Chapter IVIMPORTANT POINTS IN CONNECTION WITHTHE USE OF THE SKI-OPTOMETER
TheSki-optometer is equipped with an adjustable head-rest, permitting its lenses to be brought as close as possible to the eye without touching the patient’s lashes, a matter of importance in every examination.
Fig. 11—The nasal lines of the Ski-optometer fit the contour of face with mask-like perfection, patient remaining in comfortable position.
Fig. 11—The nasal lines of the Ski-optometer fit the contour of face with mask-like perfection, patient remaining in comfortable position.
Where the Ski-optometer is correctly fitted to the face, the patient invariably remains in a comfortable position (Fig. 11). The instrumentis shaped to fit the face like a mask, so that even with a pupillary distance of but 50 m/m (that of a child) there still remains, without pinching, ample room for the widest nose of an adult.
Before making an examination, the correct pupillary distance should always be obtained by drawing an imaginary vertical line downward through the center of each eye from the 90° point on the Ski-optometer axis scale. The pupillary distance will then register in millimeters on the scale of measurements for each eye separately. If the Ski-optometer is correctly adjusted, the patient is securely held in position, the cumbersome trial-frame being entirely eliminated.
Illustration on following page (Fig. 11a) shows the reinforced double bearing arms which hold the Ski-optometer lens batteries at two points. This eliminates possibility of the instrument getting out of alignment, and prevents wabbling or loose working parts.
The broad horizontal slides shown in the cut, move in and out independently so that the pupillary distance is obtained for each eye separately by turning the pinioned handle on either side of the instrument. The scale denotes in millimeters the P.D. from the medianline of the nose outward, the total of both scales being the patient’s pupillary distance.
Fig. 11aalso serves to show the staunch construction of the base of the Ski-optometer.
Fig. 11a—Showing staunch construction of Ski-optometer base.
Fig. 11a—Showing staunch construction of Ski-optometer base.
The patient should be placed in a comfortable position with “chin up,” as though looking at a distant object. The instrument should then be raised or lowered by the adjustable ratchet wheel of the bracket. The wall bracket gives best results when suspended from the wall, back of the patient, as shown onpage 135. This bracket should be placed aboutten inches above the head of the average patient. When the Ski-optometer is placed in position for use, its lower edge will barely touch the patient’s cheeks. It is sometimes advisable to request the patient to lightly press toward the face the horizontal bar supporting the instrument. Particularly good results are secured where a chair with a head-rest is employed in conjunction with the Ski-optometer. (See illustration of Model Refraction Room,Page 112).
The time-waste of perpetually cleaning lenses is overcome where the Ski-optometer is employed. For the convenience of the operator and protection of Ski-optometer lenses, the latter are concealed in a dust-proof cell, overcoming all dust and finger-print annoyances. When not in use, the instrument should be covered with the standardized hood forming part of the equipment.
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 eightcylindrical 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.
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.
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.
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; hencecorrect 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.
Whenever necessary, or in case of repair, these parts may be readily removed with the blade of a knife.