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PubMedDate not supplied

Anisometropic amblyopia.

One hundred seventy-two consecutive cases of pure anisometropic amblyopia have been studied. Of them 167 were anisohypermetropic and five of them were anisomyopic. The majority of the cases (65.1%) were teenagers. A difference of 1 to 2 diopters between the two eyes formed the single largest group comprising 28.5% cases. Amblyopia was dense and the fixation was foveal in majority of the cases. Statistical analysis of the data revealed that the age at presentation has no relationship to the degree of anisometropia. The higher the age at presentation the greater is the depth of amblyopia. A higher degree of anisometropia is associated with a more severe degree of amblyopia. Persons with a lesser degree of anisometropia are more likely to have fixation at or near the fovea than persons with higher degree of anisometropia. There is a significant association between the age at presentation and the eccentricity of fixation. The farther the fixation is from the fovea the greater is the loss of vision.

Adolescent↗
PubMedDate not supplied

Unexpected good results after therapy for anisometropic amblyopia associated with unilateral peripapillary myelinated nerve fibers.

Unilateral extensive myelination of the peripapillary nerve fibers may be associated with anisometropic myopia, strabismus, and reduced vision. Despite aggressive occlusion of the normal eye, visual results are often disappointing, presumably due to associated structural abnormalities in the macula which limit visual potential. We report two cases, a 21-month-old child and a 23-month-old child with unilateral peripapillary myelination, ipsilateral high myopia, and dense amblyopia. Despite an abnormal macular reflex in each child, vision improved to 20/30 in one child and 20/50 in the other child after occlusion therapy. Visual results in these patients suggest that aggressive amblyopia therapy should be considered in patients with anisometropic amblyopia associated with extensive myelination continuous with the optic nerve. Not all patients with unilateral peripapillary myelinated nerve fibers, an abnormal macula, and myopia will have refractory amblyopia.

Amblyopia↗
PubMedDate not supplied

Factors affecting treatment compliance in amblyopia.

Amblyopia is the most common form of visual disability in children. Successful treatment by patching depends on compliance, but evidence of factors affecting compliance is limited and contradictory. Because there is a well established relationship between social deprivation and access to health care, we hypothesized that social deprivation might be associated with noncompliance. Data from a historical cohort of 961 children from seven English orthoptic clinics starting treatment for amblyopia in 1983 were used to study factors affecting compliance with amblyopia treatment. Children were classified as noncompliant if they failed to attend all appointments prescribed during the first year of treatment. There was a significant difference in compliance between centers (P = .0001). Overall, children with anisometropic amblyopia were more compliant than those with strabismus but this varied significantly between centers. A relationship between social deprivation and compliance was also found (P = .00001). Only 41% of children from the most deprived wards were compliant compared with 61% in the least deprived wards. Compliance was not found to be related to age at starting treatment.

Amblyopia↗
PubMedDate not supplied

Unilateral or asymmetric congenital ptosis, head posturing, and amblyopia.

PURPOSE: To determine the prognostic implication of compensatory head posturing in patients with unilateral or asymmetric congenital ptosis. METHODS: A retrospective review of 80 consecutive patients with unilateral or asymmetric congenital ptosis was performed. The presence of documented compensatory head posturing, age of onset, age of presentation, visual acuity, refraction, and amblyopia were recorded, and binocularity was tested. RESULTS: Five of seven (71%), patients with unilateral or asymmetric congenital ptosis and compensatory head posturing had amblyopia. All of these patients had straight eyes and four of the five amblyopic patients had anisometropia of less than 2 diopters (D). CONCLUSION: The high incidence of amblyopia in this group can occur in the absence of significant anisometropia and strabismus. This unusually high incidence of amblyopia in this subgroup of patients with unilateral or asymmetric congenital ptosis and compensatory head posturing warrants compulsive examination and prophylactic part-time occlusion therapy of the nonptotic eye until reliable vision testing can be performed.

Amblyopia↗
PubMedDate not supplied

Binocular fixation pattern and visual acuity in children with strabismic amblyopia.

BACKGROUND: A prospective study was undertaken to compare the binocular fixation pattern and presence of amblyopia in strabismic children. METHODS: Fifty-three children with manifest strabismus and the ability to cooperate with an optotype acuity test were examined. The binocular fixation pattern and logMAR visual acuity were recorded by separate, masked observers under standardized conditions. The binocular fixation pattern was divided into four grades from alternation to uniocular fixation. RESULTS: Patients who freely alternated did not have amblyopia, while those who maintained or preferred fixation with a given eye tended to have amblyopia in the nonpreferred eye. CONCLUSION: The binocular fixation pattern can be rapidly assessed with minimal equipment and training. These findings confirm the usefulness of a graded assessment of the binocular fixation pattern in the detection of amblyopia.

Adolescent↗
PubMedDate not supplied

Thickness of the retinal nerve fiber layer, macular thickness, and macular volume in patients with strabismic amblyopia.

OBJECTIVE: To compare the thickness of the retinal nerve fiber layer (RNFL), the macular volume, and the macular thickness of the amblyopic eye with those of the non-amblyopic eye in patients with unilateral strabismic amblyopia using optical coherence tomography (OCT). PATIENTS AND METHODS: OCT was performed for 14 patients with unilateral strabismic amblyopia who had no neurologic disease. Nine male and 5 female patients, whose ages ranged from 5 to 18 years, were enrolled in the study. The RNFL thickness average analysis program was used to evaluate mean superior, inferior, temporal, and nasal thickness. The data for all clock quadrants (12 values averaged) were identified as the overall RNFL. The retinal thickness and volume analysis program was used to evaluate macular scans. Data were compared using the Mann-Whitney U test. RESULTS: The mean age (+/- standard deviation) was 10.43 years (+/- 4.09 years). There were 6 right eyes and 8 left eyes with amblyopia; this group had a mean visual acuity (+/- standard error) of 0.3 (+/- 5.70). OCT parameters including the RNFL thickness in all quadrants, overall RNFL thickness, macular thickness, and macular volume showed no significant differences between the two groups (P > .05). CONCLUSION: Assessment of RNFL thickness, macular thickness, and macular volume with OCT revealed no difference between the two eyes of patients with unilateral strabismic amblyopia.

Adolescent↗
PubMedDate not supplied

Posterior polymorphous dystrophy associated with astigmatism and amblyopia in children.

BACKGROUND: Posterior polymorphous dystrophy has been described in the scientific literature as having more than a casual association with keratoconus in adults. We studied four consecutive children with posterior polymorphous dystrophy who had coexisting astigmatism. In our patients, the posterior changes appeared to be associated with the corneal astigmatism, as evidenced by videokeratography. METHODS: Four consecutive cases of posterior polymorphous dystrophy in children were found over a 3-year period by one of the authors (PD). They presented with varying degrees of amblyopia in the eyes with the greater amount of posterior polymorphous dystrophy. Cycloplegic refractions and keratometry readings were performed. The more affected eyes had greater degrees of astigmatism, presumably causing the amblyopia. Whenever possible, the results were supplemented by confirmation by a corneal specialist, specular microscopy, slit-lamp photographs and videokeratography. RESULTS: Greater asymmetry of posterior polymorphous dystrophy was associated with greater astigmatism in the more affected eye. When more astigmatic anisometropia was present there was a greater amblyopia. Videokeratography of one of the patients showed that an area of confluent blebs forming a crescent shape compared exactly with a steep cylinder along the same axis. With-the-rule astigmatism was associated with a more diffuse pattern of blebs. CONCLUSION: Decreases in visual acuity in children with posterior polymorphous dystrophy may sometimes be due to an amblyopia caused by the astigmatism of asymmetric disease.

Amblyopia↗
PubMed1999

Functional visual loss in amblyopia and the effect of occlusion therapy.

PURPOSE: The aim of this study was to define the nature of functional visual loss in amblyopia and to identify those subjects whose amblyopia is chiefly due to one or more of the following deficits: abnormal contour interaction, abnormal eye movements, abnormal contrast perception, or positional uncertainty. METHODS: Fifty amblyopic children with a mean age of 5.6+/-1.3 years were referred from diverse sources. In addition to routine orthoptic and optometric evaluation the principal visual deficits in the amblyopic eye of each subject were identified using the following measures of visual acuity: high contrast linear, single optotype, repeat letter and low contrast linear, plus Vernier and displacement thresholds. These measures were repeated as the children underwent a prescribed occlusion therapy regime, after parental consent. RESULTS: All amblyopic subjects demonstrated a functional loss in each of the tests used, and occlusion therapy appeared to improve all aspects of the amblyopia. High contrast visual acuity was not always the primary deficit in visual function, and when amblyopic subjects were divided according to their primary visual loss, this visual function was found to show the greatest improvement with treatment. CONCLUSIONS: These results suggest that to successfully identify the primary visual deficit and monitor the success of occlusion therapy it is necessary to assess other aspects of visual function in amblyopia.

Amblyopia↗
PubMed1999

[Amblyopia without strabismus in context of research on concomitant strabismus].

PURPOSE: To evaluate pathogenic factors for unilateral amblyopia in the group of amblyopic patients without strabismus. MATERIAL AND METHODS: In the study 141 patients with unilateral amblyopia without strabismus were evaluated according to age, sex, visual acuity, refraction error, presence of anisometropia, age of mother on delivery, weight on birth, hereditary transmission of strabismus or refractive error, pregnancy and delivery complications, response to treatment. RESULTS: Serious birth and pregnancy complications were noted only in 14.2% of cases, hereditary transmission might be suspected in 41.2% of patients. Anisometropia was found in 72% of cases. No significant difference in prevalence of possible pathogenic or risk factors such as age, sex, birth-weight, age of mother on delivery, hereditary transmission, pregnancy or delivery complications were found between anisometropic and isometropic group. Anisometropic group had bigger refractive error and deeper amblyopia, but responded better to treatment. CONCLUSION: Etiology of amblyopia without strabismus, particularly in the group of patients with isometropia, should be associated with trauma to central nervous system either in pre-natal or early after birth period.

Adolescent↗
PubMed1999

[The role of the NMDA receptors in the creating of amblyopia].

The present state of knowledge concerning the etiopathogenesis of amblyopia is discussed. The morphological and functional changes taking place in the neuronal system of the Brodmann's 17th area during the amblyopia creation are described. The factors affecting the primary and secondary visual cortex are characterized. Special attention was focused on the N-methyl-D-aspartate (NMDA) receptors. Their structure and function is described. The role of the NMDA receptors in the formation of the visual cortex plasticity is discussed. The necessity of amblyopia treatment before the critical period is over has been pointed out. The possibilities of using the newest experimental results in amblyopia treatment are indicated.

Amblyopia↗
PubMed2000

Retinal nerve fiber layer thickness in human strabismic amblyopia.

BACKGROUND AND PURPOSE: Amblyopia is characterized by histopathological changes in the visual cortex and lateral geniculate nucleus. In the retina, however, no abnormalities have yet been reported. The purpose of this study was to compare the nerve fiber layer (NFL) thickness in the amblyopic eye with that in the sound eye of patients with strabismic amblyopia. As a practical implication, we investigated the validity of comparing Nerve Fiber Analyzer (NFA) measurements obtained in amblyopic eyes to the normative database built into the NFA. METHODS: NFL thickness was measured with a third generation NFA, the GDx (Laser Diagnostic Technologies, San Diego, CA). This is a scanning laser polarimeter, designed for monitoring glaucoma. The following NFL thickness parameters (all in microns) were compared: average thickness, superior maximum, inferior maximum, superior average, inferior average, nasal median and temporal median. Twenty patients with strabismic amblyopia were imaged with the NFA. Patients had no nystagmus, neurological disease or glaucoma. Nine patients had amblyopia in the right eye, and 11 patients in the left eye. RESULTS: In general, the sound eyes yielded higher thickness measures than the amblyopic eyes. These differences, however, were small, averaging only 1.5%, p = 0.6, and therefore not "statistically significant" at the p&le 0.05 level. CONCLUSIONS: Using the standard of "Statistical Significance = p< or =0.05", when amblyopic eyes are measured with the NFA, the built-in normative database may serve as the reference data

Adolescent↗
PubMed2000

Astigmatism and Amblyopia among Native American Children (AANAC): design and methods.

The overall goal of the AANAC study is to improve detection of astigmatism and prevention of amblyopia in populations with a high prevalence of astigmatism. To meet this goal, the study will evaluate four methods of screening for astigmatism in preschool children and will assess both the short-term and long-term benefits of early correction of astigmatism in improving acuity and preventing amblyopia. This paper presents an overview of the design and methodology of the AANAC study. Subjects are members of the Tohono O'Odham Nation, a Native American tribe with a high prevalence of astigmatism. Preschool-age children who attend Head Start are screened with four tools: the Marco Nidek KM-500 autokeratometer, the MTI photoscreener, the Nikon Retinomax K-Plus autorefractor, and the Lea Symbols acuity chart. Sensitivity and specificity for detection of significant astigmatism, as measured by a technique that uses both cycloplegic retinoscopy and cycloplegic autorefraction, is determined for each of the four screening tools. Presence of amblyopia is evaluated by measurement of best-corrected recognition acuity and acuity for orthogonal gratings. Spectacles are provided to all 3-year-old children with > or =2.00 diopters (D) of astigmatism and all 4- and 5-year-old children with > or =1.50 D of astigmatism. Persistence of amblyopia after glasses wearing is evaluated by follow-up measurement of best-corrected recognition acuity and acuity for orthogonal gratings, conducted 2-5 months after glasses are prescribed. Long-term effectiveness of early screening and glasses prescription is evaluated through measurement of recognition acuity in two groups of first-grade children: one group who participated in the Head Start program before the intensive vision screening program was initiated, and a second group who participated in the study's Head Start vision screening program.

Amblyopia↗
PubMed2001

[Value of the Bébé-Vision test in the screening of strabismus and anisometropic amblyopia in infants].

PURPOSE: To evaluate the accuracy of the Bébé-Vision test for detecting strabismic, ametropic and anisometropic amblyopia in childhood. METHODS: We screened 199 infants under 20 months of age. The screening consisted of a full orthoptic examination by a trained orthopist (cover test, fixation test), a forced choice preferential looking technique (Bébé-Vision test) prior to cycloplegia to test visual acuity, cycloplegic refraction by retinoscopy, and examination of the fundi. RESULTS: Fifteen infants were abnormal on orthoptic examination (clinical evidence of esotropia and/or limitation of abduction and/or amblyopia). The Bébé-Vision test demonstrated a significant interocular difference on the same side of the suspected amblyopic eye in 3 cases and on the opposite side in 3 cases, and no difference in 9 cases. The monocular Bébé-Vision test was abnormal in 51 cases and there was an abnormal cycloplegic refraction in 33 cases. Statistical analysis of these tests demonstrated a very low sensitivity (42%) and a good specificity (90%) for the Bébé-Vision test in detecting amblyopia related to refractive error. CONCLUSION: The Bébé-Vision test does not reliably reveal strabismic or anisometropic amblyopia and is not recommended as a screening test. Diagnosis should continue to be based mainly on the classical clinical methods.

Amblyopia↗
PubMed1976

[Value of functional and electrophysiological studies in amblyopia].

In a group of patients suffering from amblyopia, the authors confront the results after orthoptic treatment with data provided by functional and electrophysiological examination. In 37 patients the clinical diagnosis of functional amblyopia had been made, but in 8 of these cases complimentary functional and electrophysiological examinations showed organic perturbations. This explains the failure, in these cases, of the orthoptic treatment. In the remaining 29 patients, clinical forms of functional amblyopia were found. In this group, the authors studied 20 cases showing no improvement with treatment: in 15 out of the 20 the VERs were pathological. In the 9 remaining cases which have showed improvement the VER'S were never abnormal. VER study can be undertaken, without general anaesthesia, as from 3 to 4 years of age. The authors conclude that all clinical forms of amblyopia should undergo VER investigation: patients showing pathological changes should be excluded from orthoptic treatment, from which they have no possibility of deriving benefit.

Amblyopia↗
PubMed2004

[Fixation in patients with anisometropic amblyopia without strabismus].

PURPOSE: To determine the type of fixation in patients with anisometropic amblyopia without strabismus and find correlation between amount of anisometropia and eccentricity of fixation. MATERIAL AND METHODS: 100 patients with anisometropic amblyopia without strabismus were examined. The following data was obtained: visual acuity, type of fixation, refraction error after cycloplegia. Amount of anisometropia was calculated as the difference of spherical equivalents. RESULTS: Only 44% of patients demonstrated central fixation. The amount of amblyopia corresponded to eccentricity of fixation. For most cases (anisometropia up to 6D of SE) the amount of anisometropia did not correlate with eccentricity of fixation. CONCLUSIONS: Simply difference of refraction must not be the only factor affecting development of anisometropic amblyopia.

Adolescent↗
PubMed1991

[Anisocoria: a suspicious sign of anisotropy and/or amblyopia].

A four-year retrospective study among children who attend a Primary Care Pediatric Service has been made, in search of a connection between the infant anisocoria and the anisometropia and/or amblyopia detected on the screening of visual acuity at the age of three-four years. Four out of five children with anisocoria (that is, the 80%) later suffered anisometropia and/or amblyopia, and, reciprocally, four out of eight children with anisometropia and/or amblyopia (50%) have previously presented anisocoria. The existence of a clear association is shown between both pathologies, and consequently, children with anisocoria (after putting aside other possible reasons, oculars or neurologicals) should be promptly examined on refraction and visual acuity in order to diagnose anisometropia and to prevent development of amblyopia.

Amblyopia↗
PubMed1990

[An investigation of the multi-channel VEP topography by full field stimulation in functional amblyopia of children].

37 children of functional amblyopia and 40 normal children were examined with the multi-channel VEP topography by full field pattern reversal stimulation. The average results of esotropia showed a "half field stimulation effect", or an asymmetric distribution, in the amblyopic eyes, and a minor "half field stimulation effect" also existed in the nonamblyopic fellow eyes. However, the "half field stimulation effect" did not appear in both the amblyopic and non-amblyopic fellow eyes in anisometropic amblyopia. The findings suggest that (1) the pathological mechanism may be different between esotropic and anisometropic amblyopia, and (2) the non-amblyopic eye in esotropic amblyopia may not actually be "normal".

Amblyopia↗
PubMed1979

Abnormal ocular movements in amblyopia.

The visual afferent pathways affect the oculogyric centres in two ways: (1) By maintaining the oculomotor tonus; (2) By inducing optically elicited movements. In organic amblyopia the diminution of central visual acuity is not sufficient to impair the oculomotor reflexes which usually remain unchanged until the vision becomes very poor. Howver, abnormal movements are typically observed in the inhibition of strabismic amblyopia. Sensorimotor difficulties are observed in both version and vergence movements. Abnormal version patterns have two main effects: suppression of optokinetic nystagmus and kinetic anarchy of pursuit and saccadic movements. Vergences are found to be much more brittle and vulnerable to amblyopia than versions, and amblyopia is often accompanied by anomalies of fusional, accommodative, and fast vergence movements.

Amblyopia↗