, respectively. Urban school children showed the worst visual acuity. The school children in urban and suburban residential area had 2 and 3 times higher risk of developing the URE.
基金Supported by Hyderabad Eye Research Foundation,India and Christoffel-Blindenmission(CBM),Bensheim,Germany
文摘AIM： To report the prevalence and causes of unilateral visual impairment（UVI） in rural population of all ages in rural Andhra Pradesh, India.·METHODS： A population-based cross sectional study using a multi-stage cluster sampling methodology was carried out in West Godavari, Adilabad and Mahbubnagar districts in south India. A comprehensive eye examination that included presenting and best corrected visual acuity and dilated fundus examination was conducted by trained professionals. UVI is defined as presenting visual acuity 6/18 in one eye but ≥6/18 in other eye. Multiple logistic regression analysis was used to test association of UVI with socio-demographic risk factors.· RESULTS： Data were analyzed for 6634/7771 participants after excluding those with bilateral visual impairment. The mean age of the participants was 27.4y（Standard deviation： 17.9y）, 51.9% were women and49.1% were educated. The prevalence of UVI was 7.8%（95% CI： 7.2%- 8.5%）. Uncorrected refractive error（60.8%）, cataract（17.4%） and retinal causes（6.6%） were the leading causes of UVI. On multiple logistic regression analyses, older age, not having education, living in welloff district had significantly higher odds of being associated with UVI. UVI was not associated with gender.·CONCLUSION： UVI is common in rural south India.Most of it is due to cataract and refractive errors, both of which can be addressed at primary and secondary levelsof eye care. Burden of UVI should also be considered in planning eye care services.
文摘In visual cryptography, many shares are generated which are illogical containing certain message within themselves. When all shares are piled jointly, they tend to expose the secret of the image. The notion of visual secret sharing scheme is to encrypt a secret image into n illogical share images. It is unable to reveal any data on the original image if at least one of the shares is not achieved. The original image, in fact, is realized by overlapping the entire shares directly, in order that the human visual system is competent to identify the collective secret image without employing any complicated computational tools. Therefore, they are communicated steadily as number of shares. The elliptic curve cryptography approach, in turn, is employed to augment the privacy and safety of the image. The new.fangled technique is utilized to generate the multiple shares which are subjected to encryption and decryption by means of the elliptic curve cryptography technique. The test outcomes have revealed the fact that the peak signal to noise ratio is 58.0025, Mean square error value is 0.1164 and the correlation coefficient is 1 for the decrypted image without any sort of distortion of the original image.
文摘Introduction: WHO estimated that uncorrected refractive errors are the leading cause of visual impairment and second leading cause of blindness globally. University students are prone to developing refractive errors due to their curriculum that requires a lot of near work affecting their performance and quality of life unknowingly. Genetic and environmental factors are thought to play a role in the development of refractive errors. This study addresses the paucity of knowledge about refractive errors among university students in East Africa, providing a foundation for further research. Objectives: To determine the prevalence and factors associated with refractive errors among students in the Faculty of Medicine at Mbarara University of Science and Technology. Methodology: This was a cross-sectional descriptive and analytical study in which 368 undergraduate students selected using random sampling were assessed for refractive errors from March 2021-July 2021. Eligible participants were recruited and their VA assessment done after answering a questionnaire. Students whose VA improved on pin hole had subjective retinoscopy and results were compiled and imported to STATA 14 for analysis. Results: The prevalence of refractive errors was 26.36% with (95% CI) among university students especially myopia. Myopia is most predominant at 60%, followed by 37% Astigmatism and hyperopia of 3% among medical students. Astigmatism consisted of largely myopic astigmatism 72% (26) and 28% (10) compound/mixed astigmatism only. Student positive family history of refractive error was found to have a statistically significant relationship with refractive errors with AOR 1.68 (1.04 - 2.72) (95% CI) and P (0.032). Conclusion: The prevalence of refractive errors among university students, especially myopia, was found to be high and family history was associated with students having refractive errors.
