Ophthalmology Book

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Light Flashes

Aka: Light Flashes, Light Flickers, Light Scintillations, Photopsias
  1. See Also
    1. Floaters
  2. Definition
    1. Light Flashes in visual field
  3. Pathophysiology
    1. Traction or inflammation of Choroid or Retina
    2. Results in inappropriate Neuronal firing within Visual Pathway
  4. Risk Factors
    1. Older age
    2. High Myopia
    3. Recent intraocular surgery or Eye Trauma
  5. Causes: Occular
    1. Posterior Vitreous Detachment (progresses to Retinal Detachment in 15% of cases)
    2. Retinal Detachment
    3. Inflammation or infection of Retina or Choroid
  6. Causes: Cortical
    1. Optic Neuritis
    2. Hypotension (bilateral)
    3. Occipital Epilepsy
      1. Stationary flashes of colored light of variable duration
      2. Unlike Migraine Headaches, flashes typically affect the same visual hemifield, and Headache is rarely associated
    4. Migraine Headache (bilateral)
      1. Zig-zag flashes of colorless light across the visual field lasting from 20-30 minutes
      2. Progress from small scotoma (blind spot) and may gradually expand to obscure an entire visual hemifield
      3. Typically switch hemi-fields on successive episodes but are otherwise similar in pattern between episodes
      4. Scintillations are variably followed by progression to Migraine Headache
    5. Transient Ischemic Attack
      1. Stationary flashes or flickers lasting seconds to hours
      2. Accompanied by Posterior Circulation symptoms
        1. Diplopia, Dysarthria, Dysphagia and Dysequilibrium
        2. Headache is rarely associated (but Headache may precede CVA)
  7. Symptoms
    1. Brief peripheral visual field Light Scintillations
    2. Provoked by eye movement or head movement
  8. History
    1. Expand to involve greater areas of visual field?
      1. Migraine Headache
    2. Provoked by head movement or eye movement?
      1. Vitreoretinal traction (Posterior Vitreous Detachment)
    3. Duration?
      1. Seconds
        1. Retinal Detachment
      2. Minutes 15-30
        1. Migraine Headache
      3. Seconds to hours
        1. Transient Ischemic Attack (TIA)
      4. Minutes to hours
        1. Epilepsy
    4. New or increased Floaters?
      1. Vitreous Detachment
      2. Retinal Hemorrhage
      3. Choroidal inflammation
    5. New Vision Loss?
      1. Retinal Detachment
      2. Cortical cause as above
    6. Headache
      1. Prior to Light Flashes
        1. Consider TIA or CVA
      2. After Light Flashes
        1. Migraine Headache (however not all migrainous scintallations are followed by Headache)
  9. Exam
    1. Visual Acuity
      1. Decreased vision in Retinal Detachment
    2. Visual fields by confrontation (distinguishes Retinal Detachment from cortical defect)
      1. Retinal Detachment: Monocular visual field defect
      2. Visual cortical defect: Binocular visual field defect
    3. Pupil Exam
      1. Relative Afferent Pupillary Defect (suggests Optic Nerve injury or Retinal injury)
    4. Red Reflex
      1. Absent Red Reflex in Vitreous Hemorrhage
    5. Dilated Eye Exam
      1. Retinal Detachment
      2. Retinal Hemorrhage
  10. Findings: Red Flags
    1. Retinal Detachment
      1. Sudden onset of Light Flashes
      2. New Vision Loss
      3. Recent Eye Trauma, Head Trauma or eye surgery
    2. Retinal Hemorrhage
      1. Diabetes Mellitus
      2. Hypertension
      3. Sickle Cell Anemia
  11. Imaging
    1. Ocular Ultrasound
      1. May visualize Retinal Detachment
  12. Management: Referral
    1. Emergent referral indications
      1. Light Flashes with new Decreased Visual Acuity (or visual field cut)
    2. Urgent referral indications
      1. Light Flashes new or worsening
      2. Light Flashes with new Floaters
    3. Non-urgent referral indications
      1. Chronic, stable Light Flashes without Vision Loss
      2. Consider neurology evaluation for occipital Epilepsy and Migraine Headache
  13. References
    1. Trobe (2012) Physicians Guide to Eye care, p. 43-45
    2. Noble (2001) Primary Care Medicine, p. 1701
    3. Gariano (2004) Am Fam Physician 69:1691-8 [PubMed]

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