Testing Spatial Detection and Light Sensitivity in Homonymous Hemianopia by Rarebit and Conventional Automated Perimetry

Purpose of the study was to compare Rarebit Perimetry (RP) with Standard Automatic Perimetry (SAP) in patients with ischemic retrochiasmal lesions. Seventeen patients with homonymous hemianopia underwent SAP and RP. Correlation between the two techniques was evaluated, congruent defects were quantified in the spared hemifield and residual vision areas were investigated in the blind hemifield. A strong correlation was found between SAP and RP. In the spared hemifield, RP detected congruent defects in a higher percentage of cases. Residual detection function has been found at RP in 69,2 % of perimetrically blind visual field quadrants as assessed by SAP. In conclusion, RP appears to be useful to assess visual function in hemianopic patients. As compared to SAP, it seems able to detect small congruent defects in a higher percentage of cases. Finally, a certain residual function seems to be present at RP in the blind regions of the visual field, however, for this finding further demonstrations are required

Evaluation of Spatial Anisotropy by Curvature Analysis of Elliptical Targets

Spatial relationship perception (SRP), defined as the function able to detect the difference between the perceived extent of a shape along the x/y cardinal coordinates, has been investigated in 42 eyes of 21 emmetropic subjects by means of a psychophysical test conceived on purpose. Aiming to the highest sensibility and since curvature detection is reckoned as an hyperacuity, elliptical stimuli have been chosen to measure the spatial relationship anisotropy (SRA) in the visual system. Observers turned out to be able to detect curvature differences along the elliptical contour as low as 33.6 sec arc, which in terms of SRP means an aspect ratio (i.e. the ratio between the height and the width of the ellipse) as low as 1.0022-1.0035. By comparing these results with those obtained in previous investigations from other curvature discrimination tasks, it is argued that recognition threshold is conditioned by the amount of space anisotropy of the visual system. Indeed, in about half of the recruited subjects, vertical/horizontal anisotropy is found to a certain extent and such SRA correlates with the recognition threshold (r= 0.69, p<0.01). There is direct evidence of visual spatial distortion and in particular increased anisotropy in neuro-ophtalmological diseases such as hemianopia and around scotomatous regions in the visual field. Thence, apart from theoretical considerations in physiological field, results collected in this study may be regarded as normative data for future clinical investigations

Detection of Visual Field Loss Progression in Glaucoma: An Overview and Food for Thought

The damage to the visual field is the main outcome of glaucoma. Basically, there are two different approaches to establish the rate of the functional loss in this clinical condition: event-based analysis and trend-based analysis. The event-based analysis, that relies on the occurrence of pre-established events to detect the progression of the visual field damage, cannot quantify the decay rate of sensitivity. In turn, the trend-based analysis, that aims to measure the rate of progression according to linear regression models, requires a long follow-up. Despite considerable effort, there is still no consensus on the optimal procedure, and a gold standard is still missing. This paper provides a quick overview of the topic as a tribute to the researchers engaged in this field.</jats:p

The Game of Reading: When Saccades and Fixations Play on a Seesaw

Abstract Although in experimental psychology the fixation/saccadic sequence is a main topic of debate, so far in the clinical ophthalmological field such an argument has raised relatively few interest. Nevertheless, studying the possible alterations of the saccadic rate and of the positioning of fixations when analyzing a visual scene may illuminate on the source of reading difficulty in a variety of patients, like dyslexic children or those affected by hemianopia as well as central visual field impairment. Recently, new light has been shed on the saccadic/fixation dynamics, both in the temporal and spatial domain. In addition, according to recent findings a visuoperceptive distortion could potentially affect the saccades/fixation sequence, making the matter much more complex than expected. The aim of this article is therefore to describe the saccadic/fixation seesaw under the temporal and spatial perspective and to disclose the possible influence of visuoperceptive impairments

A Self-report Oriented Toward Visuoperceptive and Visuomotor Alterations for the Early Identification of Dyslexic Children

Background: Early diagnosis is the main requisite for rehabilitating children suspected to suffer from dyslexia, and self-reports may be as reliable as ordinary screenings, but far less expensive. Research shows that the visual function can be involved in the pathogenesis of dyslexia so that self-reports should inquire about visual signs as well. A questionnaire made of 21 items that provide scores based on the visual signs commonly reported by dyslexics and on the most relevant comorbidities according to the literature has been devised. The aim of this exploratory study is to evaluate its potential for the early identification of dyslexic children.&#x0D; Methods: The AAP-DD is a set of 21 items subdivided into 4 sections that inquire about visual signs (section S), fatty acid deficiency, inheritance of dyslexia, and related conditions in children and parents. Each item is assigned a specific visuomotor and visuosensory weight in the form of a coefficient. The parents of twenty-three dyslexic children (9.34±0.80 years) and twenty-four normal readers filled the questionnaire. To assess the correspondence between the outcome of the questionnaire and the actual visual function of each participant, spatial relationship perception and ocular movements have been tested psychophysically.&#x0D; Results: The score of the dyslexic sample was almost double (i.e. worse) compared to the control group (P &lt;.0001). Sensitivity and specificity were, respectively, 87% and 62%. Section S was the most informative, accounting for up to 41% of the variance of the reading rate. Correlation between the DEM and the AAP-DD scores suggests the questionnaire reflects the actual visuomotor condition of the subject.&#x0D; Conclusion: The AAP-DD seems promising to screen children at risk for dyslexia, and is, therefore, worth to be further investigated in a larger population. The obtained results support the role of the visual function in the pathogenesis of this condition.</jats:p