In focus: the use of bifocal spectacles with children with Down''s syndrome

PURPOSE: Over 75% of children with Down's syndrome fail to accommodate accurately on near targets. This deficit must result in optically blurred images for near work. This present study set out to evaluate the controlled use of bifocal spectacles as an aid to near focusing. Although sometimes used clinically, no systematic studies of bifocals for children with Down's syndrome have been reported. METHODS: This was a comparative non-randomised interventional study. Thirty-four children with Down's syndrome of primary school age (5-11 years) took part, assigned in equal numbers to form two matched groups. All children received a full optometric assessment prior to entering the study. The treatment group was prescribed bifocal spectacles with a +2.50 addition, and the control group provided with single vision lenses to correct any clinically significant refractive error. Three follow-up visits were made over a 5-month period after spectacle provision. RESULTS: The treatment group showed consistently more accurate accommodation than the control group both through the bifocal segment, and, unexpectedly, through the distance part of the lens (p < 0.05). Compliance with new spectacles was high in both groups (>82% fully compliant). CONCLUSIONS: Bifocals confer benefit to children with Down's syndrome who under-accommodate, both directly (better focusing through the bifocal) and indirectly (by encouraging improved accommodation through the distance part of the lens). Based on the results of this study, eye examinations of children with Down's syndrome should routinely include a measure of accommodation at near, and bifocal spectacles should be considered for those who show under-accommodation.     

Transient pattern Visual Evoked Potentials in children with Down''s syndrome

Visual acuity and contrast sensitivity are lower in children with Down's syndrome than in those developing normally. In many cases, this difference might be accounted for by the relatively high incidence of ocular abnormalities (including refractive error and strabismus) in Down's syndrome. However, abnormal spatial vision persists in children with Down's syndrome in the absence of ocular abnormality, suggesting that abnormal retino-cortical visual processing explains reduced visual function in this group. The aim of the present study was to assess retino-cortical function in children with Down's syndrome by recording transient visual evoked potentials (VEPs) in response to pattern stimuli. Responses from children with Down's syndrome were compared with those recorded from children developing normally. Response latency is similar in the two groups, but morphology differs, with the N75 component being clearly present in the normal responses, but diminished or undetectable in responses from children with Down's syndrome. Our findings may suggest a cortical abnormality specific to the source of the N75 component of pattern-reversal achromatic VEPs.     

Refractive Errors and Strabismus in Down's Syndrome in Korea

Purpose

The aims of this study were to examine the distribution of refractive errors and clinical characteristics of strabismus in Korean patients with Down''s syndrome.

Methods

A total of 41 Korean patients with Down''s syndrome were screened for strabismus and refractive errors in 2009.

Results

A total of 41 patients with an average age of 11.9 years (range, 2 to 36 years) were screened. Eighteen patients (43.9%) had strabismus. Ten (23.4%) of 18 patients exhibited esotropia and the others had intermittent exotropia. The most frequently detected type of esotropia was acquired non-accommodative esotropia, and that of exotropia was the basic type. Fifteen patients (36.6%) had hypermetropia and 20 (48.8%) had myopia. The patients with esotropia had refractive errors of +4.89 diopters (D, ±3.73) and the patients with exotropia had refractive errors of -0.31 D (±1.78). Six of ten patients with esotropia had an accommodation weakness. Twenty one patients (63.4%) had astigmatism. Eleven (28.6%) of 21 patients had anisometropia and six (14.6%) of those had clinically significant anisometropia.

Conclusions

In Korean patients with Down''s syndrome, esotropia was more common than exotropia and hypermetropia more common than myopia. Especially, Down''s syndrome patients with esotropia generally exhibit clinically significant hyperopic errors (>+3.00 D) and evidence of under-accommodation. Thus, hypermetropia and accommodation weakness could be possible factors in esotropia when it occurs in Down''s syndrome patients. Based on the results of this study, eye examinations of Down''s syndrome patients should routinely include a measure of accommodation at near distances, and bifocals should be considered for those with evidence of under-accommodation.     

Refractive development in children with Down's syndrome: a population based, longitudinal study

AIMS: To study the refractive development in children with Down's syndrome longitudinally. METHODS: An unselected population of 60 children with Down's syndrome was followed with repeated retinoscopies in cycloplegia for 2 years or more (follow up 55 (SD 23) months). Accommodation was assessed with dynamic retinoscopy. RESULTS: From longitudinal spherical equivalent values of the right eye, three main categories of refraction were defined: stable hypermetropia (<1.5 D difference between the first and last visit) (n=34), increasing hypermetropia ("hypermetropic shift"; >/=1.5 D difference) (n=11), and decreasing hypermetropia/development of myopia ("myopic shift"; >/=1.5 D difference) (n=9). Patients with anisometropia (n=6) were evaluated separately. In the stable hypermetropia group three sublevels were chosen: low (+4.0 D). An accommodation weakness was found in 55% of the children. Accommodation weakness was significantly less frequent in the stable, low grade hypermetropia group (22%) than in all the other groups (p=0.008). The frequency of astigmatism >/=1.0 D at the last visit was 57%, the direction of axis being predominantly "with the rule." All the eyes with oblique astigmatism had a side specific direction of axis; the right eyes belonging to the 135 degrees axis group and the left eyes to the 45 degrees axis group. CONCLUSION: A stable, low grade hypermetropia was significantly correlated with a normal accommodation. Accommodation weakness may be of aetiological importance to the high frequency of refractive errors encountered in patients with Down's syndrome. A striking right-left specificity in the oblique astigmatic eyes suggests that mechanical factors on the cornea from the upward slanting palpebral fissures may be a major aetiological factor in the astigmatism.     

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.     

Heart defects and ocular anomalies in children with Down's syndrome

AIMS: To investigate whether ocular anomalies are associated with congenital heart defects in children with Down's syndrome. METHODS: 58 children with Down's syndrome were entered into a retrospective observational study. Children were assigned to heart defect groups based on medical records. Optometric tests had previously been carried out at the homes of the children. RESULTS: A relation between congenital cardiac defects, myopia, and nystagmus was observed. Heart problems were not related to accommodative insufficiency, hyperopia, or strabismus. CONCLUSION: In children with Down's syndrome heart defects were associated with both myopia and nystagmus.     

Visual Outcome in 879 Children Treated for Strabismus: Insufficient Accommodation and Vision Deprivation,Deficient Emmetropisation and Anisometropia

Purpose: To identify the effect of infant hypermetropia on residual amblyopia in children remaining after treatment.

Materials and Methods: 879 strabismic children had cycloplegic retinoscopy at the age of 6 months and later when strabismus was diagnosed. A total of 26 hypermetropes consistently wore glasses from the age of 6 months, and 305 other hypermetropes had their accommodation periodically assessed by dynamic retinoscopy before strabismus was diagnosed. The relation between the last known visual acuity after treatment and all other clinical findings was analysed using t-tests and regression analysis.

Results: Vision less than 6/12 in nonfixing eyes was associated with infantile hypermetropia > +5.0D, and in rare instances in excess of -3.0D of myopia. In hypermetropes only, anisometropia was associated with worse amblyopia. Astigmatism was associated with myopia and low levels of hypermetropia but not with worse vision. The vision of fixing eyes that were hypermetropic was significantly worse than that of emmetropic or myopic eyes. Wearing spectacles from the age of 6 months was associated with better vision in the nonfixing eye. Vision in the nonfixing eye of 19 hypermetropic heterotropes who started wearing glasses between 6 and 18 months of age also was better than that of those who started wearing glasses after 18 months of age. Insufficiency of accommodation was related to the degree of infantile hypermetropia, to worse vision and to failure to emmetropise. Difference in amplitude of accommodation between the eyes was largest in hypermetropes with anisometropia > +1.50 D and was marginally associated with worse vision in microtropes who became anisometropic after infancy. Hypermetropia decreased more in fixing eyes than in nonfixing eyes, thereby causing anisohypermetropia to increase after infancy. This change was most pronounced in hypermetropic microtropes. Conversely, failure of fixing eyes to emmetropise was associated with an increase in their inability to accommodate and heterotropia.

Conclusions: On the basis of these findings, severe residual amblyopia in children remaining after treatment could be explained by additional vision deprivation. It can be reduced by starting spectacle correction of hypermetropia before the age of 18 months. Anisometropia seemed the result of deficient emmetropisation.     

Costs and methods of preventive visual screening and the relation between esotropia and increasing hypermetropia

Atkinson has shown that early correction of hypermetropia reduces the incidence of esotropia. If esotropia is reduced by prescribing glasses early, the rate of esotropia-induced amblyopia can be similarly reduced; this would have important economic consequences. We have studied (1) how costs compare to benefits in early visual screening, (2) how videorefraction as used by Atkinson compares to retinoscopy, and (3) whether esotropia is more likely to occur in children who have increasing as opposed to decreasing hypermetropia. The costs of the study so far have been high. It was exceedingly difficult to get all infants invited, come to the clinic and examined. Videorefraction did not compare favourably with retinoscopy in terms of costs and precision, whereas the amount of skill and time needed was approximately equal. The third question, whether esotropia is more likely to occur in children who have increasing as opposed to decreasing hypermetropia, arose from the controversy whether, in the general population, refraction increases or decreases during the first years of life. We found that papers reporting a decrease of hypermetropia in early childhood were studies of large cross-sections of the general population, whereas papers that reported an initial increase originated from ophthalmological practices or strabismus departments. These conflicting results could be reconciled by assuming a population bias: if esotropia is more likely to occur in children with increasing hypermetropia, children with increasing hypermetropia will preferentially be seen by ophthalmologists. It seems natural that children with increasing hypermetropia are more likely to squint, because additional accommodation, needed to overcome increasing hypermetropia, will inevitably confer additional convergence. This relationship has meanwhile been confirmed by others.     

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.     

儿童远视眼的屈光演变

目的：探讨儿童远视服的屈光演变规律。方法：观察197例(394眼)3～8岁远视儿童，按首诊年龄分6组，按有无斜视分2组，按远视程度分3组。每年扩瞳孔验光1次，连续5年观察远视度数的发展规律。结果：3～8岁年龄组儿童远视眼的远视球镜部分和远视散光部分，每年平均降低的幅度相邻组比较差异无显著性；斜视组和屈光不正组，远视平均每年降低的幅度比较差异无显著性；轻度、中度、高度远视服，远视平均每年降低的幅度比较，差异有高度显著性。结论：儿童远视服远视屈光度(球镜)部分逐年降低，平均每年降低幅度相近，远视散光部分变化较小；斜视和屈光不正儿童，远视度数逐年降低的幅度相近；屈光程度越高远视度数逐年降低的幅度越多；儿童远视散光95％为顺规性散光。     

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 refractive error and strabismus in children with Down syndrome

PURPOSE: To investigate the development of refractive errors and strabismus in a cohort of children with Down syndrome. METHOD: Data for 55 children with Down syndrome who are participating in this longitudinal study of visual development, first examined by us when aged less than 2 years and on at least two other occasions, were analyzed. Mohindra retinoscopy was used to measure refractive error. Ocular alignment was assessed using the Hirschberg test and, when possible, the cover test. RESULTS: Despite the high prevalence of large refractive errors in children with Down syndrome, longitudinal data showed that these are not always present in early infancy. Twenty-one (38%) of the children were emmetropic throughout the study. Of the 24 children with a significant refractive error at the outset, only 6 (25%) showed emmetropization. The others retained or increased their refractive errors. The remaining 10 children were emmetropic at the outset, but then had a significant refractive error develop. There is a high prevalence of strabismus in children with Down syndrome (29% of the total group), which cannot be attributed to the presence of hypermetropia or anisometropia. CONCLUSIONS: The retention or development of infantile refractive errors in many children with Down syndrome indicates a failure of emmetropization. All children were at risk of strabismus whatever the refractive error. The findings have implications for timing of screening programs.     

Adie syndrome: evidence for refractive error and accomodative asymmetry as the cause of amblyopia.

PURPOSE: To report objective changes in accommodation in a child with Adie syndrome. METHODS: A child aged 2 years 10 months when initially examined was found to have good visual acuity in both eyes, a low degree of hypermetropia (isometropic), and Adie pupil presumed to be caused by chicken pox that had occurred 2 months earlier. Amblyopia developed but responded well to treatment, which involved correction of the refractive error and occlusion therapy. Objective changes in the refraction of the eye were measured on the Canon R1 autorefractor at 3.8 m and 33 cm. RESULT: The degree of accommodation in the affected eye when both eyes were open was markedly reduced. CONCLUSION: The presence of isometropic hypermetropia, which remains uncorrected when Adie syndrome is present, can lead to the development of amblyopia in a child.     

A longitudinal study of children with a family history of strabismus: factors determining the incidence of strabismus.

A longitudinal study of ocular refraction, position, and fixation was performed in children with a family history of strabismus. The children were examined at regular intervals between 3 months and 4 years of age, and the results are discussed in terms of changes in refraction between different ages and correlations between refraction and development of strabismus and amblyopia. Six of 34 children (17.6%) developed constant or intermittent esotropia. The strabismus was first noted between 18 and 30 months of age except in one case. All esotropic children were 4 dioptres hypermetropic or more at 6 months, and their hypermetropia remained almost unchanged through the years. Seven additional children were 4 dioptres or more hypermetropic at 6 months but did not develop a squint. In contrast to the squinting children the hypermetropia in these children changed towards emmetropia. This emmetropisation was most pronounced during the first 2 years of age. The implications of these results for an early diagnosis of strabismus amblyopia are discussed.     

Characteristic ocular findings in Asian children with Down syndrome

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.     

Spatial localization in esotropia: does extraretinal eye position information change?

PURPOSE: To investigate the accuracy of spatial localization in children with a specific type of convergent strabismus, fully accommodative esotropia. METHODS: Two groups of children, with right and left fully accommodative esotropia, respectively, pointed at targets located centrally and eccentrically on a computer touchscreen without being able to see their hands. The size and the direction of the horizontal pointing responses were recorded under two conditions: when their eyes were aligned (wearing spectacles) and when they were squinting (not wearing spectacles). A group of children without strabismus but with hypermetropia were assessed as controls. RESULTS: For both fully accommodative groups, the pointing responses to the central target shifted in the direction of the nonsquinting eye when deviations were manifest. No difference was found for the eccentric targets. No difference was found for the hypermetropia group with any target. CONCLUSIONS: These results are consistent with an alteration in the extraretinal eye position information (efference copy, extraocular muscle proprioception, or both) that is used in spatial localization.     

Importance of studying the accommodation function in the diagnosis of clinical forms of hypermetropia

Two hundred and thirty-one patients, aged 6 to 18, with hypermetropia were examined. They were shared between two groups with respect to an accommodation state: group 1--patients with weak accommodation, group 2--patients with normal accommodation. The below ocular parameters were registered for groups 1 and 2, respectively: axial size--22.35 mm and 21.58 mm, corneal diameter--11.48 mm and 10.74 mm, scleral ring diameter in the projection of the scleral central portion--14.66 mm and 13.98 mm, ocular refracting power--59.79 d and 62.23 d, corneal refraction--41.85 d and 42.82 d, and lens refraction--22.05 d and 24.03 d. New clinical signs were specified for uncomplicated type of congenital hypermetropia. The parameters of patients with normal-accommodation hypermetropia are typical of axial hypermetropia in adults due to growth inhibition, while the parameters of patients with weakened accommodation are typical of optical hypermetropia as a variation of normal eye development.     

Effect of spectacles on changes of spherical hypermetropia in infants who did, and did not, have strabismus

AIM: To explore why emmetropisation fails in children who have strabismus. METHODS: 289 hypermetropic infants were randomly allocated spectacles and followed. Changes in spherical hypermetropia were compared in those who had strabismus and those who did not. The effect of wearing glasses on these changes was assessed using t tests and regression analysis. RESULTS: Mean spherical hypermetropia decreased in both eyes of "normal" children (p<0.001). The consistent wearing of glasses impeded this process in both eyes (p<0.007). In the children with strabismus, there were no significant changes in either eye, irrespective of treatment (p>0. 05). CONCLUSIONS: In contrast with normal infants, neither eye of those who had strabismus emmetropised, irrespective of whether the incoming vision was clear or blurred. It is suggested that these eyes did not "recognise" the signal of blurred vision, and that they remained long sighted because they were destined to squint. Hence, the children did not squint because they were long sighted, and glasses did not prevent them squinting.     

Microphthalmos in a family

Details of 22 members from three generations of a family exhibiting systemic and ocular abnormalities are presented. The former include mild mental retardation and a high incidence of abortion or death in the neonatal period. Ocular features comprise: microphthalmos, strabismus, hypermetropia, reduced ocular axial length and abnormal peripapillary pigmentation.

The microphthalmos was seen in three forms: bilateral, severe or mild and severe microphthalmos of one eye with the fellow eye mildly affected. No individual with any degree of microphthalmos had a normal sized fellow eye and no normal individual produced an affected child. The genetic implications are discussed. The possible aetiologies of the various features are discussed and that this condition is a neurocristopathy is also considered.