ABSTRACT
Visual perceptual learning refers to the special improvement of perceptual performance benefit from repetitive training with a visual task.A typical time course of visual perceptual learning presents an initial rapid improvement,and then gradually processes like an asymptote in gain.During the process of perceptual learning,the influence of critical amount and perceptual learning rules on learning effect,memory consolidation and interference,and the role of sleep on preventing interference and promoting consolidation in perceptual learning,all get involved.This article reviewed the aforesaid content and then elaborated some strategies in application of visual perceptual learning in the treatment of amblyopia.
ABSTRACT
Background The characteristics of anisometropic amblyopia in ocular morphology are becoming a hot topic in amblyopia field.And the interocular difference in corneal parameters of anisometropic amblyopia is to be understood here.Corneal topography is a non-invasive method for in vivo corneal examination and applied in our study.Objective This study was to investigate the interocular difference of corneal topography in anisometropic amblyopic patients Methods This was a serial cases observation.Thirty anisometropic amblyopes were selected in Center for Optometry and Visual Science,People's Hospital of Guangxi Zhuang Autonomous Region.The patients were divided into amblyopic eye group and fellow eye group based on the best corrected distance visual acuity.Corneal topography was examined with Orbscan Ⅱ z,and corneal morphological parameters such as Diff values of the anterior and posterior corneal surface,Sim K 's astigmatism,Kmax,angle kappa and central corneal thickness (CCT) were measured.The interocular differences in these parameters were evaluated by paired t test,and the correlations in these parameters between the amblyopic eyes and the fellow eyes were analyzed by Pearson linear correlation and simple regression analysis.Results The Diff values of the anterior corneal surface were (0.011±0.006)mm and (0.011±0.017)mm,and those in the posterior corneal surface were (0.031 ±0.012)mm and (0.026 ±0.008)mm in the amblyopic eye group and the fellow eye group,respectively.In addition,Sim K's astigmatism were (1.8± 1.1)D and (1.1 ±0.6) D,JCC were (77±80) °and (100±80) °,J0 values were (-0.17±0.72) D and (0.02±0.41) D,J45 values were (-0.16±0.79) D and (0.13 ±0.48) D,CCT values were (551 ±37) μm and (551 ±31) μm,angle kappa values were (6.4± 1.4) ° and (4.9 ± 1.2) ° in the amblyopic eye group and the fellow eye group,respectively.Significant differences were found in the Diff values of the anterior and posterior corneal surface,Sim K's astigmatism and angle kappa between the two groups (t=-3.041,P=0.005 ;t=-4.317,P=0.000 ;t=-4.571,P=0.000).Pearson's linear correlation test demonstrated significant interocular positive correlations in parameters such as the anterior corneal surface Diff values (r =0.444),J0 (r =0.383),posterior Diff values (r =0.600),and Sim K 's astigmatism (r =0.479),and CCT (r =0.948,P＜0.05).The linear regression equation between the two groups was Y =-0.005 +1.392X (R2 =0.197,F=6.858,P=0.014) in the Diff values in the anterior corneal surface,Y =-0.013+0.421X (R2=0.360,F=15.761,P=0.000) in the Diff values in the posterior corneal surface,Y =0.616+0.27X (R2=0.230,F=8.348,P=0.007) in the Sim K's astigmatism,Y=0.060+0.219X (R2 =0.147,F=4.814,P=0.037) in theJo and Y=i08.289+0.804X (R2 =0.899,F=250.293,P=0.000) in CCT.Conclusions Corneal morphological interocular differences exist significantly in anisometropic amblyopic patients.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the prevalence, type and distribution of astigmatism in children with amblyopia.</p><p><b>METHODS</b>A total of 2023 children with amblyopia (aged 4-11 years, 3657 eyes) were recruited. The prevalence of astigmatism was investigated.</p><p><b>RESULTS</b>Of the 3657 amblyopic eyes, 91.9% presented astigmatism (≥0.5 D). The proportion of eyes with astigmatism decreased with the increasing age. Compound hyperopic astigmatism was the most common type of astigmatism (38.8%) and its prevalence increased with the increasing age in children with amblyopia. Astigmatism with the rule was the most common (90.1%) in the axial distribution test. There were statistical significances in the axial distribution of astigmatism in different age groups. Statistical significances were also found in the degree, type and axis of astigmatism among the children with mild, moderate and severe amblyopia (P<0.05).</p><p><b>CONCLUSIONS</b>The prevalence of astigmatism in children with amblyopia is high but is reduced with age. The age and the degree of amblyopia might be influential factors in the distribution of astigmatism.</p>