Prevalence of refraction errors and color blindness in heavy vehicle drivers

AIM: To investigate the frequency of eye disorders in heavy vehicle drivers.METHODS: A cross-sectional type study was conducted between November 2004 and September 2006 in 200 driver and 200 non-driver persons.A complete ophthalmologic examination was performed,including visual acuity,and dilated examination of the posterior segment.We used the auto refractometer for determining refractive errors.RESULTS: According to eye examination results,the prevalence of the refractive error was 21.5% and 31.3% in study and control groups respectively (P <0.05).The most common type of refraction error in the study group was myopic astigmatism (8.3%) while in the control group simple myopia (12.8%).Prevalence of dyschromatopsia in the rivers,control group and total group was 2.2%,2.8% and 2.6% respectively.CONCLUSION: A considerably high number of drivers are in lack of optimal visual acuity.Refraction errors in drivers may impair the traffic security.

Prevalence of visual impairment and estimation of refractive errors among school children in Kakamega,Kenya

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.

Relative peripheral refractive errors in Chinese children with myopic anisometropia

AIM:To compare relative peripheral refractive errors(RPREs)in Chinese children with and without myopic anisometropia(MAI)and to explore the relationship between RPRE and myopia.METHODS:This observational cross-sectional study included 160 children divided into two groups according to the interocular spherical equivalent refraction(SER)difference≥1.0 D in the MAI group(n=80)and<1.0 D in the non-MAI group(n=80).The MAI group was further divided into two subgroups:ΔSER<2.0 D group and ΔSER≥2.0 D group.Basic ocular biometric parameters of axial length(AL),average keratometry(Ave K),cylinder(CYL),surface regularity index(SRI),and surface asymmetry index(SAI)were recorded.In addition,multispectral refraction topography was performed to measure RPRE,and the parameters were recorded as total refraction difference value(TRDV),refraction difference value(RDV)0-10,RDV10-20,RDV20-30,RDV30-40,RDV40-53,RDV-superior(RDV-S),RDV-inferior(RDV-I),RDV-temporal(RDV-T)and RDV-nasal(RDV-N).RESULTS:In the non-MAI group,the interocular differences of all parameters of RPRE were not significant.In the MAI group,the interocular differences of TRDV,RDV10-53,RDV-S,RDV-I,RDV-T,and RDV-N were significant.In subgroup analysis,the interocular differences of TRDV,RDV30-53,RDV-I,and RDV-T were significant in ΔSER<2.0 D group and ΔSER≥2.0 D group,but the interocular differences of RDV10-30,RDV-S and RDV-N were only significant in the ΔSER≥2.0 D group.In correlation analysis,ΔTRDV,ΔRDV 10-53,ΔRDV-S,and ΔRDV-N were negatively correlated with ΔSER but positively correlated with ΔAL.CONCLUSION:The more myopic eyes have larger hyperopic RPRE in Chinese children with MAI in certain retinal range,and partialΔRPRE is closely associated with ΔSER and ΔAL.

Prevalence and Factors Associated with Refractive Errors among University Students at Mbarara University of Science and Technology, Uganda

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.

Prevalence of Refractive Errors among School Children Aged 5 to 15 Years Old at CHU-IOTA

Introduction: Undetected refractive errors constitute a health problem among school children who cannot take advantage of educational opportunities. The authors studied the prevalence of refractive errors in school children aged 5 to 15 at CHU-IOTA. Patients and Method: This is a prospective, descriptive cross-sectional study carried out in the ophthalmic-pediatrics department of CHU-IOTA, from October to November 2023. Results: We received 340 school children aged 5 to 15, among whom 111 presented ametropia, i.e. a prevalence of 32.65%. The average age was 11.42 ± 2.75 years and a sex ratio of 0.59. The average visual acuity was 4/10 (range 1/10 and 10/10). We found refractive defects: astigmatism 73.87%, hyperopia 23.87% of cases and myopia 2.25%. The decline in distance visual acuity was the most common functional sign. Ocular abnormalities associated with ametropia were dominated by allergic conjunctivitis (26.13%) and papillary excavation (6.31%) in astigmatics;allergic conjunctivitis (9.01%) and papillary excavation (7.20%) in hyperopic patients;turbid vitreous (0.90%), myopic choroidosis (0.45%) and allergic conjunctivitis (0.45%) in myopes. Conclusion: Refractive errors constitute a reality and a major public health problem among school children.

Prevalence of refractive errors in children of Puerto Rico

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.

Uncorrected refractive errors are important causes of avoidable visual impairment in Hungary: re-evaluation of two existing national data sets

·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.

Residual refractive errors in pseudophakic eyes and related factors:a population-based study

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.

Age-specific distribution of oculometric parameters and myopia in children aged 8-12y

AIM:To describe the distribution of ocular biometrics and to evaluate its associations with refractive error and to assess the contribution from ocular parameters to refractive error among Chinese myopic children.METHODS:This cross-sectional study evaluated subjects aged 8-12y.Keratometry,ocular biometry,and cycloplegic autorefraction were performed on each subject.Spherical equivalent refraction(SER)and ocular biometrics were assessed as a function of age and gender.The Pearson correlation analysis between SER and ocular biometrics was carried out.Multiple linear regression was performed to analyze the association between SER and ocular parameters.RESULTS:A total of 689 out of 735 participants(321 boys,48.1%)were analyzed,with a mean SER of-2.98±1.47 diopter(D).Axial length(AL),anterior chamber depth(ACD),corneal radius of curvature(CR),horizontal visible iris diameter(HVID),central corneal thickness(CCT)and lens power(LP)showed normal distribution.The AL,AL/CR ratio,ACD and CR increased from 8 to 12y of age,while SER and LP decreased,HVID and CCT remained stable.There was no difference in gender.SER decreased by 0.929 D for every 1 mm increase in AL and decreased by 1.144 D for every 0.1 increase in AL/CR ratio.The Pearson correlation coefficient between SER and AL was-0.538(P<0.01)and-0.747(P<0.01)between SER and AL/CR ratio.For the SER variance,AL explained 29.0%,AL/CR ratio explained 55.7%,while AL,CR,ACD and LP explained 99.3%after adjusting for age and gender.CONCLUSION:The AL,CR,ACD and LP are the most important determinants of myopic refractive error during myopia progression.

Two different autorefractors for vision screening in children and adolescents

AIM:To compare the consistency of two autorefractors(Tianle RM-9000 and Topcon KR-800)for school-age myopia children,and to provide a basis for largescale data analysis and comparison.METHODS:The refractive error in 909 subjects(age 4–18y)were measured using both autorefractors without cycloplegia.The data were analyzed using Fourier decomposition and the correlation coefficients,intraclass correlation coefficients(ICC),and Bland-Altman limits of agreement(LoA)for each parameter were calculated.RESULTS:There was a strong correlation between the spherical equivalent(SE),sphere diopter(DS),and cylinder diopter(DC)readings of the Tianle RM-9000 and those of the Topcon KR-800,with correlation coefficient values of 0.98,0.98 and 0.83 and ICC values of 0.99,0.99 and 0.93,respectively.However,the correlation coefficients and ICC values of J0 and J45 were unreliable(R=-0.004,-0.034;both ICC<0.10).Bland-Altman analysis revealed that SE,DS,and DC measured by the Tianle RM-9000 were significantly biased toward myopia compared with the Topcon KR-800,and the mean differences were-0.072,-0.026,-0.091 D,respectively(all P<0.01).The minimum absolute value of the difference within the 95%LoA for SE,DS,and DC was 0.63 D,0.50 D,0.62 D,respectively;all these values were in the clinically acceptable range.For J0 and J45,the mean differences were close to zero(P=0.43,0.84);however,the 95%LoA were relatively wide(J0 SD:0.53;95%CI:-1.00,1.10;J45 SD:0.52;95%CI:-1.00,1.00).CONCLUSION:The two autorefractors are consistent with each other,as the differences in SE,DS,and DC were within the clinically acceptable range.Readers can compare the data measured by either device in different studies and use the two devices in the same study to generate a dataset that can be analyzed together.However,the J0 and J45 vectors are unreliable and should not be used to assess astigmatism.

Retinoscopes:Past and present

BACKGROUND Retinoscopy is arguably the most important method in the eye clinic for diagnosing and managing refractive errors.Advantages of retinoscopy include its noninvasive nature,ability to assess patients of all ages,and usefulness in patients with limited cooperation or communication skills.AIM To discuss the history of retinoscopes and examine current literature on the subject.METHODS A search was conducted on the PubMed and with the reference citation analysis(https://www.referencecitationanalysis.com)database using the term"Retinoscopy,"with a range restricted to the last 10 years(2013-2023).The search string algorithm was:"Retinoscopy"(MeSH Terms)OR"Retinoscopy"(All Fields)OR"Retinoscopes"(All Fields)AND[(All Fields)AND 2013:2023(pdat)].RESULTS This systematic review included a total of 286 records.Publications reviewed iterations of the retinoscope into autorefractors,infrared photo retinoscope,television retinoscopy,and the Wifi enabled digital retinoscope.CONCLUSION The retinoscope has evolved significantly since its discovery,with a significant improvement in its diagnostic capabilities.While it has advantages such as non-invasiveness and broad applicability,limitations exist,and the need for skilled interpretation remains.With ongoing research,including the integration of artificial intelligence,retinoscopy is expected to continue advancing and playing a vital role in eye care.

Pattern of Eye Diseases among Tea Workers

Background: Bangladesh’s tea industry is essential to the country’s economic expansion. Since tea workers in Bangladesh are marginalized within our community, they have limited access to comprehensive eye care services. Productivity and well-being are cornerstones of comprehensive health care strategy. Ocular disorders are influenced by life expectancy, sociodemographic status, and the epidemiological transition. In this context, the state of ocular health and the many eye illnesses remain to be significantly addressed. Purpose: To evaluate the pattern of eye diseases among tea workers in a tea estate of Bangladesh. Methods: This cross-sectional observational study was carried out in Halda Valley Tea Estate, Nazirhat, Fatickchari, Chattogram, Bangladesh, under the supervision of the Department of Community Ophthalmology, BSMMU, following ethical clearance and approval by the IRB board of BSMMU. With informed written consent and approval from the authority of the tea estate, a total of 110 tea workers were recruited. Socio-demographic characteristics, ocular findings, and patterns of eye diseases were determined and recorded. Results: The mean age of the study participants was 39.60 ± 11.63 years. The maximum (58.1%) study participants were 31 - 50 years old, female (64.5%), illiterate (82.7%), and tribal (71.8%) indigenes. Eye diseases were found in 94.5% of workers. Presbyopia (28.2%), cataracts (27.3%), and refractive error (26.4%) were the most common. Tea workers with eye diseases were significantly older than those who did not have any eye diseases (40.20 ± 11.57 vs. 29.17 ± 7.31 years, p Conclusion: A significant number of tea workers had eye diseases, of which presbyopia, cataracts, and refractive error were the most common.

Refractive errors in high myopic eyes after phacovitrectomy for macular hole

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.

Refractive surgery: the most cost-saving technique in refractive errors correction

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.

Prevalence of refractive errors in Hungary reveals three-fold increase in myopia

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.

Refractive errors among children, adolescents and adults attending eye clinics in Mexico

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.

Prevalence and inconformity of refractive errors and ocular biometry of 3573 medical university freshman students for 4 consecutive years

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.

Prevalence of visual impairment and refractive errors in an urban area of Mexico

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.

Main visual symptoms associated with refractive errors and spectacle need in a Brazilian population

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.

Prevalence of Refractive Errors in the Total Population and the Analysis of Myopic Progression in Adults Aged 20 to 39 in the Urban Area of Tirana, Albania

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.