What could cause the edge of my vision to pulse white?

Several causes: The most common causes are migraine headache, ocular migraine, and posterior vitreous detachment. Your specialist eye md (ophthalmologist) will be able to help you sort it out.

Migraine: This sounds like an classical migraine aura, sometimes referred to as an ophthalmic migraine. These episodes of white, shimmering in the vision may not always be accompanied by a headache. See your ophthalmologist for a complete examination.