The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: A Randomized Controlled Trial

Abstract

IntroductionHomonymous visual field defects (HVFD) are a common consequence of postchiasmatic acquired brain injury and often lead to mobility-related difficulties. Different types of compensatory scanning training have been developed, aimed at decreasing consequences of the HVFD by changing visual scanning.AimThe aim of the present study is to examine the effects of a compensatory scanning training program using horizontal scanning on mobility-related activities and participation in daily life.MethodThe main interest of this study is to assess the effectiveness of training on mobility-related activities and participation in daily life. Visual scanning tests, such as dot counting and visual search, and control measures for visual functions and reading have been included as well. First, it is examined how performance on scanning and mobility-related measures is affected in patients with HVFD by comparing scores with scores of a healthy control group (n = 25). Second, the effect of training is assessed using an RCT design, in which performance of 26 patients before and after training is compared to performance of 23 patients in a waiting list control group.ResultsSelf-reported improvements after training were found, accompanied by improvements in detecting peripheral stimuli and avoiding obstacles during walking, especially in dual task situations in which a second task limits the attentional capacity available for compensatory scanning. Training only improved mobility-related activities in which detection of peripheral stimuli is important, while no improvement was found on tests that require other visual skills, such as reading, visual counting and visual search.ConclusionThis is the first RCT to evaluate the effects of a compensatory scanning training that is based on a systematic horizontal scanning rhythm. This training improved mobility-related activities. The results suggest that different types of compensatory scanning strategies are appropriate for different types of activities.Trial RegistrationISRCTN Registry ISRCTN16833414

Adaptation to poststroke visual field loss: A systematic review

“…A number of studies have specifically reported on subjective improvements in activities of daily living following compensatory therapy, such as improvements in mobility, reading, driving, and detection of obstacles (Bergsma et al., 2011; Ong et al., 2015; Keller & Lefin‐Rank, 2010; Aimola et al., 2014; Jacquin‐Courtois et al., 2013; Kerkhoff et al., 1994; Mazer et al., 2003; de Haan, Melis‐Dankers, Brouwer, Tucha, & Heutink, 2015; Hayes, Chen, Clarke, & Thompson, 2012; Nelles et al., 2001; Rowe, Conroy, et al., 2016). A study by de Haan et al.…”

“…A study by de Haan et al. (2015) examined the effect of compensatory scanning training on mobility‐related activities and found a link between visual scanning training and detection of peripheral stimuli and obstacle avoidance. This evidence provides further support for the role of compensatory treatment in the adaptation process.…”

Comments about outcome measures for clinical trials of interventions for post-stroke patients with hemianopia

“…There are neither theoretical reasons nor empirical evidence to support the idea that either visual search training or peripheral prisms would result in visual field recovery. In fact, prior studies have reported no effects of search training 8, 9, 11 or peripheral prisms 4 on visual field size (when measured without prisms). Indeed, the Rowe et al paper 1 even cited a recent Cochrane systematic review 15 of interventions for post-stroke field loss stating that the review “concluded that, generally, interventions for homonymous hemianopia do not result in improvement of visual field”.…”

“…3, 4, 6, 7 When not worn, the prisms are not expected to provide any help or effect. Visual search training is expected to increase visual exploration (scanning) toward the blind hemifield, 8–10 which may in turn improve detection of objects on the blind side. 8, 11 …”

“…Earlier studies have examined separately the effect of peripheral prisms, and the effect of visual search/explorative saccade/compensatory scanning training, in stable hemianopia. Some of those studies used performance-based measures of effectiveness relevant to activities of daily living, such as avoidance of obstacles in a mobility course, 8, 11 responses to potential hazards during on-road driving, 12 and responses to pedestrian hazards in a driving simulator. 13 All these measures were found to be responsive to the intervention.…”