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PubMed2004

Full-time occlusion compared to part-time occlusion for the treatment of amblyopia.

BACKGROUND: Occlusion of the better-seeing eye as a method of treatment for amblyopia has long been a standard of care. A difference exists between practitioners on using either full-time occlusion or part-time occlusion. METHODS: A retrospective review of pediatric patients (ages 3 to 7 years) with amblyopia was performed. The patients were prescribed either full-time occlusion or part-time occlusion for the primary treatment of their amblyopia. Exclusions were made for patients with an organic or structural component of their amblyopia. Twenty-one patients were included in the full-time occlusion group and 24 patients were included in the part-time occlusion group. RESULTS: Seventy-six percent of patients who completed full-time occlusion achieved 20/40 acuity or better and 67% achieved 20/30 or better, with an average treatment time of six weeks. Fifty-eight percent of patients who completed part-time occlusion achieved 20/40 acuity or better and only 46% achieved 20/30 or better, with an average treatment time of 26 weeks. For patients with 20/80 or worse amblyopia, 82% achieved 20/40 or better with full-time occlusion. Only 40% of part-time occluders with 20/80 or worse achieved 20/40. Occlusion amblyopia did not develop in any patient. CONCLUSION: A higher percentage of amblyopic patients treated with full-time occlusion achieved 20/30 acuity in the amblyopic eye over a shorter duration of treatment.

Amblyopia↗
PubMed1999

Can interocular pattern reversal visual evoked potential and motor reaction time differences distinguish anisometropic from strabismic amblyopia?

PURPOSE: With the use of the pattern reversal visual evoked potential and the motor reaction time, we sought to differentiate anisometropic amblyopia from strabismic amblyopia on the basis of the visual transmission time. METHODS: Pattern reversal visual evoked potentials and motor reaction times were obtained in nine normal subjects, eight anisometropic and seven strabismic amblyopes. RESULTS: Our results show that while the peak time of the pattern visual evoked potential in anisometropic amblyopia and strabismic amblyopia was significantly delayed, it could not distinguish the two types of amblyopia. In contrast, a significantly longer interocular increment in strabismics compared to anisometropes was found with the reaction time, but not with the pattern visual evoked potential. CONCLUSION: Our findings thus show that it is possible to distinguish strabismic from anisometropic amblyopes using interocular differences in reaction time measurements. Our results bring support to the contention that the two types of amblyopia represent different neural abnormalities.

Adult↗
PubMed2001

Is it mandatory to treat amblyopia prior to surgery in esotropia?

PURPOSE: To determine whether presence of amblyopia has any influence on the outcome of motor and sensory success in cases of esotropia. METHODS: 100 patients were taken for this study. Patients were divided into two groups of 50 each. Amblyopia was fully treated in group I and patients in group II underwent surgery before full treatment of amblyopia. Motor success (+/- 10 PD of orthophoria) was assessed three months after surgery and at the child's most recent visit by comparing the motor alignment at 6 meter and 0.33 meter distance using accommodative target in primary position. Sensory success was assessed by comparing the frequency of detectable stereoacuity. RESULTS: There was no significant difference in motor success (84% vs 75%) and sensory success (55% vs 50%) whether amblyopia was fully treated or partially treated. CONCLUSION: It is not mandatory to treat ambloypia prior to surgery, unless it is a case of infantile esotropia with moderate amblyopia and amblyopia therapy is continued post operatively.

Age of Onset↗
PubMed1988

Amblyopia and strabismus in congenital ptosis.

Seventeen per cent of 216 cases of simple congenital ptosis developed amblyopia and 19% had a squint. Of those patients with amblyopia, 14% had amblyopia attributable to stimulus deprivation, 21% had anisometropic amblyopia and 51% had strabismic amblyopia. Early refraction, orthoptic assessment and treatment and, where the pupillary axis is occluded, surgery to prevent stimulus deprivation amblyopia are recommended.

Amblyopia↗
PubMed1990

Risk factors in amblyopia.

Any intervention to prevent serious amblyopia is based on the knowledge about normal versus subnormal visual development. Our ability to predict with high degree of certainty which children will develop amblyopia will be dependent on the characteristics of various risk factors for initiating the development of squint or amblyopia. We have used longitudinal studies of population based cohorts of young children to define some of these risk factors such as refractive errors. Three hundred and ten children with an astigmatism greater than or equal to 1.0 D at one year of age were refracted yearly between the age one and four years. Astigmatism and anisometropia were found to be highly variable during infancy and early childhood. Longitudinal follow-up seems to be needed to separate the normal from the abnormal refraction development, which initiates the development of the amblyopia. Children with constant or increasing astigmatism or anisometropia between one and four years were 'at risk'. In parallel we have studied important factors for successful treatment of amblyopia. Based on these findings we conclude that a population screening at four years of age seems to be advantageous in Sweden in order detect and successfully treat most cases of amblyopia.

Age Factors↗
PubMed2002

Contact lenses in the management of high anisometropic amblyopia.

UNLABELLED: Poster at College Congress, Birmingham 2001. Oral presentation at European Strabismus Association, Florence 2001. PURPOSE: Anisometropia of more than one dioptre during the sensitive visual period may cause amblyopia. Its management requires refractive correction, and occlusion. Compliance with treatment is critical if visual improvement is to obtained. High anisometropia, poor initial acuity and mixed strabismic/anisometropia amblyopia are predictive factors for a poor outcome. We evaluated contact lens use in the management of high anisometropic amblyopia. METHODS: Retrospective analysis of anisometropic amblyopia managed in a paediatric contact lens clinic (July 1996-July 2000), after standard amblyopia therapy of spectacles and occlusion therapy had been tried. Presenting age, acuity and refraction, duration of lens wear and occlusion, and final visual outcomes were noted. RESULTS: Seven children (four male, three female) presented at age 3.5-6 years (mean 4.5). Six had myopic anisometropia 6.0-18.4 dioptres (mean 10.4 dioptres) and one 6.75 dioptres hypermetropic anisometropia. The initial corrected acuities of the amblyopic eyes were 6/18 to 1/60. Five patients used contact lenses with a range from 5 months to 4 years. Final acuities were 6/12-1/60. Two myopes with 6 dioptres anisometropia improved three to four Snellen lines, one with 8.8 dioptres improved one line. Three with >10 dioptres anisometropia did not improve. The hypermetropic patient improved part of one Snellen line. CONCLUSIONS: High anisometropic amblyopia is challenging to treat. In our study contact lenses improved visual acuity in myopic anisometropia of up to 9 dioptres.

Amblyopia↗
PubMed2003

[Resource utilisation and cost of amblyopia treatment].

BACKGROUND: The cost-effectiveness of screening for amblyopia is a controversial issue of international debate. The purpose of this study was to estimate the cost of amblyopia treatment to be used as a component for modelling the cost-effectiveness of prevention programmes. Cost was calculated from the perspective of the German social health insurance in the year 2002. MATERIALS AND METHODS: A standardised detailed survey was conducted in writing among 13 experienced experts in amblyopia treatment from various offices and strabismological units in Germany. Average volumes of treatment items were estimated for a maximum treatment period of nine years. Cost was calculated using administrative prices (based on the social health insurance's uniform fee schedule for physician services and reference prices for therapeutic aids) and market prices. RESULTS: The questionnaires were fully completed by 12 of the 13 experts. The mean total cost of treatment was estimated at 2.472 Euro (95 %-CI: 1.171 - 3.774) for strabismic amblyopia and 2.051 Euro (95 %-CI: 426 - 3.675) for amblyopia of refractive origin. About 70 % of the total cost was caused by the therapeutic aids (e. g. glasses, patches). The price of the patches had a marked impact on the total treatment cost. CONCLUSIONS: The results may be used for modelling the cost-effectiveness of screening programmes for the prevention of amblyopia.

Amblyopia↗
PubMed2004

Amblyopia & Strabismus Questionnaire: design and initial validation.

Literature on the benefits of screening and treatment of amblyopia emphasizes the costs of insufficiently treated amblyopic patients who lose their better eye. However, patients with insufficiently treated amblyopia and strabismus who do not lose their better eye only experience a slight decrease in their quality of life, and such patients occur more frequently. We designed and validated a questionnaire for amblyopia and strabismus in order to assess the decrease in quality of life of such patients. Complaints were collected from outpatients and reduced to five domains, pertaining to distance estimation, visual disorientation, problems with social contacts and cosmetic problems, diplopia, and fear of losing the better eye. For these domains 26 questions were formulated that constitute the Amblyopia & Strabismus Questionnaire (A&SQ). The A&SQ, the National Eye Institute Visual Function Questionnaire-25 (VFQ-25) and the Short Form-12 Health Survey (SF-12) were presented to 53 healthy controls, 68 outpatients and a cohort of 174 outpatients born between 1962 and 1972 and treated between 1968 and 1974 for amblyopia and strabismus. The quality of life was best in healthy controls and worst in current outpatients, not only on the SF-12 and the VFQ-25 but also on the A&SQ, demonstrating an acceptable construct validity of the A&SQ. The decrease in the quality of life as measured by the A&SQ was most outspoken in our outpatient group of amblyopia and strabismus patients, less in the cohort that had been treated 30 years previously and least in the healthy controls, demonstrating an acceptable discriminatory validity of the A&SQ.

Adult↗
PubMed1985

Identifying amblyopia using associated conditions, acuity, and nonacuity features.

Reduced visual acuity is the most notable feature of functional amblyopia--so much so that it is common to think that it is the only, main, or even the fundamental defect. To identify all amblyopic eyes by acuity alone would require an acuity criterion of 6/6 (20/20) or somewhat better acuity--a criterion that would necessarily include more normal than amblyopic eyes. The association of amblyopia with strabismus and anisometropia is sufficiently specific to make these two nonacuity features useful in identifying amblyopia. The diagnosis of amblyopia derives from a syndrome of features, most of which are nonacuity features. Two recently quantified nonacuity features--spatial uncertainty and distortion--are not only clinically useful but they may be the fundamental defects in strabismic amblyopia, with impaired resolution being fundamental in anisometropic amblyopia.

Amblyopia↗
PubMed1999

Relationship between anisometropia, amblyopia, and binocularity.

PURPOSE: To determine if higher degrees of anisometropia cause deeper amblyopia and poorer binocularity than lower degrees of anisometropia in children and adults. METHODS: The clinical records for 60 patients with untreated anisometropic amblyopia without strabismus, ranging in age from 3 to 39 years, were reviewed. The refractive error, the initial best corrected visual acuities in the amblyopic and nonamblyopic eyes, and the level of binocularity were recorded from each chart. The degree of anisometropia was determined by: (1) calculating the difference between spherical equivalents for each eye; (2) calculating the difference in the vertical meridians for each eye; (3) calculating the difference in the horizontal meridians for each eye; and (4) calculating the root mean square difference which also takes into account differences in astigmatic axis. The depth of amblyopia was determined by converting the visual acuity score to its logarithmic value, logarithm of the minimum angle of resolution (logMAR), and calculating the difference between the amblyopic and nonamblyopic eye. The level of binocularity was determined from stereopsis testing. RESULTS: For all patients, there was a significant relationship between the four measures of anisometropia, the depth of amblyopia, and the level of binocularity (median correlations 0.61 and 0.61, respectively). For the myopes (N = 10), there was no significant relationship between the 4 measures of anisometropia, the depth of amblyopia, and the level of binocularity (median correlations 0.34 and 0.61, respectively). For the hyperopes (N = 50), the relationship was significant for all 4 measures of anisometropia (median correlations 0.72 and 0.62, respectively). CONCLUSION: As the degree of anisometropia increases, the depth of amblyopia becomes greater and the level of binocularity becomes poorer, at least for hyperopic patients.

Adolescent↗
PubMed1998

Detection, prevention, and rehabilitation of amblyopia.

Although there is a continuing effort to develop effective measures for detecting amblyopia, the debate continues in many countries as to the real value of population-wide pediatric vision screening programs. Nevertheless, amblyopia still represents a significant and treatable clinical problem for the practicing ophthalmologist. In this past year's literature, we can find that many visual functions are abnormal in amblyopia, but only a few are measured to reach a diagnosis or monitor treatment. Unfortunately, the wide variety of the measurement methods and the lack of definition for a cure of amblyopia are the cause of serious criticism of our "scientific" literature on the subject. All the while, old methods of treatment are resurfacing again: optical and pharmacological penalizations. The search for a possible "pill" to either replace or at least complement conventional methods of treatment also has continued in 1997 and 1998. As well, there have been quite a few papers on the long-term management of amblyopia. Finally, this review would not be complete without reporting on the "controversy du jour:" a report that challenges the need to cure amblyopia before operating on esotropia.

Amblyopia↗
PubMed1999

The detection, prevention, and rehabilitation of amblyopia.

Some of the past year's important papers on amblyopia are reviewed. Preschool screening for amblyopia is still controversial in regard to its effectiveness, the best age, and the most cost-effective method. In Sweden, where screening for amblyopia is well established, the prevalence of deep and moderate amblyopia has been markedly reduced. Several studies in the past year underscored the importance of anisometropia as a risk factor for amblyopia. Clear evidence for the importance of early treatment of unilateral cataracts in the first 8 weeks of life has been shown. Cytidine-5'-diphosphocholine administration has been shown to positively influence amblyopia and represents, in addition to levodopa, another promising pharmacologic treatment.

Amblyopia↗
PubMed1983

Effects of amblyopia therapy on contrast sensitivity as reflected in the visuogram.

A quantitative evaluation of the Cambridge amblyopia treatment on contrast sensitivity was performed for 2 groups, one comprising 11 children with strabismic amblyopia (S) and another of 10 children with combined strabismic and anisometropic amblyopia (S & A). Contrast sensitivity deficits were expressed in dB CSL (Contrast Seeing Level) in relation to normal sensitivity of the same age group and represented in the form of visuograms. Mean contrast sensitivity losses in dB CSL were estimated within the low, medium and high spatial frequency ranges, as well as over the total frequency band. On an average S & A amblyopia was found to affect contrast sensitivity of all spatial frequencies, while S amblyopia affected mainly the higher frequency band, but to a smaller extent. After therapy average contrast sensitivity improved for both S and S & A groups, and reached the same, subnormal levels. The relation between highest resolvable spatial frequency (according to our method) and Snellen acuity was different for the 2 amblyopia groups. No correlation was found between improvements in contrast sensitivity and Snellen acuity, which is why both parameters should be estimated.

Adolescent↗
PubMed1990

A longitudinal study of a population based sample of astigmatic children. I. Refraction and amblyopia.

The refraction changes in 310 children with astigmatism greater than or equal to 1.0 D in at least one eye at one year of age were followed during a period of 3 years. At the age 4 years amblyopia was found in 23 children (7%). The refraction data of these children were compared to the rest of the sample. We found that an increasing astigmatism during the test period was associated with an increased risk to develop amblyopia. The majority of children (n = 280) showed a decrease of their astigmatism, whereas all cases with a marked amblyopia (V.A. less than 0.5) or binocular amblyopia, except one, had an increasing or unchanged astigmatism during the age period 1 to 4 years. Strabismus and oblique astigmatism at any time during the test period was also strongly related to amblyopia. The incidence of strabismus (1%) was unexpectedly low. The study also showed that independent of age there was no simple relationship between amblyopia and refraction errors measured at a single test session. The main conclusion of this study is that failure of emmetropization may play an important role in visual development.

Amblyopia↗
PubMed2004

Refractive adaptation in amblyopia: quantification of effect and implications for practice.

AIM: To describe the visual response to spectacle correction ("refractive adaptation") for children with unilateral amblyopia as a function of age, type of amblyopia, and category of refractive error. METHOD: Measurement of corrected amblyopic and fellow eye logMAR visual acuity in newly diagnosed children. Measurements repeated at 6 weekly intervals for a total 18 weeks. RESULTS: Data were collected from 65 children of mean (SD) age 5.1 (1.4) years with previously untreated amblyopia and significant refractive error. Amblyopia was associated with anisometropia in 18 (5.5 (1.4) years), strabismus in 16 (4.2 (0.98) years), and mixed in 31 (5.2 (1.5) years) of the study participants. Mean (SD) corrected visual acuity of amblyopic eyes improved significantly (p<0.001) from 0.67 (0.38) to 0.43 (0.37) logMAR: a mean improvement of 0.24 (0.18), range 0.0-0.6 log units. Change in logMAR visual acuity did not significantly differ as a function of amblyopia type (p = 0.29) (anisometropia 0.22 (0.13); mixed 0.18 (0.14); strabismic 0.30 (0.24)) or for age (p = 0.38) ("under 4 years" 0.23 (0.18); "4-6 years" 0.24 (0.20); "over 6 years" 0.16 (0.23)). CONCLUSION: Refractive adaptation is a distinct component of amblyopia treatment. To appropriately evaluate mainstream therapies such as occlusion and penalisation, the beneficial effects of refractive adaptation need to be fully differentiated. A consequence for clinical practice is that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided.

Adaptation, Ocular↗
PubMed1991

Anisometropic and strabismic amblyopia in the age group 2 years and above: a prospective study of the results of treatment.

Forty-four children aged 2-9 years with strabismic and anisometropic amblyopia were prospectively followed up during amblyopia treatment. The efficacy of optimised treatment in terms of number of cured children, time to achieve cure, and rate of initial improvement of visual acuity was evaluated in relation to age at start of treatment, type and initial degree of amblyopia, and adherence to treatment regimen. Compliance with treatment was the most critical factor predicting a successful outcome. Among the compliant children 35 out of 36 were cured (visual acuity difference between amblyopic and non-amblyopic eyes not more than one line) within five months regardless of age, treatment regimen, and type or initial degree of amblyopia as compared with none in the group with low compliance. Most of these compliant children were cured within three months, with shorter treatment times on average for the younger children. The initial improvement of visual acuity was also faster at 2 years than at 4 years of age. Anisometropes with moderate amblyopia at the start of treatment were over-represented in the group with low compliance. We conclude that early diagnosis of strabismus in combination with general population screening at the age of 4 to detect amblyopia caused by anisometropia or microstrabismus seems to be efficacious for the cure of most cases. The major factor in treatment failure was found to be inadequate adherence to the treatment regimen.

Age Factors↗
PubMed1999

Amblyopia and visual acuity in children with Down's syndrome.

BACKGROUND/AIMS: Amblyopia in people with Down's syndrome has not been well investigated. This study was designed to determine the prevalence and associated conditions of amblyopia in a group of home reared children with Down's syndrome. METHODS: All children in the study group underwent an evaluation of visual acuity. In addition, previous ophthalmological records were reviewed, and a subgroup of children was examined. For the purposes of this study, amblyopia was defined quantitatively as a difference of two Snellen acuity lines between eyes or if unilateral central steady maintained (CSM) vision and a clear fixation preference was observed. A high refractive error was defined as a spherical equivalent more than 3 dioptres and astigmatism more than 1.75 dioptres. Anisometropia was defined as a difference of at least 1.5 dioptres of sphere and/or 1.0 dioptre of cylinder between eyes. 68 children with Down's syndrome between the ages of 5 and 19 years were enrolled in the final study group. RESULTS: Amblyopia was observed in 15 (22%) of 68 patients. An additional 16 (24%) patients had bilateral vision less than 20/50. Strabismus, high refractive errors, and anisometropia were the conditions most commonly associated with decreased vision and amblyopia CONCLUSION: This study suggests that the prevalence of amblyopia is higher than previously reported. Fully 46% of these children with Down's syndrome had evidence of substantial visual deficits. These patients may be at higher risk for visual impairment and should be carefully examined for ophthalmological problems.

Adolescent↗
PubMed2003

Differences in the management of amblyopia between European countries.

BACKGROUND: Amblyopia treatment is not standardised and differences between centres and countries have not been systematically investigated. This survey compares the different patterns of orthoptic treatment of amblyopia in the United Kingdom (UK) and three German speaking countries (GSC). METHODS: Questionnaires were sent to orthoptists in the UK and the GSC asking for their preferred choices of treatment of amblyopia between the ages of 6 months to 10 years. RESULTS: The following significant differences in management of amblyopia were found: (1) the number of hours of occlusion per week was higher in the GSC, p<0.0001, (2) orthoptists in the GSC treat amblyopia up to an older age. Orthoptists in the GSC and in the UK predicted similar treatment outcomes. CONCLUSION: Orthoptists in the GSC usually treat patients more intensively and for longer, while the prediction of visual outcome does not differ significantly between countries. These results highlight the lack of standardisation in the treatment of the various types of amblyopia.

Age Factors↗