Detection Of Amblyopia Research Articles

Assessment of an inner city visual screening programme for preschool children.

The efficiency of preschool visual screening programmes to detect amblyopia is questionable. In this study such a programme in an inner city was assessed to determine its effectiveness. The results of screening and hospital treatment of 712 patients who were considered to require referral were entered into a database for analysis. Default rates were assessed and the efficacy of treatment determined. The only effective screening test for the detection of amblyopia was visual acuity. A large proportion of referred patients had refractive problems only. High default rates, particularly in geographical areas of lower socioeconomic grading, severely handicapped any attempt to reduce the incidence of amblyopia. A fresh approach to the detection and care of amblyopia in the inner city community is required, perhaps by performing screening of children in their first year of attendance at school to reduce default rates. Cycloplegic refraction of children who are found to have reduced visual acuity before their referral to hospital is also recommended.

Validity of the Bruckner reflex in the detection of amblyopia.

To establish the sensitivity and specificity of the Bruckner reflex (comparison of the fundus red reflexes) in the detection of amblyopia or its risk factors. A single masked study using a medical student's diagnostic ability against the gold standard of a full clinical examination by a paediatric ophthalmologist. A university teaching hospital outpatient facility. Three hundred and one patients consecutively referred for ophthalmic assessment. The sensitivity of the test for the detection of children with amblyopia risk factors was 86% and the specificity was 65%. Of 70 children with a definite diagnosis of amblyopia, the sensitivity of the test was 95%. The Bruckner reflex is a useful screening test for primary eye care personnel. However, there is a significant false-positive rate which will result in unnecessary referrals. We recommend that it form part of a battery of tests, including, for example, the modified base down prism test, which are useful in assessing the vision of preverbal children.

Amblyopia in unilateral congenital ptosis: early detection by sweep visual evoked potential

•Background: Fixation preference assessment is a clinical tool widely used to determine amblyopia in young infants and children. It is our clinical experience that this tool underestimates amblyopia. The purpose of this study was to compare the results of sweep visual evoked potentials to fixation preference assessment in cases of unilateral ptosis. • Methods: Sweep visual evoked potentials were performed in 17 children with unilateral ptosis thought to have equal acuity by fixation preference asessment. Binocular and monocular sweep visual evoked potentials were recorded to square-wave gratings of 80% contrast counterphase modulated at 6 Hz. A range of spatial frequencies from 1 to 30 cycles per degree were presented over a 10-s period. Resolution acuity was determined as the zero-microvolt intercept of linear regression analysis on the visual evoked potential amplitude versus spatial frequency. • Results: Nine of the 17 children had interocular resolution acuity differences ranging from 0.8 to 2 octaves by sweep visual evoked potential testing. This correlates to a Snellen equivalent interocular difference of 2 to 7 lines and clinical amblyopia. • Conclusion: This study confirms our clinical impression that children who are unable to preform recognition acuity tasks and are thought to have equal vision by fixation preference assessment often have 2 or more lines of Snellen acuity difference (amblyopia) when they are finally old enough to be tested by Snellen methods. It also implies that amblyopia precedes refractive errors and strabismus in unilateral ptosis cases. Clinical methods to determine amblyopia other than fixation preference assessment need to be explored with a view to earlier detection, better definition and treatment of amblyopia.

Measurement of letter acuity in preschool children

Measurement of visual acuity remains the most frequently used technique for the assessment of vision in both adults and children. Visual acuity is usually measured clinically in adults using a Snellen chart. However. this technique demands a level of cognition and literacy which is beyond the majority of young children. The measurement of visual acuity in preschool children presents an additional set of problems but it is important that measures of acuity arc made with sufficient precision and accuracy to provide the clinician with valid information. While visual acuity can be measured in infants and very young children using behavioural and clectrophysiological techniques, clinical measurement of letter acuity usually commences when the child is old enough to interact and co-operate with the examiner. By 3 years of age 67% of children will cooperate with visual acuity testing, and by the age of 3.5 years a level of 80% compliance is achieved. The need to detect and correct visual disorder5 during childhood has been recognized for many years by eye-care professionals. Although identification of reduced visual function due to ametropia is important, the detection and treatment of amblyopia is essential

Comparison of Two Preferential Looking Tests in the Detection of Amblyopia

Visual acuities were assessed using a letter acuity test (the Bailey-Lovie Chart) and two preferential looking tests (the Cardiff Cards and Teller Acuity Cards) in twenty-one children with strabism...

Sensitivity of random dot stereoacuity and Snellen acuity to optical blur.

The purpose of this study is to investigate the usefulness of a random dot stereogram for the detection of refractive blur by determining the relative sensitivity of random dot stereoacuity (RDS) and Snellen visual acuity to the effects of optically induced blur. Measurements of Snellen and stereoacuity were compLeted on four young adult subjects under cycloplegia and through artificial pupils. Optical blur was varied binocularly and monocularly in 0.50 D steps up to +/- 6.00 D while the subjects viewed targets composed of stimuli arranged in 0.1 log unit size increments. The results show the relation between RDS and Snellen acuity to be SA = 1.341 (VA) + 0.281 for equal amounts of binocularly induced optical blur. Moreover, the RDS appeared more highly sensitive when the blur in the 2 eyes was unequal [SA = 3.774 (VA) - 1.180], a condition approximating refractive anisometropic amblyopia. These results provide a rationale for the use of random element stereograms for the detection of refractive amblyopia and ametropia in the vision screening of children.

TNO stereopsis test as an aid to the prevention of amblyopia*

In this investigation, carried out under a Youth Health Care postgraduate course in Nijmegen, the stereopsis of a school population of 730 children, aged 4-18 years, was recorded and clinically evaluated. Stereopsis was measured using the TNO test, a random-dot stereo test especially designed for the early detection of amblyopia. The main aims of this study were to establish the validity of the TNO test as a screening test for amblyopia, obtain information about the variability and age dependence of stereopsis, and to evaluate the efficacy of amblyopia prevention. The most important findings can be summarized as follows: 1. All amblyopes are detected by the TNO test's recommended referral criterion of 240 sec arc (binocular threshold parallax in sec arc). 2. The red-green anaglyphs used in the test do not pose problems for individuals with a colour vision deficiency. 3. The ability to discriminate depth improves by a factor of two over the age interval 4-12 years. 4. A stereoacuity of < or = 120 sec arc is a good predictor of normal or correctable normal vision, and may therefore help in evaluating the often incomplete results of eye tests of young children. 5. Where there is an increased perinatal risk, there is a greater chance of disturbed binocular vision. 6. It is estimated that 75% of amblyopes remain amblyopic, possibly because of delayed detection; 60% of the amblyopes in the population examined were not identified before the age of 5 years.

Amblyopia: Diagnosis and Management

Amblyopia is a difficult challenge for physicians caring for these children. If detected early with screening programs, the prognosis for successful treatment is greatly increased. If missed, the child may suffer from a lifetime of poor vision in one eye. Children who fail a visual screening test should be promptly referred to an ophthalmologist. Prompt detection and treatment of amblyopia secure a child the best chance for a good visual outcome.

Detection of amblyopia and development of binocular vision in infants and children.

Studies of visual development indicate that rapid changes occur in the first months of life and that it is during this period that the visual system is prone to aberrant development. The call for visual screening of children younger than 3 years of age is sensible in light of recent research findings. For children with visual problems, some recovery of visual function can occur if treatment is begun early. New tests of stereoacuity and vernier acuity may aid in the diagnosis of amblyopia, which is underestimated by grating acuity measures. Electrophysiologic testing, using visual evoked potentials and electroretinograms, is helpful in diagnosing visual problems at an early age.

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: 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 amblyopie 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 opthalmologist, and prompt treatment.

Vision screening in preschool children: comparison of orthoptists and clinical medical officers as primary screeners.

To see if there were differences in referral rates and abnormalities detected from two areas that were operating different preschool vision screening programmes. Cohort study using case notes of referrals. Community based secondary referral centres in the county of Avon. 263 referrals from a child population of 7105 in Southmead district, an area that used orthoptists as primary vision screeners; 111 referrals from a child population of 2977 in Weston-super-Mare, an area that used clinical medical officers for screening. Amblyopia and squint detection rates, together with false positive referral rates. The amblyopia detection rate in Southmead district was significantly higher than in Weston-super-Mare (11/1000 children v 5/1000), as was the detection rate of squint (11/1000 v 3/1000). However, the false positive referral rate from Southmead was significantly lower than that from Weston-super-Mare (9/1000 v 23/1000). Preschool vision screening using orthoptists as primary screeners offers a more effective method of detecting visual abnormalities than using clinical medical officers.

Factors Associated With Delay in Diagnosis of Childhood Amblyopia

The prevention of permanent visual impairment from amblyopia is an important goal of pediatric vision screening. Unfortunately, many cases of amblyopia are not diagnosed until the child is too old to benefit maximally from treatment. A review of patient records from the practice of a private pediatric ophthalmologist confirmed that late detection is a frequent occurrence among children with amblyopia who have had good access to health care. A case-control study was then used to identify factors associated with delayed diagnosis, in which children with an adverse outcome (diagnosed at or after 5 years of age) were compared with those with an optimal outcome (diagnosed before 5 years of age). The chart review identified 161 children with amblyopia who participated in this study; 75 had late diagnoses (case patients) and 86 served as control patients. Children with early diagnoses more often had the following characteristics: a positive family history of strabismus, greater degrees of strabismus (when strabismus was present), higher maternal educational level, greater parental suspicion that an eye problem existed, and an increased chance that the parents requested the eye examination that led to the diagnosis. The parents of children with late diagnoses expressed less concern over the seriousness of amblyopia but were more likely to report that their children had suffered adverse consequences of amblyopia. When diagnosed early, amblyopia was more often detected by the child's primary health care provider. Physicians of the children with early diagnoses more often reported compliance with both the American Academy of Pediatrics guidelines for vision screening in infancy and referral for vision problems.(ABSTRACT TRUNCATED AT 250 WORDS)

A Diagnostic Ruler for Strabismus and Amblyopia

We designed a diagnostic slide ruler for easier detection of strabismus and amblyopia, both of which begin in childhood. This new instrument makes the Parks three-step test easier to use and faster than other methods in diagnosing isolated cyclovertical muscle paralysis. Furthermore, the slide ruler tests visual acuity with both series letters and single letters. Incorporated into the instrument are Laurence's strabismometer, Haab's pupillometer, occluder, pinhole, and millimeter ruler. A laboratory model is now available, and this slide ruler can assist the ophthalmological practitioner in analyzing three-step test data more rapidly than graphs and computer programs can. This instrument can also diagnose pediatric patients in the early stages of microstrabismus and amblyopia to obtain the best therapeutic results.

A Comparison of Visual Acuity Testers to the Preferential Looking 20/20 Vision Tester

Early detection of amblyopia requires several different visual acuity tests to confirm the diagnosis. Our prospective study compares two groups composed of pre-verbal children and verbal patients. Visual assessment in the non-verbal group is evaluated with the new Preferential Looking 20/20 Vision Tester and fixation patterns, whereas in the verbal group, the “E” game, or letters are compared to the results from the Preferential Looking 20/20 Vision Tester (PL 20/20 VT) to determine reliability in detecting amblyopia. Our findings indicate that the use of this instrument is valid only for verbal children.

Detection of amblyopia with P-VEP during chloral hydrate sedation.

A major limitation of methods presently used for detecting amblyopia in preverbal children and infants is their dependence on patient cooperation. In response to this problem, we have introduced the use of chloral hydrate sedation as a means of obtaining the pattern visual evoked potential (P-VEP) in uncooperative infants. Twenty-five infants were studied: 14 with clinically diagnosed amblyopia, four with questionable amblyopia, and seven with no clinical sign of amblyopia. In patients with known amblyopia, P-1 amplitudes from the amblyopic eye were greatly diminished when compared with responses obtained from the non-amblyopic fellow eye, with amplitude ratios ranging from 0 to 0.66 (mean 0.36). In contrast, P-1 responses from non-amblyopic infants were quite symmetrical, with amplitude ratios of 0.82 to 0.98 (mean 0.92). These results indicate that the P-VEP can be obtained during chloral hydrate sedation and that P-1 responses reflect the presence or absence of amblyopia. Performing P-VEP during chloral hydrate sedation thus holds promise as an important clinical tool for the diagnosis of amblyopia in uncooperative infants and children.

Management of infantile esotropia.

The population of patients with infantile esotropia is etiologically and neuroanatomically heterogeneous, and major advances in management will probably require more accurate subgroup delineation. Amblyopia is relatively common in patients with infantile esotropia. It should always be suspected and, when found, should be vigorously treated. Present methods of amblyopia detection and evaluation in young children are still imperfect. Most clinical evidence suggests rather strongly that sensory and motor functions are more nearly normal if alignment (within 10 prism diopters of orthotropia) is attained within the first 2 years of life. Whether alignment obtained within the first year of life provides higher grades of binocular vision is less certain. Virtually all patients with infantile esotropia fail to develop normal binocular vision. Central scotomas are almost always identifiable, even in patients with optimal motor alignment and with the highest levels of binocular vision. Past surgical protocols have tended to produce an excess of under-corrections. More recent surgical protocols are more generous in terms of millimeters of surgery per prism diopter of deviation. Higher cure rates are now being reported. Patients who are successfully aligned early in life still need careful postoperative monitoring for amblyopia, nystagmus, inferior oblique overactions, dissociated vertical divergence, and accommodative esotropia. These patients require frequent follow-up visits until they reach the age of approximately 9 years.

Recent advances in the management of amblyopia.

Methods of detection and treatment of amblyopia as a developmental visual defect are reviewed. Traditional occlusion therapy is compared with recent therapy techniques using square-wave grating patterns as stimuli to increase visual sensitivity. Both methods can help manage amblyopia particularly during stages of early visual development. It is found that the grating pattern stimuli are not in themselves therapeutic, but rather it is probably occlusion in combination with demanding visual tasks which help reduce amblyopia.

Amblyopia in Ptosis

Amblyopia can result from strabismus, anisometropia, media opacities, and congenital disorders such as nystagmus. Complicated forms of ptosis (ie, associated with neurofibroma or hemangioma) are also known to cause amblyopia. A previously unconfirmed cause of amblyopia is uncomplicated ptosis. We carefully examined 123 consecutive surgical ptosis patients with uncomplicated congenital or early acquired ptosis. Twenty-five cases of amblyopia (20%) were seen. Four cases (3.2%) were thought to be caused by the ptosis. In two of these cases (1.6%), the amblyopia was directly attributed to the ptosis. In one of the remaining two cases, exotropia and amblyopia developed on the ptotic side while the patient was being observed for the ptosis. In another patient, a progressively increasing cylindrical refractive error and amblyopia developed, which were attributed to the ptosis. We recommend careful evaluation of cases of congenital ptosis for the detection and treatment of amblyopia.

Survey of the Clinical Uses and Reliability Random — Dot Stereogram

The paper proposes that stereopsis assessment by a clinical version of Julesz's Random-Dot Stereogram is a more efficient and sensitive screening test for the detection of amblyopia —associated visual dysfunction than traditional screening measures. Further applications of the Random-Dot Stereogram (RDS) as a trainer of stereopsis and detector of stereo-anomalies are also discussed.