The instrument should not be taken apart under any circumstances. To clean its lenses, not a single screw need be removed, as the lenses of each disk may be cleaned individually through the opening of the other disks. These openings are conveniently indicated by the white zeros ([Fig. 2]). The Ski-optometer contains but eleven spherical and eight cylindrical lenses on each side, so that the actual work of cleaning should not require over ten minutes at the most, cleaning the lenses every other week proving quite sufficient.
Accuracy Assured in Every Test
Loss of refraction is completely eliminated through the use of the Ski-optometer. The most casual examination of the trial-frame or any other instrument shows that the construction necessitates the placing of the spherical lens next to the eye with the cylinder lens outermost—a serious fault wholly overcome in the Ski-optometer.
Not only do the cylindrical lenses of the Ski-optometer set directly next to the patient’s eye, thus overcoming any possible loss of refraction, but the strong spherical lenses of the supplementary disk are set directly next to the cylinder. There is apparently but a hair’s distance between these lenses; the two disks containing the spherical lenses of the Ski-optometer likewise setting close together.
In a word, the Ski-optometer’s cylinder lenses set directly next to the patient’s eye, followed by the stronger sphericals, so that the weakest spherical or +.25 (the lens of least importance) sets farthest away. This is 3½ m/m closer than any trial-frame manufactured, however, and at least 10 m/m closer than any other instrument—another reason for implicitly relying on the Ski-optometer for uniformly accurate results.
Built to Last a Lifetime
Fig. 12—(A. and B.)—This unique, patented split-spring device of screwless construction, securely holds all movable parts. In case of repair, they may be removed with the blade of a knife.
The Ski-optometer is built on the plan of ¹/₁₀₀₀″, insuring absolute rigidity and accuracy and a lifetime of endurance. Particular and detailed attention has been given to the novel means of eliminating screws which either bind, create friction or continually work loose, causing false indications of findings on scales of measurements; hence correct and accurate indications are insured in the Ski-optometer by means of a split-spring washer construction similar to that of an automobile tire’s detachable rim ([Fig. 12]).
This patented spring washer construction securely holds the phorometer lenses, the rotary prism and the revolving cylinder lens cells.