Visual signs and symptoms of progressive supranuclear palsy

Progressive supranuclear palsy is a rare, degenerative brain disorder and the second most common syndrome in which the patient exhibits 'parkinsonism', that is, a variety of symptoms involving problems with movement. General symptoms include difficulties with gait and balance; the patient walking clumsily and often falling backwards. The syndrome can be difficult to diagnose and visual signs and symptoms can help to separate it from closely related movement disorders such as Parkinson's disease, multiple system atrophy, dementia with Lewy bodies and corticobasal degeneration. A combination of the presence of vertical supranuclear gaze palsy, fixation instability, lid retraction, blepharospasm and apraxia of eyelid opening and closing may be useful visual signs in the identification of progressive supranuclear palsy. As primary eye-care practitioners, optometrists should be able to identify the visual problems of patients with this disorder and be expected to work with patients and their carers to manage their visual welfare.

Early visual detection of oriented line targets: spatial characteristics,and reference frames of early visual orientation-processing

The orientations of lines and edges are important in defining the structure of the visual environment, and observers can detect differences in line orientation within the first few hundred milliseconds of scene viewing. The present work is a psychophysical investigation of the mechanisms of early visual orientation-processing. In experiments with briefly presented displays of line elements, observers indicated whether all the elements were uniformly oriented or whether a uniquely oriented target was present among uniformly oriented nontargets. The minimum difference between nontarget and target orientations that was required for effective target-detection (the orientation increment threshold) varied little with the number of elements and their spatial density, but the percentage of correct responses in detection of a large orientation-difference increased with increasing element density. The differing variations with element density of thresholds and percent-correct scores may indicate the operation of more than one mechanism in early visual orientation-processIng. Reducing element length caused threshold to increase with increasing number of elements, showing that the effectiveness of rapid, spatially parallel orientation-processing depends on element length. Orientational anisotropy in line-target detection has been reported previously: a coarse periodic variation and some finer variations in orientation increment threshold with nontarget orientation have been found. In the present work, the prominence of the coarse variation in relation to finer variations decreased with increasing effective viewing duration, as if the operation of coarse orientation-processing mechanisms precedes the operation of finer ones. Orientational anisotropy was prominent even when observers lay horizontally and viewed displays by looking upwards through a black cylinder that excluded all possible visual references for orientation. So, gravitational and visual cues are not essential to the definition of an orientational reference frame for early vision, and such a reference can be well defined by retinocentric neural coding, awareness of body-axis orientation, or both.

Adults with dyslexia exhibit large effects of crowding, increased dependence on cues, and detrimental effects of distractors in visual search tasks

Difficulties in visual attention are increasingly being linked to dyslexia. To date, the majority of studies have inferred functionality of attention from response times to stimuli presented for an indefinite duration. However, in paradigms that use reaction times to investigate the ability to orient attention, a delayed reaction time could also indicate difficulties in signal enhancement or noise exclusion once oriented. Thus, in order to investigate attention modulation and visual crowding effects in dyslexia, this study measured stimulus discrimination accuracy to rapidly presented displays. Adults with dyslexia (AwD) and controls discriminated the orientation of a target in an array of different numbers of - and differently spaced - vertically orientated distractors. Results showed that AwD: were disproportionately impacted by (i) close spacing and (ii) increased numbers of stimuli, (iii) did use pre-cues to modulate attention, but (iv) used cues less successfully to counter effects of increasing numbers of distractors. A greater dependence on pre-cues, larger effects of crowding and the impact of increased numbers of distractors all correlated significantly with measures of literacy. These findings extend previous studies of visual crowding of letters in dyslexia to non-complex stimuli. Overall, AwD do not use cues less, but they do use cues less successfully. We conclude that visual attention is an important factor to consider in the aetiology of dyslexia. The results challenge existing theoretical accounts of visual attention deficits, which alone are unable to comprehensively explain the pattern of findings demonstrated here.

The visual cortex in Alzheimer disease:laminar distribution of the pathological changes in visual areas V1 and V2

Alzheimer’s disease (AD) is an important neurodegenerative disorder causing visual problems in the elderly population. The pathology of AD includes the deposition in the brain of abnormal aggregates of ?-amyloid (A?) in the form of senile plaques (SP) and abnormally phosphorylated tau in the form of neurofibrillary tangles (NFT). A variety of visual problems have been reported in patients with AD including loss of visual acuity (VA), colour vision and visual fields; changes in pupillary responses to mydriatics, defects in fixation and in smooth and saccadic eye movements; changes in contrast sensitivity and in visual evoked potentials (VEP); and disturbances in complex visual tasks such as reading, visuospatial function, and in the naming and identification of objects. In addition, pathological changes have been observed to affect the eye, visual pathway, and visual cortex in AD. To better understand degeneration of the visual cortex in AD, the laminar distribution of the SP and NFT was studied in visual areas V1 and V2 in 18 cases of AD which varied in disease onset and duration. In area V1, the mean density of SP and NFT reached a maximum in lamina III and in laminae II and III respectively. In V2, mean SP density was maximal in laminae III and IV and NFT density in laminae II and III. The densities of SP in laminae I of V1 and NFT in lamina IV of V2 were negatively correlated with patient age. No significant correlations were observed in any cortical lamina between the density of NFT and disease onset or duration. However, in area V2, the densities of SP in lamina II and lamina V were negatively correlated with disease duration and disease onset respectively. In addition, there were several positive correlations between the densities of SP and NFT in V1 with those in area V2. The data suggest: (1) NFT pathology is greater in area V2 than V1, (2) laminae II/III of V1 and V2 are most affected by the pathology, (3) the formation of SP and NFT in V1 and V2 are interconnected, and (4) the pathology may spread between visual areas via the feed-forward short cortico-cortical connections.

Visual signs and symptoms of dementia with Lewy bodies

Dementia with Lewy bodies ('Lewy body dementia' or 'diffuse Lewy body disease') (DLB) is the second most common form of dementia to affect elderly people, after Alzheimer's disease. A combination of the clinical symptoms of Alzheimer's disease and Parkinson's disease is present in DLB and the disorder is classified as a 'parkinsonian syndrome', a group of diseases which also includes Parkinson's disease, progressive supranuclear palsy, corticobasal degeneration and multiple system atrophy. Characteristics of DLB are fluctuating cognitive ability with pronounced variations in attention and alertness, recurrent visual hallucinations and spontaneous motor features, including akinesia, rigidity and tremor. In addition, DLB patients may exhibit visual signs and symptoms, including defects in eye movement, pupillary function and complex visual functions. Visual symptoms may aid the differential diagnoses of parkinsonian syndromes. Hence, the presence of visual hallucinations supports a diagnosis of Parkinson's disease or DLB rather than progressive supranuclear palsy. DLB and Parkinson's disease may exhibit similar impairments on a variety of saccadic and visual perception tasks (visual discrimination, space-motion and object-form recognition). Nevertheless, deficits in orientation, trail-making and reading the names of colours are often significantly greater in DLB than in Parkinson's disease. As primary eye-care practitioners, optometrists should be able to work with patients with DLB and their carers to manage their visual welfare.

Visual data mining using principled projection algorithms and information visualization techniques

We introduce a flexible visual data mining framework which combines advanced projection algorithms from the machine learning domain and visual techniques developed in the information visualization domain. The advantage of such an interface is that the user is directly involved in the data mining process. We integrate principled projection algorithms, such as generative topographic mapping (GTM) and hierarchical GTM (HGTM), with powerful visual techniques, such as magnification factors, directional curvatures, parallel coordinates and billboarding, to provide a visual data mining framework. Results on a real-life chemoinformatics dataset using GTM are promising and have been analytically compared with the results from the traditional projection methods. It is also shown that the HGTM algorithm provides additional value for large datasets. The computational complexity of these algorithms is discussed to demonstrate their suitability for the visual data mining framework. Copyright 2006 ACM.

Anterior segment anomalies and effects on visual quality

The tear film, cornea and lens dictate the refractive power of the eye and the retinal image quality is principally defined by diffraction, whole eye wavefront error, scatter, and chromatic aberration. Diffraction and wave aberration are fundamentally pupil diameter dependent; however scatter can be induced by refractive surgery and in the normal ageing eye becomes an increasingly important factor defining retinal image quality. The component of visual quality most affected by the tear film, refractive surgery and multifocal contact and intraocular lenses is the wave aberration of the eye. This body of work demonstrates the effects of each of these anomalies on the visual quality of the eye. When assessing normal or borderline self-diagnosed dry eye subjects using aberrometry, combining lubricating eye drops and spray does not offer any benefit over individual products. However, subjects perceive a difference in comfort for all interventions after one hour. Total higher order aberrations increase after laser assisted sub-epithelial keratectomy performed using a solid-state laser on myopes, but this causes no significant decrease in contrast sensitivity or increase in glare disability. Mean sensitivity and reliability indices for perimetry were comparable to pre-surgery results. Multifocal contact lenses and intraocular lenses are designed to maximise vision when the patient is binocular, so any evaluation of the eyes individually is confounded by reduced individual visual acuity and visual quality. Different designs of aspheric multifocal contact lenses do not provide the same level of visual quality. Multifocal contact lenses adversely affect mean deviation values for perimetry and this should be considered when screening individuals with multifocal contact or intraocular lenses. Photographic image quality obtained through a multifocal contact or intraocular lens appears to be unchanged. Future work should evaluate the effect of these anomalies in combination; with the aim of providing the best visual quality possible and supplying normative data for screening purposes.

Severe visual impairment due to diabetes mellitus:can this be influenced by community & hospital retinal screening and formal hospital diabetic annual review?

Purpose: Diabetes is a leading cause of visual impairment in working age population in the UK. This study looked at the causes of Severe Visual Impairment(SVI) in the patients attending diabetic eye clinic and influence on the rate of SVI, over a 12 year period, after introducing retinal screening programmes in the hospital and the community in 1993 (review in 1992, 1998 & 2004). Methods: Medical records of all the patients attending the diabetic eye clinic over a period of 5months(April to August) in 1992, 1998 and 2004 were reviewed. The data collected for each patient included age, sex, ethnic origin, diabetes (type,duration &treatment), the best corrected visual acuity (present and at time of presentation), type and duration of retinopathy and attendance record to both diabetic clinic and diabetic eye clinic. In this study, SVI is defined as a visual acuity of 6/36 or worse in at least one eye. Results: In 1992, of a total 245 patients, 58patients(23.6%) had SVI {38 (15.5% of total) due to diabetic retinopathy [31(12.6%) maculopathy, 2(0.8%) vitreous haemorrhage and 5(2%) retinal detachment] and 20(8.1%) due to non–diabetic retinopathy causes}. In 1998, of a total 297, 77patients(25.9%) had SVI {33(11.1% of total) due to diabetic retinopathy [19(6.4%) maculopathy, 9(3%) proliferative retinopathy, 8(2.7%) vitreous haemorrhage and 3(1%) retinal detachment]and 44(14.8%)due to non–diabetic retinopathy}. In 2004, of a total 471, 72patients(15.2%) had SVI{46(9.7%of total) due to diabetic retinopathy [37(7.8%) maculopathy, 1(0.2%) proliferative retinopathy, 6(1.8%) vitreous haemorrhage and 2(0.4%) retinal detachment]and 26(5.5%) due to non– diabetic retinopathy causes}. Conclusions: Introduction of formalised annual diabetic review including retinal screening and a community retinal screening programme has reduced the rate of severe visual impairment due to diabetic retinopathy, in patients attending diabetic eye clinic, from 15.5% in1992 to 9.7% in2004. Keywords: diabetic retinopathy

Bilateral visual outcomes and service utilization of patients treated for 3 years with ranibizumab for neovascular age-related macular degeneration

Background: The aim of this study was to describe bilateral visual outcomes and the effect of incomplete follow-up after 3 years of ranibizumab therapy for neovascular age-related macular degeneration. Secondarily, the demands on service provision over a 3-year period were described. Methods: Data on visual acuity, hospital visits, and injections were collected over 36 months on consecutive patients commencing treatment over a 9-month period. Visual outcome was determined for 1) all patients, using last observation carried forward for missed visits due to early discontinuation and 2) only those patients completing full 36-month follow-up. Results: Over 3 years, 120 patients cumulatively attended hospital for 1,823 noninjection visits and 1,365 injection visits. A visual acuity loss of <15 letters (L) was experienced by 78.2% of patients. For all patients (n=120), there was a mean loss of 1.68 L using last observation carried forward for missing values. Excluding five patients who died and 30 who discontinued follow-up, mean gain was 1.47 L. In bilateral cases, final acuity was on average 9 L better in second eyes compared to first eyes. Also, 91% of better-seeing eyes continued to be the better-seeing eye. Conclusion: We have demonstrated our approach to describing the long-term service provision and visual outcomes of ranibizumab therapy for neovascular age-related macular degeneration in a consecutive cohort of patients. Although there was a heavy burden with very frequent injections and clinic visits, patients can expect a good level of visual stability and a very high chance of maintaining their better-seeing eye for up to 3 years. © 2014 Chavan et al. This work is published by Dove Medical Press Limited.

Conceptual Idea of Identification of Patterns and Problem Solving in the Human’s Memory and the Possibilities to Use it in Artificial Intelligent

Given cybernetic idea is formed on the basis of neurophysiologic, neuropsychological, neurocybernetic data and verisimilar hypotheses, which fill gaps of formers, of the author as well. First of all attention is focused on general principles of a Memory organization in the brain and processes which take part in it that realize such psychical functions as perception and identification of input information about patterns and a problem solving, which is specified by the input and output conditions, as well. Realization of the second function, essentially cogitative, is discussed in the aspects of figurative and lingual thinking on the levels of intuition and understanding. The reasons of advisability and principles of bionic approach to creation of appropriate tools of artificial intelligent are proposed.

Oculo-visual changes and clinical considerations affecting older patients with dementia

Purpose: Dementia is associated with various alterations of the eye and visual function. Over 60% of cases are attributable to Alzheimer's disease, a significant proportion of the remainder to vascular dementia or dementia with Lewy bodies, while frontotemporal dementia, and Parkinson's disease dementia are less common. This review describes the oculo-visual problems of these five dementias and the pathological changes which may explain these symptoms. It further discusses clinical considerations to help the clinician care for older patients affected by dementia. Recent findings: Visual problems in dementia include loss of visual acuity, defects in colour vision and visual masking tests, changes in pupillary response to mydriatics, defects in fixation and smooth and saccadic eye movements, changes in contrast sensitivity function and visual evoked potentials, and disturbance of complex visual functions such as in reading ability, visuospatial function, and the naming and identification of objects. Pathological changes have also been reported affecting the crystalline lens, retina, optic nerve, and visual cortex. Clinically, issues such as cataract surgery, correcting the refractive error, quality of life, falls, visual impairment and eye care for dementia have been addressed. Summary: Many visual changes occur across dementias, are controversial, often based on limited patient numbers, and no single feature can be regarded as diagnostic of any specific dementia. Nevertheless, visual hallucinations may be more characteristic of dementia with Lewy bodies and Parkinson's disease dementia than Alzheimer's disease or frontotemporal dementia. Differences in saccadic eye movement dysfunction may also help to distinguish Alzheimer's disease from frontotemporal dementia and Parkinson's disease dementia from dementia with Lewy bodies. Eye care professionals need to keep informed of the growing literature in vision/dementia, be attentive to signs and symptoms suggestive of cognitive impairment, and be able to adapt their practice and clinical interventions to best serve patients with dementia.

Evaluating techniques to improve visual performance with and assessment of premium intraocular lenses

Premium Intraocular Lenses (IOLs) such as toric IOLs, multifocal IOLs (MIOLs) and accommodating IOLs (AIOLs) can provide better refractive and visual outcomes compared to standard monofocal designs, leading to greater levels of post-operative spectacle independence. The principal theme of this thesis relates to the development of new assessment techniques that can help to improve future premium IOL design. IOLs designed to correct astigmatism form the focus of the first part of the thesis. A novel toric IOL design was devised to decrease the effect of toric rotation on patient visual acuity, but found to have neither a beneficial or detrimental impact on visual acuity retention. IOL tilt, like rotation, may curtail visual performance; however current IOL tilt measurement techniques require the use of specialist equipment not readily available in most ophthalmological clinics. Thus a new idea that applied Pythagoras’s theory to digital images of IOL optic symmetricality in order to calculate tilt was proposed, and shown to be both accurate and highly repeatable. A literature review revealed little information on the relationship between IOL tilt, decentration and rotation and so this was examined. A poor correlation between these factors was found, indicating they occur independently of each other. Next, presbyopia correcting IOLs were investigated. The light distribution of different MIOLs and an AIOL was assessed using perimetry, to establish whether this could be used to inform optimal IOL design. Anticipated differences in threshold sensitivity between IOLs were not however found, thus perimetry was concluded to be ineffective in mapping retinal projection of blur. The observed difference between subjective and objective measures of accommodation, arising from the influence of pseudoaccommodative factors, was explored next to establish how much additional objective power would be required to restore the eye’s focus with AIOLs. Blur tolerance was found to be the key contributor to the ocular depth of focus, with an approximate dioptric influence of 0.60D. Our understanding of MIOLs may be limited by the need for subjective defocus curves, which are lengthy and do not permit important additional measures to be undertaken. The use of aberrometry to provide faster objective defocus curves was examined. Although subjective and objective measures related well, the peaks of the MIOL defocus curve profile were not evident with objective prediction of acuity, indicating a need for further refinement of visual quality metrics based on ocular aberrations. The experiments detailed in the thesis evaluate methods to improve visual performance with toric IOLs. They also investigate new techniques to allow more rapid post-operative assessment of premium IOLs, which could allow greater insights to be obtained into several aspects of visual quality, in order to optimise future IOL design and ultimately enhance patient satisfaction.

The visual cortex in alzheimer's disease:laminar distribution of the pathological changes in visual areas V1 and V2

Alzheimer's disease (AD) is an important neurodegenerative disorder causing visual problems in the elderly population. The pathology of AD includes the deposition in the brain of abnormal aggregates of β-amyloid (Aβ) in the form of senile plaques (SP) and abnormally phosphorylated tau in the form of neurofibrillary tangles (NFT). A variety of visual problems have been reported in patients with AD including loss of visual acuity (VA), colour vision and visual fields; changes in pupillary responses to mydriatics, defects in fixation and in smooth and saccadic eye movements; changes in contrast sensitivity and in visual evoked potentials (VEP); and disturbances in complex visual tasks such as reading, visuospatial function, and in the naming and identification of objects. In addition, pathological changes have been observed to affect the eye, visual pathway, and visual cortex in AD. To better understand degeneration of the visual cortex in AD, the laminar distribution of the SP and NFT was studied in visual areas V1 and V2 in 18 cases of AD which varied in disease onset and duration. In area V1, the mean density of SP and NFT reached a maximum in lamina III and in laminae II and III respectively. In V2, mean SP density was maximal in laminae III and IV and NFT density in laminae II and III. The densities of SP in laminae I of V1 and NFT in lamina IV of V2 were negatively correlated with patient age. No significant correlations were observed in any cortical lamina between the density of NFT and disease onset or duration. However, in area V2, the densities of SP in lamina II and lamina V were negatively correlated with disease duration and disease onset respectively. In addition, there were several positive correlations between the densities of SP and NFT in V1 with those in area V2. The data suggest: (1) NFT pathology is greater in area V2 than V1, (2) laminae II/III of V1 and V2 are most affected by the pathology, (3) the formation of SP and NFT in V1 and V2 are interconnected, and (4) the pathology may spread between visual areas via the feed-forward short cortico-cortical connections. © 2012 by Nova Science Publishers, Inc. All rights reserved.

The role of exploration and critical decision making and problem solving in making life choices

Although the literature on the types of abilities and processes that contribute to identity formation has been growing, the research has been mainly descriptive/correlational. This dissertation conducted an experimental investigation of the role of two theoretically distinct processes (exploration and critical problem solving) in identity formation, one of the first to be reported. The experimental training design (pre-post, training versus control) used in this study was intended to promote identity development by fostering an increase in the use of exploration and critical problem solving with respect to making life choices. Participants included 53 psychology students from a large urban university randomly assigned to each group. The most theoretically significant finding was that the intervention was successful in inducing change in the ability to use critical skills in resolving life decisions, as well as effecting a positive change in identity status. ^

The role of exploration and critical decision making and problem solving in making life choices

Although the literature on the types of abilities and processes that contribute to identity formation has been growing, the research has been mainly descriptive/correlational. This dissertation conducted an experimental investigation of the role of two theoretically distinct processes (exploration and critical problem solving) in identity formation, one of the first to be reported. The experimental training design (pre-post, training versus control) used in this study was intended to promote identity development by fostering an increase in the use of exploration and critical problem solving with respect to making life choices. Participants included 53 psychology students from a large urban university randomly assigned to each group. The most theoretically significant finding was that the intervention was successful in inducing change in the ability to use critical skills in resolving life decisions, as well as effecting a positive change in identity status.