SEARCH · Search PubMed

Results for “Amblyopia”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources

PubMed2001

The cortical deficit in humans with strabismic amblyopia.

To further our understanding of the cortical deficit in strabismic amblyopia, we measured, compared and mapped functional magnetic resonance imaging (fMRI) activation between the fixing and fellow amblyopic eyes of ten strabismic amblyopes. Of specific concern was whether the function of any visual area was spared in strabismic amblyopia, as recently suggested by both positron emission tomography (PET) and fMRI studies, and whether there was a close relationship between the fMRI response and known psychophysical deficits. To answer these questions we measured the psychophysical deficit in each subject and used stimuli whose relationship to the psychophysical deficit was known. We observed that stimuli that were well within the amblyopic passband did produce reduced fMRI activation, even in visual area V1. This suggests that V1 is anomalous in amblyopia. A similar level of reduction was observed in V2. In two subjects, we found that stimuli outside the amblyopic passband produced activation in visual area V3A. We did not find a close relationship between the fMRI response reduction in amblyopia and either of the known psychophysical deficits even though the fMRI response reduction in amblyopia did covary with stimulus spatial frequency.

Adolescent↗

PubMed1996

Results of treatment of amblyopia with a screening program for early detection.

The Swedish program for early intervention in children with visual dysfunction, was evaluated with respect to the results of treatment of amblyopia. One hundred and seventy-two amblyopic children were examined before and at 6, 12 and 18 months after the beginning of treatment. The mean visual acuity of the amblyopic eye was 0.76 and the mean ratio of visual acuity between the two eyes was 0.75 or better in all types of amblyopia. Children with strabismic amblyopia showed slightly poorer treatment results than the other types, in spite of the fact that their amblyopia had been detected earlier than the others. The results attest to the importance of careful screening of monocular visual acuity in all children, which in Sweden occurs at 4 years of age. This provides a good basis for detection and treatment of amblyopia. Only one child in the group had a visual acuity at 0.2 and may therefore be at risk for visual handicap if the better eye should be lost later in life.

Amblyopia↗

PubMed1981

Contrast sensitivity in children with strabismic and anisometropic amblyopia. A study of the effect of treatment.

The contrast threshold of sinusoidal gratings of varying contrast and frequency was examined in children with amblyopia due to strabismus or anisometropia. In strabismic amblyopia the contrast sensitivity is depressed for only a limited band of high spatial frequencies. In anisometropic amblyopia depression of the contrast sensitivity function (CSF) was found over the whole frequency range. The CSF could not be predicted from the visual acuity measurements in amblyopic eyes due to strabismus, whereas a rough correlation was observed in anisometropia. During occlusion treatment of the dominant eye in anisometropia the visual acuity and the contrast sensitivity function of the amblyopic eye improved in parallel. The study indicates that the abnormalities in spatial vision are different in amblyopia due to strabismus or anisometropia during childhood. Determination of the contrast sensitivity function seems to be an additional tool besides acuity measurements to document changes of visual function during treatment of amblyopia.

Amblyopia↗

PubMed2004

Cost effectiveness of treatment for amblyopia: an analysis based on a probabilistic Markov model.

AIMS: To estimate the long term cost effectiveness of treatment for amblyopia in 3 year old children. METHODS: A cost utility analysis was performed using decision analysis including a Markov state transition model. Incremental costs and effects during the children's remaining lifetime were estimated. The model took into account the costs and success rate of treatment as well as effects of unilateral and bilateral visual impairment caused by amblyopia and other eye diseases coming along later in life on quality of life (utility). Model parameter values were obtained from the literature, and from a survey of experts. For the utility of unilateral visual impairment a base value of 0.96 was assumed. Costs were estimated from a third party payer perspective for the year 2002 in Germany. Costs and effects were discounted at 3%. Uncertainty was assessed by univariate and probabilistic sensitivity analysis (Monte-Carlo simulation). RESULTS: The incremental cost effectiveness ratio (ICER) of treatment was euro2369 per quality adjusted life year (QALY). In univariate sensitivity analysis the ICER was most sensitive to uncertainty concerning the utility of unilateral visual impairment-for example, if this utility was 0.99, the ICER would be euro9148/QALY. Monte-Carlo simulation yielded a 95% uncertainty interval for the ICER of euro710/QALY to euro38 696/QALY; the probability of an ICER smaller than euro20 000/QALY was 95%. CONCLUSION: Treatment for amblyopia is likely to be very cost effective. Much of the uncertainty in results comes from the uncertainty regarding the effect of amblyopia on quality of life. In order to reduce this uncertainty the impact of amblyopia on utility should be investigated.

Amblyopia↗

PubMed2005

Monocular and binocular reading performance in children with microstrabismic amblyopia.

AIM: To evaluate if functionally relevant deficits in reading performance exist in children with essential microstrabismic amblyopia by comparing the monocular and binocular reading performance with the reading performance of normal sighted children with full visual acuity in both eyes. METHODS: The reading performance of 40 children (mean age 11.6 (SD 1.4) years) was evaluated monocularly and binocularly in randomised order, using standardised reading charts for the simultaneous determination of reading acuity and speed. 20 of the tested children were under treatment for unilateral microstrabismic amblyopia (visual acuity in the amblyopic eyes: logMAR 0.19 (0.15); fellow eyes -0.1 (0.07)); the others were normal sighted controls (visual acuity in the right eyes -0.04 (0.15); left eyes -0.08 (0.07)). RESULTS: In respect of the binocular maximum reading speed (MRS), significant differences were found between the children with microstrabismic amblyopia and the normal controls (p = 0.03): whereas the controls achieved a binocular MRS of 200.4 (11) wpm (words per minute), the children with unilateral amblyopia achieved only a binocular MRS of 172.9 (43.9) wpm. No significant differences between the two groups were found in respect of the binocular logMAR visual acuity and reading acuity (p>0.05). For the monocular reading performance, significant impairment was found in the amblyopic eyes, whereas no significant differences were found between the sound fellow eyes of the amblyopic children and the control group. CONCLUSION: In binocular MRS, significant differences could be found between children with microstrabismic amblyopia and normal controls. This result indicates the presence of a functionally relevant reading impairment, even though the binocular visual acuity and reading acuity were both comparable with the control group.

Amblyopia↗

PubMed1983

Amblyopia in 4-year-old children treated with grating stimulation and full-time occlusion; a comparative study.

We have compared the effects on visual acuity and binocular functions of grating stimulation (CAM therapy) and full-time occlusion in 38 4-year-old, previously untreated amblyopic children. The patients were divided into subgroups with regard to amblyopia type and fixation pattern. We found that grating stimulation was slightly better than occlusion in improving visual acuity of anisometropic amblyopes with central fixation, but that both types of therapy were equally effective in strabismic amblyopia with central fixation and in amblyopia with eccentric fixation. However, maximal treatment effects were not reached with grating stimulation alone, as shown at follow-up after continued conventional therapy. Grating stimulation may be regarded as a valuable method at the initiation of treatment, particularly in anisometropic amblyopia, but it has to be supplemented with occlusion, which still must be regarded as the prime form of amblyopia therapy.

Amblyopia↗

PubMed1997

Atropine penalisation versus occlusion as the primary treatment for amblyopia.

AIMS/BACKGROUND: Pharmacological penalisation of non-amblyopic eyes is an infrequently used alternative to occlusion for treating amblyopia. The authors compared the efficacy of atropine penalisation and that of occlusion as a primary treatment for amblyopia. METHODS: Thirty six newly diagnosed patients with amblyopia were allocated to two groups for treatment. Eighteen patients in each group were treated either with atropine penalisation (group A) or occlusion therapy (group P). RESULTS: There was a statistically significant improvement in visual acuity in both groups treated. In group A improvement of the geometric mean visual acuity of the amblyopic eye was from 6/50 to 6/11 (p < 0.001). In group P improvement of the geometric mean visual acuity was from 6/60 to 6/19 (p < 0.001). In group A non-compliance with treatment was only 6% (2/18). Non-compliance in group P was 45% (8/18) at some stages of the treatment. Neither group produced an incidence of occlusion amblyopia. CONCLUSIONS: In this study atropine penalisation has been shown to be as effective as occlusion therapy in the treatment of amblyopia. Patient acceptance of atropine penalisation was superior to that for occlusion therapy as was shown by the compliance rate. Atropine treatment was also advantageous in that compliance could be readily checked by inspection.

Amblyopia↗

PubMed1998

Movement hyperacuity in childhood amblyopia.

BACKGROUND: Amblyopia results in deficits in a number of visual functions in both the amblyopic and dominant eye. The present work describes oscillatory movement displacement thresholds (OMDT) in childhood amblyopia. METHODS: The OMDT from the dominant and amblyopic eyes of 50 orthoptic patients (aged 74 (SD 16) months) were compared with those from a group of 24 controls (79 (21) months). OMDT were measured using a forced choice staircase procedure. Subjects were asked to identify which of the computer controlled monitors displayed the oscillating stimulus. Visual acuity and stereoscopic responses were noted from clinical records. RESULTS: Amblyopic children demonstrating stereopsis showed no significant OMDT deficit in the amblyopic eye. Those children having no stereopsis had elevated OMDT in the amblyopic eye (p < 0.05). Results suggest that the dominant eye of children with amblyopia may also have a pattern of visual development which is anomalous (difference in correlation coefficient with age; p < 0.05). CONCLUSION: OMDT deficits demonstrated in some amblyopic eyes indicate that amblyopia is incompletely described by its "clinical" definition. Results suggest that the dominant eye in those with unilateral amblyopia may not be "normal".

Aging↗

PubMed2003

Defining and measuring treatment outcome in unilateral amblyopia.

AIM: To offer a critique of current methods of defining amblyopia treatment outcome and to examine alternative approaches. METHOD: Literature appraisal and descriptive case presentations. RESULTS: Currently, the outcome of amblyopia treatment is expressed as the number of acuity chart lines gained or, alternatively, achievement of an arbitrarily adopted level of visual acuity. As binocular vision is optimised with equal visual input from each eye the authors propose that the optimum outcome of amblyopia therapy is to achieve a visual acuity in the amblyopic eye equal to that of its fellow. In addition, improvement should be graded as the proportion of change in visual acuity with respect to the absolute potential for improvement (that is, that pertaining in the fellow eye at end of treatment). CONCLUSIONS: There are two methods of appropriately describing the outcome of amblyopia treatment: firstly, by the difference in final visual acuity of amblyopic and fellow eye (residual amblyopia); secondly, the proportion of the deficit corrected.

Amblyopia↗

PubMed2006

Does amblyopia affect educational, health, and social outcomes? Findings from 1958 British birth cohort.

OBJECTIVE: To determine any association of amblyopia with diverse educational, health, and social outcomes in order to inform current debate about population screening for this condition. DESIGN, SETTING, AND PARTICIPANTS: Comparison of 8432 people with normal vision in each eye with 429 (4.8%) people with amblyopia (childhood unilateral reduced acuity when tested with correction and unaccounted for by eye disease) from the 1958 British birth cohort, with respect to subsequent health and social functioning. RESULTS: No functionally or clinically significant differences existed between people with and without amblyopia in educational outcomes, behavioural difficulties or social maladjustment, participation in social activities, unintended injuries (school, workplace, or road traffic accidents as driver), general or mental health and mortality, paid employment, or occupation based social class trajectories. CONCLUSIONS: It may be difficult to distinguish, at population level, between the lives of people with amblyopia and those without, in terms of several important outcomes. A pressing need exists for further concerted research on what it means to have amblyopia and, specifically, how this varies with severity and how it changes with treatment, so that screening programmes can best serve those who have the most to gain from early identification.

Adolescent↗

PubMed2000

BOLD fMRI response of early visual areas to perceived contrast in human amblyopia.

In this study, we used a temporal two-alternative forced choice psychophysical procedure to measure the observer's perception of a 22% physical contrast grating for each eye as a function of spatial frequency in four subjects with unilateral amblyopia and in six subjects with normal vision. Contrast thresholds were also measured using a standard staircase method. Additionally, blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to measure the neuronal response within early visual cortical areas to monocular presentations of the same 22% physical contrast gratings as a function of spatial frequency. For all six subjects with normal vision and for three subjects with amblyopia, the psychophysically measured perception of 22% contrast as a function of spatial frequency was the same for both eyes. Threshold contrast, however, was elevated for the amblyopic eye for all subjects, as expected. The magnitude of the fMRI response to 22% physical contrast within "activated" voxels was the same for each eye as a function of spatial frequency, regardless of the presence of amblyopia. However, there were always fewer "activated" fMRI voxels during amblyopic stimulation than during normal eye stimulation. These results are consistent with the hypotheses that contrast thresholds are elevated in amblyopia because fewer neurons are responsive during amblyopic stimulation, and that the average firing rate of the responsive neurons, which reflects the perception of contrast, is unaffected in amblyopia.

Adult↗

PubMed2004

Recovery of contour integration in relation to LogMAR visual acuity during treatment of amblyopia in children.

PURPOSE: In several studies, researchers have found that integration of orientation information along contours defined by Gabor patches is abnormal in patients with strabismus and in untreated patients with anisometropic amblyopia. In this study, the rate and degree of recovery of contour-integration deficits were compared with the recovery of logMAR (logarithm of the minimum angle of resolution) visual acuity deficits in patients newly diagnosed with amblyopia secondary to anisometropia, strabismus, or both. METHOD: Contour-detection thresholds and optotype acuity were measured in 17 newly diagnosed anisometropic amblyopes, in 6 patients with strabismic amblyopia, and in 4 patients with combined anisometropic and strabismic amblyopia. Contour-detection thresholds were measured with a card-based procedure. Treatment comprised full refractive correction and full-time total occlusion therapy, when necessary. Visual function was measured at monthly visits during the course of treatment, with an average follow-up period of 16 weeks (12-24 weeks) for the entire group. Complete data were obtained from 23 patients through 8 weeks of follow-up. RESULTS: Significant interocular differences in contour-detection thresholds were present in 16 of the 27 patients at the first visit after initial refractive correction. Interocular differences in contour-detection thresholds declined to normal levels in most of the patients within 8 weeks of the initiation of treatment. Interocular acuity differences remained significant in many of the patients (19/23) at 8 weeks of follow-up and continued to decline, but did not fully normalize, over the remainder of the follow-up period. CONCLUSIONS: Refractive correction alone or in combination with occlusion therapy produces a normalization of contour-integration thresholds in amblyopia that is more rapid and complete than that achieved for visual acuity.

Adolescent↗

PubMed1992

Amblyopia: etiology, detection, and treatment.

Amblyopia is a preventable cause of visual loss in children that may be permanent unless it is detected and treated early. It may be caused by strabismus, refractive errors, or cataracts. Primary strabismus may lead to loss of vision from amblyopia and the loss of binocularity. Secondary strabismus may be a sign of primary visual loss in one or both eyes. The most serious disorder that may present as secondary strabismus is retinoblastoma. It is imperative to detect retinoblastoma early because of its morbidity and mortality. Amblyopia is detected by assessing the visual acuity of each eye. Strabismus is detected by using the corneal light reflex test and the cover test. Focusing problems are detected by assessing the visual acuity and the red reflex. Cataracts and retinoblastoma may be detected by examining the red reflex of the eye. Treatment of amblyopia consists of correcting the amblyogenic factor with appropriate glasses and surgery. The preferred eye is patched with an adhesive patch to stimulate visual development in the amblyopic eye. The pediatrician plays a crucial role in the early detection of amblyopia, strabismus, and cataracts. The key to successful visual outcome is early recognition by the pediatrician, referral to the pediatric ophthalmologist, and prompt treatment.

Amblyopia↗

PubMedDate not supplied

Bilateral hypermetropic amblyopia.

A retrospective analysis was performed on the records of 184 children who had hyperopia of at least 4.0 diopters in each eye to see if bilateral amblyopia was more than just a rare occurrence and to evaluate how well it responded to treatment. Twelve patients were found to have bilateral amblyopia of 20/50 or worse. The mean age at diagnosis was four and a half years (two and a half to six and a half) and mean follow-up was 22 months (five months to seven years, four months). Ten of 12 patients showed improvement of vision to 20/40 or better in both eyes. Treatment consisted of full cycloplegic correction in all cases. Six patients had accommodative esotropia but this did not account for the bilateral nature of the amblyopia. Bilateral amblyopia should be considered in patients with large amounts of hyperopia. It responds well to treatment with standard amblyopia therapy.

Accommodation, Ocular↗

PubMedDate not supplied

The diagnosis of amblyopia in cross-fixation.

Customarily, it is taught that cross-fixation, in a patient with congenital esotropia, obviates the development of amblyopia. However, our clinical experience has shown significant amblyopia in 50% of cross-fixators. In our hands, the diagnosis of amblyopia is made based on the point at which alternation of fixation takes place. By this method, if there is equal visual acuity, alternation will occur at the midline with each eye. If amblyopia exists, the sound eye will continue to follow the target beyond midline, into abduction, before the poorer seeing eye picks up fixation. In order to test the reliability of this method, using Teller acuity cards as the standard, we compared estimates of objective and subjective vision in 25 consecutive patients with congenital esotropia and cross-fixation. Our findings suggest that there may be a significant prevalence of amblyopia in cross- fixating patients and that the point at which alternation of fixation occurs is a reliable means of detecting a difference in visual acuity between the two eyes.

Amblyopia↗

PubMedDate not supplied

Brain electrical activity mapping in the study of visual development and amblyopia in young children.

Brain electrical activity mapping (BEAM) allows the study of electrical visual reactivity on a computerized electroencephalogram (EEG). We carried out 150 BEAM studies on 120 infants to evaluate the usefulness and reliability of this noninvasive technique in the assessment of vision in very young children, compared with other methods (clinical testing, preferential looking, and visual evoked potentials). BEAM demonstrated amblyopia at a cortical level and showed specific electrical signs of amblyopia. The visual reactivity was variably affected depending on the type of amblyopia present. In addition, different results of BEAM corresponded to different kinds of visual maturation delay and strabismus in the absence of amblyopia. BEAM appears to be useful in the initial screening and during treatment of deprivation and strabismic amblyopia, especially when other methods have failed to elicit the level of vision.

Adolescent↗

PubMedDate not supplied

A comparison of Wright card with Teller card for detection of amblyopia.

PURPOSE: Teller acuity cards are used to assess visual acuity in infants but can underestimate amblyopia. In order to improve amblyopia detection, a new luminance balanced checkered card of 4.8 cycles/cm frequency was developed by Wright and Vistech (Dayton, Ohio). The Wright card was compared with a corresponding Teller card (of 4.8 cycles/cm) for detection of amblyopia. METHODS: A prospective masked study of 44 children was carried out. Each was assessed for amblyopia using both the Wright and Teller cards in addition to the Snellen or Allen card (optotype). The results were analyzed statistically using repeated measures of ordinal data. RESULTS: Thirteen eyes were found to be amblyopic with optotype testing, two with the Teller card and 17 with the Wright card. With optotype acuity as the standard, the sensitivity and specificity of the Teller card was 15.3% and 100%, while that of the Wright card was 100% and 94.6%. DISCUSSION: The Teller card is associated with high false negative test rate because it assesses grating acuity and allows spurious resolution possibly due to an edge artifact. This artifact is less pronounced with the Wright card. Further, the stripes on the Teller card require resolution only in horizontal axis, while the checkers requires uniform resolution in all axes. Different pathways for neural processing may also contribute to the disparate results with these methods. CONCLUSIONS: The Wright card was more sensitive than the Teller card for the detection of amblyopia in this study population and has potential value in preverbal children.

Amblyopia↗

PubMedDate not supplied

Congenital ptosis and amblyopia: a retrospective study of 130 cases.

PURPOSE: To provide supplementary data on the association between congenital ptosis and amblyopia. METHODS: In a retrospective chart study of 130 patients whose congenital ptosis was surgically corrected between 1987 and 1999, 27 (20.8%) had strabismus and 30 (23%) had amblyopia. In 9 patients (6.3%), it was not attributable to any cause except ptosis. RESULTS: There was a high incidence (6.9%) of amblyopia in patients with congenital ptosis. CONCLUSION: We recommend early examination and follow-up of patients with congenital ptosis to diagnose and treat any subsequent amblyopia. Surgery may be indicated should stimulus deprivation amblyopia develop.

Adolescent↗