AUGMENTING REALITY FOR VISUAL FIELD LOSS: INTEGRATING OVERLAID INFORMATION TO INCREASE THE FIELD OF VIEW

The evolutionary survival of the human race has depended heavily on vision. It is the sense that is most employed for daily tasks including identifying and interacting with things, navigating through a busy environment, finding food, and avoiding predators (Tong, 2018). It is easy to take vision and the capacity to comprehend the visual world for granted since they seem so natural. The visual field is the full space in which visual inputs are viewed; its defect occurs when a person loses the capacity to perceive visual stimuli that are presented in some portion of the visual field. Visual field loss is a defect that makes an individual lose an area of vision in the visual field. According to Rowe (2013), it is a common outcome of stroke that affects the optic nerve fibers, resulting in hemianopia or quadrantanopia depending on the location of the lesion and the severity of the damage to the optic nerve. Pollock et al. (2011) report the prevalence of visual field loss among stroke patients to affect 20% to 57% of such patients.

The visual system is frequently depicted as a hierarchical feedforward network of interconnected, functionally specialised regions. The physiological processing of visual sensory information begins with an electrochemical chain response to light at the retina of the eye, where light information is converted into brain signals. These impulses go sequentially through a series of specialized, hierarchically organised brain regions that transmit information on motion, color, shape, and depth (Mahalakshmi & Vasudevan, 2015). Normally, sensory processing from the retina moves on to the LGN in the thalamus, which serves as the relay system for visual information. The sensory data is separated for processing by more specialised sections of the LGN. The main visual area, Area V1, has a number of specialised sub-layers, while higher cortical areas V3, V4, and V5 have bigger neurons that are less specialised to specific features and “pool” or average sensory data across a variety of low-level receptive fields.

Vision loss is one of the most frequent and devastating outcomes of stroke, second only to arm or leg paralysis. In the United Kingdom, it is reported that a stroke strikes every five minutes. It is also estimated that 100,000 people in the UK suffer from stroke each year, with an estimated 1.3 million stroke survivors (Stroke Association, 2022). It is also reported that 60% of stroke survivors have visual impairment immediately after their stroke, which results in anomalies in peripheral and/or central vision, eye movements, and a variety of visual perception issues like inattention, agnosia, and a more complicated issue that may involve both ocular and cortical damage (Rowe et al., 2009). Hemianopia, which is the most prevalent kind of visual field loss, is characterised by the loss of a part or the same half of the visual field in both eyes (Rowe, 2007). There has been reporting of a 50% possibility of spontaneous recovery from hemianopia within the first 30 days of stroke, which declines to about 20% between 1 and 6 months with no chance of recovery after that (Kerkhoff, 2000). Recovery tends to happen mostly in the visual periphery (Olson & Weiskrantz, 2006). Though less than 5% of the population has been anticipated to fully recover, this is a relatively small number. Consequently, Kerkhoff (1999) reports that 70% of patients with visual field loss still retain a little portion of centre vision (macular sparing) that can be managed.

There are four key activities that visual functions are important for: binocular vision and depth perception, patient movement, reading, and subsequent language processing. In our visually and PC-dominated world, vision is one of the primary input routes to memory and one of the most important media at work.As a result, deficiencies in one or more of the visual abilities required for these reasons will have a negative impact on patients’ functional capacity and quality of life through loss of confidence, decreased mobility, an inability to gauge distances, and an increased risk of falling (Gall et al. 2010).People with visual field defects generally lose the capacity to see the full space in front of them (Alex et al., 2011), especially in busy or unfamiliar locations where the chances of slipping and falling into items are high (Ramrattan, 2001). The capacity to find a target object amid distracting objects has been tested using visual search tasks. Patients sometimes take longer than healthy people to accomplish these tasks (Zihl, 1995). difficulties with other visual activities, including identification and sorting (Zihl, 1995). In addition, “hemianopia dyslexia” is a phrase used to describe a specific pattern of reading difficulties that affects 48% of hemianopia patients. It is caused by a reduction in the parafoveal field area, which narrows the perceptual window for reading. The perceptual window spans around 13 letters to the right of fixation and 6 letters to the left of fixation. As a consequence, right hemianopia makes it difficult to recognise whole words, whereas left hemianopia causes missing initial letters and sentence beginnings, causing delayed reading for both conditions (Rowe et al., 2011). It is frequently mentioned as the most significant behavioural challenge (Kasten et al., 1999).