Classification and diversity of amblyopia.

Amblyopia is a developmental disorder that affects the spatial vision of one or both eyes in the absence of an obvious organic cause; it is associated with a history of abnormal visual experience during childhood. Subtypes have been defined based on the purported etiology, namely, strabismus (misaligned eyes) and/or anisometropia (unequal refractive error). Here we consider the usefulness of these subclassifications.

A pragmatic approach to amblyopia diagnosis: evidence into practice.

Amblyopia is a common cause of reduced vision in children. The clinical diagnosis is complicated and requires consideration of the severity of vision loss relative to the characteristics of the disrupting amblyogenic factor. Added to the challenge of a thorough examination of very young children, is the weight of consequence if the amblyogenic factor is not identified and treated appropriately within clinically recommended time frames. Further, the poor visual function may be a symptom of more sinister underlying pathology impacting the visual pathway. This review presents an evidence-based, pragmatic approach to the diagnosis of amblyopia, as a means for guiding best practice for the care of children who present with reduced vision.

Choroidal Thickness in Strabismus and Amblyopia Cases.

PURPOSE: The aim of our study was to examine the effect of hypermetropia and anisometropic, exotropic, and esotropic amblyopia on choroidal thickness. METHODS: A prospective, cross-sectional, comparative study of 120 children under the age of 16 years was conducted. Choroidal thickness was measured in patients with hypermetropia, anisometropia, esotropia, exotropia, and controls. RESULTS: The mean subfoveal choroidal thickness in the control and hypermetropia groups was 323.9±69.0 µm and 348.9±64.5 µm, respectively. Mean choroidal thickness in amblyopic and fellow eyes was 387.4 and 351.9 µm in anisometropic, 353.8 and 338.7 µm in exotropic, 347.5 and 336.5 µm in esotropic, and 389.3 and 359.3 µm in esotropic+anisometropic groups, respectively. Choroid was significantly thicker in amblyopic eyes of anisometropic group compared to fellow (P=0.004) and control (P=0.03) eyes. The difference of choroidal thickness was not significant between both eyes and when compared to control eyes in the other groups. CONCLUSIONS: Anisometropic amblyopic eyes had thicker choroids compared to controls and fellow eyes. However the choroidal thickness was not significantly different between amblyopic and fellow eyes of esotropic or exotropic patients.

Refractive error change and vision improvement in moderate to severe hyperopic amblyopia after spectacle correction: Restarting the emmetropization process?

PURPOSE: The aims of the study were to develop guidelines for prescribing spectacles for patients with moderate to severe hyperopic amblyopia and to demonstrate how emmetropization progresses. METHODS: Children with hyperopic amblyopia who had a spherical equivalent of ≥ +4.0 diopters (D) or more were included, while those who had astigmatism of > 2.0 D or anisometropia of > 2.0 D were excluded. The patients were divided into a full correction group and an under-correction group according to the amount of hyperopia correction applied. The under-correction group was further subdivided into a fixed under-correction group and a post-cycloplegic refraction (PCR) under-correction group. The duration of amblyopia treatment and changes in initial hyperopia were compared between the groups. RESULTS: In total, 76 eyes of 38 patients were analyzed in this study. The full correction group and under-correction group were subjected to 5.5 months and 5.9 months of amblyopia treatment, respectively (P = 0.570). However, the PCR under-correction group showed more rapid improvement (2.9 months; P = 0.001). In the under-correction group, initial hyperopia was decreased by -0.28 D and -0.49 D at 6 months and 12 months, respectively, after initial cycloplegic refraction. Moreover, the amount of hyperopia under-correction was correlated with the amount of hyperopia reduction (P = 0.010). CONCLUSION: The under-correction of moderate to severe hyperopic amblyopia has beneficial effects for treating amblyopia and activating emmetropization. PCR under-correction can more rapidly improve visual acuity, while both fixed under-correction and PCR under-correction can induce emmetropization and effectively reduce initial hyperopia.

Resultados clínicos en niños ambliopes de cuarto grado de la Escuela de rehabilitación visual / Clinic Results in Children with Fourth Level Amblyopia of Visual Rehabilitation School

Introducción: la ambliopía es primariamente un fenómeno cortical, causado por la desigual influencia competitiva de los dos ojos en el área 17 de la corteza visual primaria. El término ambliopía significa ojo vago o perezoso.Objetivo: describir los resultados del tratamiento de rehabilitación visual en niños ambliopes.Método: se realizó un estudio transversal a niños ambliopes de cuarto grado de la escuela de rehabilitación visual La Edad de Oro de Holguín, durante el curso escolar 2014- 2015. La muestra constó de 13 alumnos, la misma se caracterizó según sexo, etiología, tipo de fijación y recuperación visual. La información se recogió en las historias clínicas.Resultado: prevaleció el sexo masculino; la ambliopía estrábica y la ametrópica fueron las más frecuentes y representaron el 38,46 por ciento cada una. La fijación foveal se observó en pacientes con ambliopía ametrópica y la fijación excéntrica en la ambliopía estrábica. La mayoría de los casos alcanzó recuperación parcial, seguido de los que lograron recuperación total.Conclusión: con el tratamiento establecido, mejoró la agudeza visual en la mayoría de los pacientes.(AU)

Introduction: amblyopia is primarily a cortical phenomenon, caused by the unequal competitive influence of the two eyes in area 17 of the primary visual cortex. The term amblyopia means lazy or lazy eye.Objective: to describe the results of the visual rehabilitation therapy of ambliopic children.Method: an cross-sectional study was conducted to amblyopic children from the fourth level of the visual rehabilitation of La Edad de Oro School in Holguín, in the 2014-2015 school year. The sample comprised 13 students, characterized by sex, etiology, fixation type and visual recovery. The information was gathered in medical histories.Results: male sex prevailed; the strabic and the ametropic amblyopia were the most frequent, representing 38.46 percent. The foveate fixation was observed in patients with ametropic amblyopia, and the eccentric fixation was in the estrabic amblyopia. The majority of the cases reached partial recovery, followed of those that obtained full recovery.Conclusions: the majority of the patients improved the visual acuity with the established treatment.(AU)

Analysis of association between type of amblyopia and gender at a tertiary care hospital in Karachi.

OBJECTIVE: To analyse the frequency of different types of amblyopia and its association with gender. METHODS: The cross-sectional study was conducted from March 2014 to October 2014 at the Department of Ophthalmology of a tertiary care hospital inKarachi. The patients were classified into different types of amblyopia like anisometropic, strabismic, sensory deprivation and meridional amblyopia. Stratification was done according to age, gender and type of amblyopia by using SPSS version 21. RESULTS: Out of 130 patients, 71 were male and 59 were female. The amblyopia rate determined was anisometropic 69.23%, strabismic amblyopia 21.51% and others 9.23%. The mean age of subjects was 18.02±9 years. Type of amblyopia was independent of gender, and anisometropic amblyopia was the most common type of amblyopia found in both genders. CONCLUSIONS: This study found no significant association between gender and types of amblyopia and anisometropic amblyopia was the most common type of amblyopia in the data collected.

Evaluation of Occlusion Treatment Outcomes for Unilateral Amblyopia Using Different Definitions of Outcome.

We studied 87 cases of children aged 3 to 10 with unilateral amblyopia (with types of anisometropia, strabismus, or both) who received good recovery after occlusion therapy. The proportional improvement had moderate positive correlation with amblyopic eye improvement (p < 0.05) and negative correlation with residual amblyopia (p < 0.05); the amblyopia residual had no correlation with amblyopic eye improvement (p < 0.05). In multivariate analysis, the proportion of the deficit-corrected of the <5 years group with 2 h/d occlusion therapy group displayed the best outcome (p < 0.05). The BCVA of amblyopia eye and residual amblyopia are simple and direct indicators for clinical application. The proportion of the deficit-corrected method should be graded as the proportion of change in visual acuity with respect to the absolute potential for improvement, and these optimum outcomes can provide powerful evidence for good therapeutic effect.

[Functional amblyopia]. / Ambliopia functionala.

Amblyopia is a disorder of the visual system that represents unilateral or bi-lateral reduction of visual acuity in which an organic cause cannot be detected. The illness represents a syndrome of visual deficits, not only a deterioration of visual acuity. This syndrome includes: presence of crowding phenomena, contrast sensitivity deterioration, deficits in accommodation, deterioration of spatial orientation and ocular motility dysfunction. Depending on its etiology, amblyopia is classified into four main types: strabismic amblyopia, anisometropic amblyopia, isoametropic amblyopia and stimulus deprivation amblyopia. To successfully treat the "lazy eye" it is essential to remove the amblyopic factor with techniques addressing each disturbing factor. Techniques used for treating amblyopia include: occlusion, optical penalty or pharmacological, therapy with Levodopa and computer vision therapy. Amblyopia treatment is lengthy and it is very important to counsel not only the child but the whole family and to establish a relationship of trust between doctor and patient in order to get high treatment compliance and high child motivation.

Photorefractive keratectomy in treatment of refractive amblyopia in the adult population.

PURPOSE: To evaluate changes in corrected distance visual acuity (CDVA) after photorefractive keratectomy (PRK) in amblyopic cases. SETTING: Ankara Ataturk Training and Research Hospital 1st Ophthalmology Clinic, Ankara, Turkey. DESIGN: Retrospective case series. METHODS: The medical records of cases of anisometropic amblyopia treated by excimer laser PRK were reviewed. Inclusion criteria were no previous refractive correction, occlusion treatment, or chemical penalization before age 15 years. Anisometropic amblyopia was defined as a more than 2-line difference in CDVA and a refractive error difference greater than 3.00 diopters (D) between 2 eyes of the same patient. Final visual acuity measurements were performed at the end of the sixth postoperative month. RESULTS: The study enrolled 16 hyperopic patients and 34 myopic patients with a mean age of 33.3 years. The mean preoperative spherical equivalent was -7.46 D ± 2.90 (SD) in myopic eyes and +4.15 ± 2.56 D in hyperopic eyes. The differences between the preoperative and postoperative uncorrected distance visual acuity and CDVA were statistically significant (P=.001). The mean CDVA was 0.47 ± 0.17 preoperatively and 0.61 ± 0.19 postoperatively. The CDVA decreased in 3 cases (6%), stayed the same in 12 cases (24%), and increased in 35 cases (70%). There was no statistically significant correlation between the severity of amblyopia and the increase in CDVA (r = 0.20, P=.165). CONCLUSION: After PRK to eliminate and correct refractive errors in anisometropic amblyopia, visual acuity improved significantly in 70% of adult patients with no previous occlusion or chemical penalization treatment.

[Amblyopia, a public health problem]. / L'amblyopie, un problème de santé publique.

Amblyopia or the alteration of the visual function is a common and disabling condition which takes various forms. Screening is carried out during a baby's first week of life and then at regular intervals during early childhood. It is a public health issue insofar as the disorders are curable and treatment is effective when they are detected early.

Characterization of Bangerter filter effect in mild and moderate anisometropic amblyopia: predictive factors for the visual outcome.

PURPOSE: To evaluate the outcome achieved by using Bangerter filters in cases of mild and moderate anisometropic amblyopia, and to define the predictive factors for the final visual outcome. METHODS: Prospective study comprising 62 children (age range 3-11 years) with unilateral amblyopia associated with myopic or hyperopic anisometropia. In all cases, the use of Bangerter filters were prescribed for amblyopia treatment due to the unsuccessful outcome with refractive correction. The prescribed filter always induced a visual acuity reduction in the non-amblyopic eye of 2 lines below the BSCVA of the amblyopic eye. A follow-up of 12 months was completed. RESULTS: A statistically significant improvement in visual acuity was observed at 3 months in both groups, amblyopic and non-amblyopic eyes (p < 0.01). At 6, 9 and 12 months, additional small but statistically significant improvements in visual acuity were detected only in the amblyopic group (p ≤ 0.02). Filter density had to be changed during the follow-up in a total of 22 eyes (35.5%). A significant correlation of the visual acuity with the baseline interocular visual acuity difference was found at 3 months (r = 0.44, p < 0.01), but not at the end of the follow-up (r = 0.12, p = 0.36). Multiple linear regression analysis revealed that the final visual outcome was significantly correlated with the baseline visual acuity, sphere and the difference in visual acuity between eyes (R²: 0.42, p < 0.01). CONCLUSIONS: Bangerter filters are useful for treating mild or moderate amblyopia due to anisometropia, but ocular dominance inversion should be maintained during treatment for obtaining an optimized outcome.

[Comparison of deficits in visual cortex between anisometropic and strabismic amblyopia by fMRI retinotopic mapping].

OBJECTIVE: To study the neural mechanism of visual cortical deficits between anisometropic and strabismic amblyopia comparatively by BOLD-fMRI retinotopic mapping. METHODS: Ten anisometropic amblyopes, 10 strabismic amblyopes and 9 normal subjects underwent fMRI with retinotopic mapping and luminous spots stimuli (spatial frequency: 6 cpd, contrast: 0.5). 1.5T MRI system was used to obtain functional images of visual cortex. Responses in primary and secondary visual cortex were compared among the dominant (normal subject group), anisometropic and strabismic amblyopic eyes by one-way ANOVA, successively analyzed by paired-samples t test between amblyopic eyes and fellow fixing eyes (anisometropic and strabismic amblyopia group respectively). Their fMRI deficits of amblyopes were analyzed regressively in two amblyopia groups respectively. RESULTS: The result of one-way ANOVA showed significantly a lower activation (average T value) in V1, V2, V3, Vp and V7 visual areas (P < 0.05, P values 0.018, 0.007, 0.002, 0.000, 0.025 respectively) between anisometropic amblyopia and normal group. This was in accordance with the result of paired-samples t test between amblyopic eyes and fellow fixing eyes in anisometropic amblyopia group (P < 0.05, P values 0.035, 0.007, 0.020, 0.009, 0.023 respectively). Statistical difference was found in V1, V2 and Vp areas between strabismic amblyopia and normal group (P < 0.05, P values 0.010, 0.007 & 0.003 respectively). The paired-samples t test in strabismic amblyopia group showed statistical difference only in V2, Vp areas (P < 0.05, P values 0.026 and 0. 009 respectively. ). So the two results were discordant. Between the two amblyopic groups, there was no statistical difference (P > 0.05) except in V7 area (P < 0.05, P value = 0.048). There was no causal relation between the primary visual cortical deficits and the secondary cortex in amblyopia (P > 0.05). CONCLUSION: Anisometropic amblyopia and strabismic amblyopia both have functional deficits in the primary and secondary visual cortex. The neural mechanism of secondary visual cortical deficits may be more complex than decreased cortex activation induced by the deficit of primary cortex. In the primary cortex, strabismic amblyopia and anisometropic amblyopia have neuronal deficits and/or abnormal interaction. In addition, strabismic amblyopia may also have suppressive influences of the fixing eyes upon the amblyopic eyes. Anisometropic amblyopia has the neural undersampling at a high spatial frequency in the secondary visual cortex as compared to amblyopic amblyopia.

qCSF in clinical application: efficient characterization and classification of contrast sensitivity functions in amblyopia.

PURPOSE: The qCSF method is a novel procedure for rapid measurement of spatial contrast sensitivity functions (CSFs). It combines Bayesian adaptive inference with a trial-to-trial information gain strategy, to directly estimate four parameters defining the observer's CSF. In the present study, the suitability of the qCSF method for clinical application was examined. METHODS: The qCSF method was applied to rapidly assess spatial CSFs in 10 normal and 8 amblyopic participants. The qCSF was evaluated for accuracy, precision, test-retest reliability, suitability of CSF model assumptions, and accuracy of amblyopia screening. RESULTS: qCSF estimates obtained with as few as 50 trials matched those obtained with 300 Ψ trials. The precision of qCSF estimates obtained with 120 and 130 trials, in normal subjects and amblyopes, matched the precision of 300 Ψ trials. For both groups and both methods, test-retest sensitivity estimates were well matched (all R > 0.94). The qCSF model assumptions were valid for 8 of 10 normal participants and all amblyopic participants. Measures of the area under log CSF (AULCSF) and the cutoff spatial frequency (cutSF) were lower in the amblyopia group; these differences were captured within 50 qCSF trials. Amblyopia was detected at an approximately 80% correct rate in 50 trials, when a logistic regression model was used with AULCSF and cutSF as predictors. CONCLUSIONS: The qCSF method is sufficiently rapid, accurate, and precise in measuring CSFs in normal and amblyopic persons. It has great potential for clinical practice.

[Bilateral blindness and visual impairment in children aged 0-5 years in the women's and children's hospital of Yaounde]. / Cécité et malvoyance bilatérales de l'enfant de 0 à 5 ans à l'hôpital gynéco-obstétrique et pédiatrique de Yaoundé.

A retrospective study covering the period from March 2002 to December 2008 at the Yaounde Women's and Children's Hospital sought to identify the causes of blindness and severe visual impairment in children younger than 5 years old. Of the 55 cases recorded (prevalence: 2.4%), 33 patients were boys and 22 girls. Total blindness were found among 69% of the group, while 31% had severe visually impairment. The most frequent anatomical sites of the disease leading to blindness and severe visual impairment were the lens (27.3%), the visual cortex (25.5%) and the retina (14.5 %). As the initial prognosis is severe, close collaboration between all those responsible for these children must be set up to enable early specialised management and education.

Restoration of underdeveloped cortical functions: evidence from treatment of adult amblyopia.

Amblyopia is a reduction of visual functions that cannot be attributed directly to the effect of any structural abnormality of the eye or the posterior visual pathway. It is caused by abnormal binocular visual experience early in life, during the 'critical period' that prevents normal development of the visual system. It is widely accepted that therapy can only be effective during the critical period, and that it is not administered after the first decade of life. Here we provide an overview describing a recent finding of visual abnormalities in amblyopia and propose a treatment that we developed based on this finding. Both previous and new results that are presented here clearly show the success of the structured method, targeted at the specific deficiencies in amblyopia, to improve vision in children and adults. Our results suggest that the training was successful in rejuvenating the visual system and in restoring lost development from the sensory obstacle period. It is possible that the perceptual learning method used here can be applied to other sensory and non-sensory brain modules suffering from developmental problems.

[Retinal bioelectrical activity in amblyopia].

The mechanisms of visual dysfunction in high amblyopia have not been adequately investigated. Different types of electroretinograms (ERG) as part of the ISCEV standard, as well as macular (15%) pattern and multifocal ERG were recorded in 41 children aged 5-17 years who had high amblyopia with varying gaze fixation and a visual acuity of 0.03-0.1. In high amblyopia, the mixed, macular, and flicker (30 Hz) ERGs were unchanged; however, some patients had supernormal a-wave of a mixed ERG, subnormal a-a- and b-waves of a macular ERG, and a moderately subnormal ERG pattern. Recording of a multifocal ERG showed lower retinal density values in the first and second rings. Thus, in high amblyopia, there are characteristic retinal bioelectrical activity impairments recorded under different conditions of stimulation and adaptation, which suggest that there are impaired interreceptor relations at the retinal level. These changes statistically significantly differ from those in organic retinal defects, which may be a criterion for their differential diagnosis.

The age-dependent effect of anisometropia magnitude on anisometropic amblyopia severity.

INTRODUCTION: Anisometropia is an important cause of amblyopia. The relationship between anisometropia depth and amblyopia magnitude is not well characterized, as previous studies have been limited to patients identified because of their amblyopia. We analyzed results from anisometropic patients identified with photoscreening to eliminate this selection bias. METHODS: We performed a retrospective observational study of preschool children with anisometropia >1.0 D identified during a statewide photoscreening program. Nine hundred seventy-four children with anisometropia were detected over a 9-year period. Visual acuity, cycloplegic refraction data, and patient age from a formal follow-up examination were analyzed. Effect of anisometropia magnitude on amblyopia was measured by ordinal logistic regression, taking age into account. RESULTS: Six hundred forty (65.7%) children had amblyopia > or =2 lines. Three hundred sixty-four (37.4%) had > or =4 lines amblyopia. There was a statistically significant increase in risk of amblyopia with increasing magnitude of anisometropia. Calculated odds ratios for amblyopia with maximal meridional anisometropia of > or =2 to <4 D compared with >1 to <2 D was 2.13 (95% CI [1.63, 2.78], p < 1 x 10(-7)), and 2.34 (95% CI [1.67, 3.28], p < 1 x 10(-6)) when comparing > or =4 D to > or =2 to <4 D. Odds ratios for spherical equivalent anisometropia were also highly statistically significant. CONCLUSIONS: Children with higher magnitudes of anisometropia had higher prevalence and greater depth of amblyopia. Older children had an increased risk of amblyopia compared with younger children for moderate levels of anisometropia. Low magnitude anisometropia in young children may not predispose to amblyopia; these findings have implications for vision screening criteria at various ages.