Abstract
PurposeDamage along the visual pathway results in a visual field defect (scotoma), which retinotopically corresponds to the damaged neural tissue. Other parts of the visual field, processed by the uninjured tissue, are considered to be intact. However, perceptual deficits have been observed in the “intact” visual field, but these functional impairments are poorly understood. We now studied temporal processing deficits in the intact visual field of patients with either pre- or post-chiasmatic lesions to better understand the functional consequences of partial blindness.MethodsPatients with pre- (n = 53) or post- chiasmatic lesions (n = 98) were tested with high resolution perimetry – a method used to map visual fields with supra-threshold light stimuli. Reaction time of detections in the intact visual field was then analyzed as an indicator of processing speed and correlated with features of the visual field defect.ResultsPatients from both groups exhibited processing speed deficits in their presumably “intact” field as indicated by comparison to a normative sample. Further, in both groups processing speed was found to be a function of two factors. Firstly, a spatially restricted (retinotopic) influence of the scotoma was seen in longer reaction times when stimuli were presented in intact field sectors close to the defect. Secondly, patients with larger scotomata had on average longer reaction times in their intact field indicating a more general (non-retinotopic) influence of the scotoma.ConclusionsProcessing speed deficits in the “intact” visual field of patients with visual system damage demonstrate that visual system lesions have more widespread consequences on perception than previously thought. Because dysfunctions of the seeing field are expected to contribute to subjective vision, including visual tests of the presumed “intact” field may help to better understand vision loss and to improve methods of vision restoration and rehabilitation.
Highlights
When structures along the cerebral visual pathway are damaged, vision is lost in sectors of the visual field that retinotopically correspond to the damaged tissue
A spatially restricted influence of the scotoma was seen in longer reaction times when stimuli were presented in intact field sectors close to the defect
Patients with larger scotomata had on average longer reaction times in their intact field indicating a more general influence of the scotoma
Summary
When structures along the cerebral visual pathway are damaged, vision is lost in sectors of the visual field that retinotopically correspond to the damaged tissue. Scotomata are the result of different diseases such as glaucoma, optic nerve damage, or hemianopia following posterior artery stroke. Such visual field loss is typically tested with perimetry assessing the detection accuracy of near-threshold or supra-threshold stimuli across the visual field [3]. Data collected in this manner are used to construct visual field charts (Fig. 1) showing defective (blind) regions which can be subdivided into areas of relative defect ( called ‘‘areas of residual vision’’, ARV, [4]), and areas of absolute blindness. As the remaining sectors of the visual field are considered fully intact, presumably without any visual dysfunction, it is believed that the scotoma is the only vision problem that patients encounter
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
