Correction of refractive error and presbyopia in Timor-Leste

AIM: To investigate the aspects of spectacle correction of vision-impairing refractive error and presbyopia in those aged >or=40 years in Timor-Leste. METHOD: A population-based cross-sectional survey with cluster random sampling was used to select 50 clusters of 30 people. Those who had uncorrected or undercorrected refractive error (presenting acuity worse than 6/18, but at least 6/18 with pinhole), uncorrected or undercorrected presbyopia (near vision worse than N8), and/or who were using or had used spectacles were identified. Dispensing history, willingness to wear and willingness to pay for spectacles were elicited. RESULTS: Of 1470 people enumerated, 1414 were examined (96.2%). The "met refractive error need" in the sample was 2.2%, and the "unmet refractive error need" was 11.7%. The "refractive error correction coverage" was 15.7%. The "met presbyopic need" was 11.5%, and the "unmet presbyopic need" was 32.3%. The "presbyopia correction coverage" was 26.2%. Lower correction coverage was associated with rural domicile, illiteracy and farming. Of the sample, 96.0% were willing to wear spectacles correcting impaired vision. Of these, 17.0% were willing to pay US$3 ( pound 1.52, euro 2.24) for spectacles, whereas 50.2% were unwilling to pay US$1 ( pound 0.51, euro 0.75). Women and rural dwellers were less likely to be willing to pay at least US$1 for spectacles. CONCLUSION: Refractive error and presbyopia correction coverage rates are low in Timor-Leste. There is a large need for spectacles, especially for elderly and illiterate people, farmers and rural dwellers: those least able to pay for them. An equitable cross-subsidisation spectacle system should be possible.     

Survey of spectacle wear and refractive error prevalence in USAF pilots and navigators

A retrospective survey of 5000 active aircrew records was performed at 12 United States Air Force (USAF) bases to obtain information about the prevalence of spectacle wear and refractive error. The data revealed that 27.4% of pilots and 51.5% of navigators/weapons systems operators (Nav/WSO) required spectacles when flying. Of the spectacle-wearing pilots, 12.4% required bifocals. Myopia was the predominant refractive error and a relatively large percentage of aircrew members had astigmatism of 0.75 D or more, e.g., 33.1% of pilots. At the time of entry into the USAF, refractive error data were clustered around emmetropia with a definite skew toward hyperopia.     

Effects of myopic spectacle correction and radial refractive gradient spectacles on peripheral refraction

The recent observation that central refractive development might be controlled by the refractive errors in the periphery, also in primates, revived the interest in the peripheral optics of the eye. We optimized an eccentric photorefractor to measure the peripheral refractive error in the vertical pupil meridian over the horizontal visual field (from −45° to 45°), with and without myopic spectacle correction. Furthermore, a newly designed radial refractive gradient lens (RRG lens) that induces increasing myopia in all radial directions from the center was tested. We found that for the geometry of our measurement setup conventional spectacles induced significant relative hyperopia in the periphery, although its magnitude varied greatly among different spectacle designs and subjects. In contrast, the newly designed RRG lens induced relative peripheral myopia. These results are of interest to analyze the effect that different optical corrections might have on the emmetropization process.     

The prevalence of vision impairment and refractive error in 3654 first year students at Tianjin Medical University

AIM: To determine the prevalence of vision impairment (VI) and refractive error in first year university students at the Tianjin Medical University. METHODS: This is a cross-sectional observational cohort study of VI and refractive error among first year university students at the Tianjin Medical University. The first year university students were involved in this study and were given a detailed questionnaire including age, birth date, and spectacle wearing history. A standardized ophthalmologic examination including visual acuity (VA), slit-lamp examination, non-cycloplegic auto-refraction, objective refraction, fundus photography, and examination of their spectacles were recorded. RESULTS: A total of 3654 participants were included in this study. Totally 3436 (94.03%) individuals had VI in this population. Totally 150 (4.10%) individuals had VI due to ocular disease, including amblyopia, congenital cataract, retinal atrophy or degeneration, strabismus, congenital nystagmus, refractive surgery orthokeratology. Totally 3286 (89.93%) subjects had VI due to refractive error. Only 218 (5.97%) students were emmetropia. Moreover, refractive error was the main cause for the VI (95.63%). Totally 3242 (92.52%) students were myopia and the prevalence of mild, moderate, and high myopia subgroup was 27.05%, 44.35%, and 21.26% respectively. Totally 44 (1.29%) subjects were hyperopic. The rates of uncorrected visual acuity (UCVA), presenting visual acuity (PVA) and best corrected visual acuity (BCVA) which better than 20/20 in both eyes were 5.65%, 22.32% and 82.13% respectively. The rates of correction, under correction and well correction in myopia subjects were 82.73%, 84.39% and 15.61%, respectively. CONCLUSION: We present a high prevalence of refractive errors and high rates of under correction refractive error among first year university students. These results may help to promote vision protection work in young adults.     

Need and challenges of refractive correction in urban Chinese school children.

PURPOSE: Uncorrected refractive error is recognized as the principal cause of visual impairment in school-aged children. Although correction of refractive error is easy, safe, and effective, many children are without the necessary spectacles. Empiric research on barriers to refractive correction remains limited, precluding the formulation of effective remedial actions. The aims of this study were to characterize parental awareness and other barriers to spectacle use among children considered to be in need of refractive correction and to determine the proportion undercorrected for those already with spectacles. METHODS: A population-based sample of children 5 to 15 years of age was examined in Guangzhou, China. Visual acuity was measured followed by cycloplegic refraction and best-corrected vision. Parental awareness of the child's vision difficulties, spectacle use, and frequency of vision checkups were collected by questionnaire. Associations between these variables and demographic and socioeconomic characteristics were investigated with multiple logistic regression. RESULTS: Among the 4359 examined children, 919 (21.1%) were found to be in need of refractive correction. Need was defined as uncorrected visual acuity < or = 0.50 in both eyes correctable by at least two lines in the better eye. Parental awareness was apparent for 85% of cases; 74% had spectacles. Awareness of vision difficulties was associated with older child age, greater visual impairment, and higher parental education. The purchase of spectacles was associated with greater visual impairment; the child's age, gender, parental education, and family income were not significant factors. Undercorrection by two lines or more in the better eye was found in 30% of those already with spectacles; undercorrection was associated with greater visual impairment and less frequent refraction checkups. CONCLUSIONS: Half of the children in need of first-time or updated spectacles are without them, an unacceptably high proportion. Younger children with moderate visual impairment are at particular risk for uncorrected refractive error. Parental education and enhanced school-based screening programs may be necessary to address the unfilled need for refractive correction among school-aged children.     

Clinical features predictive of successfully weaning from spectacles those children with accommodative esotropia.

PURPOSE: It has been reported that most children with accommodative esotropia are not able to discontinue spectacle wear as they become older. We conducted a prospective study to determine which factors are predictive of successfully weaning children from spectacles. METHODS: Beginning in 1995, children with fully accommodative esotropia with a baseline refractive error of + 1.50 to + 5.00 diopters (D) were gradually weaned from their hyperopic correction. Patients with amblyopia or who had previously undergone strabismus surgery were excluded. Children were weaned in 0.50 D increments until spectacles were discontinued or they developed esotropia, asthenopia, or decreased vision. A multivariate analysis was performed to assess the association between successful weaning and various clinical characteristics. RESULTS: Twelve of 20 children (60%) were successfully weaned from spectacles. Spectacles were prescribed at a mean age of 4.2 +/- 1.5 years, and weaning was initiated at a mean age of 8.0 +/- 1.1 years. The spherical equivalent of the least hyperopic eye when spectacles were prescribed was 2.99 +/- 1.06 D. The clinical characteristic most clearly associated with successful weaning was the refractive error at the time glasses were prescribed. Whereas 10 of 11 (91%) patients with < 3 D of hyperopia were weaned from spectacles, only 2 of 9 (22%) patients with 3 to 5 D of hyperopia were successfully weaned from their spectacles (P =.005). CONCLUSIONS: Many children with fully accommodative esotropia can be weaned out of spectacles during the grade school years. The degree of baseline hyperopia appears to be one of the best predictors of success.     

学龄前儿童弱视的屈光不正临界值的研究

目的:测定我国学龄前儿童中引起屈光不正性弱视的临界值。方法:诊断性试验,符合纳入标准的5～7岁单纯散光147例294眼(附带球镜<1.00DS),单纯远视633眼(附带散光<0.50DC),远视伴轻度散光(0.50DC≤散光值<1.00DC)312眼,用受试者工作特征(receiver operating characteristic,ROC)曲线找出临界值。结果:通过诊断效能和ROC曲线观察,5～7岁儿童单纯散光≥1.00DC诊断弱视的敏感度和特异度分别是89.7%和88.7%,≥1.50DC诊断弱视的敏感度和特异度分别是83.3%和95.2%;单纯远视≥2.25DS诊断弱视的敏感度和特异度分别是63.0%和82.0%,单纯远视≥2.75DS诊断弱视的敏感度和特异度分别是45.2%和91.3%;远视伴轻度散光≥2.25DS诊断弱视的敏感度和特异度分别是60.0%和54.3%,远视伴轻度散光≥2.75DS诊断弱视的敏感度和特异度分别是24.9%和88.2%。结论:临界值提供小儿眼科医师诊断学龄前儿童屈光不正性弱视病因证据;提供了学龄前儿童屈光不正验光配镜的起点依据。适合5～7岁儿童普查筛选要求是散光≥1.00DC;适合诊断危险值的是散光≥1.50DC,单纯远视引起弱视的筛查临界值是≥2.25DS,适合诊断危险值的是≥2.75DS,远视伴轻度散光的临界值同单纯远视。     

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

Background

Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties.

Methods

A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3–6 (aged 9–11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n?=?46) and a without-treatment group (n?=?36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed.

Results

Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p?=?0.01).

Conclusion

No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.     

Spectrum of visual impairment among urban female school students of Surat

Aim:

Eye morbidities with or without symptoms delineate a significant morbidity among adolescent schoolgirls in India. The study was undertaken to assess the extent of visual impairment and ocular morbidity to identify influencing factors and the impact on scholastic performance.

Materials and Methods:

A population-based cross-sectional study was undertaken among 3002 urban girl students of Surat in Gujarat, India. Overall prevalence of refractive error was found to be 15.22%; myopia affected 91.47%, hyperopia 4.60%, and astigmatism 0.04%. The prevalence of myopia and astigmatism was more in higher age groups, while hyperopia was more in lower age groups; even students with good vision reported ophthalmic symptoms. Of all spectacle users, in 29.73% cases the eyesight was not found to be with the best possible corrections. Refractive error was observed to be higher among the general caste (50.98%) and among Muslims (54.05%). Still, among those with problems of eyesight, 75.93% students had good academic performance. Associated ocular morbidity was noted in 20.35% participants along with the refractive error.

Conclusion:

This study highlighted the load of eye morbidities of adolescent Indian urban girls.     

Normal emmetropization in infants with spectacle correction for hyperopia

PURPOSE: The development of emmetropic refraction is known to be under visual control. Does partial spectacle correction of infants' refractive errors, which has been shown to have beneficial effects in reducing strabismus and amblyopia, impede emmetropization? The purpose of the present study was to perform the first longitudinal controlled trial to investigate this question in human subjects. METHODS: Children identified as having significant hyperopia in a population screening program at age 8 to 9 months were assigned to treated (partial spectacle correction) or untreated groups. A control group of infants with no significant refractive errors at screening was also recruited. Measurements of retinoscopic refraction under cycloplegia were taken at 4- to 6-month intervals up to the age of 36 months, and changes in refraction of 148 subjects were analyzed longitudinally. RESULTS: Refractive error decreased toward low hyperopic values between 9 and 36 months in both hyperopic groups. By 36 months, this reduction of hyperopia showed no overall difference between children who were treated with partial spectacle correction and those who were not. Despite the improvement, both hyperopic groups' mean refractive error at 36 months remained higher than that of the control group. When infants in all three groups were considered together, the rate of reduction of refractive error was, on average, a linear function of the initial level of hyperopia. CONCLUSIONS: The benefits of spectacle correction for infants with hyperopia can be achieved without impairing the normal developmental regulation of refraction.     

Uncorrected refractive errors and spectacle utilisation rate in Tehran: the unmet need

AIM: To determine the prevalence of the met and unmet need for spectacles and their associated factors in the population of Tehran. METHODS: 6497 Tehran citizens were enrolled through random cluster sampling and were invited to a clinic for an interview and ophthalmic examination. 4354 (70.3%) participated in the survey, and refraction measurement results of 4353 people aged 5 years and over are presented. The unmet need for spectacles was defined as the proportion of people who did not use spectacles despite a correctable visual acuity of worse than 20/40 in the better eye. RESULTS: The need for spectacles in the studied population, standardised for age and sex, was 14.1% (95% confidence interval (CI), 12.8% to 15.4%). This need was met with appropriate spectacles in 416 people (9.3% of the total sample), while it was unmet in 230 people, representing 4.8% of the total sample population (95% CI, 4.1% to 5.4%). The spectacle coverage rate (met need/(met need + unmet need)) was 66.0%. Multivariate logistic regression showed that variables of age, education, and type of refractive error were associated with lack of spectacle correction. There was an increase in the unmet need with older age, lesser education, and myopia. CONCLUSION: This survey determined the met and unmet need for spectacles in a Tehran population. It also identified high risk groups with uncorrected refractive errors to guide intervention programmes for the society. While the study showed the unmet need for spectacles and its determinants, more extensive studies towards the causes of unmet need are recommended.     

Tolerance to prism induced by readymade spectacles: setting and using a standard.

PURPOSE: To determine first how much induced horizontal and vertical prism could be comfortably tolerated with readymade spectacle wear. Ultimately, the purpose is to develop a guide for dispensing decisions for blindness prevention programs in low-resource countries. METHODS: Nine participants each wore plano spectacles with differing prism power for 8 h (plano control). If visual discomfort could not be tolerated, participants removed the spectacles, noting duration of wear and reason for discontinuation. Distance and near visual comfort were rated, and participants asked if they would be able to adapt to wearing the spectacles. RESULTS: On average, half of the wearing time was spent on concentrated near viewing tasks. The highest prism powers (1 Delta BU, 2 Delta BO, 2 Delta BI) could not be worn for 8 h by the majority of participants. Comfort ratings at near (similar to those at distance) were statistically significantly different when the highest prism power was compared with each of the lower powers (vertical prism: both the control and 0.5 Delta differed from 1 Delta; horizontal prism: the control, 0.5 Delta and 1 Delta all differed from 2 Delta). CONCLUSIONS: Most spectacle wearers would likely comfortably tolerate 相似文献   

Non-cycloplegic refractive screening can identify infants whose visual outcome at 4 years is improved by spectacle correction

The Second Cambridge Population Infant Vision Screening Programme using the VPR-1 videorefractor without cycloplegia was undertaken in order to identify those infants with refractive errors who were potentially amblyogenic or strabismogenic. Infants identified at eight months were entered into a control trial of treatment with partial spectacle correction and underwent a long-term follow-up that monitored a wide range of visual, visuoperceptual, visuocognitive, visuomotor, linguistic and social development. In the present paper, the authors report on the outcome measures of visual acuity and strabismus. Poor acuity was defined as a best-corrected acuity of 6/12 or worse on crowded letters or 6/9 or worse on single letters, at age 4 years. Acuity was measured in 79 infants who were significantly hyperopic and/or anisometropic at 11-12 months of age, 23 who showed hyperopia of +3D but less than +3.5D, 196 control subjects, 14 controls with refractive errors, and 126 others who showed an accommodative lag on screening but were not significantly hyperopic on first retinoscopy. There was a poorer acuity outcome in the untreated group of hyperopes compared to controls (p < 0.0001) and to the children who were compliant in spectacle wear (p < 0.001) or who were prescribed spectacles (p < 0.05). Children who were significantly hyperopic at eight months were also more likely to be strabismic by 5.5 years compared to the emmetropic control group (p < 0.001). However, the present study did not find a significant difference in the incidence of strabismus between corrected and uncorrected hyperopic infants. Children who were not refractively corrected for significant hyperopia were four times more likely to have poor acuity at 5.5 years than infants who wore their hyperopic correction, supporting the findings of the First Cambridge Population Infant Vision Screening Programme.