IMPORTANT POINTS IN CONNECTION WITH THE USE OF THE SKI-OPTOMETER
The Ski-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.
[Illustration: Fig. 11—The nasal lines of the Ski-optometer fit the
contour of face with mask-like perfection, patient remaining in
comfortable position.]
ELIMINATION OF TRIAL-FRAME DISCOMFORT
Where the Ski-optometer is correctly fitted to the face, the patient
invariably remains in a comfortable position (Fig. 11). The instrument
is 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.
RIGIDITY OF CONSTRUCTION
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 median
line of the nose outward, the total of both scales being the patient’s
pupillary distance.
Fig. 11a also serves to show the staunch construction of the base of
the Ski-optometer.
[Illustration: Fig. 11a—Showing staunch construction of Ski-optometer
base.]
HOW TO PLACE THE SKI-OPTOMETER IN POSITION
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 on page 135. This bracket should be placed
about ten 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).
CLEANING THE LENSES
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 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
[Illustration: 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.
Whenever necessary, or in case of repair, these parts may be readily
removed with the blade of a knife.