Differential diagnosis

• certain visual experiences do not correspond to any object in the external environmental
• these may be grouped as
  • entopsias (floaters) (1)
    • these are visual perceptions that originate due to intrinsic structures of the eye (eg, vitreous cells shedding images on retina are perceived as floaters)
    • these images may be normal or pathologic
    • the precipitating structures can usually be identified on eye examination
  • photopsias (flashes) (1)
    • flashing lights thought to be stimulated by vitreous traction on the retina
    • may sometimes be considered a visual hallucunation
  • a variety of diseases cause flashes and floaters
    • these may be unilateral or bilateral
    • when unilateral , mainly due to disorders of the anterior visual pathway
  • acute posterior vitreous detachment is the most common cause of sudden-onset flashes and floaters
  • the differential diagnosis of floaters include (2)
    • retinal detachment
    • acute posterior vitreous detachment
    • proliferative diabetic retinopathy
    • trauma
    • uveitis
  • the differential diagnosis of flashes include (2)
    • posterior vitreous detachment
    • optic neuritis
    • migraine
    • hypotension
    • transient ischemic attack

Reference:

• (1) Margoet al. Posterior vitreous detachment, how to approach sudden-onset floaters and flashing lights. Post Grad Med. 2005; 117(3).
• (2) Gariano RF et al.Evaluation and management of suspected retinal detachment 2004 by the American Academy of Family Physicians