Left Hemianopia: Diagnosis and Rehabilitation
Left hemianopia is most commonly caused by damage to the right posterior cerebral pathway and requires compensatory scanning training as the primary rehabilitation approach to improve quality of life and functional outcomes.
Diagnosis and Etiology
Left homonymous hemianopia is characterized by vision loss in the left half of the visual field in both eyes, resulting from damage to the right-sided visual pathway posterior to the optic chiasm.
Common Causes:
- Stroke: Most common cause in adults 1
- Traumatic brain injury
- Brain tumors
- Multiple sclerosis
- Neurosurgical procedures
Diagnostic Evaluation:
- Visual field testing to confirm the pattern and extent of field loss
- Neuroimaging (CT/MRI) to identify the underlying lesion
- Assessment for associated neurological deficits that may indicate the location of the lesion 2
Clinical Presentation:
- Difficulty seeing objects in the left visual field
- Bumping into objects on the left side
- Problems with reading, particularly difficulty finding the beginning of the next line of text 3
- Patients may be unaware of the deficit initially
- May present with right occipital lobe stroke symptoms (left hemianopia with preserved central vision)
Rehabilitation Approaches
1. Compensatory Training (First-Line Approach)
- Scanning training: Teaching patients to make larger eye movements into the affected field
- Evidence level: Moderate quality evidence, discretionary recommendation 3
- Benefits: Improves quality of life compared to placebo or control
- Technique: Systematic practice of visual search strategies and scanning patterns
2. Substitution Methods
- Peripheral prism glasses: Expand the visual field by redirecting images from the blind field
- Evidence: Low quality evidence of minor, frequent adverse events 3
- Application: May be useful for some patients but requires careful fitting and training
3. Restitution Therapy
- Visual field restitution: Attempts to restore function in the damaged visual field
- Evidence: Insufficient evidence to reach generalized conclusions 3
- Newer approaches: Multisensory training using visual-auditory stimulation has shown promising results in recent research 4
Practical Strategies for Reading Difficulties
- Mark the left margin of text to help locate the beginning of each line 3
- Tilt text vertically to aid in line tracking 3
- Practice with laterally scrolling text may improve reading ability 3
- Use a ruler or finger to guide reading from line to line
Multidisciplinary Approach
- Ophthalmology: For diagnosis and optical interventions
- Neurology: To address underlying neurological conditions
- Occupational therapy: For functional adaptation strategies
- Vision rehabilitation specialists: For specialized training
Important Considerations
- Spontaneous recovery may occur within the first few months after injury, particularly with stroke 1
- Rehabilitation should begin early but may still be effective in chronic cases
- Patients with left hemianopia often have difficulty identifying the beginning of the next line of text, whereas those with right hemianopia struggle with seeing the ends of words and finding subsequent words 3
- Associated cognitive or language deficits (especially with left hemisphere strokes) may complicate rehabilitation 2
Coding Information
For documentation and billing purposes:
- ICD-10 CM: H53.462 (Homonymous bilateral field defects left eye) 3
- Code any underlying cause of the blindness first
Prognosis
Recovery depends on:
- Cause and severity of the brain injury
- Time since onset
- Patient's age and cognitive status
- Consistency with rehabilitation exercises
- Associated neurological deficits
Even without complete recovery of the visual field, significant functional improvements can be achieved through proper rehabilitation techniques that focus on compensatory strategies.