Myopia in secondary school students in Mwanza City, Tanzania: the need for a national screening programme.
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BACKGROUND/AIMS: The prevalence of significant refractive errors and other eye diseases was measured in 2511 secondary school students aged 11-27 years in Mwanza City, Tanzania. Risk factors for myopia were explored. METHODS: A questionnaire assessed the students' socioeconomic background and exposure to near work followed by visual acuity assessment and a full eye examination. Non-cycloplegic objective and subjective refraction was done on all participants with visual acuity of worse than 6/12 in either eye without an obvious cause. RESULTS: 154 (6.1%) students had significant refractive errors. Myopia was the leading refractive error (5.6%). Amblyopia (0.4%), strabismus (0.2%), and other treatable eye disorders were uncommon. Only 30.3% of students with significant refractive errors wore spectacles before the survey. Age, sex, ethnicity, father's educational status, and a family history of siblings with spectacles were significant independent risk factors for myopia. CONCLUSION: The prevalence of uncorrected significant refractive errors is high enough to justify a regular school eye screening programme in secondary schools in Tanzania. Risk factors for myopia are similar to those reported in European, North-American, and Asian populations. (+info)
The impact of visual impairment and eye disease on vision-related quality of life in a Mexican-American population: proyecto VER.
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PURPOSE: To describe the relationship of visual acuity impairment and eye disease on vision-related quality of life, as measured by the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25), in a cross-sectional, population-based study of older Hispanic persons living in Arizona. METHODS: A random sample of block groups with Hispanic residents in Nogales and Tucson, Arizona, were selected for study. Participants were interviewed at home with a questionnaire that included the NEI-VFQ-25, an instrument measuring vision-related quality of life. Acuity was obtained with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and standard protocol. Cataract was determined by clinical examination, diabetic retinopathy was diagnosed on stereo fundus photographs, and glaucoma was diagnosed on the basis of clinical examination and visual field results. Analyses were done to determine the degree of association between subscale scores and acuity in the better-seeing eye, monocular visual impairment, and specific eye diseases, with adjustment for acuity. RESULTS: Of the 4774 participants in the study, 99.7% had completed questionnaires that were not completed by proxy. Participants with visual impairment had associated decrements in scores on all subscales, with a decrease in presenting acuity associated with a worse score (P < 0.05), after adjustment for demographic variables. Monocular impairment was also associated with lower scores in several subscales. In those with cataract, low acuity explained most of the low scores, but those with glaucoma or diabetic retinopathy had low scores independent of acuity. CONCLUSIONS: In this study of Mexican-American persons aged 40 or more, monocular impairment and better-eye acuity was associated with a decrease in most domains representing quality of life. Subjects with uncorrected refractive error, cataract, diabetic retinopathy, and glaucoma had associated decrements in quality of life, many not explained by loss of acuity. Further work on the specific measures of vision associated with reported decreases in quality of life, such as visual field or contrast sensitivity, is warranted. (+info)
Measuring higher order optical aberrations of the human eye: techniques and applications.
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In the present paper we discuss the development of "wave-front", an instrument for determining the lower and higher optical aberrations of the human eye. We also discuss the advantages that such instrumentation and techniques might bring to the ophthalmology professional of the 21st century. By shining a small light spot on the retina of subjects and observing the light that is reflected back from within the eye, we are able to quantitatively determine the amount of lower order aberrations (astigmatism, myopia, hyperopia) and higher order aberrations (coma, spherical aberration, etc.). We have measured artificial eyes with calibrated ametropia ranging from +5 to -5 D, with and without 2 D astigmatism with axis at 45 degrees and 90 degrees. We used a device known as the Hartmann-Shack (HS) sensor, originally developed for measuring the optical aberrations of optical instruments and general refracting surfaces in astronomical telescopes. The HS sensor sends information to a computer software for decomposition of wave-front aberrations into a set of Zernike polynomials. These polynomials have special mathematical properties and are more suitable in this case than the traditional Seidel polynomials. We have demonstrated that this technique is more precise than conventional autorefraction, with a root mean square error (RMSE) of less than 0.1 micro m for a 4-mm diameter pupil. In terms of dioptric power this represents an RMSE error of less than 0.04 D and 5 degrees for the axis. This precision is sufficient for customized corneal ablations, among other applications. (+info)
Characteristic ocular findings in Asian children with Down syndrome.
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AIMS/PURPOSE: To identify the characteristic ocular findings in Asian children with Down syndrome. METHODS: A total of 123 Korean children with Down's syndrome between 6 months and 14 years of age were examined for ocular findings from March 1999 to April 2000. Ocular examinations including visual acuity assessment, slit-lamp biomicroscopy, ocular motility, cycloplegic refraction, and ophthalmoscopy were performed. RESULTS: The ocular findings in decreasing prevalence were the following: upward slanting of the palpebral fissure (78 patients, 63%), epicanthus (75 patients, 61%), epiblepharon (66 patients, 54%), astigmatism (38 patients, 31%), hyperopia (35 patients, 28%), myopia (31 patients, 25%), strabismus (31 patients, 25%, 18 esotropia and 13 exotropia), nystagmus (27 patients, 22%), nasolacrimal duct obstruction (21 patients, 17%), blepharoconjunctivitis (20 patients, 16%), retinal abnormalities (18 patients, 15%), cataract (four patients, 13%), and glaucoma (one patient, 0.8%). Brushfield spots and keratoconus were not found. CONCLUSIONS: Asian children with Down syndrome demonstrate unreported, high incidence of epiblepharon, the high rate of exotropia, and essentially no notable Brushfield spots, which are in contrast to the ocular findings in Caucasian patients with Down syndrome. (+info)
The ophthalmic findings in Cohen syndrome.
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AIM: Cohen syndrome is an uncommon autosomal recessive condition comprising a characteristic facial appearance, mental retardation, benign neutropenia, and retinal dystrophy. This study aimed to identify patients with Cohen syndrome from across the United Kingdom in order to define the variability of ophthalmic manifestations. METHODS: Ophthalmic assessment was undertaken and past ophthalmic records reviewed in 22 patients with classic features of Cohen syndrome. RESULTS: All patients had visual problems which commonly started in the preschool years. 82% developed strabismus or refractive error during the first 5 years of life. 70% developed high myopia by the second decade. By contrast with the findings of others, early onset retinal dystrophy was common, occurring in 80% of study patients under age 5 years. 35% of patients were registered partially sighted or blind. CONCLUSION: The ophthalmic abnormalities associated with Cohen syndrome, including high myopia and a generalised, severe retinal dystrophy, are of early onset and frequently result in severe visual handicap. Cohen syndrome should be considered in the young, developmentally delayed child who presents with severe myopia and nyctalopia. (+info)
The induction of refractive errors by retinal detachment surgery.
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This report consists of a retrospective clinical study of the effect of retinal detachment repair, specifically the encircling procedure, on induced spherical refractive error. The analyze the findings we include optical and supplementary clinical and in vitro studies of corneal curvature, axial length, and anteiror chamber depth. The results of each of these help confirm and are sufficient to explain the discoveries of the original clinical study. (+info)
Weaning children with accommodative esotropia out of spectacles: a pilot study.
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BACKGROUND/AIM: Many children with accommodative esotropia must continue spectacle use throughout life. This study was undertaken to determine which factors are predictive of successfully weaning children with accommodative esotropia out of spectacles. METHODS: A retrospective review of 10 children with accommodative esotropia, who were gradually weaned from their hyperopic correction, and three age matched controls was performed. The main outcome measure was resolution or non-resolution of esotropia following weaning and eventual discontinuation of spectacles. Secondary outcome measures were final refractive error and the final esotropic or esophoric angle without correction. RESULTS: Six patients were successfully weaned from spectacles. At the completion of the weaning period one child was orthophoric and the other five children had well controlled esophorias. The other four patients remained spectacle dependent because of persistent esotropia or decreased vision without spectacles. The baseline and final refractive errors were significantly lower in the children successfully weaned from spectacles (p = 0.014). While the children who were successfully weaned from spectacles were older when initially diagnosed with accommodative esotropia (4.6 v 2.5 years), this difference was not statistically significant (p = 0.09). CONCLUSION: Some children with accommodative esotropia may be weaned out of spectacles during the grade school years with resolution of their esotropia. It is likely that gradual reduction of the hyperopic correction increases divergence amplitudes, but it is unclear whether this facilitates emmetropisation. (+info)
Optic disc morphology in south India: the Vellore Eye Study.
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AIM: To evaluate the morphology of the optic nerve head in an unselected population group in south India. METHODS: The study included 70 subjects forming a population based sample, selected in a random manner. Mean age was 47.5 (SD 8.7) years, mean refractive error measured -0.07 (1.11) dioptres (range -4.50 to +2.50 dioptres). Optic disc slides were morphometrically analysed. RESULTS: Mean optic disc area measured 2.58 (0.65) mm(2). It was statistically independent of age and refractive error. Optic disc shape was slightly vertically oval. Mean neuroretinal rim area was 1.60 (0.37) mm(2). It was significantly and positively correlated with optic disc size and optic cup size. It was independent of age, sex, refractive error, and axial length. In all subjects included in the study, the rim was smallest in the temporal horizontal optic disc sector. Mean horizontal cup/disc diameter ratio (0.66 (0.07)) was significantly (p<0.001) higher than the mean vertical cup/disc diameter ratio (0.56 (0.08)). Both ratios were highly significantly (p <0.001) and positively correlated with optic disc size. The alpha zone of parapapillary atrophy (0.84 (0.29) mm(2)), and beta zone (0.13 (0.38) mm(2)), respectively, occurred in 69 (98.6%) subjects and in eight (11.4%) subjects, respectively. They were significantly larger in the temporal horizontal sector. The alpha zone was significantly (p<0.001) larger and occurred significantly more often than beta zone. Retinal arterioles and venules were wider, and in spatial correlation, the visibility of the retinal nerve fibre layer was significantly better, in the temporal inferior disc arcade and the temporal superior arcade than in the nasal superior arcade and the nasal inferior vessel arcade. Except for the absolute size measurements these optic nerve head parameters did not differ markedly (p >0.05) from the values found in white people. CONCLUSIONS: South Indians and white people do not show marked differences in the morphology of the optic nerve head as measured by morphometric optic disc parameters, with the possible exception of the absolute optic disc dimensions. (+info)