The use of distant light
Glasses wearer see the distant objects, it is assumed that a clearer definition of a fixed reference, the chin moved up and down to observe the reference, and a clear change in the position to determine the most appropriate.
The use of light transition zone
Views myopia were told to watch the vision cards to find and watch the most clear characters, and then slowly shift distance vision cards, increased reading distance, how to use the guidance of head movement to get a clear vision, and vision about translation table, so that definition of wear are observed changes in astigmatic lenses to determine the impact of the scope of the district, told the limitations of its vision to adapt to this.
The use of short distant light
Please watch the past used to wear those visual form, the most clear and determine the most appropriate reading distance and position, told the pan around until the head appeared blurred, the district to determine the scope of progressive lenses to adapt to the recent use of optical characteristics of the district.