Slit Lamps

• The slit lamp exam uses an instrument that provides a three-dimensional, magnified view of the various parts of the eye. This enhanced view helps the optometrist look deep into the eye and see different structures within that cannot normally be seen. Oftentimes a small camera can be attached to the slit lamp to capture images of what is seen for further review.
  
  

Phoropter

• Phoropters aid in determining the strength of your glasses or contacts you will wear.Jupiterimages/Goodshoot/Getty Images
  
  A phoropter is the contraption that, during almost every visit, will be placed in front of the patient's face and she will be required to look through different lenses while the optometrist flips various prescription strengths over them. A phoropter manually determines refraction, the angle at which a prescription lens needs to be to obtain optimal vision correction.
  
  

Tonometer

• Tonometry measures the resistance of the eye's cornea to pressure. This is done by measuring how much force is needed to flatten the cornea and this reading is known as intraocular pressure. A patient will be asked to hold his face in front of a small machine and keep his eye open for a short, fast puff of air against the cornea.
  
  

Snellen Chart

• Snellen vision charts are a test of eye health.Jupiterimages/Photos.com/Getty Images
  
  A Snellen chart is in every optometrist's office. This is the chart with one big letter at the top and descending rows of smaller and smaller letters towards the bottom of the chart. A Dutch ophthalmologist, Herman Snellen, created the first eye chart, which measures visual acuity. This is the test that derives the label 20/20 vision.