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In clinical practice Cerebral Visual Impairment (CVI) is typically diagnosed by observation of abnormal visually guided behaviors which indicate higher visual function deficits (HVFDs) suggesting abnormal brain development or brain damage in a child with a suitable clinical history. HVFDs can occur even in the presence of good visual acuity and may remain undiagnosed because the good visual acuity does not prompt further investigation. This leads to a lack of understanding of the child’s visual perceptual difficulties. In a prospective study, we determined the spectrum of HVFDs in a group of children with history suggestive of brain damage or disruption of brain development and an independent diagnosis of CVI in comparison with typically developing children with a structured 51 question inventory, the Higher Visual Function Question Inventory (HVFQI-51) adapted from the Cerebral Vision Impairment Inventory, CVI-I. Here, we show that the HVFQI-51 can detect a range of HVFDs in children with CVI with good visual acuity and clearly distinguishes these children from typically developing children. HVFDs in our study group could mostly be attributed to dorsal stream visual processing dysfunction though the spectrum varied between children. We report on the inclusion of the “not applicable” response option in analysis providing a picture of HVFDs more in tune with the overall disability of each child. We also propose a subset of 11 questions (Top-11) which discriminate between children with CVI vs. behaviors seen in typical children: this provides both a potential screening tool for initial assessment of HVFDs and a measure of CVI-related impairment, and needs further validation in a secondary independent sample.

Purpose The PowerRef 3 is frequently used in studying the near triad of accommodation, vergence and pupil responses in normal and clinical populations. Within a range, the defocus measurement of the PowerRef 3 is linearly related to the eye's defocus. While the default factory‐calibrated slope of this relation (calibration factor) is 1, it has been shown that the slope can vary across individuals. Here, we addressed the impact of changes in viewing distance, age and defocus of the eye on the calibration factor. Methods We manipulated viewing distance (40 cm, 1 m and 6 m) and recruited participants with a range of accommodative capabilities: participants in their 20s, 40s and over 60 years old. To test whether any effect was larger than the range of measurement reliability of the instrument, we collected data for each condition four times: two in the same session, another on the same day, and one on a different day. Results The results demonstrated that viewing distance did not affect the calibration factor over the linear range, regardless of age or uncorrected refractive error. The largest proportion of the variance was explained by between‐subject differences. Conclusions Calibration data for the PowerRef 3 were not sensitive to changes in viewing distance. Nevertheless, our results re‐emphasise the relevance of calibration for studies of individual participants.

Cerebral Visual Impairment (CVI), vision loss due to brain injury in early childhood, is the leading cause --- approximately 40% --- of bilateral visual impairment in children from industrialized countries and is the most rapidly growing cause among children in developing countries. Typical causes of CVI include abnormal brain development or brain damage, often consequential to birth-related complications such as hypoxic ischemic encephalopathy, meningitis, hydrocephalus, and head injury. The current gold standard for clinical diagnosis require a trained clinician to administer visual-motor integration tests in conjunction with a thorough review of a patient's clinical history. This approach does not scale to meet the needs of undiagnosed children with CVI. Recently, non-invasive screening methods such as administering a higher visual function question inventory (HVFQI), have been shown to accurately capture the observations of teachers and guardians of children. Analysis of those observations has been shown to have very high correlation with visual-motor integration tests (p values The HVFQI web app is an online clinical diagnostic tool and database system designed to gather participant responses to over 50 questions and follow-up questions. No personally identifying information is stored in the database. The web app provides three critical functions: (1) scalable and accurate administration of the HVFQI; (2) global coordination of screening efforts; and (3) a consolidated database for efficacy analysis studies and rapid iteration of the HFVQI to maximize impact, accuracy, and accessibility. The HVFQI consists of a question inventory, a scoring rubric, and a conditional intervention strategy list. The question inventory is carefully curated and designed to capture observations from teachers and guardians that may indicate specific pediatric higher visual function deficits (HVFDs). In many instances HVFDs are accompanied by normal visual acuity, making diagnosis difficult, and requiring multiple questions to elicit HVFDs. These questions are presented at random to avoid leading the participant. The responses are scored according to the HVFQI scoring rubric, which indicates which HVFDs may be present, and relevant intervention strategies. The rubric responds to varying degrees of affirmative responses in a 5-category Likert scale, which includes 3 non-applicable responses with different causes. The rubric also responds to categorical responses for multiple-choice and multiple-answer questions. The web app prepares a report of relevant intervention strategies for the participant, along with the questions and responses as context. The web app is also designed to coordinate international clinical efforts. The web application administrators, led by a superadministrator, can create, manage, and remove centers and staff corresponding to physical (or virtual) locations as demand grows. Each center has a local administrator that can authorize staff to administer the HVFQI, interpret and discuss the results and relevant strategies with participants. The data is stored in a central secure database, accessible only to authorized researchers, and the site administrator. All data are anonymous and non-personally identifying. Authorized researchers can analyze the results for their local centers to estimate efficacy and submit suggestions to update the HVFQI to meet the needs of local participants. Researchers authorized by the super-administrator have full access to the entire database and can perform global analysis for rapid improvement. The HVFQI web app is the result of a collaboration between the SeeLab of the Smith-Kettlewell Eye Research Institute, and the Kulkarni Group of the Computer Science Department at San Francisco State University.

Attention is important for selecting targets for action. Several studies have shown that attentional selection precedes eye movements to a target, and results in an enhanced sensitivity at the saccade goal. Typically these studies have used isolated targets on blank backgrounds, which are rare in real-world situations. Here, we examine the spatial profile of sensitivity around a saccade target on a textured background and how the influence of the surrounding context develops over time. We used two textured backgrounds: a uniform texture, and a concentric arrangement of an inner and an outer texture with orthogonal orientations. For comparison, we also measured sensitivity around the target on a blank background. The spatial profile of sensitivity was measured with a brief, dim, probe flashed around the saccade target. When the target was on a blank or a uniformly textured background, spatial sensitivity peaked near the target location around 350 ms after cue onset and declined with distance from the target. However, when the background was made up of an inner and outer texture, sensitivity to the inner texture was uniformly high, peaking at about 350 ms after cue onset, suggesting that the entire inner texture was selected along with the target. The enhancement of sensitivity on the inner texture was much smaller when observers attended the target covertly and performed the probe-detection task. Thus, our results suggest that the surface representation around the target is taken into account when an observer actively plans to interact with the target.

Crowding increases with eccentricity and is most readily observed in the periphery. During natural, active vision, however, central vision plays an important role. Measures of critical distance to estimate crowding are difficult in central vision, as these distances are small. Any overlap of flankers with the target may create an overlay masking confound. The crowding factor method avoids this issue by simultaneously modulating target size and flanker distance and using a ratio to compare crowded to uncrowded conditions. This method was developed and applied in the periphery (Petrov & Meleshkevich, 2011b). In this work, we apply the method to characterize crowding in parafoveal vision (

We use eye movements constantly to gather information. Saccades are efficient when they maximize the information required for the task, however there is controversy regarding the efficiency of eye movement planning. For example, saccades are efficient when searching for a single target (Nature, 434 (2005) 387–391), but are inefficient when searching for an unknown number of targets in noise, particularly under time pressure (Vision Research 74 (2012), 61–71). In this study, we used a multiple-target search paradigm and explored whether altering the noise level or increasing saccadic latency improved efficiency. Experiments used stimuli with two levels of discriminability such that saccades to the less discriminable stimuli provided more information. When these two noise levels corresponded to low and moderate visibility, most observers did not preferentially select informative locations, but looked at uncertain and probable target locations equally often. We then examined whether eye movements could be made more efficient by increasing the discriminability of the two stimulus levels and by delaying the first saccade so that there was more time for decision processes to influence the saccade choices. Some observers did indeed increase the proportion of their saccades to informative locations under these conditions. Others, however, made as many saccades as they could during the limited time and were unselective about the saccade goal. A clear trend that emerges across all experiments is that conditions with a greater proportion of efficient saccades are associated with a longer latency to initiate saccades, suggesting that the choice of informative locations requires deliberate planning.