• An eye examination uses a series of tests to evaluate your vision. These series of tests may be performed by vision professionals. During an eye examination, a vision professional may use medical terminology to describe the types of eye tests. Some of these eye tests include vision acuity, refraction assessment, tonometry and vision field tests.
  
  

Vision Acuity Tests

• A vision professional uses vision acuity tests during eye examinations. These acuity tests are used to measure the eye's ability to see objects in your vision field clearly. Each eye is measured separately for accuracy. The Snellen chart is a common method used is determining vision acuity. The Snellen chart uses an eye chart with printed black letters. The first letter is very large; subsequent rows of letters decrease in size. Two common reasons for vision acuity tests include routine eye examinations and recent eye injuries such as a fall.
  
  

Refraction Assessment

• A refraction assessment ,which measures how lightwaves are viewed as they travel through the cornea and lens. A special device called a refractor is used as the patient sits in a chair and looks through the device. Normal results are classified as perfect vision; abnormal results may indicate eye conditions such as myopia (nearsightedness) or astigmatism (curvature of the cornea). The most common reason for a refraction assessment is to confirm the need for glasses or contact lenses.
  
  

Tonometry

• Tonometry measures eye pressure after a topical anesthetic is placed into the eye. Two of these topical anesthetics include proparicaine and tetracaine. Once the eye surface is numbed, a vision professional uses a tonometer device to record the eye pressure reading. The most common reason for a tonometry is to check for glaucoma. Glaucoma is an eye disease which may cause gradual vision loss when left untreated.
  
  

Vision Field Tests

• Vision professionals use vision field tests to measure both the central and peripheral vision. Patients are requested to look ahead and are asked a series of questions. Vision field tests may be used for medical reasons. One medical reason may include checking for eye diseases such as glaucoma. Other medical reasons may include testing the optic nerve function and screening for nerve damage after a motor vehicle accident.