The DVLA has certain requirements in place for drivers. This includes being required to take a Visual Field test if you have any sort of eye disease or condition that affects your daily vision.
The Esterman Visual Field Test is performed on a machine that sends out tiny flashes of light that you must react to by pushing a button. This is done on both eyes at the same time, and while wearing any corrective lenses that you would normally wear when driving.
The Esterman Visual Field Test is done to ensure that you will be able to respond to traffic appropriately without being affected by blind spots.