5th—In the event of working down to “zero” with spheres, the supplementary disk handle or indicator should next be set at -6.D sphere, while the spherical reel should be turned toward the nasal side—thus building up on minus spheres (Fig. 6). In short, the strongest plus sphere or weakest minus sphere should always be determined before employing cylinders. 6th—With the best spherical lens that the patient will accept left in place, direct attention to the letter E or F in the lowest line of type the patient can see on the distant test letter chart. Then set axis indicator at 180° (Fig. 7). 7th—Next increase concave cylinder power until vision is improved. If vision is not improved after increasing cylinder strength to -.50 axis 180°, merely reverse the axis to 90°. If vision is improved, cylinder lens strength should be increased. If not, it should be decreased (Fig. 8). 8th—Slowly move axis indicator through entire arc of axis, thus locating best possible axis (Fig. 7). 9th—After sphere and cylinder test of right eye has been made, place supplementary disk handle at “shut.” Then repeat procedure in testing left eye. 10th—After completing examination for each eye separately, then, with both of the patient’s eyes open, direct attention to lowest line of type he can see, concentrating on the E or F, simultaneously increasing or decreasing spherical power before both eyes. The refractionist merely recalls that by turning the Ski-optometer’s single reel toward the temporal side, convex spherical power is increased, by turning toward the nasal side for either eye, spherical power is decreased. Cylinder lens strength may be changed in a like manner before both eyes simultaneously. 11th—After making the distance test, then only is it necessary to copy the result of the examination as recorded by the Ski-optometer. SUBJECTIVE READING TEST Tilt Ski-optometer forward in making reading test. The wide groove in the horizontal bar supporting the instrument, permits it to be slightly tilted. 12th—Place Ski-optometer reading rod in position with card at about 14 inches. Close off one eye. Direct patient’s attention to the name “Benjamin” printed at top of card. 13th—Leave cylinder lens in place. Proceed as in distance test with +6.D sphere, fogging down until the first word “laugh” on the reading card, in line 75M, is perfectly clear, this being slightly smaller than the average newspaper type. 14th—After completion of examination for each eye separately, then with both eyes direct patient’s attention to word “laugh.” Move reading card in or out a few inches either side of 14 inch mark. This will determine any possibility of an over-correction. Then record prescription just as Ski-optometer indicates. For a detailed description of above, as well as for objective testing with the Ski-optometer, read chapter three. CHAPTER VI MUSCULAR IMBALANCE