Acquired visual field defects rehabilitation: Critical review and perspectives

Abstract

Visual field deficit (VFD) is one of the most commonly observed symptoms following brain injury. Persistent VFD and defective exploratory oculomotor scanning patterns often cause severe impairment in daily activities, particularly as regards visual exploration and reading. Homonymous hemianopia is consequently a powerful negative predictor of patient outcome. In spite of these quantitative and qualitative factors, there currently exists no consensus on rehabilitative therapy and treatment. Different approaches have nevertheless been developed, all of them having one therapeutic principle in common; repeated practice of a specific visual task, with the hope/expectation that improved performance will extend to a wide range of ecologically useful visual functions. The four main available methods aim at replacing part of the intact visual field with part of the damaged visual field (optical therapy using prisms), at partially restoring the lost visual field region (restorative therapies), at stimulating detection capacities in the blind field (stimulation or blindsight) or at substituting for the lost region by reorganizing the control of visual information processing and eye movements (compensatory therapies). This review explores the key data relative to these different approaches in terms of behavioral or imagery results. It also aims at critically analyzing the advantages and limits of each one. The importance of strict assessment in terms of deficiencies or disabilities is underlined. Finally, upon consideration of these data taken as a whole, it is suggested that efficient treatment would probably have to associate general components and more specific elements, according to what may be done with regard to other aspects of cognitive rehabilitation.

Functional Connectivity of the Precuneus Reflects Effectiveness of Visual Restitution Training in Chronic Hemianopia

“…VRT has been criticised due to inconsistent outcomes in previous research, ranging from significant improvements to minimal or no effects at all. A source of this inter-subject variation could be that the perimetric techniques are subjective and biased towards a positive outcome and that VRT outcomes are confounded by eye movements (Pouget et al, 2012;Reinhard et al, 2005). Indeed, the reliability of an extension of the visual field from perimetric data can be hampered by insufficient eye fixation control.…”

Probing Human Visual Deficits with Functional Magnetic Resonance Imaging

“…Various strategies have been adopted for visual system rehabilitation following injury. Chief among them (Das & Huxlin 2010, Pelak et al 2007, Pouget et al 2012, Schofield & Leff 2009 are (a) relocating the visual field via prismatic correction, (b) teaching compensatory strategies for oculomotor exploration of the blind field, and (c) improving residual detection capability and recovering lost visual function (improving visual perception). Recovery induced by compensatory strategies (a) and (b) is not discussed in this review, but instead the focus is on the recovery of visual perception.…”

Visualizing the blind brain: brain imaging of visual field defects from early recovery to rehabilitation techniques

“…In most cases reported, visual expansion did not exceed 5% (Kasten and Sabel, 1995; Kasten et al, 1998b) and was less pronounced in others studies (from 1° to 6.7°) (Pommerenke and Markowitsch, 1989; Kerkhoff et al, 1992, 1994) or even absent (Balliet et al, 1985). Some authors suggested that visual field improvements could be an artefact of eye movements (Horton, 2005a; Reinhard et al, 2005) and that controversial results could be related to (1) the perimeter techniques employed; (2) lesion localization; or (3) explanatory mechanisms (Pouget et al, 2012). …”