Management options offer promising solutions for patients with hemianopic field loss

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Hemianopic field loss is a significant impairment of vision defined as the loss of half of the visual field.¹ This condition causes difficulties in daily activities such as driving, navigating indoors or outdoors, and reading signs. These difficulties can affect the overall well-being of patients with this condition.¹ Whether you are a primary care optometrist or a low-vision optometrist, it is important to understand the management options that are available for patients. Every eye care provider is expected to be able to discuss various tools that can be helpful to any patient who is experiencing acute or chronic hemianopic field loss. When considering management options for patients with hemianopic field loss, a thorough case history and discussion are vital to first understand the cause of the visual impairment as well as determine which methods and interventions are best for the patient.

Options for optical devices

For those with hemianopic field loss, prism glasses and visual field expanders are useful optical devices. Prism glasses employ specifically engineered prismatic lenses to optically transfer pictures from the nonfunctioning side of the visual field to the functional side, effectively enlarging the perceived visual area. Prism glasses improve safety and mobility by strengthening peripheral awareness, which helps patients detect objects, obstacles, and stimuli they might otherwise miss.²

Visual field expanders can be attached to spectacles or used in isolation to increase the overall field of vision, not specifically targeting the blind spots. By extending the field of vision, these devices improve general spatial awareness and make up for visual field deficiencies. Visual field expanders help with tasks such as reading, navigating congested spaces, and interacting with others by providing a wider visual perspective.³

Prism glasses and visual field expanders are tailored to the specific needs of each patient and are prescribed after thorough low-vision evaluations. These tools are important because of their ability to reduce the effects of hemianopic field loss. The continuous progress in optical technology is always improving these aids, offering even better results in terms of efficacy and patient outcomes. A great example of the continuous progress in technology is assistive technology, which works to augment the patient’s field of vision digitally. Wearable devices and smartphone applications equipped with electronic vision improvement systems offer digitized assistance for tasks such as reading, navigation, and object recognition.⁴

Rehabilitation training

Saccadic training is a method of rehabilitation for patients with hemianopic field loss. The goal is to improve visual scanning skills to compensate for a lack of awareness on the side of the hemianopic field loss. Saccadic training aims to train patients to quickly and deliberately create eye movement toward the missed areas of their visual field. The goal is to increase the efficacy and precision of these quick eye movements, enabling patients to recognize visual stimuli they would otherwise miss.⁵

Patients with hemianopic field loss typically have multiple sessions with a trained professional, such as an occupational therapist or low-vision optometrist,² both of whom often collaborate in this process. The initial appointment is dedicated to evaluating the patient’s baseline visual scanning skills and pinpointing shortcomings associated with visual field loss. After conducting this evaluation, specific training objectives are set to address areas that need improvement.

Saccadic training uses a range of strategies and exercises to improve visual scanning abilities. These may encompass visual search, target detection, and functional complexity.⁵

During training for visual search, patients are given activities that demand locating specific targets by methodically scanning complex visual situations. This promotes the formation of effective scanning patterns and enhances the capacity to identify stimuli in the periphery. This bleeds into training for target detection, which involves visual stimuli being positioned strategically within the blind patient’s field of vision. Patients are given instructions on how to quickly look for stimuli in the blind spots using coordinated eye movement.⁵

Lastly, to put everything together, these new techniques are practiced in a more realistic environment. This involves combining saccadic training with cognitive tasks. Patients execute visual scanning while simultaneously engaging in other activities, such as walking while talking or running errands. The goal of combining saccadic training and cognitive tasks is to practice with realistic visual demands in practical situations.

The progress of saccadic training is assessed using objective measures such as timing target identification, increasing difficulty of target identification in size and contrast, and measuring decreased response time of saccadic movements with or without prompts. These objective measurements can determine whether the patient has improved total visual scanning efficiency.⁵ At each visit, the patient can also report whether they have noticed an increase in their ability to read or navigate through crowded spaces in between training appointments.

Although the patient is adjusting to and learning to manage their visual field loss optical devices and rehabilitation training, it is worthwhile to make environmental changes to help reduce obstacles that can be hazardous to the patient. Simple changes in the home can include optimizing lighting conditions, minimizing clutter, keeping furniture peripheral in a room, and using contrasting colors to mark changes in landmarks such as the stairs.

To better comprehend the effects of hemianopic field loss and discuss coping mechanisms, counseling sessions might be beneficial for patients and their families. Counseling educates patients on various assistive devices and environmental modifications to help them effectively manage their visual impairment.

Research on the more detailed causes of hemianopic field loss and the effectiveness of various management techniques is ongoing. Progress in brain and ocular imaging tools will hopefully offer valuable information for eye care providers to develop tailored management strategies. Furthermore, the advancement of smart devices and novel technologies will lead to improved autonomy and independence for patients with field loss.

Hemianopic field loss poses significant challenges for individuals, affecting their ability to read, navigate, and pursue education or careers. Recognizing the various factors that contribute to this condition and integrating a tailored plan of management options are essential. Because patients with severe visual field loss require many health care providers working together to best assist them, it is vital for optometrists to actualize their role of ensuring access to the necessary resources to achieve the best possible quality of life.

References:

1. Ruddy J, Asuncion RMD, Cardenas AC. Hemianopsia. In: StatPearls. StatPearls Publishing; 2024. September 12, 2024. https://www.ncbi.nlm.nih.gov/books/NBK562262/

2. Working with homonymous hemianopsia. Chadwick Optical. Accessed September 12, 2024. https://chadwickoptical.com/options-for-hemianopsia/

3. Drasdo N. Visual field expanders. Am J Optom Physiol Opt. 1976;53(9 pt 1):464-467. doi:10.1097/00006324-197609010-00005

4. Lewis V. A to Z of assistive technology for low vision. Perkins School for the Blind. February 2020. Updated May 2024. Accessed September 12, 2024. https://www.perkins.org/resource/z-assistive-technology-low-vision/

5. Murray NP, Hunfalvay M, Roberts CM, Tyagi A, Whittaker J, Noel C. Oculomotor training for poor saccades improves functional vision scores and neurobehavioral symptoms. Arch Rehabil Res Clin Transl. 2021;3(2):100126. doi:10.1016/j.arrct.2021.100126