AIM:To investigate the prevalence of visual impairment(VI)and provide an estimation of uncorrected refractive errors in school-aged children,conducted by optometry students as a community service.METHODS:The study was...AIM:To investigate the prevalence of visual impairment(VI)and provide an estimation of uncorrected refractive errors in school-aged children,conducted by optometry students as a community service.METHODS:The study was cross-sectional.Totally 3343 participants were included in the study.The initial examination involved assessing the uncorrected distance visual acuity(UDVA)and visual acuity(VA)while using a+2.00 D lens.The inclusion criteria for a subsequent comprehensive cycloplegic eye examination,performed by an optometrist,were as follows:a UDVA<0.6 decimal(0.20 logMAR)and/or a VA with+2.00 D≥0.8 decimal(0.96 logMAR).RESULTS:The sample had a mean age of 10.92±2.13y(range 4 to 17y),and 51.3%of the children were female(n=1715).The majority of the children(89.7%)fell within the age range of 8 to 14y.Among the ethnic groups,the highest representation was from the Luhya group(60.6%)followed by Luo(20.4%).Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17(range 1.70 to 0.22).Out of the total,246 participants(7.4%)had a full eye examination.The estimated prevalence of myopia(defined as spherical equivalent≤-0.5 D)was found to be 1.45%of the total sample.While around 0.18%of the total sample had hyperopia value exceeding+1.75 D.Refractive astigmatism(cil<-0.75 D)was found in 0.21%(7/3343)of the children.The VI prevalence was 1.26%of the total sample.Among our cases of VI,76.2%could be attributed to uncorrected refractive error.Amblyopia was detected in 0.66%(22/3343)of the screened children.There was no statistically significant correlation observed between age or gender and refractive values.CONCLUSION:The primary cause of VI is determined to be uncorrected refractive errors,with myopia being the most prevalent refractive error observed.These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.展开更多
·AIM: To review existing data for the prevalence of corrected, uncorrected, and inadequately corrected refractive errors and spectacle wear in Hungary.·METHODS: Data from two nationwide cross-sectional studi...·AIM: To review existing data for the prevalence of corrected, uncorrected, and inadequately corrected refractive errors and spectacle wear in Hungary.·METHODS: Data from two nationwide cross-sectional studies were analysed. The Rapid Assessment of Avoidable Blindness study collected population-based representative national data on the prevalence of visual impairment due to uncorrected refractive errors and spectacle coverage in 3523 people aged ≥50y(Group I). The Comprehensive Health Test Program of Hungary provided data on the use of spectacles in 80 290 people aged ≥18y(Group Ⅱ).·RESULTS: In Group I, almost half of the survey population showed refractive errors for distant vision, about 10% of which were uncorrected(3.2% of all male participants and 5.0% of females). The distance spectacle coverage was 90.7%(91.9% in males;90.2% in females). The proportion of inadequate distance spectacles was found to be 33.1%. Uncorrected presbyopia was found in 15.7% of participants. In all age groups(Group Ⅱ), 65.4% of females and 56.0% of males used distance spectacles,and approximately 28.9% of these spectacles were found to be inappropriate for dioptric power(with 0.5 dioptres or more). The prevalence of inaccurate distance spectacles was significantly higher in older age groups(71y and above) in both sexes.·CONCLUSION: According to this population-based data, uncorrected refractive errors are not rare in Hungary. Despite recent national initiatives, fur ther steps are required to reduce uncorrected refractive errors and associated negative effects on vision, such as avoidable visual impairment.展开更多
AIM:To determine the prevalence of refractive error in 5-to 17-year-old schoolchildren in Puerto Rico.METHODS:A quantitative descriptive study of 2867 children aged 5 to 17y from all seven educational regions of Puert...AIM:To determine the prevalence of refractive error in 5-to 17-year-old schoolchildren in Puerto Rico.METHODS:A quantitative descriptive study of 2867 children aged 5 to 17y from all seven educational regions of Puerto Rico was conducted from 2016–2019.Refractive error was determined via static and subjective refraction.Children with distance acuity≤20/40 or near visual acuity≤20/32 had a cycloplegic refraction.Data analysis included descriptive statistics,correlation coefficient,Kruskal-Wallis,Chi-square,and t test calculations.RESULTS:Twenty percent of the children had a spherical equivalent refractive error≤-0.50 D,3.2%had a spherical equivalent≥+2.00 D,and 10.4%had astigmatism≥1 D.There was a statistically(but non-clinically)significant myopic change in spherical equivalent refractive error with age(P<0.001).The prevalence of myopia increased with age(P<0.001)but not hyperopia(P=0.59)or astigmatism(P=0.51).Males had a significantly higher hyperopic spherical equivalent than females(P<0.001).Females had a higher prevalence of myopia(P<0.001)than males,but there was no difference in the hyperopia(P=0.74)or astigmatism prevalence(P=0.87).CONCLUSION:The prevalence of a spherical equivalent equal to or less than-0.50 D(myopia,20.7%)is one of the highest among similar-aged children worldwide.Further studies should explore the rate of myopia progression in children in Puerto Rico.Individual children must be monitored to examine the need for treatment of myopia progression.展开更多
AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length(AL).METHODS: In this population-based cross-sectional study, the sampling wa...AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length(AL).METHODS: In this population-based cross-sectional study, the sampling was performed on individuals aged 60y and above in Tehran, Iran using a multi-stage stratified random cluster sampling method. Pseudophakic eyes with a best-corrected visual acuity of 20/32 or better were analyzed and their refractive results were reported.RESULTS: The mean spherical equivalent(SE) refraction was-0.34±0.97 diopters(D) and the mean absolute SE was 0.72±0.74 D with a median of 0.5 D. Moreover, 32.68%(n=546, 95%CI: 30.27%-35.08%), 53.67%(n=900, 95%CI: 51.23%-56.1%), 68.99%(n=1157, 95%CI: 66.96%-71.02%), and 79.73%(n=1337, 95%CI: 77.69%-81.76%) of the eyes had a residual SE within ±0.25, ±0.50, ±0.75, and ±1.00 D of emmetropia, respectively. According to the multiple logistic regression model, increasing age was associated with a statistically significant decrease in predictability for all cut points. Moreover, the predictability based on all cut points was significantly lower in individuals with an AL longer than 24.5 mm than in those with an AL between 22 to 24.5 mm.CONCLUSION: Based on the results, the accuracy of intraocular lens(IOL) power calculation is lower for those who underwent cataract surgery during the last 5y in Tehran, Iran. Among the most important influential factors, the choice of IOL or it's power disproportionate to eye conditions and age can be mentioned.展开更多
AIM: To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of refractive errors.METHODS: This is a cross-sectional study with convenience sampling whi...AIM: To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of refractive errors.METHODS: This is a cross-sectional study with convenience sampling which 120 patients were interviewed in a tertiary referral hospital in the Iranian health care system. The bottom-up based cost of illness approach was estimated using a face-to-face interview to assess the direct and indirect cost of different refractive errors correction of any correction technologies. RESULTS: Correction with spectacle imposes a total direct cost of US dollar (US$) 342.5 (±8.41) per year and US$9373.5 (±230.1) per lifetime to each patient. These figures for the contact lenses were obtained US$198.3 (±0.12) and US$5203.1 (±256.3) and for refractive surgery were obtained US$19.1 (±1.2) and US$568.1 (±64.6), respectively. Overall, based on age-adjusted prevalence rates, astigmatism had the highest share of refractive errors economic burden with a lifetime direct cost of slightly less than US$5.49 billion, while hyperopia and myopia imposed less than US$5.24 and 4.2 billion on patients, respectively. The annually imposed cost on each individual Iranian patient with refractive errors is US$308.5. CONCLUSION: Based on 18mo post refractive surgery course observation, which is generalized to whole life, refractive surgery significantly imposed much less cost compared with spectacles and contact lenses. Refractive errors among Iranians result in considerable economic burden. Using the refractive surgery instead of other two correction methods has the ability to reduce this economic loss in the future.展开更多
AIM: To determine the distribution of refractive errors in a school-age population in Quintana Roo(Mexico) in the framework of an international cooperation campaign for the prevention of blindness. METHODS: A sample o...AIM: To determine the distribution of refractive errors in a school-age population in Quintana Roo(Mexico) in the framework of an international cooperation campaign for the prevention of blindness. METHODS: A sample of 2647 school-age children(ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity(VA) and refractive errors. The first screening examination included uncorrected distance visual acuity(UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25(0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25.RESULTS: A total of 633(23.9%) children underwent the second complete eye examination. Mean logMAR UDVA was 0.035±0.094(range 1.00 to 0.00 logMAR) for the right eyes and 0.036±0.160(range 1.00 to 0.00 logMAR) for the left eyes. Bilateral amblyopia was found in 17 children(2.7% of refracted eyes;0.64% of the total). The main reason for visual impairment(VI) in the sample analyzed was found to be refractive errors. In 12 children(1.9% of refracted eyes;0.45% of the total) the VI was bilateral and 9(1.4% of refracted eyes;0.34% of the total) achieved a corrected distance visual acuity of 20/25 or better in both eyes. Mean magnitude of sphere and refractive cylinder was +0.20±0.96 D and-0.43±0.85 D in right eyes, and +0.24±1.08 and-0.43±0.83 D in left eyes. The proportion of myopic eyes [standard equivalent(SE) ≤-0.50 D] was 4.6% of the whole sample(5290 eyes). The mean magnitude of myopia was-0.84±3.44 D for the right eyes and-0.82±5.21 D for the left eyes. The proportion of hyperopic patients(SE≥+2.00 D) was 2.4%(15/633), which corresponded to 0.60% of the whole sample(32/5290 eyes). No statistically significant correlation of age to manifest sphere or cylinder was found.CONCLUSION: VI due to uncorrected refractive errors can be easily corrected with glasses but it is still a burden to be treated. Myopia is prevalent in this sample. More efforts towards correcting uncorrected refractive errors are needed.展开更多
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
AIM: To examine the refractive prediction error in high myopic eyes after phacovitrectomy.METHODS: This retrospective comparative case series included 91 eyes(18 high myopic eyes and 73 non-high myopic eyes) of 91 pat...AIM: To examine the refractive prediction error in high myopic eyes after phacovitrectomy.METHODS: This retrospective comparative case series included 91 eyes(18 high myopic eyes and 73 non-high myopic eyes) of 91 patients who underwent successful phacovitrectomy(phacoemulsification, intraocular lens implantation, and pars plana vitrectomy). The high myopic eyes were defined as the eye with more than 26.0mm of axial length. The postoperative prediction error of mean error and mean absolute error were evaluated at4 mo postoperatively. Axial length and keratometry measurement were performed preoperatively and 4mo postoperatively using the IOL Master.RESULTS: The refractive outcome after phacovitrectomy showed significantly greater myopic shift in the high myopic eyes [-1.08 ±0.87 diopters(D)] than that in the non-high myopic eyes(-0.43 ±0.63 D, P =0.004). Axial length and keratometric value in the high myopic eyes were significantly increased(P =0.043, 0.037 respectively),whereas those in the non-high myopic group were not significantly increased(P =0.135, 0.347 respectively). The change of the axial length in the myopic eye(0.46±0.28 mm)was greater than that in the non- high myopic eye(0.11 ± 0.34 mm; P 【0.001).CONCLUSION: High myopic eyes showed more myopic shift than non-high myopic eyes after phacovitrectomy.The cause of myopic shift in high myopic eyes seems tobe attributed to actual elongation of the axial length in high myopia.展开更多
The multiple regression formulas and correlation of ocular components with refractive errors are presented by Gaussian optics. The refractive error changing rate for the cornea and lens power, the axial length, anteri...The multiple regression formulas and correlation of ocular components with refractive errors are presented by Gaussian optics. The refractive error changing rate for the cornea and lens power, the axial length, anterior chamber depth(ACD) and vitreous chamber depth(VCD) are calculated, including nonlinear terms for more accurate rate functions than the linear theory. Our theory, consistent with the empirical data, shows that the Pearson correlation coefficients for spherical equivalent(SE) and ocular components are highest for SE with axial length, ACD and VCD and weakest for corneal power, lens power and lens thickness. Moreover, our regression formulas show the asymmetric feature of the correlation that the axial length, ACD and VCD are more strongly correlated(with higher negative regression constants) with refractive errors in eyes with hyperopia than in eyes with myopia, particularly for severe hyperopia.展开更多
AIM: To investigate the effect of capsular tension ring(CTR) implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation(PEX) syndrome.METHODS: This double-blind randomized cli...AIM: To investigate the effect of capsular tension ring(CTR) implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation(PEX) syndrome.METHODS: This double-blind randomized clinical trial was conducted on 60 patients with PEX syndrome referring to Imam Khomeini Hospital affiliated to Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, for undergoing cataract surgery. The study population was divided into two groups, namely CTR group(n=30) and non-CTR group(control group;n=30). The refractive error and anterior chamber depth(ACD) were measured 1 wk, 1 mo, and 3 mo after phacoemulsification(PE) surgery.RESULTS: The results indicated no statistically significant difference between the two groups in terms of predicted refractive error(obtained by subtracting preoperative predicted refractive error from actual postoperative refractive error) 1 wk(P=0.47), 1 mo(P=0.30), and 3 mo(P=0.06) after the PE surgery. Regarding the CTR group, the changes of ACD was statistically significant 1 and 3 mo after the PE surgery, compared to those obtained 1 wk post-surgery(P=0.005).CONCLUSION: The CTR implantation in PEX cataractous patients without zonulysis has no statistically significant effect on the predicted refraction and ACD changes after PE. The predicted refraction error has a hyperopic shift in both groups. The results reveal the unnecessary of calculating modified IOL in CTR implantation.展开更多
AIM:To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. METHODS:Refractive data from 676 856 patients aged 6 to 90 y were...AIM:To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. METHODS:Refractive data from 676 856 patients aged 6 to 90 y were collected from optometry clinics in fourteen states of Mexico between 2014 and 2015. The refractive errors were classified by the spherical equivalent(SE), as follows:sphere+? cylinder. Myopia(SE〉-0.50 D), hyperopia(SE〉+0.50 D), emmetropia(-0.50≤SE≤+0.50), and astigmatism alone(cylinder≥-0.25 D). A negative cylinder was selected as a notation.RESULTS:The proportion(95% confidence interval) among all of the subjects was hyperopia 21.0%(20.9-21.0), emmetropia 40.7%(40.5-40.8), myopia 24.8%(24.7-24.9) and astigmatism alone 13.5%(13.4-13.5). Myopia was the most common refractive error and frequency seemed to increase among the young population(10 to 29 years old), however, hyperopia increased among the aging population(40 to 79 years old), and astigmatism alone showed a decreasing trend with age(6 to 90y; from 19.7% to 10.8%). There was a relationship between age and all refractive errors(approximately 60%, aged 50 and older). The proportion of any clinically important refractive error was higher in males(61.2%) than in females(58.3%; P〈0.0001). From fourteen states that collected information, the proportion of refractive error showed variability in different geographical areas of Mexico.CONCLUSION:Myopia is the most common refractive error in the population studied. This study provides the first data on refractive error in Mexico. Further programs and studies must be developed to address the refractive errors needs of the Mexican population.展开更多
AIM:To examine the prevalence and composition of refractive errors in Hungary.METHODS:Nationwide cross-sectional data collected between 2014 and 2019 were analysed from the Comprehensive Health Screening Program of Hu...AIM:To examine the prevalence and composition of refractive errors in Hungary.METHODS:Nationwide cross-sectional data collected between 2014 and 2019 were analysed from the Comprehensive Health Screening Program of Hungary,which provided spectacle dioptric power and autorefractometry data for 68227 people(35850 women and 32377 men).Their age distribution,18-99y,was similar to the national demographic distributions.RESULTS:Of the total population,16.50%of the refractive errors exhibited hyperopia,40.05%emmetropia,and 43.45%myopia.Myopia was 3 times more frequent(58.7%)in younger ages(18-35y of age)compared to older age groups(19.4%of those 56-70y of age;P<0.001).High myopia showed a low prevalence(0.21%),and an increase parallel with ageing(r=0.716;P=0.009).CONCLUSION:Myopia is the most frequent refractive error in Hungary.The prevalence of myopia is especially increased,up to 2-3 times,in the younger age groups.Nationwide actions need to be taken to reduce the onset of myopia and its associated consequences.展开更多
AIM:To evaluate the prevalence of refractive errors and ocular biometry in 3573 freshman students at Tianjin Medical University for 4 consecutive years.METHODS:In this university-based, cross-sectional study, comprisi...AIM:To evaluate the prevalence of refractive errors and ocular biometry in 3573 freshman students at Tianjin Medical University for 4 consecutive years.METHODS:In this university-based, cross-sectional study, comprising 3573 students, visual acuity(VA), slitlamp examination, non-cycloplegic auto-refraction, and ocular biometry were recorded.RESULTS:The prevalence of myopia increased annually, from 2017 to 2020 were 93.5%, 94.5%, 95.9%, and 96.2%, respectively(P=0.03), and the prevalence of high myopia was 25.7%, 26.9%, 28.6%, and 28.6%, respectively. Males tended to have a higher percentage of total astigmatism than females, with astigmatism ≥0.75 and ≥1.0 D criteria. The percentage of with-the-rule astigmatism, against-therule astigmatism, and oblique astigmatism was 90.3%, 5.8%, and 3.9%, respectively, with astigmatism ≥1.00 D criteria. The mean spherical equivalent, axial length(AL), central corneal thickness(CCT), anterior chamber depth(ACD), lens thickness(LT), corneal radius(CR), and lens position(LP) were 4.37±2.52 D, 25.28±1.24 mm, 539.49±34.98 μm, 3.31±0.34 mm, 3.47±0.21 mm, 7.8±0.28 mm, and 5.04±0.32 mm, respectively. With diopter increase in myopia, the AL became longer, CR became steeper, ACD became deeper, LT became thinner, and LP became more posterior(all P<0.01). Females had a shorter AL, thinner CCT, smaller CR, shallower ACD, thicker lens, and more anterior LP than males(P<0.01). The 64% of high myopia had AL≥26 mm, meanwhile, 5.8% mild myopia and 21.1% moderate myopia had AL≥26 mm. With AL≥26 mm, mild and moderate myopia compared to high myopia, AL was shorter(26.51±0.46 vs 26.87±0.70 mm), CR was larger(8.10±0.3 vs 7.85±0.23 mm) and LT was thinner(3.39±0.19 vs 3.45±0.19 mm, P<0.001).CONCLUSION:The prevalence of myopia and high myopia is significantly high in freshman students. The majority of astigmatism is with-the-rule. Inconformity of refractive errors and ocular biometry existed in some students. Attention should be paid to the ocular biometry of myopia.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
Objective: To determine the prevalence of refractive errors among primary school children in Zahedan District, Southeastern Iran, as a tropical area.Methods: In this cross sectional study, a total of 400 students were...Objective: To determine the prevalence of refractive errors among primary school children in Zahedan District, Southeastern Iran, as a tropical area.Methods: In this cross sectional study, a total of 400 students were selected randomly using multi-stage sampling technique. Myopia was defined as spherical equivalent(SE)of-0.5 diopter(D) or more, hyperopia was defined as SE of +2.00 D or more and a cylinder refraction greater than 0.75 D was considered astigmatism. Anisometropia was defined as a difference of 1 D or more between two eyes. Cycloplegic refractive status was measured using auto-refractometer(Topcon 8800). Data were analyzed using SPSS,version 22 software program.Results: Mean ± SD of SE was(1.71 ± 1.16) D. A total of 20 students [6.3%, 95%confidence interval(CI): 3.96%–9.64%] were myopic(-0.5 D), 186 students(58.1%,95% CI: 52.50%–63.56%) were hyperopic( +2.00 D) and 114 students(35.6%, 95%CI: 30.43%–41.18%) were emmetropic. The prevalence of astigmatism( 0.75 D)among students was 3.4%(95% CI: 1.82%–6.25%). Anisometropia of 1 D or more was found in 21.3%(95% CI: 16.98%–26.23%) of the studied population. The prevalence of refractive errors was higher among girls than boys(73.1% vs. 55.6%, P = 0.001), but it was not significantly different among different age groups(P = 0.790).Conclusions: Refractive errors affect a sizable portion of students in Zahedan. Although myopia is not very prevalent, the high rate of hyperopia in the studied population emphasizes its need for attention.展开更多
In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper,...In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper, the complementary error function is proposed instead of the cubic spline function as the transition zone function, due to the availability of analytical expression of its derivatives and the nonnegativity fact. It is shown that with the use of the complementary error function, transition zones for all refractive types work correctly.展开更多
Purpose:The aim of this paper was to examine the distribution of macular,retinal nerve fiber layer(RNFL)thickness and optic disc parameters of myopic and hyperopic eyes in comparison withemmetropic control eyes and to...Purpose:The aim of this paper was to examine the distribution of macular,retinal nerve fiber layer(RNFL)thickness and optic disc parameters of myopic and hyperopic eyes in comparison withemmetropic control eyes and to investigate their variation according to axial length(AL)andspherical equivalent(SE)in healthy children.Methods:This study included 293 pairs of eyes of 293children(145 boys and 148 girks),ranging in age from 6 to 17 years,Subjects were dividedaccording to SE in control(emmetropia,99 children),myopia(100 children)and hyperopia(94children)groups and according to axial AL in 68 short(<22.00 mm,68),medium(from≥22.00 mmto 25.00 mm,189)and long eyes(>25.00 mm,36).Macular parameters,RNFL thickness and opticdisc morphology were assessed by the Cirrus^(TM) HD-OCT.AL was measured using the IOL-Mastersystem.Littmann's formula was used for calculating the corrected AL-related ocular magnification.Results Mean age(±SD)was 10.84±3.05 years;mean(±SD)SE was+0.14±0.51 D(range from8.75 to+8.25 D)and mean AL(±SD)was 23.12±1.49.Average RNFL thickness,averagemacular thickness and macular volume decreased as AL and myopia increased.No correlationsbetween AL/SE and optic disc parameters were found after correcting for magnification effect.Conclusions:AL and refractive error affect measurements of macular and RNFL thickness inhealthy children.To make a correct interpretation of ocT measurements,ocular magnificationeffect should be taken into account by clinicians or OCT manufacturers.展开更多
This study is a retrospective analysis of data stored digitally for 13 years in a Vision Center located in the urban area of Tirana, Albania. In a population of 19,686 people (39.5% M and 60.5% F) who met the criteria...This study is a retrospective analysis of data stored digitally for 13 years in a Vision Center located in the urban area of Tirana, Albania. In a population of 19,686 people (39.5% M and 60.5% F) who met the criteria, there was a prevalence of astigmatism 42% (12% only astigmatism, 30% associated with hyperopia or myopia), myopia 25%, hyperopia 22% and 24% presbyopic prescriptions for the medium and near distance. The myopia progression study (mean spherical equivalent) indicates that 20% of people had no change, 42% had an increase in myopic correction from 0.25D to 0.50D, 17% from 0.75D to 1.00D, 11% from 1.25D to 1.50D, 5% from 1.75D to 2.00D and 5% of the population had myopic progression greater than 2.00D.展开更多
Between 2011 and 2013,two large-scale cohort epidemiology studies were launched in Shanghai:the SCALE study,which aimed to provide ocular public health services to cover the entire youth population in Shanghai,and the...Between 2011 and 2013,two large-scale cohort epidemiology studies were launched in Shanghai:the SCALE study,which aimed to provide ocular public health services to cover the entire youth population in Shanghai,and the SCES,which was based on sample surveys and aimed to provide information on the prevalence and incidence of visual impairment and different types of refractive errors.A total of 910,245 children and adolescents were finally enrolled in the SCALE study;three possible methods for monitoring refractive error without mydriasis were tested,and the agreement between the refractive outcomes of three commonly used autorefractors were examined to ensure the accuracy of the results of the SCALE study.A total of 8,627 children were enrolled in the SCES,and the baseline prevalence of different refractive errors,different behaviors associated with 1 year myopic shifts,and the different patterns of 2-year myopia progression between internal migrant and local resident school children have been analyzed.In some subset samples of the SCALE study and the SCES,several refraction components such as choroidal thickness(ChT)and crystalline lens power were also measured,to further elucidate the relationships between the refraction components and myopia as well as the mechanism of myopia incidence and development.The three methods used in Shanghai to prevent and intervene with childhood myopia:increasing outdoor time,low concentration atropine,and use of orthokeratology lens are also addressed in this review.展开更多
文摘AIM:To investigate the prevalence of visual impairment(VI)and provide an estimation of uncorrected refractive errors in school-aged children,conducted by optometry students as a community service.METHODS:The study was cross-sectional.Totally 3343 participants were included in the study.The initial examination involved assessing the uncorrected distance visual acuity(UDVA)and visual acuity(VA)while using a+2.00 D lens.The inclusion criteria for a subsequent comprehensive cycloplegic eye examination,performed by an optometrist,were as follows:a UDVA<0.6 decimal(0.20 logMAR)and/or a VA with+2.00 D≥0.8 decimal(0.96 logMAR).RESULTS:The sample had a mean age of 10.92±2.13y(range 4 to 17y),and 51.3%of the children were female(n=1715).The majority of the children(89.7%)fell within the age range of 8 to 14y.Among the ethnic groups,the highest representation was from the Luhya group(60.6%)followed by Luo(20.4%).Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17(range 1.70 to 0.22).Out of the total,246 participants(7.4%)had a full eye examination.The estimated prevalence of myopia(defined as spherical equivalent≤-0.5 D)was found to be 1.45%of the total sample.While around 0.18%of the total sample had hyperopia value exceeding+1.75 D.Refractive astigmatism(cil<-0.75 D)was found in 0.21%(7/3343)of the children.The VI prevalence was 1.26%of the total sample.Among our cases of VI,76.2%could be attributed to uncorrected refractive error.Amblyopia was detected in 0.66%(22/3343)of the screened children.There was no statistically significant correlation observed between age or gender and refractive values.CONCLUSION:The primary cause of VI is determined to be uncorrected refractive errors,with myopia being the most prevalent refractive error observed.These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.
基金The RAAB survey was supported by the Lions Clubs International Foundation (LCIF) Sight First Research Grant Program (No.SF 1825/UND)。
文摘·AIM: To review existing data for the prevalence of corrected, uncorrected, and inadequately corrected refractive errors and spectacle wear in Hungary.·METHODS: Data from two nationwide cross-sectional studies were analysed. The Rapid Assessment of Avoidable Blindness study collected population-based representative national data on the prevalence of visual impairment due to uncorrected refractive errors and spectacle coverage in 3523 people aged ≥50y(Group I). The Comprehensive Health Test Program of Hungary provided data on the use of spectacles in 80 290 people aged ≥18y(Group Ⅱ).·RESULTS: In Group I, almost half of the survey population showed refractive errors for distant vision, about 10% of which were uncorrected(3.2% of all male participants and 5.0% of females). The distance spectacle coverage was 90.7%(91.9% in males;90.2% in females). The proportion of inadequate distance spectacles was found to be 33.1%. Uncorrected presbyopia was found in 15.7% of participants. In all age groups(Group Ⅱ), 65.4% of females and 56.0% of males used distance spectacles,and approximately 28.9% of these spectacles were found to be inappropriate for dioptric power(with 0.5 dioptres or more). The prevalence of inaccurate distance spectacles was significantly higher in older age groups(71y and above) in both sexes.·CONCLUSION: According to this population-based data, uncorrected refractive errors are not rare in Hungary. Despite recent national initiatives, fur ther steps are required to reduce uncorrected refractive errors and associated negative effects on vision, such as avoidable visual impairment.
基金Supported by the Lions Clubs International Foundation(No.SF1757/UND)。
文摘AIM:To determine the prevalence of refractive error in 5-to 17-year-old schoolchildren in Puerto Rico.METHODS:A quantitative descriptive study of 2867 children aged 5 to 17y from all seven educational regions of Puerto Rico was conducted from 2016–2019.Refractive error was determined via static and subjective refraction.Children with distance acuity≤20/40 or near visual acuity≤20/32 had a cycloplegic refraction.Data analysis included descriptive statistics,correlation coefficient,Kruskal-Wallis,Chi-square,and t test calculations.RESULTS:Twenty percent of the children had a spherical equivalent refractive error≤-0.50 D,3.2%had a spherical equivalent≥+2.00 D,and 10.4%had astigmatism≥1 D.There was a statistically(but non-clinically)significant myopic change in spherical equivalent refractive error with age(P<0.001).The prevalence of myopia increased with age(P<0.001)but not hyperopia(P=0.59)or astigmatism(P=0.51).Males had a significantly higher hyperopic spherical equivalent than females(P<0.001).Females had a higher prevalence of myopia(P<0.001)than males,but there was no difference in the hyperopia(P=0.74)or astigmatism prevalence(P=0.87).CONCLUSION:The prevalence of a spherical equivalent equal to or less than-0.50 D(myopia,20.7%)is one of the highest among similar-aged children worldwide.Further studies should explore the rate of myopia progression in children in Puerto Rico.Individual children must be monitored to examine the need for treatment of myopia progression.
基金Supported by National Institute for Medical Research Development (NIMAD) affiliated with the Iranian Ministry of Health and Medical Education (No.963660)。
文摘AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length(AL).METHODS: In this population-based cross-sectional study, the sampling was performed on individuals aged 60y and above in Tehran, Iran using a multi-stage stratified random cluster sampling method. Pseudophakic eyes with a best-corrected visual acuity of 20/32 or better were analyzed and their refractive results were reported.RESULTS: The mean spherical equivalent(SE) refraction was-0.34±0.97 diopters(D) and the mean absolute SE was 0.72±0.74 D with a median of 0.5 D. Moreover, 32.68%(n=546, 95%CI: 30.27%-35.08%), 53.67%(n=900, 95%CI: 51.23%-56.1%), 68.99%(n=1157, 95%CI: 66.96%-71.02%), and 79.73%(n=1337, 95%CI: 77.69%-81.76%) of the eyes had a residual SE within ±0.25, ±0.50, ±0.75, and ±1.00 D of emmetropia, respectively. According to the multiple logistic regression model, increasing age was associated with a statistically significant decrease in predictability for all cut points. Moreover, the predictability based on all cut points was significantly lower in individuals with an AL longer than 24.5 mm than in those with an AL between 22 to 24.5 mm.CONCLUSION: Based on the results, the accuracy of intraocular lens(IOL) power calculation is lower for those who underwent cataract surgery during the last 5y in Tehran, Iran. Among the most important influential factors, the choice of IOL or it's power disproportionate to eye conditions and age can be mentioned.
基金Supported partially by Hormoz Chams Research Chair in Public Health Ophthalmology,Allama Tabatabaei Award,National Elite Foundation(http://bmn.ir/)
文摘AIM: To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of refractive errors.METHODS: This is a cross-sectional study with convenience sampling which 120 patients were interviewed in a tertiary referral hospital in the Iranian health care system. The bottom-up based cost of illness approach was estimated using a face-to-face interview to assess the direct and indirect cost of different refractive errors correction of any correction technologies. RESULTS: Correction with spectacle imposes a total direct cost of US dollar (US$) 342.5 (±8.41) per year and US$9373.5 (±230.1) per lifetime to each patient. These figures for the contact lenses were obtained US$198.3 (±0.12) and US$5203.1 (±256.3) and for refractive surgery were obtained US$19.1 (±1.2) and US$568.1 (±64.6), respectively. Overall, based on age-adjusted prevalence rates, astigmatism had the highest share of refractive errors economic burden with a lifetime direct cost of slightly less than US$5.49 billion, while hyperopia and myopia imposed less than US$5.24 and 4.2 billion on patients, respectively. The annually imposed cost on each individual Iranian patient with refractive errors is US$308.5. CONCLUSION: Based on 18mo post refractive surgery course observation, which is generalized to whole life, refractive surgery significantly imposed much less cost compared with spectacles and contact lenses. Refractive errors among Iranians result in considerable economic burden. Using the refractive surgery instead of other two correction methods has the ability to reduce this economic loss in the future.
文摘AIM: To determine the distribution of refractive errors in a school-age population in Quintana Roo(Mexico) in the framework of an international cooperation campaign for the prevention of blindness. METHODS: A sample of 2647 school-age children(ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity(VA) and refractive errors. The first screening examination included uncorrected distance visual acuity(UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25(0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25.RESULTS: A total of 633(23.9%) children underwent the second complete eye examination. Mean logMAR UDVA was 0.035±0.094(range 1.00 to 0.00 logMAR) for the right eyes and 0.036±0.160(range 1.00 to 0.00 logMAR) for the left eyes. Bilateral amblyopia was found in 17 children(2.7% of refracted eyes;0.64% of the total). The main reason for visual impairment(VI) in the sample analyzed was found to be refractive errors. In 12 children(1.9% of refracted eyes;0.45% of the total) the VI was bilateral and 9(1.4% of refracted eyes;0.34% of the total) achieved a corrected distance visual acuity of 20/25 or better in both eyes. Mean magnitude of sphere and refractive cylinder was +0.20±0.96 D and-0.43±0.85 D in right eyes, and +0.24±1.08 and-0.43±0.83 D in left eyes. The proportion of myopic eyes [standard equivalent(SE) ≤-0.50 D] was 4.6% of the whole sample(5290 eyes). The mean magnitude of myopia was-0.84±3.44 D for the right eyes and-0.82±5.21 D for the left eyes. The proportion of hyperopic patients(SE≥+2.00 D) was 2.4%(15/633), which corresponded to 0.60% of the whole sample(32/5290 eyes). No statistically significant correlation of age to manifest sphere or cylinder was found.CONCLUSION: VI due to uncorrected refractive errors can be easily corrected with glasses but it is still a burden to be treated. Myopia is prevalent in this sample. More efforts towards correcting uncorrected refractive errors are needed.
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.
文摘AIM: To examine the refractive prediction error in high myopic eyes after phacovitrectomy.METHODS: This retrospective comparative case series included 91 eyes(18 high myopic eyes and 73 non-high myopic eyes) of 91 patients who underwent successful phacovitrectomy(phacoemulsification, intraocular lens implantation, and pars plana vitrectomy). The high myopic eyes were defined as the eye with more than 26.0mm of axial length. The postoperative prediction error of mean error and mean absolute error were evaluated at4 mo postoperatively. Axial length and keratometry measurement were performed preoperatively and 4mo postoperatively using the IOL Master.RESULTS: The refractive outcome after phacovitrectomy showed significantly greater myopic shift in the high myopic eyes [-1.08 ±0.87 diopters(D)] than that in the non-high myopic eyes(-0.43 ±0.63 D, P =0.004). Axial length and keratometric value in the high myopic eyes were significantly increased(P =0.043, 0.037 respectively),whereas those in the non-high myopic group were not significantly increased(P =0.135, 0.347 respectively). The change of the axial length in the myopic eye(0.46±0.28 mm)was greater than that in the non- high myopic eye(0.11 ± 0.34 mm; P 【0.001).CONCLUSION: High myopic eyes showed more myopic shift than non-high myopic eyes after phacovitrectomy.The cause of myopic shift in high myopic eyes seems tobe attributed to actual elongation of the axial length in high myopia.
基金Supported by an Internal Research of New Vision Inc. and Nobel Eye Institute
文摘The multiple regression formulas and correlation of ocular components with refractive errors are presented by Gaussian optics. The refractive error changing rate for the cornea and lens power, the axial length, anterior chamber depth(ACD) and vitreous chamber depth(VCD) are calculated, including nonlinear terms for more accurate rate functions than the linear theory. Our theory, consistent with the empirical data, shows that the Pearson correlation coefficients for spherical equivalent(SE) and ocular components are highest for SE with axial length, ACD and VCD and weakest for corneal power, lens power and lens thickness. Moreover, our regression formulas show the asymmetric feature of the correlation that the axial length, ACD and VCD are more strongly correlated(with higher negative regression constants) with refractive errors in eyes with hyperopia than in eyes with myopia, particularly for severe hyperopia.
基金Supported by the Research Deputy of Ahvaz Jundishapur University of Medical Sciences,Ahvaz,Iran。
文摘AIM: To investigate the effect of capsular tension ring(CTR) implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation(PEX) syndrome.METHODS: This double-blind randomized clinical trial was conducted on 60 patients with PEX syndrome referring to Imam Khomeini Hospital affiliated to Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, for undergoing cataract surgery. The study population was divided into two groups, namely CTR group(n=30) and non-CTR group(control group;n=30). The refractive error and anterior chamber depth(ACD) were measured 1 wk, 1 mo, and 3 mo after phacoemulsification(PE) surgery.RESULTS: The results indicated no statistically significant difference between the two groups in terms of predicted refractive error(obtained by subtracting preoperative predicted refractive error from actual postoperative refractive error) 1 wk(P=0.47), 1 mo(P=0.30), and 3 mo(P=0.06) after the PE surgery. Regarding the CTR group, the changes of ACD was statistically significant 1 and 3 mo after the PE surgery, compared to those obtained 1 wk post-surgery(P=0.005).CONCLUSION: The CTR implantation in PEX cataractous patients without zonulysis has no statistically significant effect on the predicted refraction and ACD changes after PE. The predicted refraction error has a hyperopic shift in both groups. The results reveal the unnecessary of calculating modified IOL in CTR implantation.
基金sponsored by the Salud Digna Para Todos, I.A.P. and PROMEP/2014 DSA/103.5/14/11063--, Folio UAS-PTC-121-(JVR)
文摘AIM:To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. METHODS:Refractive data from 676 856 patients aged 6 to 90 y were collected from optometry clinics in fourteen states of Mexico between 2014 and 2015. The refractive errors were classified by the spherical equivalent(SE), as follows:sphere+? cylinder. Myopia(SE〉-0.50 D), hyperopia(SE〉+0.50 D), emmetropia(-0.50≤SE≤+0.50), and astigmatism alone(cylinder≥-0.25 D). A negative cylinder was selected as a notation.RESULTS:The proportion(95% confidence interval) among all of the subjects was hyperopia 21.0%(20.9-21.0), emmetropia 40.7%(40.5-40.8), myopia 24.8%(24.7-24.9) and astigmatism alone 13.5%(13.4-13.5). Myopia was the most common refractive error and frequency seemed to increase among the young population(10 to 29 years old), however, hyperopia increased among the aging population(40 to 79 years old), and astigmatism alone showed a decreasing trend with age(6 to 90y; from 19.7% to 10.8%). There was a relationship between age and all refractive errors(approximately 60%, aged 50 and older). The proportion of any clinically important refractive error was higher in males(61.2%) than in females(58.3%; P〈0.0001). From fourteen states that collected information, the proportion of refractive error showed variability in different geographical areas of Mexico.CONCLUSION:Myopia is the most common refractive error in the population studied. This study provides the first data on refractive error in Mexico. Further programs and studies must be developed to address the refractive errors needs of the Mexican population.
文摘AIM:To examine the prevalence and composition of refractive errors in Hungary.METHODS:Nationwide cross-sectional data collected between 2014 and 2019 were analysed from the Comprehensive Health Screening Program of Hungary,which provided spectacle dioptric power and autorefractometry data for 68227 people(35850 women and 32377 men).Their age distribution,18-99y,was similar to the national demographic distributions.RESULTS:Of the total population,16.50%of the refractive errors exhibited hyperopia,40.05%emmetropia,and 43.45%myopia.Myopia was 3 times more frequent(58.7%)in younger ages(18-35y of age)compared to older age groups(19.4%of those 56-70y of age;P<0.001).High myopia showed a low prevalence(0.21%),and an increase parallel with ageing(r=0.716;P=0.009).CONCLUSION:Myopia is the most frequent refractive error in Hungary.The prevalence of myopia is especially increased,up to 2-3 times,in the younger age groups.Nationwide actions need to be taken to reduce the onset of myopia and its associated consequences.
基金Science&Technology Development Fund of Tianjin Education Commission for Higher Education of China (No.2018KJ056)。
文摘AIM:To evaluate the prevalence of refractive errors and ocular biometry in 3573 freshman students at Tianjin Medical University for 4 consecutive years.METHODS:In this university-based, cross-sectional study, comprising 3573 students, visual acuity(VA), slitlamp examination, non-cycloplegic auto-refraction, and ocular biometry were recorded.RESULTS:The prevalence of myopia increased annually, from 2017 to 2020 were 93.5%, 94.5%, 95.9%, and 96.2%, respectively(P=0.03), and the prevalence of high myopia was 25.7%, 26.9%, 28.6%, and 28.6%, respectively. Males tended to have a higher percentage of total astigmatism than females, with astigmatism ≥0.75 and ≥1.0 D criteria. The percentage of with-the-rule astigmatism, against-therule astigmatism, and oblique astigmatism was 90.3%, 5.8%, and 3.9%, respectively, with astigmatism ≥1.00 D criteria. The mean spherical equivalent, axial length(AL), central corneal thickness(CCT), anterior chamber depth(ACD), lens thickness(LT), corneal radius(CR), and lens position(LP) were 4.37±2.52 D, 25.28±1.24 mm, 539.49±34.98 μm, 3.31±0.34 mm, 3.47±0.21 mm, 7.8±0.28 mm, and 5.04±0.32 mm, respectively. With diopter increase in myopia, the AL became longer, CR became steeper, ACD became deeper, LT became thinner, and LP became more posterior(all P<0.01). Females had a shorter AL, thinner CCT, smaller CR, shallower ACD, thicker lens, and more anterior LP than males(P<0.01). The 64% of high myopia had AL≥26 mm, meanwhile, 5.8% mild myopia and 21.1% moderate myopia had AL≥26 mm. With AL≥26 mm, mild and moderate myopia compared to high myopia, AL was shorter(26.51±0.46 vs 26.87±0.70 mm), CR was larger(8.10±0.3 vs 7.85±0.23 mm) and LT was thinner(3.39±0.19 vs 3.45±0.19 mm, P<0.001).CONCLUSION:The prevalence of myopia and high myopia is significantly high in freshman students. The majority of astigmatism is with-the-rule. Inconformity of refractive errors and ocular biometry existed in some students. Attention should be paid to the ocular biometry of myopia.
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 Zahedan University of Medical Sciences(Grant No.91-506)
文摘Objective: To determine the prevalence of refractive errors among primary school children in Zahedan District, Southeastern Iran, as a tropical area.Methods: In this cross sectional study, a total of 400 students were selected randomly using multi-stage sampling technique. Myopia was defined as spherical equivalent(SE)of-0.5 diopter(D) or more, hyperopia was defined as SE of +2.00 D or more and a cylinder refraction greater than 0.75 D was considered astigmatism. Anisometropia was defined as a difference of 1 D or more between two eyes. Cycloplegic refractive status was measured using auto-refractometer(Topcon 8800). Data were analyzed using SPSS,version 22 software program.Results: Mean ± SD of SE was(1.71 ± 1.16) D. A total of 20 students [6.3%, 95%confidence interval(CI): 3.96%–9.64%] were myopic(-0.5 D), 186 students(58.1%,95% CI: 52.50%–63.56%) were hyperopic( +2.00 D) and 114 students(35.6%, 95%CI: 30.43%–41.18%) were emmetropic. The prevalence of astigmatism( 0.75 D)among students was 3.4%(95% CI: 1.82%–6.25%). Anisometropia of 1 D or more was found in 21.3%(95% CI: 16.98%–26.23%) of the studied population. The prevalence of refractive errors was higher among girls than boys(73.1% vs. 55.6%, P = 0.001), but it was not significantly different among different age groups(P = 0.790).Conclusions: Refractive errors affect a sizable portion of students in Zahedan. Although myopia is not very prevalent, the high rate of hyperopia in the studied population emphasizes its need for attention.
文摘In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper, the complementary error function is proposed instead of the cubic spline function as the transition zone function, due to the availability of analytical expression of its derivatives and the nonnegativity fact. It is shown that with the use of the complementary error function, transition zones for all refractive types work correctly.
文摘Purpose:The aim of this paper was to examine the distribution of macular,retinal nerve fiber layer(RNFL)thickness and optic disc parameters of myopic and hyperopic eyes in comparison withemmetropic control eyes and to investigate their variation according to axial length(AL)andspherical equivalent(SE)in healthy children.Methods:This study included 293 pairs of eyes of 293children(145 boys and 148 girks),ranging in age from 6 to 17 years,Subjects were dividedaccording to SE in control(emmetropia,99 children),myopia(100 children)and hyperopia(94children)groups and according to axial AL in 68 short(<22.00 mm,68),medium(from≥22.00 mmto 25.00 mm,189)and long eyes(>25.00 mm,36).Macular parameters,RNFL thickness and opticdisc morphology were assessed by the Cirrus^(TM) HD-OCT.AL was measured using the IOL-Mastersystem.Littmann's formula was used for calculating the corrected AL-related ocular magnification.Results Mean age(±SD)was 10.84±3.05 years;mean(±SD)SE was+0.14±0.51 D(range from8.75 to+8.25 D)and mean AL(±SD)was 23.12±1.49.Average RNFL thickness,averagemacular thickness and macular volume decreased as AL and myopia increased.No correlationsbetween AL/SE and optic disc parameters were found after correcting for magnification effect.Conclusions:AL and refractive error affect measurements of macular and RNFL thickness inhealthy children.To make a correct interpretation of ocT measurements,ocular magnificationeffect should be taken into account by clinicians or OCT manufacturers.
文摘This study is a retrospective analysis of data stored digitally for 13 years in a Vision Center located in the urban area of Tirana, Albania. In a population of 19,686 people (39.5% M and 60.5% F) who met the criteria, there was a prevalence of astigmatism 42% (12% only astigmatism, 30% associated with hyperopia or myopia), myopia 25%, hyperopia 22% and 24% presbyopic prescriptions for the medium and near distance. The myopia progression study (mean spherical equivalent) indicates that 20% of people had no change, 42% had an increase in myopic correction from 0.25D to 0.50D, 17% from 0.75D to 1.00D, 11% from 1.25D to 1.50D, 5% from 1.75D to 2.00D and 5% of the population had myopic progression greater than 2.00D.
基金This study was funded by the Chinese National Nature Science Foundation(Project No.81670898)Three-year Action Program of Shanghai Municipality for Strengthening the Construction of the Public Health System(2015-2017)[Grant No.GWIV-13.2],Key Discipline of Public Health-Eye Health in Shanghai[Grant No.15GWZK0601]+2 种基金Overseas High-end Research Team-Eye Health in Shanghai[GWTD2015S08]The Shanghai Outstanding Academic Leader Program(Project No.16XD1402300)Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support(Project No.20172022).
文摘Between 2011 and 2013,two large-scale cohort epidemiology studies were launched in Shanghai:the SCALE study,which aimed to provide ocular public health services to cover the entire youth population in Shanghai,and the SCES,which was based on sample surveys and aimed to provide information on the prevalence and incidence of visual impairment and different types of refractive errors.A total of 910,245 children and adolescents were finally enrolled in the SCALE study;three possible methods for monitoring refractive error without mydriasis were tested,and the agreement between the refractive outcomes of three commonly used autorefractors were examined to ensure the accuracy of the results of the SCALE study.A total of 8,627 children were enrolled in the SCES,and the baseline prevalence of different refractive errors,different behaviors associated with 1 year myopic shifts,and the different patterns of 2-year myopia progression between internal migrant and local resident school children have been analyzed.In some subset samples of the SCALE study and the SCES,several refraction components such as choroidal thickness(ChT)and crystalline lens power were also measured,to further elucidate the relationships between the refraction components and myopia as well as the mechanism of myopia incidence and development.The three methods used in Shanghai to prevent and intervene with childhood myopia:increasing outdoor time,low concentration atropine,and use of orthokeratology lens are also addressed in this review.