What causes sudden visual loss?

Updated: Dec 11, 2019
  • Author: Jean Deschênes, MD, FRCSC; Chief Editor: Edsel Ing, MD, MPH, FRCSC  more...
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Multiple conditions are associated with transient visual loss. They can be classified according to origin or pathogenesis, but, for the purpose of this article, they are outlined by source. Wray has classified TMVL into 3 different groups based mostly on pathogenesis, as follows: [7]

  • Type 1 is characterized by loss of all or a portion of vision in one eye, lasting seconds to minutes, with full recovery. It is usually secondary to an embolic phenomenon. The attacks have been related to an ICA origin associated with ulceration but not critical narrowing.
  • Type 2 includes visual loss due to hemodynamically significant, occlusive, low-flow lesions in the ICAs or ophthalmic arteries. Symptoms are more frequent, less rapid in onset, and longer in duration than type 1 attacks, with gradual vision recovery.
  • Type 3 is thought to be due to vasoconstriction or vasospasm.

The pathophysiology of some types of visual loss can be explained by atherosclerotic cerebrovascular disease. The visual disturbances are usually described as dark or gray, or obscuration by a "descending shade." Visual loss lasts for minutes (10-15 minutes), is painless, and returns to normal afterward.

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