Scotoma

Localized area of partial or complete blindness or reduced vision surrounded by an otherwise intact visual field. Possible causes are migraine, stroke, multiple sclerosis due to optic neuritis, macular degeneration, glaucoma, diabetic retinopathy, hypertensive retinopathy, preeclampsia, toxins (heavy metals, methanol), and malnutrition blindness(vitamin A, vitamin B12, copper, thiamine).