Wondering why would the optometrist order me a field vision test?

Several options: Visual field tests are ordered if there is a suspicion of some possible eye condition which could cause a field loss such as glaucoma. Visual field is not usually a screening test and optometrists are notorious for ordering such a test just to rake in the cash for the test. So you should find out if there is an actual reason or get a second opinion from an ophthalmologist.