Improvements in Optometers and other Optical Instruments.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Optometers and other Optical Instruments.
We, ANGUS G. MCKENZIE, of 156, Charles Street, Boston, Massachusetts,
United States of America, Optician, and HOMER AUSTIN HUNTINGTON, M.D.
of 151, W. 15th Street, in the City, County and State of New York, United
States of America, Oculist, do hereby declare the nature of this invention to be
as follows:
The object of this invention is to construct an optical instrument for quickly
and accurately diagnosing errors of refraction in the human eye.
The invention consists in an instrument constructed on the plan of the telescope
of Galileo, but differing from that instrument in having the eye-piece arranged in
such a manner as to permit of rotating it in a plane at right angles to its optical
axis and also on that axis. It is adapted for various optical tests, but more
particularly designed and adapted for astigmatism.
Reference is to be had to the accompanying drawings, forming a part of this
Specification, in which similar letters of reference indicate corresponding parts in
all the views.
Figure 1 is a side elevation of the improved optometer.
Figure 2 is a side sectional elevation.
Figure 3 is a horizontal section taken on line 3-3 in Figure 2.
Figure 4 is a horizontal section taken on line 4-4 in Figure 2.
Figure 5 is a plan view, partly in section, of a telescope and lens-tilting
mechanism.
Figure 6 is a detail vertical transverse section, taken on line 6-6 in Figure 2.
Figure 7 is a vertical transverse section taken on line 7-7 in Figure 1.
Figure 8 is a vertical longitudinal section of one of the eye-pieces.
Figure 9 is a longitudinal section of an eye-piece supported for use on opera-glasses,
field-glasses, and telescopes; and Figure 10 is a rear elevation.
The main tube A of the optometer is jointed at the upper end of the adjustable
standard A¹ and carries in its anterior end an achromatic telescopic objective B
preferably of short focus, and to the posterior end of said tube is fitted a draw-
tube C provided with a rack which is operated by a pinion b journalled in a
housing at the side of the tube A. To the draw-tube C is fitted a tube D having
at its inner end a flange and at its outer end a screw-thread for receiving the eye-
piece E. To the tube D, between the eye-piece E and the draw-tube C, is secured
a disc F, the tube 1) and disc F being made revoluble. To the tube D is fitted a
thimble e in which is pivoted a lens frame d one of the pivots of which extends
through the thimble c and tube D and carries a bevel wheel e (see Figures 5
and 6). To the lens frame d is fitted a concave lens G. In a bracket f' (Figure 5)
which
attached to the face of the disce F and in the disc is journalled a shaft g
carries at the front of the disc a pinion which engages the bevel wheel e and to
the shaft at the rear of the disc F is attached an index i which moves in front of
a scale (Figure 10) formed on the back of the disc F. By moving the index i
the lens G is tilted more or less, according to the requirements. The eye-piece E
is provided with a diaphram k and the front thereof is recessed for receiving
different lenses and accessories. The negative lens G fitted to the lens frame d is
of suitable power to act with the objective B as a telescope. A short arm

page_text: (Figure 2) which is pivoted to the top of the standard A' is provided with a toothed
sector m which is engaged by a toothed sector n formed on or attached to the
index o and turning on a pin p passing through ears a projecting from the rear of
the top of the standard A'. The free end of the index o moves in front of a
curved scale H attached to the standard A'. On the standard A¹ below the scale H
is mounted a sleeve I provided at its upper end with a spur wheel which is
engaged by a spur wheels attached to the shaft J which is journalled in arms t, t',
projecting from the standard A. The upper end of the shaft J is connected with
the shaft, of the piniou 6 by a universal joint K of ordinary construction, the
centre of which is directly opposite the pivot of the telescope. On the sleeve I
is mounted a graduated disc L which turns under the indexes u, u¹ (Figures 3 and 10).
The disc L is provided with two sets of graduations, one for hypermetropia and the
other for myopia. By turning the disc L the pinion 6 is rotated and the rack a is
thrown out or in, according to the requirements of the case. The disc is provided
with a circle M (Figure 10) divided into thirty-degrees spaces and figured like a
clock-dial, and in the said disc is formed an aperture v in which is a collar w for
receiving an eye-piece or a tinted glass, the distance between the aperture and the
eye-piece E being the same as that between normal eyes. The optometer is
provided with a triped M furnished with levelling screws a swivelled in bloks b²
let into the base or table N which supports the entire apparatus. To the tripod M¹
is secured the disc O eccentrically, and the standard A¹ passes through the said
disc and the tripod M'. On the standard A' is placed a sleeve P which carries the
segmental gear wheel Q. A set screw (Figures 2 and 4) passes through the
sleeve P and enters a grooved in the side of the standard A'. By this con-
struction it is made possible to adjust the standard A' to any desired height without
turning it in the sleeve P. A shaft e¹ carrying a pinion is journalled in the
disc and bracket g¹ attached to the disc. The pinion f engages the segmental
wheel and the shaft e' is provided with an index h which may be moved over
a scale formed on the disc O, the scale having a zero point located on a line
drawn through the centre of the standard A¹ and centre of the shaft e¹.
divisions of the scale are numbered 1, 2, 3, 4, etc., upon each side of the zero
mark, as shewn in Figure 4.
The
In Figure 9 the improvement is shewn as adapted to the eye-pieces of opera-
glasses, to enable the opera-glass to be used by people having astigmatic eyes.
In this case the tilting lens G is mounted in the eye-piece and one of its pivots
is provided with an arm projecting at right angles to the plane of the lens.
The perforated cap R which fits over the lens cell is capable of turning on
the said cell and is provided with a slot for receiving a stud projecting from the
arm. The lens cell is constructed so that it may be turned on the tripod M
of the opera-glass so that the lens G may not only be tilted on its axis but it
may be turned in a plane at right angles to the optical axis of the opera-glass.
The index levers o, i, and ', are each provided with a small knob by which
they may be operated. To secure the smooth working of the pinion and spur
wheels of the instrument the teeth of the gearing are preferably cut on spiral
lines.
The auxiliary lenses used with the instrument consist of a -10 for correcting
myopia and a 20 for correcting high degrees of myopic error. Either of these
lenses may be inserted in the eye-piece E.
We will describe the method of using the instrument for making various tests.
HYPERMETROPIA.
When the indexes u, u', are at zero on the disc L, rays of light coming parallel
from a test object at six metres distance pass through the instrument and emerge
from it parallel, the instrument being now adjusted for a normal eye. Upon rotating
the disc L the draw-tube is caused to slide out and rays of light emerging from the
instrument are no longer parallel but converge the degree of their convergence

page_text: being indicated in dioptres upon the outer scale of the disc, as in Figure>
5 dioptres are shewn.
ΜΥΟΡΙΑ.
Where
One complete revolution is given to the disc L when the draw-tube being out to
its limit, rays emerge convergent to the extent of 10 dioptres. A-10 is now
inserted in the eye-piece which renders the emerging rays parallel, the -10 having
neutralized the convergence due to drawing out the tube. An emmetropic eye now
sees clearly through the instrument, but on causing the disc L to rotate in the
direction opposite to what it did in testing for hypermetropia, rays emerging from
the instrument are caused to diverge, the amount of their divergence being expressed
in dioptres upon the inner scale of the disc which is coloured red, to distinguish it
from the outer hypermetropic scale which is white.
SIMPLE HYPERMETROPIC ASTIGMATISM.
As in hypermetropia, the disc L is caused to rotate until the hypermetropic
meridian is corrected, the amount indicated in the drawings being 5 dioptres, but as
this movement of the draw-tube outward causes emerging rays to converge, artificial
myopic astigmatism is produced in the really emmetropic meridian of the eye under
examination. This artificial error is corrected by tilting the minus lens in the eye-
piece, for the tilting of a lens produces an effect identical to that produced by a
cylindrical lens. Thus, in Figure 2, the lens of the eye-piece is represented as tilted
on a horizontal axis, and in Figure 10 the cylindrical value of this tilting is shewn
by the indicatori to be -1. Now had the disc L been rotated only to 1 instead of 5,
the drawings would represent simple hypermetropic astigmatism.
COMPOUND HYPERMETROPIC ASTIGMATISM.
This is the condition of the refraction in an eye supposed to have been tested by
the instrument as drawn. In the beginning of the examination all the indicators
were at their respective zeros and the clock face occupied its usual position. The
eye looking through the telescope at a dial with lines radiating from its centre, saw
the horizontal one most clearly and continued to do so until the dise L had been
rotated to 4 when the horizontal line became dini and the perpendicular the most
distinct, and continued so until the indicator u stood at 5, i.e. 5 dioptres in the eye's
most hypermetropic meridian. The disc F was then rotated carrying with it the
eye-piece and its lens, bringing the latter's axis horizontal so as to allow the lens to
be tilted in a perpendicular plane and thus render the horizontal line dimly seen by
the
eye under examination as distinct as the perpendicular one; and this has been
accomplished, the result being +5 -1 cyl. ax. 180 degrees.
Simple myopic astigmatism is treated by simply tilting the lens in the plane of
the line best seen by the eye examined, the disc F being rotated until the axis of the
lens shall be at a right angle to the line so seen.
COMPOUND MYOPIC ASTIGMATISM.
The least myopic meridian is corrected by rotating the disc L and the most
myopic by tilting the lens. Supposing that a 10 had been placed in the eye-piece,
1
11

page_text: By the addition of the scale marked on the disc O the segmental gear wheel Q
and pinion and index lever for moving the same, the instrument is adapted for
testing dis-equilibrium of the ocular muscles, thus dispensing with the necessity of
using prisms for that purpose. In this test, one eye of the patient is directed
through the instrument at the object, for example, a circle, and so as to magnify,
while with his other eye uncovered he sees the same object of its natural size,
equilibrium of his ocular muscles being demonstrated when the smaller circle seen
with his natural eye seems to him to lie centrally within the larger circle seen
through the instrument, the index standing at zero on the scale i¹. If the circles
are not so seen the movements of the telescope in its horizontal and vertical planes
necessary to make the circles so appear are seen at the scales H and '.
This optometer obviates the necessity of using a multiplicity of lenses and
enables the patient to make all the necessary tests with a single simple instrument
which is perfectly accurate and comparatively inexpensive.
Dated this 12th day of February 1895
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Optometers and other Optical Instruments.
We ANGUS G. MCKENZIE, of 156 Charles Street, Boston, Massachusetts,
United States of America, Optician and HOMER AUSTIN HUNTINGTON M.D.,
of 151 W. 15th Street in the City, County and State of New York, United States
of America, Oculist do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
The object of this invention is to construct an optical instrument for quickly and
accurately diagnosing errors of refraction in the human eye. The invention
consists in an instrument constructed on the plan of the telescope of Galileo, but
differing from that instrument in having the eye piece arranged in such a manner
as to permit of rotating it in a plane at right angles to its optical axis, and also on
that axis. It is adapted for various optical tests, but more particularly designed
and adapted for astigmatism.
Reference is to be had to the drawings filed with our Provisional Specification,
in which similar letters of reference indicate corresponding parts in all the views.
Figure 1 is a side elevation of the improved optometer;
Figure 2 is a side sectional elevation ;
Figure 3 is a horizontal section taken on line 3-3 in Figure 2;
Figure 4 is a horizontal section taken on line 4-4 in Figure 2;
Figure 5 is a plan view, partly in section, of a telescope and lens-tilting
mechanism;
Figure 6 is a detail vertical transverse section taken on line 6-6 in Figure 2;
Figure 7 is a vertical transverse section taken on line 7-7 in Figure 1;
Figure 8 is a vertical longitudinal section of one of the eye-pieces;
Figure 9 is a longitudinal section of an eye-piece supported for use on opera
glasses, field glasses and telescopes; and Figure 10 is a rear elevation.
The main tube A of the optometer is jointed at the upper end of the adjustable
standard A', and carries in its anterior end an achromatic telescope objective B,
preferably of short focus, and to the posterior end of said tube is fitted a draw-
tube C, provided with a rack a, which is operated by a pinion b, journaled in a
housing at the side of the tube A. To the draw-tube C is fitted a tube D, having
at its inner end a flange, and at its outer end a screw thread for receiving the

page_text: eye-piece E. To the tube D (between the eye-piece E and the draw-tube C,) is
secured a disc F, the tube D and disc F being made revoluble.
ü
To the tube D is also fitted a thimble c, in which pivoted a lens frame d, one
of the pivots of which extends through the thimble and tube D, and carries a
bevel wheel e (Figures 5 & 6). To the lens frame d is fitted a concave lens G.
In a bracket f(Figure 5) attached to the face of the disc F, and also in the disc
itself is journaled a shaft g, which carries at the front of the disc a pinion h, which
engages the bevel wheel e, and to the shaft g at the rear of the disc F, is attached
an index i, which moves in front of a scalej (Fig. 10) formed on the back of the
disc F. By moving the index i, the lens G is tilted more or less according to the
requirements.
The eye-piece E is provided with a diaphragm k. and the front thereof is
recessed for receiving different lenses and accessories. The negative lens G, fitted-
to the lens frame d, is of suitable power to act with the objective B as a telescope.
A short arm 1, (Fig. 2) which is pivoted to the top of the standard A¹, is provided
with a toothed sector m, which is engaged by a toothed sector n formed on or
attached to the index o, and turning on a pin p passing through ears 9 projecting
from the rear of the top of the standard A¹. The free end of the index o moves in
front of a curved scale H, attached to the standard A. On the standard A' below
the scale H, is mounted a sleeve I, provided at its upper end with a spur wheel r,
which is engaged by a spur wheel's attached to the shaft J, which is journaled in
arms projecting from the standard A¹. The upper end of the shaft J is
connected with the shaft b' of the pinion b, by a universal joint K of ordinary
construction, the center of which is directly opposite the pivot of the telescope.
On the sleeve I, is mounted a graduated disc L, which turns under the
indexes uu. The disc L is provided with two sets of graduations, one for
hypermetropia and the other for myopia. By turning the disc L, the pinion b is
rotated and the rack a is thrown out or in according to the requirements of the
case.
The disc F is provided with a circle M. (Fig. 10) divided into 30° spaces and
figured like a clock dial, and in the said disc is formed an aperture v, in which is a
collar w for receiving an eye-piece or a tinted glass, the distance between the
aperture and the eye-piece E being the same as that between normal eyes.
The optometer is provided with a tripod M furnished with levelling screws a¹
swiveled in blocks 2 let into the base or table N which supports the entire
apparatus. To the tripod M' is secured the disc O eccentrically, and the
standard A' passes through the said disc and the tripod M. On the standard A¹
is placed a sleeve P which carries the segmental gear wheel Q. A set screw c¹
(Figs. 2 & 4) passes through the sleeve P and enters a groove d' in the side of the
standard A. By this construction it is made possible to adjust the standard A¹ to
any desired height without turning it in the sleeve P. A shaft el carrying
pinion is journaled in the disc O and bracket g' attached to the disc. The
pinion engages the segmental wheel Q, and the shaft e¹ is provided with an
index h', which may be moved over a scale formed on the disc O, the scale
having a zero point located on a line drawn through the centre of the standard A¹
and centre of the shaft e¹. The divisions of the scale i are numbered 1, 2, 3, 4, &c.,
upon each side of the zero mark, as shown in Figure 4.
a
In
In Figure 9 the improvement is shown as adapted to the eye-pieces of opera
glasses, to enable the opera glass to be used by people having astigmatic eyes.
this case the tilting lens G is mounted in the eye-piece, and one of its pivots is
provided with an arm j¹ projecting at right angles to the plane of the lens. The
perforated cap R, which fits over the lens cell k, is capable of turning on the said
cell, and is provided with a slot for receiving a stud projecting from the arm j¹.
The lens cell ¹ is constructed so that it may be turned on the draw tube m¹ of the
opera glass, so that the lens G may not only be tilted on its axis, but it may be
turned in a plane at right angles to the optical axis of the opera glass. The index
levers 09
i and shown in Figures 1 to 4 are each provided with a small knob n¹

page_text: Either
correcting myopia and a -20 for correcting high degrees of myopic error.
of these lenses may be inserted in the eye-piece E. I will describe the method of
u-ing the instrument for making various tests.
HYPERMETROPIA,
When the indexes u u¹ are at zero on the disc L, rays of light coming parallel
from a test object at 6 meters distance pass through the instrument and emerge from
it parallel, the instrument being now adjusted for a normal eye. Upon rotating the
disc L, the draw-tube is caused to slide out, and rays of light emerging from the
instrument are no longer parallel, but converge, the degree of their convergence
being indicated in dioptres upon the outer scale of the disc, as in Figure 3,
where 5 dioptres are shown.
MYOPIA.
One complete revolution is given to the disc L. when the draw-tube
being out to its limit, rays emerge convergent to the extent of 10 dioptres.
A -10 is now inserted in the eye-piece, which renders the emerging rays parallel,
the 10 having neutralized the convergence due to drawing out the tube. An
emmetropic eye now sees clearly through the instrument, but on causing the disc L
to rotate in the direction opposite to what it did in testing for hypermetropia, rays
emerging from the instrument are caused to diverge, the amount of their divergence
being expressed in dioptres upon the inner scale of the disc which is coloured red
to distinguish it from the outer, hypermetropic scale, which is white.
SIMPLE HYPERMETROPIC ASTIGMATISM.
As in hypermetropia, the disc L is caused to rotate until the hypermetropic
meridian is corrected, the amount indicated in the drawings being 5 dioptres; but
as this movement of the draw-tube outward causes emerging rays to converge,
artificial myopic astigmatism is produced in the really emmetropic meridian of
the eye under examination. This artificial error is corrected by tilting the minus
lens in the eye-piece; for the tilting of a lens produces an effert identical to that
produced by a cylindrical lens. Thus in Figure 2, the lens of the eye-piece is
represented as tilted on a horizontal axis, and in Figure 10 the cylindrical value
of this tilting is shown by the indicator i to be -1. Now bad the disc L been
rotated only to 1 instead of 5, the drawings would represent simple hypermetropic
astigmatism.
COMPOUND HYPERMETROPIC ASTIGMATISM.
This is the condition of the refraction in an eye supposed to have been tested
by the instrument as drawn. In the beginning of the examination all the
indicators were at their respective zeros and the clock face occupied its usual
position. The eye looking through the telescope at a dial with lines radiating
from its centre, saw the horizontal one most clearly and continued to do so until
the disc L bad been rotated to 4, when the horizontal line became dim aud the
perpendicular the most distinct, and centinued so until the indicator u stood at 5,
2.e., 5 dioptres in the eye's most hypermetropic meridian. The disc was then
rotated, carrying with it the eye-piece and its lens, bringing the latter's axis
horizontal so as to allow the leus to be tilted in a perpendicular plane, and thus
render the horizontal line dimly seen by the eye under examination as distinct as
the perpendicular one; and this has been accomplished, the result being
+51 cyl. ax. 180°.

page_text: Simple myopic astigmatism, is treated Simply
of the line best seen by the eye examined, the disc F being rotated until the axis
of the lens shall be at a right angle to the line so seen.
COMPOUND MYOPIC ASTIGMATISM.
The least myopic meridian is corrected by rotating the dise L, and the most
myopic by tilting the lens. Supposing that a -10 had been placed in the eye-
piece, as in testing myopia, then the drawings would represent compound myopic
astigmatism and be expressed by the formula-51 cyl. axis 180º.
MIXED ASTIGMATISM.
The hypermetropic meridian is first corrected by rotating the disc L, and then
the real the artificially myopic meridian by tilting the lens.
By the addition of the scale marked on the disc O, the segmental gear wheel (2,
and pinion and index lever for moving the same, the instrument is adapted for
testing disequilibrium of the ocular muscles, thus dispensing with the necessity of
using prisms for that purpose. In this test one eye of the patient is directel
through the instrument at the object, for example, a circle, and so as to magnify,
while with his other eye uncovered he sees the same object of its natural size,
equilibrium of his ocular muscles being demonstrated when the smaller circle seen
with his natural eye seems to him to lic centrally within the larger circle seen
through the instrument, the index standing at zero on the scale i¹. If the
circles are not so seen, the movements of the telescope in its horizontal and
vertical planes necessary to make the circles so appear, are seen at the scales H,
and .
This optometer obviates the necessity of using a multiplicity of lenses, and
enables the patient to make all the necessary tests with a single simple instrument
which is perfectly accurate and comparatively inexpensive.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. An optometer, comprising a suitable lens support, and a lens which is
pivoted therein on a diametric axis, i.e., on an axis at right angles to its principal
optical axis, whereby it is adapted to be tilted and placed at different inclinations
or angles to the line of vision corresponding to the existing abnormal refraction,
and means for indicating the lenticular astigmatic currection required, as
specified.
2. In an instrument for determining and correcting astigmatism, the combination,
with a suitable lens support, of a lens which is rotatable about its principal axis,
and also pivoted on a diametric axis or axis at right angles to the said principal
optical axis, substantially as specified.
3. In an improved optometer, a suitable lens support, a lens arranged to turn
on an axis coincident with its principal optical axis and rotatable on a diametric
axis or one which is at right angles to said principal optical axis, and two scales
arranged as shown, one for indicating the angle formed by the plane of the lens
with the line of vision, the other scale being for indicating the angular displace-
ment of the lens in a vertical plane, as and for the purpose specified.
4. The improved optometer, comprising a two-part telescope tube, an object
glass, and a lens which is rotatable on an axis coincident with its principal optical
axis and also rotatable on a diametric axis, or an axis which is at right angles to
the principal optical axis, substantially as specified.
5. In an optometer, the combination with the focusing mechanism of the
telescope, of one or more scales, and an index for measuring the amount of
hypermetropia, as specified.

page_text: 6. In an optometer, the combination, with the telescope constructed to swing on
vertical and horizontal pivots, of two scales for indicating the angle of the
vertical and horizontal displacement of the telescope in making dis-equilibrium
tests, as specified.
Dated this 21ot der of October 1905
A. M. & WM. CLARK,
53 Chancery Lane, London, Chartered Patent Agents.