Scotoma(redirected from incongruous diplopia)
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a blind area within the visual field, not affecting the surrounding area of the eye. Physiologic scotoma is that area of a healthy eye’s visual field corresponding with the optic disk, which does not have photoreceptors. Pathologic scotoma is a diagnostic symptom of many diseases, including retinitis and atrophy of the optic nerve. It is perceived as a dark spot (positive scotoma) or as a blank spot (negative scotoma) that can be detected only through special testing. During teichopsia (scintillating scotoma), which lasts 20–30 minutes, flickering is perceived along the eye’s periphery; the condition is usually accompanied by persistent headaches, nausea, and vomiting. Treatment of scotoma is directed toward the underlying disease.