Abstract: A novel apparatus for assessing and quantifying the ergonomic position of a video display terminal (VDT) is disclosed. In the preferred embodiment, the apparatus includes a substantially planar measurement tool having a plurality of measurement indicia formed on the front side thereof. The measurement indicia are arranged so as to indicate the distance in inches above and below an alignment indicator formed at the center of the measurement tool. The tool also includes an adhesive portion so that it can be affixed to the VDT in a manner such that the alignment indicator is substantially aligned with the center of the VDT screen. In another embodiment, the measurement tool includes two visual acuity charts, which allow for the testing of the VDT operator's visual acuity. In another embodiment, the measurement tool includes an elongate measurement tape, affixed to the front side of the tool, for determining the viewing distance between the operator and the VDT.

Abstract: A computer indicated lens movement direction protocol is utilized in combination with a lensmeter to designate required movement of lenses with respect to a lensmeter to insure sequential measurement of progressive addition lenses. Lens measurement occurs at four sample points closely spaced on the lens surface. The system uses power variations (PV.sub.1 and PV.sub.2) at each of the spaced apart lens sampling points to indicate when sampling of the lens occurs in a region of constant spherical power, when sampling of the lens occurs in a region of changing spherical power, and finally when sampling again occurs in a region of constant and increased spherical power. When sampling of the lens occurs in a region of changing power, lens movement is guided along a path of constantly changing sphere utilizing changes in astigmatism measured in the 45.degree.-135.degree. directions (C.sub.X).

Abstract: Apparatus is provided for testing subjects for fixation disparity. The apparatus includes a first sheet-like element having an opening therein which is spaced from the subject being tested. This opening defines the periphery of a target which is dimensioned to represent a fusion stimulus to the subject. Within the opening there are displayed a sequence of paired first and second discrete, parallel target elements which are mutually spaced and fixed a predetermined distance from each other along the parallel lengthwise extends thereof. A sequence of these element pairs are positioned in regularly spaced order about a movable carrier and presented sequentially at the opening in the course of testing. The angular subtense represented by the spacing of the elements is indicated upon the carrier and when the subject perceives that the elements are mutually aligned, a recordation of angular subtense is made and utilized for diagnostic purposes.