Visual function and dysfunction in early and late age-related maculopathy

Late age-related maculopathy (ARM) is responsible for the majority of blind registrations in the Western world among persons over 50 years of age. It has devastating effects on quality of life and independence and is becoming a major public health concern. Current treatment options are limited and most aim to slow progression rather than restore vision; therefore, early detection to identify those patients most suitable for these interventions is essential. In this work, we review the literature encompassing the investigation of visual function in ARM in order to highlight those visual function parameters which are affected very early in the disease process. We pay particular attention to measures of acuity, contrast sensitivity (CS), cone function, electrophysiology, visual adaptation, central visual field sensitivity and metamorphopsia. We also consider the impact of bilateral late ARM on visual function as well as the relationship between measures of vision function and self-reported visual functioning. Much interest has centred on the identification of functional changes which may predict progression to neovascular disease; therefore, we outline the longitudinal studies, which to date have reported dark-adaptation time, short-wavelength cone sensitivity, colour-match area effect, dark-adapted foveal sensitivity, foveal flicker sensitivity, slow recovery from glare and slower foveal electroretinogram implicit time as functional risk factors for the development of neovascular disease. Despite progress in this area, we emphasise the need for longitudinal studies designed in light of developments in disease classification and retinal imaging, which would ensure the correct classification of cases and controls, and provide increased understanding of the natural course and progression of the disease and further elucidate the structure-function relationships in this devastating disorder.

Robust Audio-Visual Speech Recognition under Noisy Audio-Video Conditions

This paper presents the maximum weighted stream posterior (MWSP) model as a robust and efficient stream integration method for audio-visual speech recognition in environments, where the audio or video streams may be subjected to unknown and time-varying corruption. A significant advantage of MWSP is that it does not require any specific measurements of the signal in either stream to calculate appropriate stream weights during recognition, and as such it is modality-independent. This also means that MWSP complements and can be used alongside many of the other approaches that have been proposed in the literature for this problem. For evaluation we used the large XM2VTS database for speaker-independent audio-visual speech recognition. The extensive tests include both clean and corrupted utterances with corruption added in either/both the video and audio streams using a variety of types (e.g., MPEG-4 video compression) and levels of noise. The experiments show that this approach gives excellent performance in comparison to another well-known dynamic stream weighting approach and also compared to any fixed-weighted integration approach in both clean conditions or when noise is added to either stream. Furthermore, our experiments show that the MWSP approach dynamically selects suitable integration weights on a frame-by-frame basis according to the level of noise in the streams and also according to the naturally fluctuating relative reliability of the modalities even in clean conditions. The MWSP approach is shown to maintain robust recognition performance in all tested conditions, while requiring no prior knowledge about the type or level of noise.

A systematic literature review of surgical interventions for limbal stem cell deficiency in humans

PURPOSE: To evaluate the relative benefits and to identify any adverse effects of surgical interventions for limbal stem cell deficiency (LSCD).

DESIGN: Systematic literature review.

METHODS: We searched the following electronic databases from January 1, 1989 through September 30, 2006: MEDLINE, EMBASE, Science citation index, BIOSIS, and the Cochrane Library. In addition, reference lists were scanned to identify any additional reports. The quality of published reports was assessed using standard methods. The main outcome measure was improvement in vision of at least two Snellen lines of best-corrected visual acuity (BCVA). Data on adverse outcomes also were collected.

RESULTS: Twenty-six studies met the inclusion criteria. There were no randomized controlled studies. All 26 studies were either prospective or retrospective case series. For bilateral severe LSCD, keratolimbal allograft was the most common intervention with systemic immunosuppression. Other interventions included eccentric penetrating keratolimbal allografts and cultivated autologous oral mucosal epithelial grafts. An improvement in BCVA of two lines or more was reported in 31% to 67% of eyes. For unilateral severe LSCD, the most common surgical intervention was contralateral conjunctival limbal autograft, with 35% to 88% of eyes gaining an improvement in BCVA of two lines or more. The only study evaluating partial LSCD showed an improvement in BCVA of two lines or more in 39% of eyes.

CONCLUSIONS: Studies to date have not provided strong evidence to guide clinical practice on which surgery is most beneficial to treat various types of LSCD. Standardized data collection in a multicenter LSCD register is suggested.

Sample size in studies on diagnostic accuracy in ophthalmology:A literature survey

Aim: To assess the sample sizes used in studies on diagnostic accuracy in ophthalmology. Design and sources: A survey literature published in 2005. Methods: The frequency of reporting calculations of sample sizes and the samples' sizes were extracted from the published literature. A manual search of five leading clinical journals in ophthalmology with the highest impact (Investigative Ophthalmology and Visual Science, Ophthalmology, Archives of Ophthalmology, American Journal of Ophthalmology and British Journal of Ophthalmology) was conducted by two independent investigators. Results: A total of 1698 articles were identified, of which 40 studies were on diagnostic accuracy. One study reported that sample size was calculated before initiating the study. Another study reported consideration of sample size without calculation. The mean (SD) sample size of all diagnostic studies was 172.6 (218.9). The median prevalence of the target condition was 50.5%. Conclusion: Only a few studies consider sample size in their methods. Inadequate sample sizes in diagnostic accuracy studies may result in misleading estimates of test accuracy. An improvement over the current standards on the design and reporting of diagnostic studies is warranted.

The role of semantic interference in limiting memory for the details of visual scenes

Many studies suggest a large capacity memory for briefly presented pictures of whole scenes. At the same time, visual working memory (WM) of scene elements is limited to only a few items. We examined the role of retroactive interference in limiting memory for visual details. Participants viewed a scene for 5?s and then, after a short delay containing either a blank screen or 10 distracter scenes, answered questions about the location, color, and identity of objects in the scene. We found that the influence of the distracters depended on whether they were from a similar semantic domain, such as "kitchen" or "airport." Increasing the number of similar scenes reduced, and eventually eliminated, memory for scene details. Although scene memory was firmly established over the initial study period, this memory was fragile and susceptible to interference. This may help to explain the discrepancy in the literature between studies showing limited visual WM and those showing a large capacity memory for scenes.

Uniformity of visual acuity measures in published studies

PURPOSE. To investigate the methods used in contemporary ophthalmic literature to designate visual acuity (VA). METHODS. Papers in all 2005 editions of five ophthalmic journals were considered. Papers were included if (1) VA, vision, or visual function was mentioned in the abstract and (2) if the study involved age-related macular degeneration, cataract, or refractive surgery. If a paper was selected on the basis of its abstract, the full text of the paper was examined for information on the method of refractive correction during VA testing, type of chart used to measure VA, specifics concerning chart features, testing protocols, and data analysis and means of expressing VA in results. RESULTS. One hundred twenty-eight papers were included. The most common type of charts used were described as logMAR-based. Although most (89.8%) of the studies reported on the method of refractive correction during VA testing, only 58.6% gave the chart design, and less than 12% gave any information whatsoever on chart features or measurement procedures used. CONCLUSIONS. The methods used and the approach to analysis were rarely described in sufficient detail to allow others to replicate the study being reported. Sufficient detail should be given on VA measurement to enable others to duplicate the research. The authors suggest that charts adhering to Bailey-Lovie design principles always be used to measure vision in prospective studies and their use encouraged in clinical settings. The distinction between the terms logMAR, an acuity notation, and Bailey-Lovie or ETDRS as chart types should be adhered to more strictly. Copyright © Association for Research in Vision and Ophthalmology.

Mixed Messages: American Correspondences in Visual and Verbal Practices

Mixed Messages presents and interrogates ten distinct moments from the arts of nineteenth, twentieth and twenty-first century America where visual and verbal forms blend and clash. Charting correspondences concerned with the expression and meaning of human experience, this volume moves beyond standard interdisciplinary theoretical approaches to consider the written and visual artwork in embodied, cognitive, and contextual terms.

Offering a genuinely interdisciplinary contribution to the intersecting fields of art history, avant-garde studies, word-image relations, and literary studies, Mixed Messages takes in architecture, notebooks, poetry, painting, conceptual art, contemporary art, comic books, photographs and installations, ending with a speculative conclusion on the role of the body in the experience of digital mixed media. Each of the ten case studies explores the juxtaposition of visual and verbal forms in a manner that moves away from treating verbal and visual symbols as operating in binary or oppositional systems, and towards a consideration of mixed media, multi-media and intermedia work as brought together in acts of creation, exhibition, reading, viewing, and immersion. The collection advances research into embodiment theory, affect, pragmatist aesthetics, as well as into the continuing legacy of romanticism and of dada, conceptual art and surrealism in an American context.

A Systematic Review of End-of-Life Visual Impairment in Open-Angle Glaucoma: An Epidemiological Autopsy

PURPOSE: Glaucoma patients are still at risk of becoming blind. It is of clinical significance to determine the risk of blindness and its causes to prevent its occurrence. This systematic review estimates the number of treated glaucoma patients with end-of-life visual impairment (VI) and blindness and the factors that are associated with this.

METHODS: A systematic literature search in relevant databases was conducted in August 2014 on end-of-life VI. A total of 2574 articles were identified, of which 5 on end-of-life VI. Several data items were extracted from the reports and presented in tables.

RESULTS: All studies had a retrospective design. A considerable number of glaucoma patients were found to be blind at the end of their life; with up to 24% unilateral and 10% bilateral blindness. The following factors were associated with blindness: (1) baseline severity of visual field loss: advanced stage of glaucoma or substantial visual field loss at the initial visit; (2) factors influencing progression: fluctuation of intraocular pressure (IOP) during treatment, presence of pseudoexfoliation, poor patient compliance, higher IOP; (3) longer time period: longer duration of disease and older age at death because of a longer life expectancy; and (4) coexistence of other ocular pathology.

CONCLUSIONS: Further prevention of blindness in glaucoma patients is needed. To reach this goal, it is important to address the risk factors for blindness identified in this review, especially those that can be modified, such as advanced disease at diagnosis, high and fluctuating IOP, and poor compliance.