Apparatus for and methods of determining if progressive add lenses (PALs) are properly positioned in a subject's eyeglasses

摘要

An apparatus for and methods of determining that the placement and alignment of progressive add lenses (PALs) in a subject's frame are correct. Namely, a PAL verification tool includes a chart and light source, wherein the chart is viewed by the subject and the light source is worn by the subject during a PAL verification process. The PAL verification method may include the steps of positioning the subject with respect to a near fixation point, the subject viewing the near fixation point with one eye and bringing it into best and clearest vision, measuring and recording a first head position with respect to the near fixation point, the subject viewing the near fixation point with the other eye and bringing it into best and clearest vision, measuring and logging a second head position with respect to the near fixation point, and determining the amount and direction of the difference in the first and second head positions and correlating to an amount and direction of PAL misalignment. A measured misalignment exceeding certain tolerances indicates that a subject's PALs aren't properly positioned in their frame. A subject is suitable for correction if this misalignment causes the subject to experience visual or physical discomfort.

主权项

1. An apparatus for determining correct placement of PALS in a subject's eyeglass frames comprising:
a. A chart including a measuring scale having a plurality of marked increments oriented horizontally, said increments including a left endpoint and a right endpoint; b. At least one distinguishable character on said chart, said character positioned approximately equidistant from said left endpoint and said right endpoint; and c. A light source positioned in front of said chart, said light source emitting a beam that converges with said chart.