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PubMed2006

Longitudinal study of anisometropia in Singaporean school children.

PURPOSE: The purpose of this study was to document the incidence rates of anisometropia, year-by-year prevalences, changes in the intereye difference in spherical equivalent (SE), and its association with myopia progression and axial length changes in a cohort of Singaporean school children. METHODS: This is a prospective cohort study of Singaporean school children (n = 1979) aged 7 to 9 years who were examined annually with cycloplegic refraction and ultrasonography over a 3-year period. RESULTS: In the 1908 children without anisometropia at commencement, the 3-year cumulative incidence rate of anisometropia (difference in SE at least 1.0 D) was 144 (7.55%; 95% CI: 6.42-8.85). The mean intereye difference in SE in all children at baseline was 0.29 +/- 0.46 D (SD: 0.46) and increased to 0.44 D (0.59) on the last examination. On the initial examination, 3.6% (95% CI: 2.8-4.4) or 71 children had anisometropia. Of the 59 of 71 children who completed all examinations, only 3 (5.1%) had an increase in the intereye difference in SE by at least 0.5 D, whereas 2 (3.4%) had a decrease of at least 0.5D. The mean intereye difference in SE was stable between visits. The change in intereye difference in SE correlated with the change in intereye axial length (r = 0.43). Compared with the isometropic children, each eye of the anisometropic children had a higher rate of progression of myopia. CONCLUSIONS: The 3-year incidence of anisometropia was 7.55% in these young Singaporean children. Although the frequency of anisometropia increased with time, the difference in SE between eyes tended to remain stable.

Anisometropia↗
PubMed2006

A cohort study of incident myopia in Singaporean children.

PURPOSE: To determine the risk factors of incident myopia in a school-based cohort study in Singaporean children. METHODS: A 3-year prospective cohort study was conducted in Singaporean school children aged 7 to 9 years in three schools at entry. Chinese children without myopia at baseline (n = 994) were included in the analysis. The main outcome was incident myopia, defined as spherical equivalent (SE) at least -0.75 D based on cycloplegic autorefraction. Other definitions of incident myopia, at least -0.5 D and at least -1.0 D, were also assessed. RESULTS: After controlling for school, age, gender, income, reading in books per week and intelligence quotient (IQ) test scores, we found the relative risk (RR) of incident myopia defined as -0.75 D to be 1.55 (95% confidence interval [CI] 1.18-2.04) for two versus no myopic parents. The multivariate RR of myopia for IQ in the third versus first tertile was 1.50 (95% CI, 1.19-1.89). However, the RR of incident myopia was 1.01 (95% CI, 0.97-1.05) for every unit increase in books read per week. Similar results were obtained with definitions of -0.5 and -1.0 D for incident myopia. CONCLUSIONS: These data provide new prospective evidence of essential links between parental myopia, IQ scores and subsequent myopia development. However, reading in books per week was not associated with incident myopia.

Child↗
PubMed2006

The VF-14 and psychological impact of amblyopia and strabismus.

PURPOSE: To assess the impact of amblyopia, strabismus and glasses on subjective visual and psychological function among amblyopes. METHODS: Questionnaires were administered to 120 teenagers with amblyopia (cases), with residual amblyopia after treatment, or with or without strabismus and 120 control subjects (controls) Cases underwent ophthalmic examination including cycloplegic refraction. Two questionnaires (visual function 14 [VF-14] and a newly designed eight-item questionnaire) were administered to assess the psychological impact score of general daily life, having a weaker eye, glasses wear, and current noticeable strabismus. Questionnaires were validated in 60 subjects in each group by a second administration of the questionnaire. The VF-14 scores, psychological impact scores, and clinical data were compared. RESULTS: The VF-14 and psychological impact scores were highly reproducible. The mean VF-14 score for the control group was 95.5 and for the cases was 78.9 (P < 0.0001), but the scores did not correlate with the severity of amblyopia. The psychological impact score in general daily life was sensitive in discriminating between mild (median score 31) and moderate to severe (median score 56) amblyopes (P < 0.02). The cases segregated into two clear groups; those who scored high (large detrimental psychological impact) on psychological impact, with subjectively noticeable manifest strabismus, and those who scored low (low detrimental psychological impact), without noticeable strabismus. The subjective experience of patching treatment differentiated the two groups best of all. CONCLUSIONS: Subjective visual and psychological functions are altered compared with normal subjects due to amblyopia, strabismus, and a previous unpleasant patching experience. The mean VF-14 score was similar to that previously published for patients with glaucoma. The study underlines that amblyopia and/or strabismus have an impact on teenagers' subjective visual function and well-being.

Activities of Daily Living↗
PubMed2006

Effectiveness of hyperopic defocus, minimal defocus, or myopic defocus in competition with a myopiagenic stimulus in tree shrew eyes.

PURPOSE: To examine the ability of hyperopic defocus, minimal defocus, and myopic defocus to compete against a myopiagenic -5-D lens in juvenile tree shrew eyes. METHODS: Juvenile tree shrews (n > or = 5 per group), on a 14-hour lights-on/10-hour lights-off schedule, wore a monocular -5-D lens (a myopiagenic stimulus) over the right eye in their home cages for more than 23 hours per day for 11 days. For 45 minutes each day, the animals were restrained so that all visual stimuli were >1 m away. While viewing distance was controlled, the -5-D lens was removed and another lens was substituted with one of the following spherical powers: -5 D, -3 D (hyperopic defocus); plano (minimal defocus); or +3, +4, +5, +6, or +10 D (myopic defocus). Daily noncycloplegic autorefractor measures were made on most animals. After 11 days of treatment, cycloplegic refractive state and axial component dimensions were measured. RESULTS: Eyes with the substituted -5- or -3-D-lens developed significant myopia (mean +/- SEM, -4.7 +/- 0.3 and -3.1 +/- 0.1 D, respectively) and appropriate vitreous chamber elongation. All animals with the substituted plano lens (minimal defocus) during the 45-minute period showed no axial elongation or myopia (the plano lens competed effectively against the -5-D lens). Variable results were found among animals that wore a plus lens (myopic defocus). In 11 of 20 eyes, a +3-, +4-, or +5-D lens competed effectively against the -5-D lens (treated eye <1.5 D myopic relative to its fellow control eye). In the other eyes (9/20) myopic defocus was ineffective in blocking compensation; the treated eye became more than 2.5 D myopic relative to the control eye. The +6- and +10-D substituted lenses were ineffective in blocking compensation in all cases. CONCLUSIONS: When viewing distance was limited to objects >1 m away, viewing through a plano lens for 45 minutes (minimal defocus) consistently prevented the development of axial elongation and myopia in response to a myopiagenic -5-D lens. Myopic defocus prevented compensation in some but not all animals. Thus, myopic defocus is encoded by at least some tree shrew retinas as being different from hyperopic defocus, and myopic defocus can sometimes counteract the myopiagenic effect of the -5-D lens (hyperopic defocus). However, it appears that minimal defocus is a more consistent, strong antidote to a myopiagenic stimulus in this mammal closely related to primates.

Animals↗
PubMed2006

Myopia, axial length, and OCT characteristics of the macula in Singaporean children.

PURPOSE: The purpose of this study was to evaluate the associations between macular volume and thickness, as assessed by optic coherence tomography (OCT), with refraction and axial length (AL) in children. METHODS: A total of 104 Chinese school children (51 girls and 53 boys) 11 to 12 years of age were randomly selected from one school during the 2005 examination in the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Cycloplegic autorefraction was performed to obtain refraction (defined as spherical equivalent [SE]) and ultrasound biometry performed to obtain the AL. Macular volume and thickness were then measured (StratusOCT3; Carl Zeiss Meditec, Dublin, CA). RESULTS: Children with moderate myopia (SE at least -3.0 D) tended to have smaller total macular volume and thinner quadrant-specific macular thickness (except in the inferior and superior inner quadrants), followed by children with low myopia (-0.5 -0.5 D). Total macular volume was positively associated with SE (beta=1.58, 95% CI, 0.84 to 2.32, standardized beta=0.14, P<0.001) and negatively associated with AL (beta=-1.20, 95% CI, -1.62 to -0.79, standardized beta=0.45, P<0.001) in multiple linear regression models controlling for age and gender. CONCLUSIONS: In children, increasing axial myopia was associated with reduced macular volume and thickness. These findings suggest that early anatomic changes may be present in the retinas of children with axial myopia.

Anthropometry↗
PubMed2006

Distribution of macular thickness by optical coherence tomography: findings from a population-based study of 6-year-old children.

PURPOSE: To study the distribution of macular thickness by ocular and demographic variables in a population-based study of young children. METHODS: The Sydney Childhood Eye Study examined 1765 6-year-old children from 34 randomly selected Sydney schools during 2003 and 2004 (78.9% response). A comprehensive eye examination included cycloplegic autorefraction and optical biometry. Fast macular thickness scans were performed over a 6-mm diameter central retinal region with optical coherence tomography. Multivariate analyses were performed. Macular thickness is presented on a modified Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid, with outer radii for the central, inner, and outer macular regions being 0.5, 1.5, and 3 mm, respectively. RESULTS: In the study, 1543 children (88.7% of participants; 51.1% boys) had high-quality scan data (mean age, 6.7 years). The mean (SD) minimum foveal thickness was 161.1 (19.4) microm. The thickness of the central, inner, and outer macula was normally distributed, with means (SD) of 193.6 (17.9), 264.3 (15.2), and 236.9 (13.6) microm, respectively. Total macular volume was also normally distributed, with a mean (SD) of 6.9 (0.4) mm(3). The temporal quadrant was thinner than other quadrants for both inner and outer macular regions. The foveal minimum, central, and inner macula was generally significantly thicker in boys than in girls, and in white than in East Asian children. Outer macular thickness showed no significant gender-ethnic differences. Sectoral macular thickness variations were preserved in both gender and ethnic groups. The inner and outer macula, but not the central macula, showed significant thinning with increasing axial length. These corresponding areas were significantly thicker with more hyperopic spherical equivalent refractions. CONCLUSIONS: Macular thickness and volume were normally distributed in this young childhood population. Significant gender and ethnic differences were demonstrated. Axial length and refraction were important ocular biometric determinants of macular thickness.

Anatomy, Cross-Sectional↗
PubMed2006

Associations between childhood refraction and parental smoking.

PURPOSE: Motivated by pharmacologic findings linking nicotinic acetylcholine receptors to eye development in chicks, the authors studied whether the refractions of children who were passively exposed to cigarette smoke by their parents differed from those of nonexposed children. METHODS: A cross-sectional study was conducted among 323 patients (mean +/- SD age, 8.7 +/- 4.4 years; range, 1-20) in a tertiary care pediatric ophthalmology clinic. Half (162/323) of the subjects had strabismus. The accompanying parent completed a detailed questionnaire on parental smoking history and on putative risk factors for myopia. The results were compared to the subjects' cycloplegic refractions. RESULTS: If one or both parents ever smoked, their children had a lower myopia prevalence (12.4% vs. 25.4%; P = 0.004) and more hyperopic mean refractions (1.83 +/- 0.24 vs. 0.96 +/- 0.27 diopters; P = 0.02) than those whose parents never smoked. Smoking by either parent during the mother's pregnancy had a similar effect on the child's refraction. The associations largely persisted, both in multivariate models that included adjustments for the child's age, child's body mass index, child's nearwork activity, parental myopia, and parental education and also in analysis by subgroups stratified by strabismus status. CONCLUSIONS: Despite the complex constituents of cigarette smoke, neuropharmacology perspectives may prove useful in the development of new hypotheses to understand the mechanisms governing refractive development, not only in experimental animals but also in children. The associations of less prevalent myopia and a more hyperopic mean refraction with both prenatal and childhood exposures to tobacco smoke suggest that nongenetic, environmental exposures may have long-term influences on refraction and that further study of the role of nicotinic acetylcholine receptors in refractive development is warranted.

Adolescent↗
PubMed2006

Distribution of optic disc parameters measured by OCT: findings from a population-based study of 6-year-old Australian children.

PURPOSE: To study the distribution of optic disc, cup, and neural rim size by ocular and demographic variables in a population-based sample of 6-year-old children. METHODS: The Sydney Childhood Eye Study examined 1765 of 2238 eligible 6-year-old children (78.9%) from 34 randomly selected Sydney schools during 2003 to 2004. Comprehensive standardized eye examination included cycloplegic autorefraction, optical biometry and "fast optic disc" scans performed using optical coherence tomography. RESULTS: Scans of adequate quality were available for 1309 children (75% of participants), with 70% aged 6 years; 50.9% were boys. Mean (+/- SD) horizontal and vertical disc diameter and disc area was 1.53 +/- 0.21 mm, 1.79 +/- 0.28 mm, and 2.20 +/- 0.39 mm(2), respectively. Corresponding cup dimensions were 0.70 +/- 0.28 mm, 0.73 +/- 0.27 mm, and 0.48 +/- 0.32 mm(2). A definable optic cup was absent in 7.4%, 87% of whom were European white. Cup-to-disc diameter ratios were 0.46 +/- 0.16 horizontally and 0.42 +/- 0.15 vertically, whereas cup-to-disc area ratio was 0.22 +/- 0.13. Mean +/- SD neural rim area was 1.76 +/- 0.44 mm(2) and increased with disc size (Pearson correlation = 0.68, P < 0.0001). Horizontal and vertical average nerve widths were 0.36 +/- 0.05 and 0.28 +/- 0.05 mm, respectively. In analyses adjusting for potential confounders, disc area increased significantly with axial length (P(trend) < 0.0001) and refraction (P(trend) = 0.02). Rim area increased only with axial length (P(trend) = 0.01). There were no gender differences, except for average nerve width, marginally greater in boys. Most disc and cup dimensions were significantly larger in East-Asian than European white and Middle Eastern children. CONCLUSIONS: Disc, cup, and neural rim parameters were generally normally distributed in this young population. Axial length appeared to be a stronger determinant of disc and rim size than refraction. Some ethnic but not gender differences were demonstrated for most parameters.

Australia↗
PubMed2007

Astigmatism in 12-year-old Australian children: comparisons with a 6-year-old population.

PURPOSE: To study the distributions of refractive (RA), corneal (CA), and internal astigmatism (IA) in 12-year-old Australian children and to explore differences from previous findings in 6-year-old children. METHODS: Eligible year 7 students (2353/3144 [75.3%], median age, 12 years) from a random cluster sample of 21 high schools in Sydney, Australia, were examined by keratometry, cycloplegic autorefraction, and review of questionnaire data. RESULTS: Prevalence rates of RA, CA, and IA > or =1.0 D in right eyes were 6.7% (95% confidence interval [CI], 5.0-8.4), 26.6% (CI, 22.1-31.1), and 26.5% (CI, 22.9-30.0), respectively. RA was predominantly with-the-rule (WTR; 40.4%, CI, 32.6 to 48.2) and against-the-rule (ATR; 43.6%, CI, 35.7-51.5), CA was WTR (88.8%, CI, 86.3-91.3), and IA was ATR (90.2%, CI, 87.8-92.6). The girls had significantly greater CA and IA prevalence, with greater ATR astigmatism and lower oblique IA than did the boys. The European white-Australian children had lower CA prevalence than did the East Asian-Australian children and higher IA prevalence than did the South Asian-Australian children. Ethnic differences in RA prevalence were not significant, when adjusted for confounders. RA was more frequently ATR in European white than in other ethnic groups. Compensation between CA and IA reduced the magnitude of RA. Comparison with the data on 6-year-old children revealed minimal differences for all astigmatic components. CONCLUSIONS: There was a relatively low prevalence of RA, due to compensation between CA and IA. The minimal differences in all components of astigmatism between the two age cohorts suggest that astigmatism is stable between ages 6 and 12 years, although this conclusion needs to be confirmed in longitudinal studies.

Adolescent↗
PubMed1997

The efficacy of calcium gluconate in ocular hydrofluoric acid burns.

1. Although calcium gluconate (CG) is recommended in the treatment of hydrofluoric acid (HF) eye burn its efficacy seems to be controversial, and controlled human or animal studies are limited. The study's objective is to compare the efficacy of 1% CG and normal saline irrigation for the treatment of HF eye injury in animals. 2. 0.05 ml 2% HF was instilled to anesthetized rabbit's eyes. One minute later, four treatment groups were studies: (1) irrigation with normal saline followed by topical antibiotics, corticosteroids and cycloplegics for 48 h (n = 10); (2) irrigation with 1% CG followed by the same topical treatment (n = 9); (3) as group 1 and 1% CG drops over 48 h (n = 10); (4) as group 3, and injection of 1% CG subconjunctivally after irrigation (n = 9). 3. Corneal erosion area, corneal haziness, conjunctival status, vascularization (pannus) and acidity were assessed before injury, immediately after initial treatment and 1, 2, 7 and 14 days thereafter by slit lamp aided by fluorescein staining. 4. Conjunctival pH dropped from 6.0-6.5 to 2.5-3 after injury and increased to 6-6.5 after irrigation. Corneal erosion: smaller in groups 2, 3, significantly so at 2 days, but not different at 14 days. Corneal haziness: more severe in group 4, at 14 days, insignificant. Conjunctival damage: significantly worse in group 4 at 2, 7 and 14 days. Pannus appeared in 2-4 eyes in each group. 5. It seems that for HF injury 1% CG did not have any significant advantage over saline irrigation and topical treatment only. It might have some initial and temporary effect on healing process especially that involving erosion. Given subconjunctivally, 1% CG may be toxic and worsens clinical outcome.

Administration, Topical↗
PubMed1990

The potential for mental status changes associated with systemic absorption of anticholinergic ophthalmic medications: concerns in the elderly.

Several cases have been reported of anticholinergic toxicity following the administration of commonly used parasympatholytic cycloplegics and mydriatics. Cases have been reported in children, adults, and the elderly. The risk of developing mental status changes secondary to anticholinergic ophthalmic medications is of particular concern in the elderly. Drug-induced mental status or behavior changes should not be mistaken for exacerbation of an underlying disorder or the onset of a new disease (e.g., Alzheimer's disease, dementia). Clinicians should be aware of these potential complications, monitor for changes in mental status, and take appropriate action.

Absorption↗
PubMedDate not supplied

The effects of 2% ibopamine eye drops on the intraocular pressure and pupil motility of patients with open-angle glaucoma.

PURPOSE: Ibopamine is a prodrug of N-methyldopamine that has a non-cycloplegic mydriatic action due to its alpha-adrenergic properties and is able to induce, when topically given, a transient increase of intraocular pressure (IOP) in eyes with hydrodynamic disorders. METHODS: This is a randomized, crossover, open-labeled, two- center study. Forty patients (20 open-angle glaucoma patients and 20 healthy subjects) were treated with ibopamine 2% eye drops and phenylephrine 10% eye drops. RESULTS: Ibopamine induced a significant increase in IOP only in glaucomatous eyes (p<0.001) without a significant hypertensive effect in normal eyes. Ibopamine and phenylephrine showed a similar mydriatic activity but ibopamine was able to induce an hypertensive effect only in glaucomatous eyes. CONCLUSIONS: The results confirm the use of ibopamine as provocative test in detection of hydrodynamic disorders.

Administration, Topical↗
PubMedDate not supplied

Zyoptix wavefront-guided versus standard photorefractive keratectomy (PRK) in low and moderate myopia: randomized controlled 6-month study.

PURPOSE: To evaluate the refractive and aberrometric outcome of wavefront-guided photorefractive keratectomy (PRK) compared to standard PRK in myopic patients. METHODS: Fifty-six eyes of 56 patients were included in the study and were randomly divided into two groups. The study group consisted of 28 eyes with a mean spherical equivalent (SE) of -2.25+/-0.76 diopters (D) (range: -1.5 to -3.5 D) treated with wavefront-guided PRK using the Zywave ablation profile and the Bausch & Lomb Technolas 217z excimer laser (Zyoptix system) and the control group included 28 eyes with a SE of -2.35+/-1.01 D (range: -1.5 to -3.5 D) treated with standard PRK (PlanoScan ablation) using the same laser. A Zywave aberrometer was used to analyze and calculate the root-mean-square (RMS) of total high order aberrations (HOA) and Zernike coefficients of third and fourth order before and after (over a 6-month follow-up period) surgery in both groups. Preoperative and postoperative SE, un-corrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were evaluated in all cases. RESULTS: There was a high correlation between achieved and intended correction. The differences between the two treatment groups were not statistically significant for UCVA, BCVA, or SE cycloplegic refraction . Postoperatively the RMS value of high order aberrations was raised in both groups. At 6-month control, on average it increased by a factor of 1.17 in the Zyoptix PRK group and 1.54 in the PlanoScan PRK group (p=0.22). In the Zyoptix group there was a decrease of coma aberration, while in the PlanoScan group this third order aberration increased. The difference between postoperative and preoperative values between the two groups was statistically significant for coma aberration (p=0.013). No statistically significant difference was observed for spherical-like aberration between the two groups. In the study group eyes with a low amount of preoperative aberrations (HOA RMS lower than the median value; <0.28 microm) showed an increase of HOA RMS while eyes with RMS higher than 0.28 microm showed a decrease (p<0.05). CONCLUSIONS: Zyoptix wavefront-guided PRK is as safe and efficacious for the correction of myopia and myopic astigmatism as PlanoScan PRK. Moreover this technique induces a smaller increase of third order coma aberration compared to standard PRK. The use of Zyoptix wavefront-guided PRK is particularly indicated in eyes with higher preoperative RMS values.

Adult↗
PubMedDate not supplied

Hyperopic shift after 4-8 incision radial keratotomy: eight-year follow-up.

PURPOSE: To evaluate the prevalence, amount and possible factors connected with the hyperopic shift after radial keratotomy. BASIC PROCEDURES: We studied 86 eyes (51 patients) which underwent 4-8 incision radial keratotomy (delayed technique), consecutively performed by the same surgeon between February 1983 and November 1988. The diamond-bladed knife was set at 95% of the smallest paracentral ultrasonic corneal thickness measurement and the clear zone diameter was between 3.0 and 3.5 mm. Preoperative myopia ranged from -2.00 to -7.25 diopters (D). The average follow-up was 97.4 months (range 78 to 122 months). MAIN FINDINGS: After eight years of follow-up, the cycloplegic spherical equivalent was satisfactory: 66.2% of the eyes showed a refractive error within 0.5 D, 17.4% were myopic by more than 0.5 D and 16.2% were hyperopic by more than 0.5 D. The mean refractive error was 0.02 D (SD +/- 0.75 D). Between six months and eight years after surgery a hyperopic shift of more than 0.5 D was found in 40.6% of the eyes. The mean hyperopic shift was higher (0.78 D) in the eyes which had keratometry less than 36 D six months after surgery. Compared to the eyes with keratometry greater than 36 D (mean hyperopic shift 0.38 D), the difference was statistically significant (p < 0.02). CONCLUSIONS: These results show that keratometry, measured six months postoperatively, plays a fundamental role in the stability of postsurgical refraction, as the risk of hyperopic shift is higher in eyes with keratometry < 36 D.

Adult↗
PubMedDate not supplied

Unilateral anterior uveitis in Melkersson-Rosenthal syndrome: a case report.

Melkersson-Rosenthal syndrome (MRS) is an uncommon granulomatous condition characterized by persistent or recurrent orofacial oedema, relapsing facial paralysis and fissured tongue. We report here a case of MRS with the classical triad of signs accompanied by unilateral anterior uveitis. A 35-year-old man with a fissured tongue, recurrent facial palsy and orofacial oedema presented with a 3-month history of conjunctival redness and decreased vision in the right eye. On evaluation of visual acuity, the patient was only able to count fingers. Slit lamp examination revealed severe conjunctival injection, cells and flare, posterior synechiae and keratic precipitates. Examination of the left eye revealed no evidence of inflammation. Examination of the other systems was normal. The patient was treated with topical corticosteroids and cycloplegics and the visual acuity improved to 7/10. To our knowledge, there are no previous reports of an association between uveitis and MRS.

Administration, Topical↗
PubMed2004

Candidate high myopia loci on chromosomes 18p and 12q do not play a major role in susceptibility to common myopia.

BACKGROUND: To determine whether previously reported loci predisposing to nonsyndromic high myopia show linkage to common myopia in pedigrees from two ethnic groups: Ashkenazi Jewish and Amish. We hypothesized that these high myopia loci might exhibit allelic heterogeneity and be responsible for moderate /mild or common myopia. METHODS: Cycloplegic and manifest refraction were performed on 38 Jewish and 40 Amish families. Individuals with at least -1.00 D in each meridian of both eyes were classified as myopic. Genomic DNA was genotyped with 12 markers on chromosomes 12q21-23 and 18p11.3. Parametric and nonparametric linkage analyses were conducted to determine whether susceptibility alleles at these loci are important in families with less severe, clinical forms of myopia. RESULTS: There was no strong evidence of linkage of common myopia to these candidate regions: all two-point and multipoint heterogeneity LOD scores were < 1.0 and non-parametric linkage p-values were > 0.01. However, one Amish family showed slight evidence of linkage (LOD>1.0) on 12q; another 3 Amish families each gave LOD >1.0 on 18p; and 3 Jewish families each gave LOD >1.0 on 12q. CONCLUSIONS: Significant evidence of linkage (LOD> 3) of myopia was not found on chromosome 18p or 12q loci in these families. These results suggest that these loci do not play a major role in the causation of common myopia in our families studied.

Adolescent↗
PubMed2003

The Tehran Eye Study: research design and eye examination protocol.

BACKGROUND: Visual impairment has a profound impact on society. The majority of visually impaired people live in developing countries, and since most disorders leading to visual impairment are preventable or curable, their control is a priority in these countries. Considering the complicated epidemiology of visual impairment and the wide variety of factors involved, region specific intervention strategies are required for every community. Therefore, providing appropriate data is one of the first steps in these communities, as it is in Iran. The objectives of this study are to describe the prevalence and causes of visual impairment in the population of Tehran city; the prevalence of refractive errors, lens opacity, ocular hypertension, and color blindness in this population, and also the familial aggregation of refractive errors, lens opacity, ocular hypertension, and color blindness within the study sample. METHODS DESIGN: Through a population-based, cross-sectional study, a total of 5300 Tehran citizens will be selected from 160 clusters using a stratified cluster random sampling strategy. The eligible people will be enumerated through a door-to-door household survey in the selected clusters and will be invited. All participants will be transferred to a clinic for measurements of uncorrected, best corrected and presenting visual acuity; manifest, subjective and cycloplegic refraction; color vision test; Goldmann applanation tonometry; examination of the external eye, anterior segment, media, and fundus; and an interview about demographic characteristics and history of eye diseases, eye trauma, diabetes mellitus, high blood pressure, and ophthalmologic cares. The study design and eye examination protocol are described. CONCLUSION: We expect that findings from the TES will show the status of visual problems and their causes in the community. This study can highlight the people who should be targeted by visual impairment prevention programs.

Blindness↗
PubMed2005

Little evidence for an epidemic of myopia in Australian primary school children over the last 30 years.

BACKGROUND: Recently reported prevalences of myopia in primary school children vary greatly in different regions of the world. This study aimed to estimate the prevalence of refractive errors in an unselected urban population of young primary school children in eastern Sydney, Australia, between 1998 and 2004, for comparison with our previously published data gathered using the same protocols and other Australian studies over the last 30 years. METHODS: Right eye refractive data from non-cycloplegic retinoscopy was analysed for 1,936 children aged 4 to 12 years who underwent a full eye examination whilst on a vision science excursion to the Vision Education Centre Clinic at the University of New South Wales. Myopia was defined as spherical equivalents equal to or less than -0.50 D, and hyperopia as spherical equivalents greater than +0.50 D. RESULTS: The mean spherical equivalent decreased significantly (p < 0.0001) with age from +0.73 +/- 0.1D (SE) at age 4 to +0.21 +/- 0.11D at age 12 years. The proportion of children across all ages with myopia of -0.50D or more was 8.4%, ranging from 2.3% of 4 year olds to 14.7% of 12 year olds. Hyperopia greater than +0.50D was present in 38.4%. A 3-way ANOVA for cohort, age and gender of both the current and our previous data showed a significant main effect for age (p < 0.0001) but not for cohort (p = 0.134) or gender (p = 0.61). CONCLUSIONS: Comparison of our new data with our early 1990s data and that from studies of over 8,000 Australian non-clinical rural and urban children in the 1970's and 1980's provided no evidence for the rapidly increasing prevalence of myopia described elsewhere in the world. In fact, the prevalence of myopia in Australian children continues to be significantly lower than that reported in Asia and North America despite changing demographics. This raises the issue of whether these results are a reflection of Australia's stable educational system and lifestyle over the last 30 years.

Child↗