It was assumed that it required a +2.00 spherical to neutralize the strongest, or horizontal meridian, as shown in Fig. 10. The refractionist should then set the axis indicator therewith, which is the axis of the cylinder, or 180°. It is then merely a matter of increasing the Ski-optometer’s cylindrical lens power until the reversal of the shadow in the weakest meridian is determined. Assuming this proves to be -.75 cylinder, axis 180°, the patient’s complete prescription +2.00 sph. = -.75 cyl. axis 180°, would be registered in the Ski-optometer without any further lens change other than the removal of the +2.00 working distance lens. However, regardless of the method employed, the Ski-optometer greatly simplifies skioscopy. In fact, the instrument was originally intended to simplify retinoscopy or skioscopy, as the subject should be termed, the name “Ski-optometer” having been derived from the latter. USE OF THE SKI-OPTOMETER IN SUBJECTIVE TESTING In subjective refraction, especially where the “better or worse” query must be decided by the patient, it is commonly understood that the refractionist is compelled to first increase and then decrease a quarter of a diopter before the final lens is decided. With the Ski-optometer, the usual three final changes are made in far less time than it takes to make even _one_ lens change from trial-case to trial-frame. For example: Assuming, with a +1.25D spherical lens before the patient’s right eye, he remarks that he “sees better” with a +1.D. while +.75D is not as satisfactory. The refractionist can then quickly return to +1.D., simply turning the Ski-optometer’s single reel _outward_ to increase, or _backward_ to decrease, the lens strength. So rapidly have these lens changes been made, that the patient quickly sees the difference of even a _quarter_ diopter, and quickly replies, “better” or “worse.” This is made possible because the eye does not “accommodate” as quickly as the lens change made with the Ski-optometer. It should also be noted that the eye receives an image on its retina within one-sixteenth of a second; otherwise, the patient is forced to accommodate, making it difficult to see the difference of even a quarter diopter. On the other hand, in transferring trial-case lenses, with its slow, tedious procedure, the patient, being unable to detect the slight difference of only a quarter diopter, unhesitatingly replies, “no difference,” merely because they are compelled _to accommodate_. A SIMPLIFIED SUBJECTIVE METHOD