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.
The other rows contain letters that are progressively smaller. During an eye exam, your eye doctor will ask you to find the smallest line of text letters that you can make out, and ask you to read it. If you can read the bottom row of letters, your visual acuity is very good.
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.