CONDENSED PROCEDURE FOR MAKING SPHERE AND CYLINDER TEST WITH THE
SKI-OPTOMETER
Notwithstanding various methods employed, for both subjective and
objective refraction, the following synopsis of the previous chapters
will unquestionably prove most valuable to the busy refractionist,
enabling him to make error-proof examinations in practically every case
without resorting to the transference of trial-case sphere or cylinder
lenses. A careful reading of chapters one and two should be made
however, so that one may gain an understanding as to how spheres and
cylinders are obtained with the Ski-optometer.
SUBJECTIVE DISTANCE TEST
1st—Place Ski-optometer in position, employing spirit level, thus
maintaining instrument’s horizontal balance.
2nd—Adjust the pupillary distance for each eye individually, by drawing
an imaginary vertical line downward through the center of each eye from
the 90° point on the Ski-optometer’s axis scale. The opaque disk should
be placed before the patient’s left eye by setting the supplementary
disk handle at “shut.”
3rd—The Ski-optometer lens battery before the patient’s right eye
should be set at “open” (figure 2), whereupon the first turn of
spherical lens battery toward the nasal side places a +6.D sphere in
position. This should blur vision of average patient.
4th—It is now only necessary to remember that an outward turn toward
temporal side of the instrument increases plus sphere power, while
a nasal turn decreases it. Therefore continue to reduce convex
spherical lens power until the large letter “E” on the distant test
card is clear. Then request patient to read as far down as possible,—a
rapid turn of a quarter diopter being readily accomplished with the
Ski-optometer (Fig. 4).
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.