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PubMed1980

[The problem of amblyopia in subluxated lenses (author's transl)].

A re-evaluation of the incidence and development of amblyopia was carried out in 27 patients with a history of lens subluxation at pre-school age. Due to insufficiently accurate histories and the heterogeneous composition of the material it is impossible to make any valid statement regarding the critical phase of development of deprivation amblyopia. However, it appears that "form-deprivation" amblyopia may regress spontaneously up to early school age following hygienization of the optic media and if optimal spectacles or contact lenses are worn. In individual cases it has been shown that unilateral amblyopias can and should be treated (pleoptics) following hygienization of the optic media. Therefore, early surgical treatment should be considered in such cases, above all in view of the fact that complications are rare.

Adolescent↗
PubMed2002

Combined optical and atropine penalization for the treatment of strabismic and anisometropic amblyopia.

INTRODUCTION: The treatment of amblyopia by occlusion of the fellow eye is beset by problems related to compliance, stigmatization, and regression of visual acuity (VA). Atropine or optical penalization has been used as an alternative treatment for amblyopia and might be synergistic as a combination therapy. Combined optical and atropine penalization treatment (COAT) was therefore assessed in patients with anisometropic and strabismic amblyopia. METHODS: Patients with a hypermetropic refractive error in whom occlusion had failed were prescribed daily atropine 1% and a plano spectacle lens to the fellow eye. Outcome measures included VA (LogMAR units), interocular VA difference, adverse events, and adverse reactions. COAT was continued until VA failed to improve after 2 consecutive visits, and then patients were offered occlusion treatment again. RESULTS: Forty-two patients (mean age, 4.73 yrs) were treated with COAT. Patients had attempted occlusion for a mean period of 36 weeks before commencement of COAT. The mean VA of the amblyopic eyes improved after 10 weeks of COAT, from 0.85 (20/113) to 0.28 (20/37) (P <.001), an overall success (doubling of VA) rate of 76%. There was no significant change in the mean VA of the fellow eye as a result of COAT (P =.13). Twenty-two patients recommenced occlusion after COAT for regression (10), lack of further improvement (2), or parental choice (10). The remaining 20 patients maintained their VA without treatment at 93% of post-COAT levels, at a mean follow-up 6.4 months. Overall regression rate was 36%, adverse reaction rate was 2%, adverse event rate was 21%, and presumed compliance rate was 83%. DISCUSSION: COAT is an effective treatment method when occlusion therapy initially fails. COAT is well tolerated and should be considered as an alternative and/or supportive therapy in the management of amblyopia.

Amblyopia↗
PubMed2006

The treatment of amblyopia.

Recent studies suggest that children with amblyopia associated with anisometropia, strabismus, or both should be treated initially with best refractive correction until visual acuity is stable. This may take several months, and a proportion of children will achieve equal visual acuity with glasses alone. For residual anisometropic and strabismic amblyopia, the initial choice of patching or atropine should involve the parent and the child. The dose of prescribed patching or atropine may initially be quite modest, such as 2 hours of patching a day or twice weekly atropine. Treatment should be offered to children until at least 12 years of age and possibly to teenagers. Ongoing studies are addressing the role of undertaking near activities while patched and the role of atropine for severe amblyopia and for older amblyopic children. Future studies are needed to investigate the best treatment strategies for residual amblyopia, whether weaning treatment is needed at the end of a course, and how compliance can be enhanced.

Amblyopia↗
PubMed2006

Neuroimaging in human amblyopia.

Functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and magnetoencephalography (MEG) have been the principal neuroimaging tools used to assess the site and nature of cortical deficits in human amblyopia. A review of this growing body of work is presented here with particular reference to various controversial issues, including whether or not the primary visual cortex is dysfunctional, the involvement of higher-order visual areas, neural differences between strabismic and anisometropic amblyopes, and the effects of modern-day drug treatments. We also present our own recent MEG work in which we used the analysis technique of synthetic aperture magnetometry (SAM) to examine the effects of strabismic amblyopia on cortical function. Our results provide evidence that the neuronal assembly associated with form perception in the extrastriate cortex may be dysfunctional in amblyopia, and that the nature of this dysfunction may relate to a change in the normal temporal pattern of neuronal discharges. Based on these results and existing literature, we conclude that a number of cortical areas show reduced levels of activation in amblyopia, including primary and secondary visual areas and regions within the parieto-occipital cortex and ventral temporal cortex.

Amblyopia↗
PubMed2006

Long-term visual function and relative amblyopia in posterior persistent hyperplastic primary vitreous (PHPV).

BACKGROUND: Favorable results in the management of PHPV, made possible by improved surgical techniques, are described in the literature. However, the functional results are in general in the low-vision sector (rarely better than 0.025-0.1 maximum). PURPOSE: To introduce long-term acuity results and estimate the relative amblyopia in early operated PHPV. MATERIAL AND METHODS: Six patients suffering from PHPV of varying degrees (posterior polar cataract, posterior lenticonus, traction and malformation of the optic nerve head and macula region, persistent vitreous vessels) underwent pleoptic treatment after surgery (lentectomy in all, additional stalk-cutting in three cases) at the age of 3 to 7 months. The patients were followed up to age 7 to 12 years. Visual acuity was assessed by Landolt ring single and closely interspaced linear optotypes (C-Test developed by Haase/Hohmann). RESULTS: Compliance with the amblyopia treatment was good in five patients. Visual acuity (VA) improvement in the affected eye could be seen up to early school age (6-8 years). Final VA outcome was 0.1 (minimum) to 0.7 (maximum) with single optotypes. VA for crowded optotypes was maximum 1 octave below single optotype VA. The visual development of the phakic eye was not delayed, i.e. not disturbed by long-term patching. DISCUSSION: Compliance with amblyopia treatment and long-term visual acuity in the cases presented here are even more favorable than described in the literature. As the amount of crowding is small, we conclude that there is little relative (additional) amblyopia and that the functional outcome is limited only by the degree of ocular malformation. Surgical treatment in comparable cases is encouraged.

Amblyopia↗
PubMed1992

Anisometropic amblyopia: is the patient ever too old to treat?

Amblyopia is an example of abnormal visual development that is clinically defined as a reduction of best corrected Snellen acuity to less than 6/9 (20/30) in one eye or a two-line difference between the two eyes, with no visible signs of eye disease. We describe a sequential management program for anisometropic amblyopia that consists of four steps: (1) the full refractive correction, (2) added lenses or prism when needed to improve alignment of the visual axes, (3) 2 to 5 h/day of direct occlusion, and (4) active vision therapy to develop monocular acuity and improve binocular visual function. We examined records of 19 patients over 6 years of age who had been treated using this sequential management philosophy. After 15.2 (+/- 7.7) weeks of treatment the Amblyopia Success Index (ASI) documented an average improvement in visual acuity of 92.1% +/- 8.1 with a range from a low of 75% by a 49-year-old patient to a maximum of 100% achieved by 42.1% of the patients (8 of 19). Patients who had completed therapy 1 or more years ago (N = 4) maintained their acuity improvement. From these results we conclude that following a sequential management plan for treatment of anisometropic amblyopia can yield substantial long-lasting improvement in visual acuity and binocular function for patients of any age.

Adolescent↗
PubMed1995

Flash visual evoked potential (VEP) in amblyopia and optic nerve disease.

Amblyopia and optic atrophy are two very different causes of unilateral long-standing visual impairment. Yet, in some patients the differential diagnosis is not always manifest and standard clinical tests may fail to provide accurate information. We tested the efficacy of a nonstandard clinical test [flash visual evoked potentials (VEP's)] and quantitative multivariate statistical techniques as aids in the assessment of this differential. Thirty-three patients were separated into four groups (normal, anisometropic amblyopia, strabismic amblyopia, and unilateral optic atrophy). Non-patterned flash VEP's were obtained using several different temporal frequency rates. Patients with optic atrophy had significantly reduced VEP's in the affected eye at all temporal frequencies. Strabismic amblyopes, but not anisometropic amblyopes, often showed supranormal responses in the affected eye at the higher temporal frequencies. Finally, by using discriminant analysis (DA) we were able to classify correctly almost 70% of the patients, well above chance level of 25%. This DA provided very good sensitivity and specificity. We have shown that the use of flash VEP's and of multivariate statistical techniques may provide an effective way to diagnose amblyopia differentially from optic atrophy.

Amblyopia↗
PubMed2003

A cost-effectiveness model of screening strategies for amblyopia and risk factors and its application in a german setting.

PURPOSE: To develop a general setting-independent decision-analytical model that determines the costs, effectiveness, and cost-effectiveness of four screening strategies to detect amblyopia or amblyogenic factors in pre-school children and to apply the model in a German setting. METHODS: The general setting-independent decision-analytical model was developed from the perspective of society and the statutory health insurance was developed. Outcomes were the total number of newly detected true positive cases of amblyopia and the costs per newly detected true positive case of amblyopia. Strategies were screening of high-risk children up to the age of 1 year (ophthalmologists), screening of all children up to the age of 1 year (ophthalmologists), screening of all children aged 3 to 4 years (pediatricians or general practitioners), and screening of children aged 3 to 4 years visiting kindergarten (orthoptists). For the application example in a German setting, data from the published medical literature were used. RESULTS: In the base-case analysis of the application example, screening high-risk children by ophthalmologists had the lowest average cost per case detected but became dominated (less effective and more costly than an alternative) if a low (5.3%) probability of familial clustering of strabismus was assumed. Considering the various assumptions tested in the sensitivity analysis, screening of all children up to the age of 1 year by ophthalmologists was the only strategy not dominated by others. Detection rates, including cases detected before screening, were between 72% and 78% for the strategies that screen for all children. CONCLUSIONS: The model suggests that in Germany, both from a cost-effectiveness and a pure effectiveness point of view, screening all children up to the age of 1 year by ophthalmologists is the preferred strategy to detect amblyopia or amblyogenic factors. All strategies left a significant portion of children undetected.

Amblyopia↗
PubMed2006

Opaque contact lens treatment for older children with amblyopia.

PURPOSE: To investigate the usefulness of daily-wear opaque contact lens treatment for older children with amblyopia. METHODS: A retrospective chart review of all children undergoing opaque contact lens therapy for amblyopia between 2000 and 2003 was performed. All patients were included except for those younger than 5 years of age, those undergoing maintenance treatment only, those lost to follow-up, or those unable to cooperate with Snellen visual acuity testing. RESULTS: Thirteen children were identified, and seven met the inclusion criteria. The seven patients had a mean age of 7.5 years (range, 5.7-8.7 years). The causes of amblyopia were anisometropia (five patients), cataract (one patient), and strabismus (one patient). For all seven patients, the mean logMAR improvement in visual acuity was 0.52 (range, 0.26-1.22). The average duration of opaque contact lens use was 9.3 months (range, 2-21 months). Compliance problems were encountered in three patients. No major complications occurred, but one patient had an episode of mild superficial punctate keratitis. CONCLUSIONS: Daily-wear opaque contact lens treatment is a useful occlusion method for amblyopia treatment in older children with various practical and social impediments to skin patching. Meaningful improvement in visual acuity can be obtained, even in children older than 8 years of age.

Amblyopia↗
PubMed2005

Amblyopia prevalence and cigarette smoking by women.

The relationship between cigarette smoking by young women and amblyopia in children was investigated in 13 population groups. Two searches were conducted on Medline using the following keywords for the first search: amblyopia, prevalence or incidence, and the names of specific countries. The keywords for the second search were smoking, cigarettes, women and the names of the same specific countries. Relevant articles were reviewed. A positive relationship between the rate of smoking among women and the prevalence of amblyopia in school-aged children and military recruits was found. The Pearson correlation coefficient was 0.73. The occurrence of decreased visual acuity attributed to amblyopia in disparate population groups is directly related to rates of cigarette smoking by young women.

Amblyopia↗
PubMed1997

Assessment of visual acuity in adult patients with strabismic amblyopia: a comparison between the preferential looking method and different acuity charts.

PURPOSE: Grating acuity values obtained with preferential looking techniques do not correspond to test results obtained with letter charts. The aim of the study was to investigate the agreement between grating acuity and other acuity tests. METHODS: Twenty-eight adult patients with strabismic amblyopia were assessed with the preferential looking-method and other linear and single letter and symbol tests. RESULTS: Assessment with preferential looking regularly led to an overestimation of the acuity values, but between preferential looking and single optotypes there was a much better agreement. This is most likely due to 'crowding' in strabismic amblyopia. A crowding ratio was calculated in the amblyopic eye, and crowding was found to be more prominent for comparisons of preferential looking with optotypes in rows, than for preferential looking and single optotypes. CONCLUSIONS: Strabismic amblyopia cannot be reliably identified with grating acuity. Preferential looking-testing is therefore of limited use as a screening method for the detection of amblyopia, but preferential looking could still be useful in the assessment and treatment.

Adult↗
PubMed1986

Contrast sensitivity in amblyopia. IV. Assessment of vision using vertical and horizontal gratings and optotypes at different contrast levels.

The contrast sensitivity of 49 amblyopic children (mean age 9 years) was measured in the beginning and at the end of a treatment period using both vertical gratings and optotypes (LH-4 contrast test) at 2, 3, 5 and 75% contrast. The contrast sensitivity of 37 patients was also measure using horizontal gratings. The contrast sensitivity of the dominant eyes measured with vertical gratings was generally higher than when measured with horizontal gratings. The difference was statistically significant at spatial frequencies 1 and 6 c/deg. A similar difference was present in the amblyopic eyes only at the spatial frequency 1 c/deg both before and after the treatment. Individual variation was great; in a given patient the relationship between the two measurements varied from one spatial frequency to the next. It has been shown in earlier investigations that contrast sensitivity measurements using gratings reveal important new information in the study of amblyopia. Both tests, used in this investigation, measure visual function in the low contrast domain and improve follow-up of the changes in vision during treatment of amblyopia when used in addition to visual acuity measurements. Low contrast optotype test seems to measure contrast sensitivity in amblyopia closely similarly to the grating test. The slight difference in detecting a 'hidden occlusion amblyopia' at the intermediate spatial frequencies needs further study.

Adolescent↗
PubMed1995

Is community screening for amblyopia possible, or appropriate?

Photoscreeners are becoming increasingly available and are being widely used to screen for visual abnormalities in young children. However, consideration of accepted criteria for screening programs indicates there is still much further research that needs to be carried out before amblyopia screening could be recommended as a routine component of a community health surveillance program--an adequate description of the potential consequences of an individual developing amblyopia has yet to be provided and the natural history of the condition and factors that determine the effectiveness of treatment have yet to be fully described. While there is the promise of technology that satisfies specific test requirements, this still needs to be trialed in community settings and community trials are required before it will be possible to determine whether the costs that will be incurred in carrying out routine screening and in providing the resources for treatment are warranted. In conclusion, the development of new and possibly more effective technology for screening is only part of the answer to the amblyopia question. While superficially this technology makes screening for amblyopia a possibility, we do not know at this stage whether or not it is appropriate.

Amblyopia↗
PubMed1997

Screening for amblyopia: a comparison of paediatric letter tests.

AIMS/BACKGROUND: The measurement of visual acuity is the most widely accepted indicator of amblyopia and is thought by some to be the only effective screening test. The aim of this study was to investigate the effectiveness of the traditional single optotype Sheridan-Gardiner test (SGT) in the measurement of visual acuity and the detection of amblyopia, compared with the log based linear format Glasgow acuity cards (GAC). METHODS: In the present study visual acuity was measured monocularly in 702 primary 1 schoolchildren using both acuity tests. RESULTS: A significant difference was found in the mean (SD) visual acuity measured with GAC (0.9 (0.08) modified logMAR) and SGT (1.13 (0.09) modified logMAR), df = 632, t = -59.08, p = 0.0001. The majority of children (89.3%) achieved visual acuities better than 6/6 in either eye when using the single optotype test. If the 95% confidence limits for a significant interocular difference in acuity are used as-criteria for the detection of unilateral amblyopia, GAC were found to be the most sensitive, correctly identifying 100%, while SGT identified 55% of the children with unilateral amblyopia. CONCLUSION: The results of this study highlight several problems with both the test format and testing procedure in the present school screening system.

Amblyopia↗
PubMed2000

Long term follow up of premature infants: detection of strabismus, amblyopia, and refractive errors.

AIM: To establish recommendations for long term ophthalmological follow up of prematurely born infants. METHODS: 130 infants with a gestational age (GA) <37 weeks and born between 1 November 1989 and 31 October 1990 were enrolled in a prospective study about the development of strabismus, amblyopia, and refractive errors. Infants were subdivided in three groups according to GA: A <28 weeks (n=32), B >/=28-</=32 weeks (n=64), C >32-<37 weeks (n=34). Ophthalmological assessment took place at the postconceptional age of 32 weeks, at term and at 3, 6, 12, and 30 months post term. At the age of 5 years parents received a questionnaire and a majority of the children was examined again (n=99). RESULTS: At the age of 5 years 46 infants were known to have strabismus (n=29) and/or amblyopia (n=22) and/or refractive errors (n=22). Statistical analysis showed that gestational age, duration of supplementary oxygen, and duration of hospitalisation were important predictive variables for the development of strabismus, amblyopia, or refractive errors (SAR) at the age of 5 years (p<0.05). Infants with a GA </=32 weeks had a significantly higher risk of developing SAR than infants with a GA >32 weeks, who developed an incidence comparable with the normal population. Strabismus developed mainly in the first year of life and at the age of 5 years. Most infants with amblyopia were detected at the age of 2-3 years. Refractive errors were found in the first year of life and at the age of 2.5 and 5 years. CONCLUSION: Infants with a GA <32 weeks should be selected for long term ophthalmological follow up. These infants should be screened at the age of 1 year, in the third year of life (preferably at 30 months), and just before school age (including testing of visual acuity with optotypes).

Amblyopia↗
PubMed2003

Nonveridical visual perception in human amblyopia.

PURPOSE: Amblyopia is a developmental disorder of spatial vision. There is evidence to suggest that some amblyopes misperceive spatial structure when viewing with the affected eye. However, there are few examples of these perceptual errors in the literature. This study was an investigation of the prevalence and nature of misperceptions in human amblyopia. METHODS: Thirty amblyopes with strabismus and/or anisometropia participated in the study. Subjects viewed sinusoidal gratings of various spatial frequencies, orientations, and contrasts. After interocular comparison, subjects sketched the subjective appearance of those stimuli that had nonveridical appearances. RESULTS: Nonveridical visual perception was revealed in 20 amblyopes ( approximately 67%). In some subjects, misperceptions were present despite the absence of a deficit in contrast sensitivity. The presence of distortions was not simply linked to the depth of amblyopia, and anisometropes were affected as well as those with strabismus. In most cases, these spatial distortions arose at spatial frequencies far below the contrast detection acuity cutoff. Errors in perception became more severe at higher spatial frequencies, with low spatial frequencies being mostly perceived veridically. The prevalence and severity of misperceptions were frequently found to depend on the orientation of the grating used in the test, with horizontal orientations typically less affected than other orientations. Contrast had a much smaller effect on misperceptions, although there were cases in which severity was greater at higher contrasts. CONCLUSIONS: Many types of misperceptions documented in the present study have appeared in previous investigations. This suggests that the wide range of distortions previously reported reflect genuine intersubject differences. It is proposed that nonveridical perception in human amblyopia has its origins in errors in the neural coding of orientation in primary visual cortex.

Adolescent↗
PubMedDate not supplied

Prevention of amblyopia and the concept of cure.

Amblyopia is used as a comprehensive term for unexplained reduction of visual acuity, usually unilateral. As long as the visual deficit is monocular the visual loss is more of a potential problem than an actual handicap. Amblyopia is one of the most common causes of visual deficit in childhood, and since it is treatable, at least in children, considerable efforts have been made to detect it as early in life as possible. Screening programmes for amblyopia among preschool and school children have been widely organized throughout the world, although questions remain about their utility. This study evaluated amblyopia screening, focussing on some essential points that need thorough consideration before a screening programme is started. We also try to demonstrate some of the pros and cons of a screening system.

Amblyopia↗
PubMed2003

Predicting adherence to eye patching in children with amblyopia: an application of protection motivation theory.

OBJECTIVES: This study reports an application of protection motivation theory (PMT) to the prediction of parental adherence to eye patching recommendations for children with amblyopia over a 2-month period. The study also considered the role of past behaviour in PMT. DESIGN AND METHODS: A total of 151 parents of children with amblyopia who were attending follow-up appointments for orthoptic treatment participated. They completed questionnaires based on PMT to assess their beliefs about amblyopia and eye patching. Of the parents, 105 were contacted again at 2-month follow-up to obtain a measure of adherence to the recommended treatment for their child. RESULTS: PMT was found to be predictive of adherence intentions and behaviour at 2-month follow-up. Regression analyses revealed perceived vulnerability, response efficacy and self-efficacy to be significant predictors of protection motivation, whereas perceived vulnerability and response costs were significant predictors of adherence behaviour. Past adherence behaviour was found to have a direct effect on future adherence behaviour over and above the influence of PMT. CONCLUSIONS: The results are discussed in relation to the sufficiency of PMTas a model of adherence behaviour. The practical implications for attempts to increase adherence to eye patching among children with amblyopia are outlined.

Amblyopia↗