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.