Your eye doctor will ask you about any eye or vision problems you may be experiencing now, may have experienced in the past, or may have a family history of. He or she will also want to know about your overall health, medication you are taking, and any work-related or environmental conditions that may be affecting your vision. It is important that you answer all of the doctors questions thoroughly.
A visual acuity test measures how clearly each eye is seeing. Your eye doctor will likely have you read letter charts displayed at varying distances and/or sizes to perform these measurements. A fraction, such as 20/40, is used to record the results of your visual acuity in your chart. The top number in the fraction indicates the distance at which the test is performed (20 feet). The bottom number indicates the size of the smallest line you were able to read at that distance. In the example above, a person with 20/40 vision would need to be within 20 feet of a letter that a person with perfect vision (20/20) can see at 40 feet.
Your eye doctor may want to perform preliminary tests to assess specific aspects of your vision. Such evaluations can include checking your depth perception, color vision, eye muscle movements, peripheral or side vision, and the way your pupils respond to light.
Through Keratometry, your optometrist can measure the the curvature of the cornea (the clear outer surface of the eye). This is accomplished by focusing a circle of light on the cornea and measuring its reflection. If you are being fitted for contact lenses, this measurement is especially important.
Using an instrument called a phoropter, your eye doctor can determine which type of lenses you will need to compensate for any refractive errors such as nearsightedness, farsightedness or astigmatism. The phoropter in combination with a handheld lighted instrument called a retinoscope, allows your optometrist to place a series of lenses in front of your eyes and measure how they change the focus of light entering your eyes. He or she will ask you for your feedback to let them know which combination of lenses is resulting in the clearest vision for you. There are also instruments your eye doctor can use to help automatically evaluate the focusing power of the eyes.
If an eye doctor wants to see how your eyes respond under normal seeing condition, he or she may forgo using dilating eye drops. However, to get a more complete picture of your eyes’ health, or with patients who can’t respond verbally or when some of the eyes’ focusing power may be hidden, your optometrist may use eye drops to temporarily keep the eyes from changing focus during testing.
Your eyes do a lot of things simultaneously in order to produce a clear, single image, including focusing, movement and working in unison. An assessment of accommodation, ocular motility and binocular vision determines how well your eyes focus, move and work together. Through this testing, your eye doctor can determine if there are and problems that keep your eyes from focusing effectively or make using both eyes together difficult.
Additional evaluation may be necessary based on the results of previous examinations. Such tests can help confirm or rule out possible problems, clarify uncertain findings or provide a more in-depth assessment.
After finishing the examination, your eye doctor will make a diagnosis based on a review of all the findings. He or she will thoroughly explain any eye or vision problems found and lay out a treatment plan for you. Depending on the diagnosis, your optometrist may refer you to a specialist or other health care provider for consultation or treatment.