What are the management and treatment options for a patient with blind spot enlargement and ring scotoma around fixation?

Management of Blind Spot Enlargement and Ring Scotoma Around Fixation

The primary management approach for blind spot enlargement and ring scotoma around fixation should focus on identifying and treating the underlying cause, followed by vision rehabilitation strategies to optimize remaining visual function. 1

Diagnostic Evaluation

A thorough diagnostic workup is essential to determine the underlying cause:

1. Imaging Studies:

   • Begin with standard OCT to rule out macular pathology
   • Consider wide-field imaging, microperimetry, and OCT-A for peripheral scotomas
   • OCT-A can detect perfusion loss in outer retinal layers corresponding to scotomas 1

2. Visual Field Testing:

   • Microperimetry is the gold standard for detecting scotomas and fixation patterns
   • Amsler grid testing for periodic self-monitoring of central vision 1

Common Etiologies and Management

1. Acute Zonal Occult Outer Retinopathy (AZOOR)

• Presents with symptomatic blind spot enlargement
• Management:
  • Some cases show reduction in scotoma size with corticosteroid treatment
  • Regular monitoring with monocular Amsler grid testing 1, 2

2. Fixation Switch Diplopia

• Occurs when fixation preference shifts to previously nondominant eye in patients with childhood strabismus
• Management:
  • Address underlying cause (e.g., monovision correction, myopia development, incorrect refractive correction)
  • Trial of monovision with contact lenses prior to refractive surgery 3

3. Epiretinal Membrane (ERM) and Vitreomacular Traction (VMT)

• Can cause shimmering scotomas due to traction on the retina
• Management:
  • Most ERMs remain stable and require monitoring
  • Surgical intervention (membrane peeling) may be considered for severe symptoms
  • Note: Membrane peeling may improve scotomas in some patients but cause new scotomas in others 3, 1

4. Papilledema

• Can cause blind spot enlargement due to peripapillary hyperopia
• Management:
  • Treat underlying cause of increased intracranial pressure
  • Plus lenses may reduce the size of the blind spot in some patients 4

5. Acute Idiopathic Blind Spot Enlargement (AIBSE)

• Characterized by symptomatic monocular blind spot enlargement without optic disc edema
• Often presents with photopsia and visual field defects
• Management:
  • Monitoring as photopsia typically decreases over time
  • Visual fields may not improve significantly
  • Be aware of potential recurrence 5, 6, 7

Vision Rehabilitation Strategies

For patients with persistent scotomas affecting quality of life:

1. Training Interventions:

   • Device training
   • Oculomotor function training
   • Perceptual training
   • Structured reading practice
   • Training fixation with preferred retinal locus (PRL) 1

2. Magnification Devices:

   • Optimize use of remaining vision
   • Particularly helpful for central or paracentral scotomas 1

3. What to Avoid:

   • Prism spectacles for fixation relocation are not recommended (no significant benefit) 1

Patient Education and Monitoring

• Educate patients about signs and symptoms of progression
• Recommend regular monocular Amsler grid testing to detect changes
• Schedule regular follow-up examinations to monitor visual fields 1

Caveats and Pitfalls

• Misdiagnosis is common - AZOOR with paracentral scotomas is often mistaken for optic neuritis
• Multiple evanescent white dot syndrome and other retinal diseases may present similarly
• Consider immunocompromised status when evaluating peripheral scotomas (e.g., CMV retinitis in HIV patients) 1, 6
• Be aware that some conditions (like AIBSE) have a strong predilection for women 6