Acquired brain injury" refers to brain damage that impacts neurological processing, making daily activities challenging and often causing vision issues like binocular dysfunction, oculomotor problems, and visual field loss. In Spain, visual rehabilitation is limited, although it is more common in other countries.

These patients generally need an interdisciplinary approach involving professionals like physiotherapists and optometrists and often face mobility, balance, and spatial perception difficulties. Treatment tools include lenses, prisms, and technologies like virtual reality (VR). The Visionary VR program, presented by Dr. Portela, has shown promising results in visual field recovery by stimulating the affected area.

Visual rehabilitation is based on brain plasticity and involves three key strategies:

Prisms to expand the visual field. Compensatory therapy to improve eye movement. Restitution therapy to restore the visual field.

Acquired brain injury is a term that covers all brain damage, and it is common for such an injury to have a profound effect on neurological processing. This can negatively impact how a person performs their daily activities. Many of these patients experience various vision problems alongside general health deterioration. A high percentage of individuals exhibit deficits in binocular fusion, oculomotor dysfunctions, and visual field loss (Ciuffreda, 2007). While visual rehabilitation for these patients is common in other countries, in Spain, these treatments within rehabilitation are usually only carried out occasionally.

Acquired brain injury can be due to various causes, including strokes, trauma, and tumours. It should be noted that due to the aging population, the number of strokes increases every year, and mortality from this cause is decreasing, leading to a growing number of patients with sequelae. Patients with brain injury may require rehabilitation treatment from various professionals, including physiotherapists, occupational therapists, speech therapists, and optometrists. Treatment in these cases should be interdisciplinary, considering the multiple disabling conditions these patients suffer from.

Since acquired brain injury can affect any area of the visual system, a rigorous evaluation of vision is necessary, paying attention to ocular health, visual function, motor function and binocular system, oculomotor skills, accommodative state, and the integrity of the visual field (Callahan, 2003).

In addition to visual field loss, patients with hemianopia may suffer from symptoms such as dizziness, vertigo, or nausea. There is also an increased risk of falls due to mobility issues, posture problems, gait variability, and balance, as well as difficulty navigating obstacles. Alterations in body schema and location can also occur, with this altered spatial perception impacting motor coordination, orientation, and object location (Kotecha, 2013).

Visual field loss can take different forms, including central loss, hemianopia, quadrantanopia, and altitudinal loss. Hemianopia refers to the loss of half the visual field, either right or left. Depending on the area of the visual pathway where the lesion occurs, bitemporal hemianopia, homonymous hemianopia, or superior/inferior quadrantanopia can develop. Quadrantanopia refers to the loss of a quadrant of the visual field. Visual field tests provide relevant information about the location of the brain lesion in these cases (Ruddy, 2022).

Furthermore, certain visual conditions are often overlooked, especially if they are mild, such as non-strabismic binocular vision dysfunctions, accommodative deficits, or ocular motility issues. If not considered, they can act as obstacles in the patient's rehabilitation, preventing them from performing various daily activities. Patients may sometimes suffer from diplopia, photophobia, or blurred vision, but in many cases, it is the difficulties they encounter in performing certain activities that indicate the presence of a visual problem. In patients with traumatic brain injury, it is estimated that 69% had at least one visual problem, mainly affecting accommodation, convergence, and ocular motility (Armstrong, 2018).

A stroke can cause some patients (20% to 57% of stroke patients) to lose the ability to see the entire space in front of them, often losing a whole half of the normal visual field. Ocular movement disorders can affect more than 70% of stroke patients, resulting in difficulties in maintaining both eyes in their normal position when looking straight ahead or in moving the eyes correctly to look in a different direction. This can affect the patient's depth perception, make it difficult to perceive the complete environment, and severely impact their reading ability.

These patients can benefit from visual treatment through compensatory lenses, compensatory prisms, visual field treatment, filters for photosensitivity, and visual rehabilitation aimed at improving the compromised visual skills. These treatments can be proposed in isolation or in combination during the patient's rehabilitation process (Armstrong, 2018; Thiagarajan, 2014; Thiagarajan, 2013; Gallaway, 2017).

Prisms are often used for fusional problems when the patient experiences diplopia or has difficulties performing convergence or divergence movements. They are also useful for visual field loss, projecting the image from the affected side of the visual field to the intact side. In this case, their goal is to expand or relocate the affected visual field, and they can be adapted binocularly or monocularly, either sectorially or across the entire lens.

Additionally, in the past year, Dr. Juan Portela, an optometrist, presented a novel treatment with a visual rehabilitation program using Virtual Reality at the II Neuro-Ophthalmology Conference in Valencia and the VII Low Vision Conference in October in Zaragoza. He achieved remarkable results in several patients with visual field loss using the Visionary virtual reality program (Visionary Sport, Gijón, Spain), increasing the visual field with stimuli appearing at the limit of the affected field area. This field restoration is reflected in visual field tests with fixation control in patients with hemianopia and altitudinal defects, which could have been caused by traumatic brain injury or stroke, even years before starting the Virtual Reality treatment. During the treatment, patient fixation was monitored using an eye tracker to control involuntary saccadic movements (Portela, 2023).

Previously, Casco et al. conducted a study using visual rehabilitation with Gabor patches in 10 patients with homonymous visual field defects for over six months, finding a significant improvement in the visual field, although it was approximately 5 degrees. The restored area improved letter recognition and the perception of moving shapes (Casco, 2018). Portela appears to have achieved better results in the cases he recently presented at several conferences.

Brain plasticity is the basis of visual rehabilitation, aiming to enhance the patient's visual skills and improve their quality of life as much as possible. The brain and its neural connections strengthen with the use of functions that depend on them. Visionary offers a set of exercises designed to rehabilitate deficits in visual tracking and binocular vision through perceptual learning. The Visionary software has been used in other studies related to visual rehabilitation in patients with amblyopia and limited stereopsis (Portela-Camino, 2018; Portela-Camino, 2021; Molina-Martín, 2020).

It is important to consider that there are three main strategies in the rehabilitation of patients with peripheral visual field loss, which can also be used in combination:

• Optical or substitution therapy using prisms. The goal is to expand the visual field by shifting part of the affected visual field to the healthy side of the field using the prism. Various strategies exist for this.
• Oculomotor or visual compensation therapy aims to enhance the patient's residual visual skills, improving the quality of ocular motility. This method helps the patient improve environmental scanning, first statically and then dynamically, with the ultimate goal of improving mobility. Visual-assisted therapy enhances outcomes for stroke patients with homonymous hemianopia alone or combined with oculomotor dysfunction. Visual therapy increased peripheral visual awareness. Additionally, patients felt safer in traffic and outdoor activities. Reading speed significantly increased, and the ability to keep a moving object in focus improved (Smaakjær, 2018).
• Visual field restitution therapy is based on cortical plasticity theories and the possibility of restoring the affected visual field (Casco, 2018).

The main objective of this project is to evaluate motor and balance improvement in patients with acquired brain injury and to analyse the improvement in the visual field following treatment with Virtual Reality.

Inclusion Criteria:

• Adult subjects diagnosed with acquired brain injury either from a stroke or trauma.
• Subjects without cognitive impairment.
• Subjects without pre-existing musculoskeletal disorders prior to the acquired brain injury.
• Subjects without hemineglect.
• Subjects with more than 6 months of progression since the brain injury.
• Subjects who have an electronic device such as a computer and internet access to perform the exercises at home.
• Subjects with altitudinal visual field loss, hemianopia, or quadrantanopia with the central field preserved and at least 0.5 visual acuity.

Exclusion Criteria:

• Not signing the informed consent.
• Previous severe mental pathology to eliminate possible confounding factors if their daily activities are already affected.
• Uncontrolled epilepsy.
• Subjects with glaucoma or retinal pathologies affecting the visual field.
• Subjects with previous ocular surgery (cataract or refractive surgery) with less than 6 months of progression.
• Subjects who are not stable in any associated clinical pathology or otherwise diagnosed.
• Subjects who have previously undergone visual rehabilitation for the field defect.
• Not performing the proposed home exercises.