What is the management and treatment for vitelliform macular dystrophy (Best disease)?

Management and Treatment of Vitelliform Macular Dystrophy (Best Disease)

There is currently no specific treatment available for vitelliform macular dystrophy (Best disease), with management focused on monitoring disease progression and treating complications such as choroidal neovascularization with intravitreal anti-VEGF injections when they occur. 1

Disease Overview

Vitelliform macular dystrophy, also known as Best disease, is an autosomal dominant macular dystrophy caused by mutations in the BEST1 gene. This gene encodes bestrophin, which forms oligomeric chloride channels sensitive to intracellular calcium 2. The disease is characterized by:

• Symmetrical bilateral involvement
• Vitelliform (egg yolk-like) lesions centered in the fovea
• Serous detachment on OCT filled with hyperreflective material
• Hyperautofluorescence on fundus autofluorescence (FAF)
• Absent or markedly decreased light rise on electro-oculography
• No focal leakage on fluorescein angiography (FA)
• No choroidal hyperpermeability on indocyanine green angiography (ICGA)

Diagnostic Approach

1. Clinical examination:

   • Dilated fundus examination to identify characteristic vitelliform lesions
   • Assessment of visual acuity (mean BCVA at presentation is approximately 20/47) 3

2. Imaging studies:

   • Optical Coherence Tomography (OCT) to assess lesion composition and disease staging
   • Fundus Autofluorescence (FAF) to identify hyperautofluorescent lesions
   • Fluorescein Angiography (FA) to rule out leakage
   • OCT Angiography to detect macular neovascularization 4

3. Electrophysiologic testing:

   • Electro-oculography (EOG) showing absent or markedly decreased light rise 1

4. Genetic testing:

   • Molecular analysis for BEST1 gene mutations 5, 3

Management Strategy

Primary Management

• Regular monitoring of disease progression with comprehensive eye examinations and OCT imaging
• No specific treatment is currently available for the primary disease process 1

Management of Complications

1. Choroidal Neovascularization (CNV):

   • Occurs in approximately 17% of patients 3
   • Treatment: Intravitreal anti-VEGF injections
   • Evidence shows better visual outcomes in CNV cases treated with anti-VEGF agents (mean BCVA 20/38) compared to untreated eyes (mean BCVA 20/83) 3

2. Amblyopia:

   • Occurs in approximately 6% of patients 3
   • Treatment: Standard amblyopia therapy with patching and vision therapy

3. Visual Rehabilitation:

   • Low vision aids for patients with significant visual impairment
   • Visual field testing for patients with persistent symptoms

Disease Progression and Prognosis

• Disease progression is typically very slow with a mean annual loss rate of 0.013 logMAR (right eye) and 0.009 logMAR (left eye) 3
• Phenotypic variability exists based on specific BEST1 mutations:
  • p.(Ala243Val) variant is associated with later onset and better visual outcomes
  • p.(Arg218Cys) and p.(Arg218His) variants tend to have more advanced disease stages 3

Clinical Pearls and Pitfalls

• Pearl: Most eyes with Best disease exhibit hyperopic refractive error (78.7%), which should be properly corrected 3
• Pitfall: Don't confuse Best disease with other conditions causing vitelliform lesions:
  • Adult-onset foveomacular vitelliform dystrophy
  • Vitelliform lesions secondary to age-related macular degeneration
  • Acute exudative polymorphous vitelliform maculopathy 1
• Pearl: OCT staging systems based on lesion composition can help track disease evolution 4
• Pitfall: Avoid missing non-exudative choroidal neovascularization, which can develop in late disease stages and is best detected with OCT Angiography 4

Follow-up Recommendations

• Regular dilated fundus examinations and OCT imaging every 6-12 months
• More frequent monitoring for patients with signs of disease progression or development of complications
• Prompt evaluation when patients report new visual symptoms, as this may indicate development of CNV requiring treatment

Remember that while there is no cure for Best disease, proper monitoring and timely treatment of complications can help preserve vision and improve quality of life for affected individuals.