Can be done in many ways, usually it consists in a reasonably established series of measures, some of which can be described as being of an objective nature whereas others are more of a subjective sort.
The results of these tests held up against the possible complaints of the client and the habitual corrections that may be in place, brings us to a closer understanding of the functionality and needs of any given pair of eyes.
The sight function as a whole is rather complex, with close to an infinity of possible variations. Apart from keeping track on the conditions strictly related to the optics, we, as optometrists, also have a certain obligation to keep record of information about the basic health and capacities of our client’s eyes. That can possibly help explain the reason why a well done eye test, does take some time. Typically we set off an hour for you, when you book an appointment with us.
An eye test should establish the correctional need of the client; spherical and cylindrical powers, the eventual cylinder´s axis and the possible amount of prisms involved. All of this is measured in “Dioptrias” or “Degrees”, depending on what we are referring to. Furthermore your eye test should include a control of what your eyes are capable of in your habitual situation, referred to as your “Habitual Visual Acuity”. That, held together with what an eventual new correction actually can bring you to do, should give you and your optometrist the best and most solid basis for deciding whether or not to actually introduce any changes.
With the possible help of an established history, the thorough professional could, and to some degree should, detect the most frequent physical phenomena. See “Screenings for Pathologies”.