Abstract
Visual search is a task often used in the rehabilitation of patients with cortical and non-cortical visual pathologies such as visual field loss. Reduced visual acuity is often comorbid with these disorders, and it remains poorly defined how low visual acuity may affect a patient’s ability to recover visual function through visual search training. The two experiments reported here investigated whether induced blurring of vision (from 6/15 to 6/60) in a neurotypical population differentially affected various types of feature search tasks, whether there is a minimal acceptable level of visual acuity required for normal search performance, and whether these factors affected the degree to which participants could improve with training. From the results, it can be seen that reducing visual acuity did reduce search speed, but only for tasks where the target was defined by shape or size (not colour), and only when acuity was worse than 6/15. Furthermore, searching behaviour was seen to improve with training in all three feature search tasks, irrespective of the degree of blurring that was induced. The improvement also generalised to a non-trained search task, indicating that an enhanced search strategy had been developed. These findings have important implications for the use of visual search as a rehabilitation aid for partial visual loss, indicating that individuals with even severe comorbid blurring should still be able to benefit from such training.
Highlights
The visual field is the area that can be seen when the eyes are fixating, and a visual field defect is any area of blindness within this that can result from damage to any part of the primary visual pathway
The area of blindness is restricted to one-half of the visual field in homonymous visual field defects, which are the consequence of damage to most typically primary visual cortex, followed by optic radiations, the optic tract, and lateral geniculate nucleus (Papageorgiou & Tsironi-Malizou, 2017)
Search tasks have been proposed as a behavioural treatment for various visual field conditions including homonymous visual field defects (e.g., Lane et al, 2010), and age-related macular degeneration, glaucoma, and retinitis pigmentosa, for example (Kuyk et al, 2010; Liu et al, 2007)
Summary
The visual field is the area that can be seen when the eyes are fixating, and a visual field defect is any area of blindness within this that can result from damage to any part of the primary visual pathway. Regardless of cause, visual field defects can result in significant disability and increase the chance of falling (Ramrattan et al, 2001) and collisions (Fuhr et al, 2007; McGwin et al, 2016; Papageorgiou et al, 2012) This is because the restricted field of view hinders many everyday tasks that require efficient searching, including safe navigation, and finding items such as when shopping. Search tasks have been proposed as a behavioural treatment for various visual field conditions including homonymous visual field defects (e.g., Lane et al, 2010), and age-related macular degeneration, glaucoma, and retinitis pigmentosa, for example (Kuyk et al, 2010; Liu et al, 2007) The aim with such training is to use visual search to encourage patients to develop more efficient searching eye-movement strategies, which are known to be deficient
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