If one visual cortex is damaged, optokinetic nystagmus will be lost when objects move toward the side of the cortex lesion (that is, if they approach an individual from the side of vision impairment).
90-Year-Old Activist 'Granny D' Inspires Change, Walks Across Country. I learned a few very good things during my travels with Doris Granny D Haddock. The first, which sounds hackneyed, is that one person can make a difference. It's truer than I imagined.
If you're looking for a way to get started making a positive change for your health, this visual lecture explains why the one small change you can make with the most impact is to walk for a half-hour every day.