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Background: The development of myopia is influenced by hereditary factors, environmental factors and gene-environment interaction. Reading and near-work activity are associated with myopia and myopic progression. This study sought to determine and compare the prevalence of reduced unaided vision and spectacle use among third grade Israeli students from three different educational settings., Method: A sample of 917 students (mean age 8.5 years, range seven to 10 years) was drawn from the three Israeli educational streams: secular, Orthodox and ultra-Orthodox. Children in the ultra-Orthodox education pathway begin studying at the age of three years and their daily reading involves sustained near work with increased accommodative effort accompanied by head-rocking movements. Reduced distance vision was used to indicate the likely development of or an increase in the amount of myopia. Spectacle lenses were measured to determine the prevalence of myopia., Results: Of the 917 students studied, 103 (11.2 per cent) wore spectacles (14.2 per cent of the males and eight per cent of the females); 82.5 per cent of those who wore spectacles were myopic. Males from ultra-Orthodox schools had the highest rate of reduced unaided vision (72.5 per cent) compared with males from secular schools (27.3 per cent), males from Orthodox schools (59.3 per cent) or with females from all three groups (average of 34.8 per cent, p < 0.0001, chi squared). Males had a higher rate of reduced unaided vision, especially in the Orthodox and ultra-Orthodox schools., Conclusions: Our study suggests that Jewish ultra-Orthodox males have a higher prevalence and degree of myopia. The study habits of young children, including exposure to prolonged near tasks, high accommodative demands and possibly optical defocus induced by body sway, may contribute to the development of myopia.

Purpose: To determine the prevalence of myopia in the adult populations of two different ethnic communities in the Ecuadorian Amazon., Methods: Refraction with retinoscopy after cycloplegia was performed for 507 Naporuna (an ethnic group indigenous to the jungles of the Ecuadorian Amazon) and for 776 settlers (white-mestizos from the Andes, now living in the Amazon and working for the petroleum industry). Ages ranged from 18 to 45 years. All subjects had little or no formal education., Results: The prevalence of myopia was 4.7% among the Naporuna and 5.5% among the settlers; the prevalence of hyperopia was higher, at 17.8% and 36.0%, respectively., Conclusions: The prevalence of myopia in the two communities studied agrees with the results of other studies showing a low prevalence of myopia among groups with low levels of formal education or groups living a nonurban lifestyle.

Purpose: To study the prevalence and magnitude of myopia in a group of Hong Kong Chinese microscopists and compare it with that observed in microscopists working in the United Kingdom., Methods: Forty-seven microscopists (36 women and 11 men) with a median age of 31 years and working in hospital laboratories throughout Hong Kong were recruited to the study. Information about past refractive corrections, microscopy work, and visual symptoms associated with microscope use were collected. All subjects had a comprehensive eye examination at The Hong Kong Polytechnic University Optometry Clinic, including measures of refractive error (both noncycloplegic and cycloplegic), binocular vision functions, and axial length., Results: The prevalence of myopia in this group of microscopists was 87%, the mean (+/- SD) refractive error was -4.45 +/- 3.03 D and mean axial length was 25.13 +/- 1.52 mm. No correlation was found between refractive error and years spent working as a microscopist or number of hours per day spent performing microscopy. Subjects reporting myopia progression (N = 22) did not differ from the refractively stable group (N = 19) in terms of their microscopy working history, working hours, tonic accommodation level, or near phoria. However, the AC/A ratio of the progressing group was significantly greater than that of the stable group (4.59 delta/D cf. 3.34 delta/D)., Conclusion: The myopia prevalence of Hong Kong Chinese microscopists was higher than that of microscopists in the United Kingdom (87% cf. 71%), as well as the Hong Kong general population (87% cf. 70%). The average amount of myopia was also higher in the Hong Kong Chinese microscopists than the Hong Kong general population (-4.45 D cf. -3.00 D). We have confirmed that the microscopy task may slightly exacerbate myopia development in Chinese people.

Objective: To report the baseline prevalence of refractive error in the study population., Design: A multicenter, longitudinal, observational study of refractive error and ocular development in children from 4 ethnic groups., Patients and Methods: The study population included 2523 children (534 African American, 491 Asian, 463 Hispanic, and 1035 white) in grades 1 to 8 (age, 5-17 years). Myopia was defined as -0.75 diopters (D) or more and hyperopia as +1.25 D or more in each principal meridian, and astigmatism was defined as at least a 1.00-D difference between the 2 principal meridians (cycloplegic autorefraction)., Results: Overall, 9.2% of the children were myopic, 12.8% were hyperopic, and 28.4% were astigmatic. There were significant differences in the refractive error prevalences as a function of ethnicity (chi2, P<.001), even after controlling for age and sex (polychotomous logistic regression, P<.001). For myopia, Asians had the highest prevalence (18.5%), followed by Hispanics (13.2%). Whites had the lowest prevalence of myopia (4.4%), which was not significantly different from African Americans (6.6%). For hyperopia, whites had the highest prevalence (19.3%), followed by Hispanics (12.7%). Asians had the lowest prevalence of hyperopia (6.3%) and were not significantly different from African Americans (6.4%). For astigmatism, Asians and Hispanics had the highest prevalences (33.6% and 36.9%, respectively) and did not differ from each other (P =.17). African Americans had the lowest prevalence of astigmatism (20.0%), followed by whites (26.4%)., Conclusion: There were significant differences in the prevalence of refractive errors among ethnic groups, even after controlling for age and sex (P<.001).

Purpose: Considerable evidence suggests that both axial and peripheral refraction play important roles in eye growth control. The large variability in peripheral refraction seen in adults and children indicates that the peripheral retina is exposed to a wide range of refractive errors. The current lack of appropriate measurement techniques has hampered the determination of whether variability in peripheral refraction between individuals can be correlated with variability in retinal steepness. An Optical Low Coherence Reflectometer (OLCR) was developed to determine retinal steepness., Methods: Retinal steepness was assessed in right eyes of 63 children 7-15 years of age by measuring eye length (EL) and spherical equivalent refraction (SER) axially and at 15 degrees temporally, nasally, inferiorly and superiorly with OLCR and Binocular Auto-Refractometry, respectively, during cycloplegia. At each peripheral location, relative peripheral EL and SER (i.e., the difference between peripheral and axial readings) were compared between myopic, emmetropic and hyperopic eyes, and the correlation between relative peripheral EL and SER was analyzed., Results: Although the standard deviations were large, significant differences in relative peripheral EL and SER between refractive groups as well as a significant correlation between relative peripheral EL and SER were observed at several of the assessed locations. CONCLUSIONS. The results strongly suggest that peripheral refraction is correlated with retinal steepness and that previously observed variability in peripheral refraction chiefly reflects variability in retinal steepness. If peripheral refraction represents a determining parameter in the control of eye growth, the precise measurement of retinal steepness could be used not only to improve estimates of myopic progression, but also to identify children who are at high risk of developing myopia. It may lead to specialized clinical/optical treatments, e.g. the correction of not only axial but also peripheral refractive errors, which are more effective than current treatments in individuals who are at risk of myopia development or progression.

Purpose: To compare the magnitude and time course of nearwork-induced transient myopia (NITM) in preadolescent Hong Kong Chinese myopes and emmetropes., Method: Forty-five Hong Kong Chinese children, 35 myopes and 10 emmetropes aged 6 to 12 years (median, 7.5), monocularly viewed a letter target through a Badal lens for 5 minutes at either 5.00- or 2.50-D accommodative demand, followed by 3 minutes of viewing the equivalent target at optical infinity. Accommodative responses were measured continuously with a modified, infrared, objective open-field autorefractor. Accommodative responses were also measured for a countercondition: viewing of a letter target for 5 minutes at optical infinity, followed by 3 minutes of viewing the target at a 5.00-D accommodative demand. The results were compared with tonic accommodation and both subject and family history of refractive error., Results: Retinal-blur-driven NITM was significantly greater in Hong Kong Chinese children with myopic vision than in the emmetropes after both near tasks, but showed no significant dose effect. The NITM was still evident 3 minutes after viewing the 5.00-D near task for 5 minutes. The magnitude of NITM correlated with the accommodative drift after viewing a distant target for more than 4 minutes, but was unrelated to the subjects' or family history of refractive error., Conclusions: In a preadolescent ethnic population with known predisposition to myopia, there is a significant posttask blur-driven accommodative NITM, which is sustained for longer than has previously been found in white adults.

Purpose: To investigate the coding exons of transforming growth factor (TGF)-beta-induced factor (TGIF) for mutations in Chinese patients with high myopia., Methods: Seventy-one individuals with high myopia of -6.00 D or less and 105 control subjects were screened by DNA sequencing for sequence alterations. Univariate analysis and logistic regression were performed to identify single-nucleotide polymorphisms (SNPs) and their interactions in TGIF that may be associated with myopia., Results: Six SNPs showed a significant difference (P < 0.05) between patient and control subject in univariate analysis. Four of them cause codon changes: G223R, G231S, P241T, and A262G. Among all the SNPs that entered multivariate analysis, only 657(T-->G) showed statistical significance in the logistic regression model (odds ratio 0.133; 95% confidence interval 0.037-0.488; P = 0.002)., Conclusions: TGIF is a probable candidate gene for high myopia. Further studies are needed to identify the underlying mechanism.

Objective: To examine the relation of refractive errors to glaucoma and intraocular pressure (IOP) in a defined white population., Design: Population-based cross-sectional and follow-up study., Participants: Persons aged 43 to 86 years living in Beaver Dam, Wisconsin (n = 4926)., Methods: All participants received a standardized assessment of refraction, IOP, and glaucoma at baseline (1988-1990), with IOP remeasured 5 years later (1993-1995). Refraction was defined at baseline as follows: myopia as spherical equivalent of -1.00 diopters (D) or less, emmetropia as -0.75 to +0.75 D, and hyperopia as +1.00 D or more., Main Outcome Measures: Relation of baseline refraction to prevalent glaucoma (defined from IOP, optic disc, and visual field criteria) and incident ocular hypertension (defined as IOP more than 21 mmHg at the 5-year examination in eyes with IOP of 21 mmHg or less at baseline)., Results: A myopic refraction was correlated with increasing IOP at baseline (P < 0.001). After controlling for age and gender, persons with myopia were 60% more likely to have prevalent glaucoma than those with emmetropia (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1, 2.3). In contrast, controlling for age, gender, and baseline IOP, persons with hyperopia were 40% more likely to have incident ocular hypertension than those who were emmetropic at baseline (OR, 1.4; 95% CI, 1.0, 2.0). Myopia was not related to incident ocular hypertension., Conclusions: In these population-based data, there was a cross-sectional association of myopia with higher IOP and prevalent glaucoma. Similar associations have been found in previous studies. Hyperopia may be associated with 5-year risk of ocular hypertension, a finding that needs further investigation.

Purpose: To investigate the refractive status and factors associated with myopia by a population-based survey of Japanese adults., Methods: A total of 2168 subjects aged 40 to 79 years, randomly selected from a local community, were assessed in a cross-sectional study. The spherical equivalent of the refractive error was calculated and used in a multiple logistic regression analysis to evaluate the relationships between myopia and possible related factors., Results: The mean (+/- SD) of the spherical equivalent was -0.70 +/- 1.40 diopters (D) in men, and -0.50 +/- 1.44 D in women. Based on +/- 0.5 D cutoff points, the prevalence of myopia, emmetropia, and hypermetropia were 45.7%, 40.8%, and 13.5% in men, and 38.3%, 43.1%, and 18.6% in women, respectively. A 10-year increase in age was associated with reduced risk of myopia [men: odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.44-0.62; women: OR = 0.65, 95% CI: 0.54-0.78]. In men, myopia was significantly associated with higher education (high school: OR = 1.6, 95% CI: 1.1-2.3; college: OR = 2.0, 95% CI: 1.3-3.1) and management occupations (OR = 1.6, 95% CI: 1.0-2.4). For women, high income (OR = 1.5, 95% CI: 1.1-2.2), and clerical (OR = 1.5, 95% CI: 1.0-2.4) and sales/service occupations (OR = 1.7, 95% CI: 1.1-2.6) were also associated with myopia., Conclusions: The prevalence of myopia in a Japanese population was similar to that in other Asian surveys but higher than in black or white populations. Our study confirmed a higher prevalence of myopia among younger vs. older populations, and a significant association with education levels and socioeconomic factors.

Purpose: To evaluate self-esteem and its relationship with various ocular and demographic characteristics in 469 myopic children participating in the Correction of Myopia Evaluation Trial (COMET), an ongoing, randomized, multicenter clinical trial designed to evaluate the effects of progressive addition lenses vs. single vision lenses on the progression of juvenile-onset myopia., Methods: Baseline data collection included demographic information, refractive error measurements, parent-reported myopia history, child-reported visual symptoms, and self-esteem in several areas (scholastic/athletic competence, physical appearance, social acceptance, behavioral conduct, and global self-worth) as measured by the Self-Perception Profile for Children. Univariate and multiple regression analyses were used to identify factors associated with self-esteem., Results: The Self-Perception Profile for Children is a reliable measure of self-esteem in COMET children as indicated by the high internal consistency reliabilities (0.74 to 0.81) obtained for the various domains. COMET children's mean self-esteem scores ranged from 2.72 +/- 0.69 for athletic competence to 3.36 +/- 0.56 for global self-worth and were similar to normative samples. Multiple regression analyses showed that less symptomatic children had higher self-esteem in all areas (p < 0.05), except athletic competence, after adjusting for other ocular and demographic characteristics. Self-esteem also varied significantly by age, gender, and ethnicity (p < 0.05)., Conclusions: Baseline self-esteem is associated with visual symptoms, age, gender, and ethnicity, but not with magnitude of refractive error. Follow-up reports will assess whether there are changes in self-esteem associated with myopia progression and lens assignment.

Objective: To examine the risk factors for variations in ocular biometry parameters in Singapore Chinese children, a population with a known high prevalence rate of myopia at an early age., Design: Cross-sectional study., Participants: Children aged 7 to 9 years (n = 1453) from three schools in Singapore., Methods: The children underwent A scan biometry and cycloplegic autorefraction measurements. Questions were asked regarding number of books read per week, night lighting, and parental myopia., Main Outcome Measures: Axial length, vitreous chamber depth, lens thickness, anterior chamber depth, refraction, and corneal curvature radius measurements were made., Results: After controlling for several factors, the axial lengths were found to be longer and vitreous chambers deeper in children who were older, male, read more than two books per week, or taller, and those who had at least one parent who was myopic. In these models, children who read more than two books per week had axial lengths that were 0.17 mm longer and vitreous chambers that were 0.15 mm deeper compared with children who read two or fewer books per week. Anterior chambers were deeper in males and taller children, whereas corneal curvature was steeper in female, older, and shorter children., Conclusions: Increases of axial length and vitreous cavity depth were associated with older age, being male, reading more than two books per week, increased height, and parental history of myopia. Of these risk factors, however, neither reading nor parental myopia history were associated with values for anterior chamber depth, corneal curvature, or lens thickness. These findings confirm that conventional risk factors for myopia associated with the vitreous cavity, but suggest that anterior segment parameters such as corneal curvature and lens thickness may be subject to unrelated postnatal growth control mechanisms.

Higher order optical aberrations were measured in 273 cyclopleged Singaporean school children using a Bausch and Lomb Zywave aberrometer, with 268 of these subjects also undergoing corneal topography measurements (Tomey TMS 2 system). Subjects with low myopia (> -3.00 to -0.50 D) showed slightly, but significantly, less positive levels of spherical aberration than other refractive error groups. Chinese subjects also showed significantly higher amounts of aberrations than Malay subjects, particularly for vertical coma, but also for horizontal coma and spherical aberration. Anterior corneal spherical aberration (calculated from topography) was significantly correlated with whole eye spherical aberration, but did not vary significantly with refractive error or racial background. Residual spherical aberration (i.e. of posterior cornea and crystalline lens) did vary significantly with refractive error and race. Our results do not provide any evidence for aberration-driven form-deprivation as a major mechanism of myopia development.

Purpose: To examine the association between the anthropometric measurements of height, weight, body mass index (BMI) and refraction and other ocular parameters in Singapore Chinese children., Methods: In a cross-sectional study of 1449 Chinese schoolchildren, aged 7 to 9 years, from three Singapore schools, height and weight were measured according to standard protocol, and BMI was calculated. Refractive error and corneal curvature measures were determined by autorefraction in eyes under cycloplegia. Axial length, vitreous chamber depth, lens thickness, and anterior chamber depth were measured using A-scan biometry ultrasonography., Results: In comparison with the children with height in the first quartile for a given age and gender, the eyeball length in children in the fourth quartile was 0.46 mm longer, the vitreous chamber depth 0.46 mm deeper, the corneal radius of curvature 0.10 mm greater (i.e., flatter), refraction more negative by 0.47 D (-0.76 D versus -0.29 D), and axial length-to-corneal curvature radius (AL-CR) ratio higher, after analyses controlling for age, gender, parental myopia, reading, school, and weight. The associations of height with refractive error and AL-CR ratio were significant in girls but not in boys. Heavier and more obese children had refractions that were more hyperopic (P = 0.01, P = 0.08), after analyses controlling for age, gender, parental myopia, reading, and school (height was also controlled for if weight was evaluated). This association was present in boys but not in girls., Conclusions: Controlling for age, gender, parental myopia, reading, school, and weight showed that taller Singapore Chinese children had eyes with longer axial lengths, deeper vitreous chambers, flatter corneas, and refractions that tended toward myopia. In multivariate analysis, eyes in children who were heavier or who had a higher BMI tended to have refractions that were more hyperopic, and eyes in heavier children had shorter vitreous chambers. Differences between the present results and a recent report in Singapore adults suggest either a cohort effect or a potential influence of systemic endocrine or metabolic factors during childhood on refractive development.

Purpose: To describe baseline refractive and ocular component measures in children with myopia enrolled in the Correction of Myopia Evaluation Trial (COMET). COMET is a multicenter, randomized clinical trial to evaluate whether progressive-addition lenses slow the progression of juvenile-onset myopia compared with single-vision lenses., Methods: Four hundred sixty-nine children with myopia between -1.25 and -4.50 D spherical equivalent and without eye or systemic conditions known to affect refractive development were recruited from four geographically and ethnically diverse communities in the United States. Their ages were 6 to 11 years inclusive, and 52% were girls. The main outcome measure for the overall trial is progression of myopia determined by cycloplegic autorefraction after inducement of cycloplegia with 2 drops of 1% tropicamide. Axial length, the secondary outcome measure, was assessed by ultrasonography. The distance correction was determined by subjective methods before cycloplegia, with noncycloplegic autorefraction values as the starting point., Results: Because data were similar in both eyes, they are reported for the right eye only. The mean spherical equivalent measured by cycloplegic autorefraction was -2.38 +/- 0.81 D. Young children had significantly less myopia than older children (P = 0.03), but the amount of myopia did not differ by gender or ethnicity. Mean axial dimensions were 4.0 +/- 0.2 mm (anterior chamber), 3.4 +/- 0.2 mm (lens), 16.8 +/- 0.7 mm (vitreous chamber), and 24.1 +/- 0.7 mm (axial length). Girls' eyes had significantly shorter axial length than boys' (P < 0.0001). Mean corneal radii were 7.73 +/- 0.25 mm (horizontal) and 7.59 +/- 0.24 mm (vertical). Ninety-five percent of the eyes had a ratio of axial length to corneal radius higher than 3.0., Conclusions: These baseline measures provide cross-sectional data on a large group of ethnically diverse children with myopia. Refractive and axial component dimensions are consistent with data in other studies showing that myopic eyes have longer vitreous chambers than emmetropic eyes. The measures reported herein will serve as a basis for examining changes that occur over a minimum of 3 years of follow-up of children enrolled in COMET.

Purpose: We undertook this study with the aim to determine static ametropias of black Cameroonians as well as their clinical manifestations. It is a prospective study carried out in the Department of Ophthalmology of Douala General Hospital from January 1996 to December 1998., Patients and Method: During this period, all patients who fulfilled our criteria had a skiascopy done under cycloplegia. We thus examined 2,484 patients (4,968 eyes). 66.2% of them were female and 33.8% were male., Results: In our series, hyperopia was found in 51% of the cases, hyperopic astigmatism in 27.5% of the cases, myopic astigmatism in 9.3% of cases, mixed astigmatism in 7.7% of cases and myopia in 4.5% of cases. Distribution of ametropias is influenced by age, not by sex or laterality., Discussion and Conclusion: Functional signs just have an indicative value; only objective refraction under cycloplegia can determine exactly the ametropia., (Copyright 2001 S. Karger AG, Basel)

Purpose: To study interethnic variation in myopia prevalence and severity in young adult males in Singapore and to determine whether these variations are related to differences in education level., Methods: A population-based survey of refractive errors in a cohort of 15,095 military conscripts between July 1996 and June 1997 using noncycloplegic autorefraction and a standard questionnaire. Prevalence rates of myopia (<-0.5 D) and severe myopia (<-6.0 D) were determined for Chinese, Malay, and Indian men; prevalence rate ratios were compared after adjusting for education level., Results: Singapore has one of the highest prevalences of myopia (79.3%) and severe myopia (13.1%), with Chinese having higher rates (82.2%, 95% confidence interval 81.5, 82.9) compared with Indians (68.7%, 95% confidence interval 65.1, 67.1) and Malays (65.0%, 95% confidence interval 62.9, 67.1). Education was strongly associated with prevalence and severity of myopia. However, significant interethnic variation persisted after adjusting for education., Conclusions: There is a high prevalence of myopia in Singapore. Although prevalence and severity of myopia were strongly associated with education, interethnic variation observed was not fully explained by differences in education level.

Purpose: Excessive nearwork is believed to be associated with myopia development and progression. To investigate this further, we studied refractive error changes and their correlation with nearwork in a cohort of grade school children in Singapore., Methods: Cycloplegic autorefraction was performed 5 times over 10 months on 168 children aged 7, 9, and 12 years who were further divided into myopic and nonmyopic subgroups based in their initial refractive errors. Information about nearwork was obtained through diaries filled out over 24 h at the commencement of the study., Results: Myopia progression was high (overall mean: -0.87 D per year) and largely linear throughout the year, but significantly higher rates were seen after the final school examinations in 7-year-old myopes and nonmyopes. Overall, myopic groups exhibited higher progression rates than nonmyopic groups, although 33.6% of subjects from the latter groups had become myopic by the end of the study. Nearwork scores derived from the diaries were generally not well correlated with overall myopia progression., Conclusions: The tendency for myopia progression rates to increase after the final school examinations in 7-year-olds is interpreted as a delayed effect of the intense nearwork associated with preparing for them. The timing of nearwork-diary data collection at the beginning of the study could be responsible for the poor correlation between these data and overall myopia progression rates.

There are no previous studies on the dimensions of ocular components and their intercorrelations in adult Saudi Arabians. In this study ocular components were measured by ultrasonography and keratometry in 152 adult Saudis. Their ages ranged from 16 to 50 years. The males had significantly longer anterior chamber depth (ACD), vitreous chamber depth (VCD), axial length (AL) and axial length/corneal radius ratio (AL/CR) than females. However, females had non-significantly steeper corneas than males. The AL/CR ratio had the highest correlation with refractive error. Corneal radius of curvature was positively correlated with VCD and AL. Lens thickness was negatively correlated with the VCD, AL and AL/CR ratio. Myopes had significantly deeper ACD, VCD, and higher AL/CR ratio than nonmyopes. Myopes had significantly thinner lenses than hyperopes. The average values of the optical components and their intercorrelations are similar to reported values obtained from subjects of other races but with comparable refractive errors.

Purpose: To describe the prevalence of refractive errors in a black adult population., Methods: The Barbados Eye Study, a population-based study, included 4709 Barbados-born citizens, or 84% of a random sample, 40 to 84 years of age. Myopia and hyperopia were defined as a spherical equivalent <-0.5 diopters and >+0.5 diopters, respectively, based on automated refraction. Analyses included 4036 black participants without history of cataract surgery. Associations with myopia and hyperopia were evaluated in logistic regression analyses., Results: The prevalence of myopia was 21.9% and was higher in men (25.0%) than in women (19.5%). The prevalence of hyperopia was 46.9% and was higher in women (51.8%) than in men (40.5%). The prevalence of myopia decreased from 17% in persons 40 to 49 years of age to 11% in those 50 to 59 years of age, but increased after 60 years of age. The prevalence of hyperopia increased from 29% at 40 to 49 years of age to 65% at 50 to 59 years of age, and tended to decline thereafter. A higher prevalence of myopia was positively associated (P < 0.05) with lifetime occupations requiring nearwork, nuclear opacities, posterior subcapsular opacities, glaucoma, and ocular hypertension. Factors associated with hyperopia were the same as for myopia, except for occupation, and in the opposite direction., Conclusions: High prevalences of myopia and hyperopia were found in this large black adult population. The prevalence of myopia (hyperopia) increased (decreased) after 60 years of age, which is inconsistent with data from other studies. The high prevalence of age-related cataract, glaucoma, and other eye conditions in the Barbados Eye Study population may contribute to the findings.

Purpose: In Chinese societies, primary and secondary schoolchildren perform large amounts of reading and homework and thus spend long periods performing near work during their growth years. Progressive lenses, which can permit a focused retinal image at distance, intermediate, and near, without accommodation, may slow the development of myopia. This paper reports results of a 2-year longitudinal study to examine the effects of progressive lenses on myopia progression in myopic Chinese children; these children were aged between 9 and 12 years at the beginning of the study., Methods: Prestudy vision screening tests and five examinations, which included noncycloplegic refraction, were conducted at half-yearly intervals. Of those who completed the study, 32 children wore single vision (SV) lenses (the SV group) and 36 wore progressive lenses; of the latter, 22 wore a +1.50 D addition (the P1 group) and 14 wore a +2.00 D addition (the P2 group). Refractive error, corneal curvature, axial length, vitreous depth, and intraocular pressure were measured at every examination. Height was measured as an index of general growth., Results: Progressive lenses significantly retarded the progression of the myopia in these children. Initially, the mean refractive error of the SV group was -3.67 D, of the P1 group was -3.73 D, and of the P2 group was -3.67 D. The mean myopic progressions over the 2 years of the study were -1.23, -0.76, and -0.66 D for the SV, P1, and P2 groups, respectively., Conclusion: Progressive lenses reduce the progression of myopia. It may be that the interaction of the progressive lenses with the accommodation system is the cause of this reduction in myopia progression because the +2.00 D addition appeared more effective than the +1.50 D addition in slowing the progression.

Thirty-two children who had been refracted in early infancy were re-refracted at the age of 7 to 8 years. Refraction comprised cycloplegic retinoscopy at the mean age of 11 weeks and noncycloplegic retinoscopy and subjective examination at the mean age of 94 months. The change in spherical equivalent refraction (SER) was highly negatively correlated with the initial refraction (-0.863), demonstrating emmetropization; however, the correlation between the refractive error at age 7 to 8 years and the refractive error in infancy was much weaker (+0.225). The SER was significantly less and the astigmatism was greater in infancy in children who were myopic at age 7 to 8 years. There was, however, extensive overlap in range between the SER for the two groups and the initial SER was not a good predictor of myopia at 7 to 8 years, although it may help to identify children who are unlikely to become myopic. One hyperopic child with bilateral ptosis failed to emmetropize.

Background: Tibetan and Sherpa children living in Nepal share a common ancestry in Tibet and areas to the north of Nepal, but it is evident that these people experience widely contrasting educational and environmental conditions. The purpose of this study was to compare the prevalence of myopia in children with similar genetic backgrounds but who are exposed to contrasting environments., Methods: Unaided vision and refractive error was measured in 555 Tibetan children in Kathmandu and 270 Sherpa children in the Solu Khumbu region of Nepal., Results: There were marked differences in vision and the prevalence of myopia in the two groups. Ninety-two percent of the Sherpa children had Snellen vision of 20/22 (0.89) or better compared with 70% of the Tibetan children. The range of refractive errors was -6.50 to +7.00 D for the Tibetan children and -1.00 to +3.50 D for the Sherpa children. The Sherpa children had a prevalence of myopia of 2.9% compared with 21.7% for the Tibetan children., Conclusions: The prevalence of myopia in Sherpa children is low and their rural lifestyle appears to be relatively unstressed. Tibetan children have a higher prevalence of myopia and more rigorous schooling. We did not establish a causal relationship between myopia and the type of schooling, or the environment in general, but we did demonstrate that a simple, rural lifestyle is at least compatible with a virtual absence of myopia.

A representative sample of Hong Kong Chinese children was followed from 7 to 12 years of age. Refractive error was measured every year (n = 123 at age 7 years and n = 83 at age 12 years), the axial length of the eye was measured at age 12 years (n = 81) and the refractive status of the parents was also determined. Thirty-one percent of the parents in the sample were myopic and at the age of 12 years 53% of the children were myopic. There was no association between the refractive status of the parents and whether or not a child had myopia. The probability of a 12-year-old child with early-onset myopia having at least one myopic parent was 0.55 and the probability of myopic parents having a myopic child was 0.6. There was no difference in the refractive error or the axial length of 12-year-old children according to whether neither, one or both parents were myopic. The genetic influence on myopia may be different in Caucasian and Chinese children, although it is also possible that non-expression of the genotype in the parents may have confounded the determination of the inheritance pattern of myopia in Hong Kong Chinese children.

Purpose: To follow the refraction values in an indigenous population group over the course of the past 50 years., Method: Case records from a population investigation carried out in Ammasalik, East Greeland, by Erik Skeller in 1950 were studied initially, a total of 1123 eyes were examined by sciascopy and 244 eyes could be followed sufficiently until about 1990-94., Result: The mean refraction was initially +0.08 D, while at the last examination the mean had increased to +0.69 D. Initially, there was no myopia, defined as at least -1.5 D, and at follow-up it was a maximum of 1%, and presumably due to immature cataract. A tendency to myopia (< -1.5 D) was found initially in 36%, but in only 22% at follow-up., Conclusion: The myopinizing factor in East Greenland has not affected persons born prior to 1942, even if they had a tendency to myopia (< -1.5 D).

A cross-sectional study of 404 Tibetan children (212 males, 192 females) aged 6 to 16 years was conducted in the Bouda region of Kathmandu, Napal in April, 1992. Examination procedures included retinoscopy (1% cyclopentolate HCl), keratometry A-scan ultrasonography, and video ophthalmophakometry. The mean refractive error was +1.11 D (SD: 0.56 D) at age 6 years decreasing to +0.63 D (SD: 0.34 D) at age 16 years with a prevalence of myopia in this group of 3.9%. Most children examined had low refractive errors, with 95.5% having errors in the range -0.50 to +1.50 D. Crystalline lens power decreased by 2.59 D, with an associated increase in its anterior radius of curvature of 1.98 mm and 0.49 mm in its posterior radius of curvature over the age range studied. Vitreous chamber depth increased by 0.69 mm, but no significant changes were recorded in anterior chamber depth, lens thickness, or corneal curvature. We conclude that the balance between the decrease in crystalline lens power and the increase in vitreous length is the major factor in maintaining the tendency to emmetropia in these children.

The distribution of refractive errors and its relationship to the optical components in 105 Hong Kong Chinese aged 19-39 years was studied. Myopia was most frequent (71%) in this population. The mean spherical equivalent was -3.00 DS. The trend of changes of the direction of refractive and corneal astigmatism from with-the-rule to against-the-rule with increasing age was shown. Significant correlations were found between age and anterior segment distance. Ultrasound examination showed that an increasing axial length was associated with higher myopia. Men had flatter corneal radii, but longer axial length. The prevalence of myopia in the Chinese population seems to be a new trend for the younger Hong Kong Chinese when compared with adults aged over 40 years. Thus the importance of genetics in determination of myopia is called into question by these findings.

We derived estimates of the van Herick ratio or grading in a retrospective study using a Chinese clinical population. We found that the van Herick ratio decreased with age and increased with higher degrees of myopia. A lower van Herick ratio was found to be associated with higher intraocular pressure. There are significantly more patients with lower van Herick ratios or grades in our population than in populations described by others.

A cross-sectional study on a normal clinical myopic population reveals that there is a difference in the pattern of myopic progression between Malays and Chinese in Malaysia. It shows that while myopia in Malays stays relatively constant throughout 10 to 50 years of age, myopia in Chinese progresses rapidly from 10 to 20 years of age, after which it starts to show hyperopic shift, reaching a level of myopia similar to that of Malays at around 35 years of age. In view of the above finding it is postulated that the difference in myopia between the two races may be due to excessive accommodation in Chinese, causing a temporary increase in crystalline lens power and hence an increase in myopia. Because the magnitude of myopia for both races for 10 +/- 1 years age group is relatively high, i.e. about -2.00 D, it is postulated that myopia in these ethnic groups may start much earlier than 10 years of age.

We looked for the earliest signs of the onset of myopia in 194 emmetropic (-0.25 to +0.75 D) eyes by following them for 1 to more than 2 years. Visual acuity examination, cycloplegic retinoscopy, and A-scan ultrasonography were performed at intervals of 6 to 12 months. Of the 194 eyes 64 became myopic during the observation time. Our results show that during the progression from emmetropia to myopia the change in visual acuity is not a good indicator of the onset of myopia. When visual acuity decreased to below 6/6 (20/20) cycloplegic retinoscopy showed that most of the 64 eyes had become truly myopic and A-scan ultrasonography revealed a significant increase in vitreous chamber depth and axial length as compared to the non-myopic eyes. In the early stage of myopia development the anteroposterior diameter of the eye elongates. However, changes in anterior chamber depth and lens thickness did not differ between the myopic and non-myopic group. Our results suggest that routine ocular refraction should be conducted in addition to the school vision screening. For those who have visual acuity 6/6 (20/20) and ametropia of -0.25 D or more minus we would like to be able to prevent or at least retard the development of myopia.

The prevalence and degree of myopia were measured in 870 teenagers, males and females. We found a statistically significant higher prevalence and degree of myopia in a group of 193 Orthodox Jewish male students who differed from the rest in their study habits. Orthodox schooling is characterized by sustained near vision and frequent changes in accommodation due to the swaying habit during study and the variety of print size. A possible myopic effect of this unique visual demand is postulated.

Intraocular pressure (IOP) was measured in one-hundred-twenty-three 6- to 7-year-old Chinese children. Children who had at least one myopic parent had higher IOP's than children with two nonmyopic parents. There was a trend for myopic children to have higher IOP's than nonmyopic children.

Computerised data of 110,236 Singaporean males aged 15 to 25 (mean 17.75) years who underwent compulsory medical examination from April 1987 to January 1992 was used to estimate the prevalence of myopia among young Chinese, Malay, Indian and Eurasian Singaporean males. The prevalence of myopia amongst the different racial groups was compared after they had been matched for important known confounding factors such as age, sex, educational attainment and degree of urbanization of place of residence. The estimated myopia prevalence was 48.5% in Chinese, 34.7% in Eurasians, 30.4% in Indians and 24.5% in Malays. The overall myopia prevalence rate for all races combined was 44.2%. Within each educational group, the Chinese generally had the highest myopia prevalence whilst the Malays generally had the lowest. Myopia prevalence among the Indians tended to be between that of the Chinese and the Malays. Having matched the various racial groups for age, sex, educational attainment and degree of residential urbanization, it would appear that racial and cultural differences are major influences responsible for the difference in myopia prevalence observed amongst the different races.

A pleiotropic relationship between intelligence and myopia has been shown to exist. Large eyes (as measured by axial length) have been shown to lead to myopia, and large brains have been shown to be more intelligent. I hypothesized that the myopia/intelligence relationship could arise because a single genetically controlled mechanism affects both brain size and eye size. This hypothesis has testable implications.

Analysis of genealogic data of 100 patients addressed on occasion of myopia in 1987-1988 has shown that in 85% of the subjects myopia was of a clearly hereditary character (in 35%--a dominant and in 50%--a recessive hereditary). The author compares his own results with literature data and draws attention to Steiger's views about formation of myopic refraction and the role of hereditary factor in this process. In the light of the mentioned data, the author considers it expedient to work out a programme of special researches for development of a method of prognosticating initial myopia and a correction of several ways for approbation of existing methods of prevention of progressive myopia.

There is considerable evidence supporting a link between abnormalities in zinc and copper metabolism and some disorders of the retinal pigment epithelium. Anatomical studies in highly myopic eyes show important changes in this retinal layer. We measured the blood concentrations of zinc and copper and the urine concentration of copper in different groups of highly myopic patients from Caucasian and African populations, and in highly myopic patients with retinal detachment. In the Caucasian myopic groups, many patients showed high levels of zinc and low levels of copper in serum. In the high myopic group with retinal detachment, serum zinc and copper concentrations were significantly elevated. The importance of our findings and their connection to the retinal pigment epithelium is discussed.