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.     

Infant hyperopia: detection, distribution, changes and correlates-outcomes from the cambridge infant screening programs.

PURPOSE: To report on two population screening programs designed to detect significant refractive errors in 8308 8- to 9-month-old infants, examine the sequelae of infant hyperopia, and test whether early partial spectacle correction improved visual outcome (strabismus and acuity). The second program also examined whether infant hyperopia was associated with developmental differences across various domains such as language, cognition, attention, and visuomotor competences up to age 7 years. Linked programs in six European countries assessed costs of infant refractive screening. METHOD: In the first program, screening included an orthoptic examination and isotropic photorefraction, with cycloplegia. In the second program we carried out the same screening procedure without cycloplegia. Hyperopic infants (> or = +4 D) were followed up alongside an emmetropic control group, with visual and developmental measures up to age 7 years, and entered a controlled trial of partial spectacle correction. RESULTS: The second program showed that accommodative lag during photorefraction with a target at 75 cm (focus > or = +1.5 D) was a marker for significant hyperopia. In each program, prevalence of significant hyperopia at 9 to 11 months was around 5%; manifest strabismus was 0.3% at 9 months and 1.5 to 2.0% by school age. Infant hyperopia was associated with increased strabismus and poor acuity at 4 years. Spectacle wear by infant hyperopes produced better visual outcome than in uncorrected infants, although an improvement in strabismus was found in the first program only. The corrections did not affect emmetropization to 3.5 years; however, both corrected and uncorrected groups remained more hyperopic than controls in the preschool years. The hyperopic group showed poorer overall performance than controls between 1 and 7 years on visuoperceptual, cognitive, motor, and attention tests, but showed no consistent differences in early language or phonological awareness. Relative cost estimates suggest that refractive screening programs can detect visual problems in infancy at lower overall cost than surveillance in primary care. CONCLUSIONS: Photo/videorefraction can successfully screen infants for refractive errors, with visual outcomes improved through early refractive correction. Infant hyperopia is associated with mild delays across many aspects of visuocognitive and visuomotor development. These studies raise the possibility that infant refractive screening can identify not only visual problems, but also potential developmental and learning difficulties.     

Strabismus,refractive errors and nystagmus in children and young adults with Down syndrome

Purpose: The aims of the present population-based, cross-sectional study were to examine the frequency and type of strabismus, refractive errors and nystagmus in children and young adults with Down syndrome (DS) in Macedonia and Croatia.

Methods: A total of 170 unselected children and young adults with DS aged 1–34 years were examined for ocular findings. The ocular examination included: a visual acuity assessment, cycloplegic refraction, ocular alignment and ocular motility.

Results: Strabismus was found in 45 of 170 children (26.5%), and esodeviation was the most common type. Nine (20%) had exodeviation and 4 (8.9%) vertical deviation. In 27 of 32 esotropic patients, the strabismus was regarded as acquired esodeviations. The frequency of strabismus was lowest in the high-grade hyperopia group (5%). Concerning esodeviations, fewer cases (3%) were in the high-grade hyperopia group. Most of the cases with esodeviations were in correlation with low-grade hyperopia (31%), myopia (28 %) and emetropia (16%). Hyperopia was the most common refractive error and high myopia increased in prevalence in the over 20 age group. Astigmatism was present in 72.4% of patients. Nystagmus was observed in 18 patients. Ten of 18 patients with nystagmus were associated with the presence of strabismus (9 esodeviations, 1 exotropia).

Conclusion: In our study, the high prevalence of strabismus can not be attributed to the presence of hyperopia. Our data show no association between refraction and strabismus in children with DS. Oblique astigmatism has been found to be the most common type of astigmatism in our study group.     

Development of refraction and strabismus

In the past year, as in recent years, most of the research on the development of refraction has focused on the following: 1) mechanisms whereby the eye can maintain coordinated growth to achieve emmetropia and 2) disruptions of emmetropization resulting in myopia or hyperopia. Preterm children and those with Down syndrome have higher refractive errors than other children, suggesting a failure of emmetropization. One of the most intriguing studies of the past year and one certain to lead to follow-up studies reported that ambient room illumination at night in a child's first two years is associated with a higher prevalence of myopia than sleeping in darkness. Reports on the development of hyperopia showed that it is axial in nature, similar to myopia. The effects of spectacle interventions to correct refractive errors are still being debated, with recent evidence from children suggesting that lenses do not exacerbate myopia. Analyses of risk factors and numerous new screening procedures detect patients with strabismus for referral at a variety of sensitivity and specificity levels. Hyperopia and high AC/A ratios are most clearly associated as causal agents for esotropia and intermittent exotropia. However, the action of even these simple mechanisms is confounded by abnormal binocular fusion mechanisms and the inability of optical correction to align the eyes of many patients. Asymmetric optokinetic nystagmus, latent nystagmus, and dissociated vertical deviation appear to be linked to infantile esotropia from before its onset. But the way the mechanisms underlying these oculomotor anomalies are causally related to the onset of infantile esotropia remains a mystery.     

Ocular components before and after acquired, nonaccommodative esotropia.

BACKGROUND: Acquired nonaccommodative esotropia describes the sudden onset of a constant, comitant strabismus of idiopathic origin in children >6 months of age. CASE REPORT: We present a case of acquired nonaccommodative esotropia at 20 months of age in a subject participating in the Berkeley Infant Biometry Study, a longitudinal study of emmetropization and ocular component development in infants between 3 months and 3 years of age. Ocular components for this child were normal before the onset of strabismus (within 2 SD's of the mean for orthotropic study participants) for refractive error, corneal power, lens radii, lens power, and ocular axial dimensions. Refractive error postsurgically was significantly more hyperopic and crystalline lens power lower than average at +2.38 D and 37.2 D, respectively. CONCLUSIONS: The lack of abnormal ocular parameters is consistent with the idiopathic etiology of acute onset esotropia. This case suggests that ocular component values may not be useful for assessing the risk of acquired nonaccommodative esotropia.     

周边视网膜相对屈光度与近视进展的关系

在正视眼或者低度远视眼中,周边视网膜呈相对远视屈光状态者比周边视网膜呈相对近视屈光状态者更容易发展为近视眼.正视眼周边视网膜呈轻度相对近视屈光状态,未矫正的远视眼周边视网膜呈稍大程度的相对近视屈光状态,未矫正的近视眼周边视网膜呈轻度相对远视屈光状态或比正视眼程度轻的相对近视状态.这两种观点已经被学者广泛接受.动物实验也证明异常视觉信号不仅能引起中央视网膜屈光不正,也能改变眼球后极部眼球形态和周边视网膜相对屈光不正的类型,并且黄斑切除并不影响正视化过程.相反,周边视网膜能单独调控眼球正视化过程并能对异常视觉信号起作用进而发展为各种屈光不正.临床研究表明,矫正视网膜周边远视性离焦的框架镜片对近视眼进展能起到一定的控制作用.虽然,周边视网膜远视性离焦是否促进近视进展的确切原因还不能肯定,但目前的研究倾向于认为两者之间可能有某种关系.     

Visual and binocular status of Down syndrome children in Malaysia

Background: Down syndrome is a common chromosomal anomaly. Few reported studies make reference to the ocular status in Asian children with Down syndrome. The purpose of this study was to determine the visual and binocular status of a sample of Down syndrome children in Malaysia. Methods: A total of 73 Malaysian children with Down syndrome (38 boys and 35 girls) in the Kuala Lumpur area aged one to 12 years were examined. Cycloplegic refraction was performed on each eye and binocular visual acuity was assessed using the Cardiff acuity card or the LogMAR chart. Binocular functions were assessed using the cover test and Lang's stereo acuity test. Results: The mean age of the subjects was 6.01 ± 3.41 years. Refraction of the right eye showed that 10 per cent of the subjects were myopic, 20 per cent were hyperopic and 70 per cent had no significant refractive error. The mean spherical equivalent was +0.92 ± 2.32 DS for the right eye and +0.99 ± 2.21 DS for the left. The mean of binocular LogMAR VA was 0.36 ± 0.22 (6/12). Cover test revealed that 21 subjects had strabismus (of those, 33 per cent had unilateral esotropia, 52 per cent had alternating esotropia, nine per cent had unilateral exotropia and five per cent had alternating exotropia). Only 22 subjects gave clear positive response to the stereotest. Other ocular findings included ptosis (one per cent), abnormal head posture (seven per cent) and nystagmus (six per cent). Conclusion: Malaysian children with Down syndrome have a high incidence of refractive error and strabismus. Regular visual examination is important so that corrective lenses can be prescribed to improve vision and to enhance the quality of life of these children in Malaysia.     

Strabismus and binocular function in children with Down syndrome. A population-based, longitudinal study

PURPOSE: We have performed a population-based, longitudinal study on strabismus in children with Down syndrome. The aims of the study were to examine the frequency and type of strabismus, the age at onset, and the binocular potential. METHODS: An unselected population of 60 children with Down syndrome born 1988-1999 was followed with repeated examinations. Mean follow-up time was 55+/-23 months (range 24--115). The alignment of the eyes was examined using Hirschberg corneal reflex test and cover test for near fixation. To evaluate binocular function, Titmus House Fly Test and Lang's stereo test were used. RESULTS: Twenty-five patients (42%) had strabismus (21 esotropias, two exodeviations and two vertical deviations). Only one case of infantile esotropia was found, the other esotropias were acquired forms. The mean age at "onset" (e.g. when strabismus was first noticed) was 54+/-35 months. In the acquired esotropia group (n=20), 15 (75%) were associated with hypermetropia (mean spherical equivalent +4.3+/-1.7 D). Seventeen of the strabismic patients had an accommodation weakness. Eleven of the strabismus patients gave a clearly positive response to one or both stereotests. CONCLUSIONS: The majority of the Down syndrome children with strabismus have an acquired esotropia and hence a potential for binocularity. Hypermetropia and accommodation weakness are probably important factors in esotropia in Down syndrome patients.     

The visual profile of Romanian children and adults assessed through vision screenings.

BACKGROUND: The purpose of this study was to databank epidemiological information from Romanian children and adults. METHODS: A vision screening was performed on 690 children (2 to 18 years of age) and 190 adults (19 to 77 years of age). Prevalence of refractive errors, binocularity, and ocular health problems were recorded and evaluated. RESULTS: Data from the childrens' population showed that 45% were emmetropic, 27% were myopic, and 28% were hyperopic. For the adults, 42% were emmetropic, 16% were myopic, and 42% were hyperopic. When compared with other nations, the average refractive error of the Romanian children was more myopic, and for the adults it was slightly more hyperopic. With-the-rule astigmatism had the highest occurrence when compared to other axis orientations, yet the overall occurrence of astigmatism was less than that found in other nations for both children and adults. The prevalence of strabismus and ocular disease was less in the Romanian children in relation to other nations. CONCLUSION: Due to many years of isolation from the Free World, little information has been available on nations such as Romania relative to the health status of its people. This study begins an epidemiological base forthe nation. It is especially important to public health officials in planning health policy measures, and provides a basis for additional U.S.-based outreach missions to such nations in Europe. It also illustrates the efficacy of using a basic screening-type examination to determine vision care needs and the use of recycled eyewear to satisfy these needs.     

Ocular status of boys with fragile X syndrome: a prospective study.

PURPOSE: The purpose of this study was to determine whether the high rates of ocular problems described in previous retrospective reports of individuals with fragile X syndrome were present in a prospective sample of young boys. Fragile X syndrome is currently considered the leading hereditary cause of mental retardation, with prevalence estimates of 1:2500 to 1:5000 males. METHODS: Forty-eight boys with fragile X syndrome between the ages of 2.5 and 11 years were evaluated for ocular abnormalities. They received complete ophthalmic evaluations including assessment of visual acuity, cycloplegic refraction, ocular motility assessment, and dilated fundus examination. RESULTS: Approximately 25% of the children had clinically significant ocular findings that included refractive errors (17%, primarily hyperopia and astigmatism) and strabismus (8%). Of the 42 children with quantifiable visual acuities, only 1 child, with diagnoses of nystagmus and hyperopia, had a Snellen visual acuity that was not within normal limits for his age. Three of the 5 children with gross measures of visual acuity had clinically significant findings: 2 had hyperopia greater than 3.5 diopters and 1 had esotropia. The other 2 children with gross measures of acuity and the 1 child without visual acuity assessment had cycloplegic refractions of +1.25 to +1.5 and ocular motility appeared normal. CONCLUSIONS: These results suggest that previous reports of high rates of vision problems, particularly strabismus, in boys with fragile X syndrome may have resulted from selection bias. Although we did observe a higher prevalence of strabismus than that found in the general population (8% vs 0.5% to 1%), the proportion of children having strabismus in our sample was much smaller than that reported in other studies of children with fragile X syndrome (30% to 40%). However, 17% of the sample did have significant refractive errors. In addition to evaluating the ocular motility of children with fragile X syndrome, cycloplegic refraction should also be performed to determine whether refractive problems are present.     

Retrospective analysis of refractive errors in children with vision impairment.

PURPOSE: Emmetropization is the reduction in neonatal refractive errors that occurs after birth. Ocular disease may affect this process. We aimed to determine the relative frequency of ocular conditions causing vision impairment in the pediatric population and characterize the refractive anomalies present. We also compared the causes of vision impairment in children today to those between 1974 and 1981. METHODS: Causes of vision impairment and refractive data of 872 children attending a pediatric low-vision clinic from 1985 to 2002 were retrospectively collated. As a result of associated impairments, refractive data were not available for 59 children. An analysis was made of the causes of vision impairment, the distribution of refractive errors in children with vision impairment, and the average type of refractive error for the most commonly seen conditions. RESULTS: We found that cortical or cerebral vision impairment (CVI) was the most common condition causing vision impairment, accounting for 27.6% of cases. This was followed by albinism (10.6%), retinopathy of prematurity (ROP; 7.0%), optic atrophy (6.2%), and optic nerve hypoplasia (5.3%). Vision impairment was associated with ametropia; fewer than 25% of the children had refractive errors < or = +/-1 D. The refractive error frequency plots (for 0 to 2-, 6 to 8-, and 12 to 14-year age bands) had a Gaussian distribution indicating that the emmetropization process was abnormal. The mean spherical equivalent refractive error of the children (n = 813) was +0.78 +/- 6.00 D with 0.94 +/- 1.24 D of astigmatism and 0.92 +/- 2.15 D of anisometropia. Most conditions causing vision impairment such as albinism were associated with low amounts of hyperopia. Moderate myopia was observed in children with ROP. CONCLUSIONS: The relative frequency of ocular conditions causing vision impairment in children has changed since the 1970s. Children with vision impairment often have an associated ametropia suggesting that the emmetropization system is also impaired.     

Peripheral refraction and the development of refractive error: a review

It has been suggested that emmetropic and low‐hyperopic eyes in which the refractive error in the periphery of the visual field is relatively hyperopic with respect to the axial refraction may be at greater risk of developing myopia than eyes with similar refractions but relatively myopic peripheral refractive errors. The animal and human evidence to support this hypothesis is reviewed. The most persuasive studies are those in which emmetropization has been shown to occur in infant rhesus monkeys with ablated foveas but intact peripheral fields, and the demonstration that, in similar animals, lens‐induced relative peripheral hyperopia produces central axial myopia. Evidence for emmetropization in animals with severed optic nerves suggests that emmetropization is primarily controlled at the retinal level but that the higher levels of the visual system play a significant role in refining the process: there appear to be no directly equivalent human studies. Since any contribution of the higher centres to the control of refractive development must depend upon the sensitivity to defocus, the results of human studies of the changes in depth‐of‐focus across the field and of the contribution of the retinal periphery to the accommodation response are discussed. Although peripheral resolution is relatively insensitive to focus, this is not the case for detection. Moreover accommodation occurs to peripheral stimuli out to a field angle of at least 10 deg, and the presence of a peripheral stimulus can influence the accommodation to a central target. Although the basic hypothesis that a relatively hyperopic peripheral refractive error can drive the development of human myopia remains unproven, the available data support the possibility of an interaction between the states of focus on axis and in the periphery.     

Ten-Year Results of Home Vision-Screening Test in Children Aged 3–6 Years in Seoul,Korea

Abstract

Purpose: To characterize the prevalence of refractive error and amblyopia among three- to six-year-old children during the period from 2002 to 2011. Methods: About 31,400 children annually (from 16,592 to 40,816) during the period from 2002 to 2011 were enrolled. The preschool vision screening was performed by the Korean Foundation for the Prevention of Blindness (KFPB) annually during a period that extended from March to September. We reviewed the KFPB annual report about the home vision-screening test as performed during the period from 2002 to 2011. Changes in the prevalence and types of refractive error, strabismus, and amblyopia that manifested throughout this period were analyzed. Results: The prevalence of refractive errors ranged from 1.10% in 2002 to 0.42% in 2011. The prevalence of hyperopia and myopia changed little throughout the 10-year study period. Myopia and hyperopia were equally common among the population examined (χ²-test, p?=?0.137). The prevalence of anisometropia decreased over time. The annual prevalence of amblyopia ranged from 0.39% to 0.06%, while the overall prevalence of amblyopia dropped from 0.25% in 2002 to 0.06% in 2011. The prevalence of strabismus was highest in 2006 (0.30%) and had decreased by 0.06% in 2011. The type of strabismus showed no significant difference over time (χ²-test, p?=?0.579). Conclusions: The prevalence of amblyopia, refractive error, anisometropia, and strabismus was lower in 2011 than in early 2000. The prevalence of hyperopia and myopia as well as strabismus remained similar throughout the study period.     

Prevalence of eye disorders in young children with eyestrain complaints

PURPOSE: To determine whether eyestrain symptoms predict eye conditions in 6-year-old children. DESIGN: Cross-sectional population-based study. METHODS: Reports of eyestrain symptoms were sought in parental questionnaires; 1740 children (79% response) underwent eye examinations (visual acuity, cover testing, cycloplegic autorefraction, and fundus examination). RESULTS: Eyestrain information was available for 1448 children; 220 (15.2%) reported eyestrain symptoms, including 60 (3.4%) who reported near work-associated headaches. Most children (82.3%) had a normal eye examination, while refractive errors, amblyopia, and strabismus were found in 15.0%, 3.6%, and 7.3%, respectively. Corresponding rates for children without eyestrain were 9.9%, 1.4%, and 1.8%, respectively. Moreover, 78.7% of children with refractive errors, 68% with amblyopia, and 58% with strabismus reported no eyestrain. CONCLUSIONS: Most children complaining of eyestrain had a normal eye examination; whereas most children with refractive error, amblyopia, or strabismus were free of eyestrain, making this complaint a poor marker of eye conditions in young children.     

Visual dysfunctions and ocular disorders in children with developmental delay. II. Aspects of refractive errors, strabismus and contrast sensitivity

PURPOSE: To evaluate the prevalence of refractive errors, strabismus and reduced contrast sensitivity in an unselected group of children with developmental delay (DD), and to propose extensions to the existing guidelines to assess the number of examinations required to optimally support children with DD. METHODS: A total of 923 children with IQ < or = 80, aged 4-15 years, from Copenhagen County, Denmark, were ophthalmically examined. The prevalence of refractive errors and strabismus and the presence of reduced contrast sensitivity were recorded and related to level of IQ. RESULTS: Among the 923 children, the following prevalences were found: significant hyperopia (> or = + 3 D) 15.3%; myopia (< - 0.5 D) 10.8%, and astigmatism (< - 1 cyl D) 20.6%. Strabismus was found in 26.8% of subjects (esotropia in 14.9%, exotropia in 10.3%, and other forms, including mixed types, in 1.6%). Refractive errors and strabismus were significantly correlated with low IQ. Reduced contrast sensitivity was correlated with age, visual acuity and level of IQ. CONCLUSIONS: To our knowledge, this study is the largest on ocular disorders in children with DD. Hyperopia, astigmatism, anisometropia, strabismus and contrast sensitivity had a high prevalence, and all disorders were related to low IQ. According to the extended guidelines, an annual minimum of 565 examinations per 100 000 children (0-17 years) is required to optimally support children with DD.     

基于儿童正视眼的眼光学模型构建

目的根据正视儿童眼部参数,构建正视儿童的眼光学模型。方法实验研究。基于“安阳儿童眼病研究”数据,包括角膜曲率半径、角膜厚度、前房深度、晶状体厚度、屈光度和眼轴长度,取右眼数据,应用ZEMAX光学设计软件构建一个符合我国儿童眼球特点的正视眼光学模型。正态性检验采用单样本K-S分析。结果共纳入正视儿童332名,年龄（7.1±0.4）岁,等效球镜度（SE）为（0.11±0.24）D。构建的正视儿童眼光学模型的光学参数为：角膜前表面曲率半径7.78 mm,非球面系数-0.18;后表面曲率半径6.4 mm,非球面系数-0.60;厚度0.54 mm,折射率1.376。前房深度3.00 mm,房水折射率1.336。晶状体前表面曲率半径12.4 mm,非球面系数-0.94;后表面曲率半径-8.1 mm,非球面系数0.96;厚度3.55 mm,折射率为梯度渐变折射率。玻璃体厚度15.94 mm,折射率1.336。视网膜曲率半径-12.3 mm,眼轴长度23.03 mm,总屈光力62.55 D。结论本研究构建了一个符合儿童正视眼特点的眼光学模型,该模型眼的总屈光力为62.55 D,眼轴长度23.03 mm,该模型可作为儿童眼正视化和近视研究的参考工具。     

Developmental visual system anomalies and the limits of emmetropization

Optical defocus can within certain limits predictably alter ocular growth and refractive development in infant monkeys. However defocus, particularly unilateral defocus associated with anisometropia, can also promote abnormal sensory and motor development. We investigated the relationship between the effective operating range for emmetropization in infant monkeys and the refractive errors that produced amblyopia. Specifically, we examined the refractive-error histories of monkeys that did not demonstrate compensating ocular growth for imposed refractive errors and used operant psychophysical methods to measure contrast sensitivity functions for 17 infant monkeys that were reared with varying degrees of optically imposed anisometropia. Imposed anisometropias that were within the operating range of the monkey's emmetropization process were eliminated by differential interocular growth and did not produce amblyopia. On the other hand imposed anisometropias that failed to initiate compensating growth consistently produced amblyopia; the depth of the amblyopia varied directly with the magnitude of the imposed anisometropia. These results indicate that amblyopia and anisometropia are frequently associated because persistent anisometropia causes amblyopia. However, the failure of emmetropization in infants with refractive conditions that are known to promote sensory and motor anomalies indicates that factors other than optical defocus, presumably factors associated with the development of amblyopia and/or strabismus, can also influence early refractive development and in some cases cause anisometropia.     

Detection, prevention, and rehabilitation of amblyopia

The necessity of visual preschool screening for reducing the prevalence of amblyopia is widely accepted. The beneficial results of large-scale screening programs conducted in Scandinavia are reported. Screening monocular visual acuity at 3.5 to 4 years of age appears to be an excellent basis for detecting and treating amblyopia and an acceptable compromise between the pitfalls encountered in screening younger children and the cost-to-benefit ratio. In this respect, several preschoolers' visual acuity charts have been evaluated. New recently developed small-target random stereotests and binocular suppression tests have also been developed with the aim of correcting the many false negatives (anisometropic amblyopia or bilateral high ametropia) induced by the usual stereotests. Longitudinal studies demonstrate that correction of high refractive errors decreases the risk of amblyopia and does not impede emmetropization. The validity of various photoscreening and videoscreening procedures for detecting refractive errors in infants prior to the onset of strabismus or amblyopia, as well as alternatives to conventional occlusion therapy, is discussed.     

Change in vision disorders among Hong Kong preschoolers in 10 years

Background: To determine the change in refractive error and the prevalence of amblyopia and strabismus among preschool children in Hong Kong over a period of 10 years. Design: Two cross‐sectional population‐based studies conducted in 1996 to 1997 (part A) and 2006 to 2007 (part B) Participants: Children attending randomly selected kindergarten participated in the study. Methods: Ocular alignment, visual acuity, cover and uncover tests, cycloplegic refraction, slit‐lamp and fundi examination were performed under a standardized testing environment. Main Outcome Measures: The prevalence of amblyopia (best‐corrected visual acuity ≤6/12 in one or both eyes, or a bilateral difference of ≥2 best‐corrected visual acuity lines), strabismus and significant refractive error (hyperopia ≥+2.50 D; myopia ≥?1.00 D; astigmatism ≥2.00 D) among preschool children. Results: Of the 601 children in part A of the study, reduced visual acuity was presented in 3.8%; whereas strabismus was found in 1.8%. The commonest type of refractive error was astigmatism in 6.3% of children, followed by hyperopia (5.8%) and myopia (2.3%). Among 823 children in part B, reduced visual acuity was presented in 2.7% of children, and strabismus was found in 1.7%. The commonest type of refractive error was myopia (6.3%), followed by astigmatism (5.7%) and hyperopia (5.1%). The percentage of children having myopia has significantly increased (P = 0.001). Conclusion: A significant increase in myopia has been noted in Hong Kong preschoolers. Visual screening programmes may need to be tailored to correspond to the local population and be adjusted accordingly from time to time.     

Screening of infants for strabismus and refractive errors with two-flash photorefraction with and without cycloplegia

35 1/2-year-old and 31 1-year-old children were screened by two-flash photorefraction for strabismus and refractive errors with and without cycloplegia. The sensitivity of the method to detect refractive errors was tested with an optical demonstration eye. All the children were examined clinically to compare the sensitivity of the method. Every child co-operated with the photography, but 4 children did not co-operate in the clinical examination and were thus excluded from the refractive material, as were also two cases of esotropias which were found. There were no false positive or negative strabismus cases. The total refractive material consisted of 120 eyes. The method was clearly more sensitive for refractive errors with cycloplegia. Even one hyperopia of +5.25 D(OD) and +6.0 D(OS) was underestimated without cycloplegia. In the material there were no cases of anisometropia of over 1.0 D in spherical equivivalent that would cause a potential risk for amblyopia. A rather good correlation of refractive results existed with the method in cycloplegia. With partial overlapping of emmetropic and moderate hyperopic cases. The screening of children aged 1/2-1 year with two-flash photorefraction is simple to perform. The underestimation of symmetrical hyperopias should be accepted when cycloplegia is not used. Only one successful photograph of each child is necessary for the interpretation.