Roca cape lighthouse in Portugal, West most point of Europe ( Cabo da Roca) Vertical. Roca cape lighthouse in Portugal, West most point of Europe ( Cabo da Roca) Vertical. The obelisk with a large white cross at Cabo da Roca. It is a cape which forms the westernmost extent of mainland Portugal and continental Europe.
[Read more about children's eye exams .]. 20/20 vision (or really, 20/20 visual acuity) is considered normal vision, meaning you can read at 20 feet a letter that most human beings should be able to read at 20 feet.
This test can be done as part of a routine eye exam. The purpose is to determine whether you have a refractive error (a need for glasses or contact lenses). For people over age 40 who have normal distance vision but difficulty with near vision, a refraction test can determine the right power of reading glasses.ou have a refractive error if you need a combination of lenses to see 20/20. Glasses or contact lenses should give you good vision. If you have a refractive error, you have a prescription.. Your prescription is a series of numbers that describe the powers of the lenses needed to make you see clearly.