Note: Descriptions are shown in the official language in which they were submitted.
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OPHTHALMIC PRISMATIC IMAGE RELOCATING
-
EYE GLASSES FOR PERSONS HAVING
RETINITIS PIGMENTOSA AND HEMIANOPIA AND
METHOD FOR MARING SAME
BACKGROUND OF THE INVENTION
Field of the Invention:
The present invention relates to visual
examining and sight corrective apparatus, and more
particularly to an optical image deflector
assembly and method for its use in scanning eyes,
locating visually sensitive peripheral areas
- thereof, and determining corrective prismatic eye
glasses adapted to focus light within and along
the peripheral edge of the visually sensitive
central areas of the eyes for expanding the normal
central field of view. More specifically, the
invention is directed to prismatic eye glasses and
method of making same for persons having retinitis
pigmentosa and hemianopia.
Description of the Prior Art:
U.S. Patent No. Re. 28,921 discloses an
automatic visual sensitivity and blind spot
measuring apparatus comprising a device for
projecting a spot at different locations on a
screen to be viewed by the person being tested
along with means for the person to indicate
perception of the spot for subsequent evaluation.
The device further comprises means for projecting
the spot in different positions in the field of
vision of the person being tested.
U.S. Patent No. 1,990,107 relates to a
reflectoscope used in the examination of an eye.
The reflectoscope comprises mirrors for reflecting
an eye focused image around an operator so that
the eye can be observed in the correct orientation
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to prescribe lenses for correcting refractive
disfunctions. The image is reflected onto the
normally sensitive portion of the eye.
U.S. Patent No. 4,264,152 relates to
apparatus for moving an image of a target in
certain preselected ways to stimulate certain
types of eye movements in the subject.
U.S. Patent No. 4,298,253 relates to
apparatus for presenting test images to a viewer
at different distances without modifying the
visual angle or acuity of the images.
-: U.S. Patent No. 3,423,151 relates to
auxiliary prismatic lenses mountable or~ an eye
glass frame for use by persons having cataracts.
The lenses extend the field of view of the person
beyond that provided by ordinary lenses by
focusing images beyond the range of the normal
lenses onto the pupil of the eye.
U.S. Patent No. 2,442,849 relates to a method
for producing a pair of lenses for providing
balanced binocular vision to a greater-degree than
was previously possible. The invention
particularly relates to the correction of
conventional disorders such as refractive
disorders.
U.S. Patent No. 4,772,113 relates to eye
glasses for improving the vision of people with
macular degeneration, optic nerve damage or
similar low vision problems, in which their
central vision has deteriorated. The eye glasses
comprise two lens assemblies, each having a
magnifying lens with two convex surfaces and a
reducing lens with two concave surfaces. The
reducing lens incorporates a prism ring which
shifts and focuses a highly intensified light
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image onto an undamaged peripheral portion of the
retina. A disadvantage of these eye glasses is
- that they are of no value for people suffering
-~ from retinitis pigmentose or hemianopia, in which
their central vision is good and the peripheral
vision is bad, since the shifted image would be
focused on a damaged peripheral portion of the
retina. Another disadvantage is that the lens do
not have a central clear or non-prism area for
accommodating the person's good central vision.
Also, in those instances where the shifted image
would strike the central functional area of the
retina, overlapping would occur, resulting in
diplopia (double vision).
In addition to the prior art patent
literature, an eye disease is known called
neovascular senile macular degeneration (N.S.M.D.)
in which central vision is greatly impaired, often
resulting in blindness by virtue of blood vessels
growing into the macula of the eye. The macula
controls central vision in the retina, and the
rest of the retina is used for peripheral vision.
The problem of central vision impairment and
blindness due to N.S.M.D. and other problems such
as retinitis pigmentosa (tunnel vision) and
hemianopia are substantially overcome by the
optical image deflector assembly and eye glasses
of this invention.
A known eye glass modification intended to
expand a person's central field of view for people
having retinitis pigmentosa and hemianopia
involves the amorphic telescopic lens system, in
which one or more telescopes are mounted on each
eye glass. The telescopes minify the images so
that more information can be seen at one time in
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the same field. Disadvantages of this form of
expanding the field is that multiple images are
- seen by each eye, and the images are almost twice
as small, so that detail is lost. Also, the
telescopes extend outwardly a distance from the
eye glasses where the force created by the moment
of inertia is constantly slipping the spectacles
from the nose resting position and falling so that
they can be easily damaged. The eye glasses
further are not cosmetically appealing, and they
- are two or more times heavier than normal eye
- glasses, making them uncomfortable to wear and
prone to slip off the wearer's ears due to the
force moments generated by the outwardly extending
telescopes.
Also known in the prior field expanding art
is the use of prisms which are cemented to the
temporal edge of the eye glass lenses (base out).
The prisms increase a person's efficiency of
information processing with reduced fields and
normally are not a means for expanding the field.
The prisms allow the eye glass wearer to scan the
periphery by making small eye movements into the
prism to check for objects in the periphery,
thereby eliminating the need for inefficient neck
movements to accomplish the same task. An
exemplary reference of such prism use is disclosed
by Dr. Weiss in S, The Optician, Cemented Prism
for Severe Field Loss, Volume 163, July 7, 1962.
The primary disadvantages of difficulties
associated with the use of such prisms are prism
blur which may be difficult to tolerate, confusion
between frontal and peripheral images,
particularly in crowds where people are moving in
all directions, diplopia caused by the wearer
` 202:~875
.
looking through the edge of the prism, or not
suppressing the other eye when one eye is looking
through the prism, the necessity for small eye
.-
movements into the prism to check for objects in
the periphery, resulting in loss of frontal image
and a blind spot between the frontal and prism
images, prismatic distortions, such as horizontal
magnification, curvature of vertical lines,
asymmetric horizontal magnification, vertical
- 10 magnification and change in vertical
magnification, with horizontal viewing angle. The
prism, when cemented onto the inner surface of the
eye glass lens, extends outwardly from the lens
and can be hazardous to the eye. The mounting of
the prism can be complicated and delicate, due to
the lens curvature, and the resulting eye glasses
are cosmetically unappealing.
A specialized form of prism known in the art
is the fresnel prism. This prism is used for
special applications, such as for diagnostic
- tests. Fresnal prisms are thin sheets of
optical plastic composed of multiple prismlets
that are pressed into this thin plastic sheet.
They are adhered to normal prescription spectacles
by capillary action and are subjected to air
bubbling during temperature and humidity changes.
Fresnel prisms are used in diagnostic and
-~ temporary correction and/or preliminary concept of
- prism requirements for such eye problems as
retinitis pigmentosa, strabismus, hemianopia, and
macular degeneration, unlike the prescription
corrected field expanding glasses herein
disclosed, which are clear and transmit or project
clear full size images to the retina. The fresnel
prisms have poor light transmission and the
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transmitted or projected images are blurred due to
~ the many prismlets that are pressed into the soft
plastic.
The fresnal prisms have a number of other
disadvantages. Projection to the retina,
especially in crowds as people move in all
directions causes multiple images. Double vision
results when the right eye looks to the right and
the left eye looks through the nasal edge of the
left spectacle lens. The multiple prismlets
~ reduce light transmission, which reduces vision
- and causes night blindness and mobility problems.
The multiple prismlets cause many reflèctions of
the same object, especially light bulbs etc., and
cause chromatic dispersion. Due to the multiple
prismlets, contrast is greatly reduced, and
patients are constantly looking through a fine
grid. With fresnel prisms the patient must rotate
his eye to look into the prism to see the expanded
field.
- In addition, the fresnel prisms suffer from
most of the problems indicated above for prisms
generally. In addition, the fresnel prisms suffer
from air bubbles when mounted on a surface, are
prone to fall off the surface, and subject the
viewer to multiple images reflected by the prism
- rings.
` Another known vision-expanding lens in the
prior art involves the use of a see-through
reflector or mirror, functioning as a beam
splitter, mounted on the eye glass frame to extend
from the nose at a 45 degree angle to the eye.
Disadvantages of this type of vision-expanding
lens are that the eye glass user sees two separate
images, front and rear, which can be confusing,
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the mounting of the reflector to the eye glass
~ frame can be complicated and difficult, the
reflector extends outwardly from the eye glass
~- lens in an exposed position where it can be
readily damaged, and the eye glasses are
cosmetically unappealing.
- Still another attempt in the prior art to
expand the field of view of persons with poor
vision involves special high-powered magnifying
glasses capable of magnifying an object up to six
times, while allowing vision from the side.
Disadvantages of this approach are that the eye
glasses resemble goggles and protrude nearly three
inches from the nose. They must be worn with soft
contact lenses, are heavy and cumbersome, and are
cosmetically unappealing.
It is clear from the prior art that a strong
need exists for eye glasses for expanding the
field of view of persons suffering from retinitis
- 20 pigmentosa and hemianopia without the person
suffering the problems and disadvantages of the
prior known efforts to expand a person's field of
view. This is achieved with the inexpensive,
light weight and cosmetically appealing eye
glasses of this invention, by refracting images
from a field outside the person's normal field of
view within and along the peripheral edge of the
visually sensitive central functional area of the
retina for expanding the central field of view
without generating diplopia, distortion and/or
blind spots.
SUMMARY OF THE INVENTION:
An object of the present invention is to
provide an opthalmic, single element, light
weight, prismatic image relocating prismatic eye
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glasses and a method of manufacturing same for a
~ person having at least one eye having a central
visually sensitive functional area of the retina
: for receiving the normal central visual field of
.,- "
: 5 view, and having at least a partial insensitive
peripheral area of the retina. The prismatic eye
- glasses comprise:
a single lens member having a non-prism
portion for accommodating the central visual field
of view; and
a prism on the lens member having the apex
-- thereof contiguous with the non-prism portion and
the base thereof extending radially outwardly, the
diopter power of the prism adapted to refract an
image within and along the peripheral edge of the
central visually sensitive functional area of the
retina, for expanding the normal central visual
field of view of the eye without generating
diplopia, distortion and/or a blind spot between
the normal central visual field of view and the
expanded visual field of view.
In accordance with a preferred embodiment of
the invention, a pair of rotatable optical image
deflecting assemblies and method are disclosed in
which the assemblies are preferably detachably
mounted via an adapter onto a standard eye testing
apparatus. The mechanical center of each optical
assembly is aligned with the optical center of an
eye. The optical assemblies are useful in
locating the most visually sensitive peripheral
~~~ portions of the retina, and determining the prism
diopters required for corrective prismatic eye
glasses for focusing images thereon.
Each optical image deflecting assembly has a
fixed light reflecting optical element such as a
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- mirror and a pivotal reflecting optical element
~ such as a mirror. Light received from one of the
mirrors is reflected onto a peripheral area of an
~ - eye for scanning an arcuate portion of the
- 5 peripheral area upon pivotal movement of the
pivotal mirror. Means are provided for
selectively incrementally rotating each optical
assembly through a complete revolution. The
pivotal optical element is pivoted at each
incremental position for scanning an annular
peripheral area of each eye and locating the most
visually sensitive areas therein. After
determining the prism diopters required and
testing with trial lens(es), a prismatic lens(es)
is then determined for each examined eye and
mounted in an eye glass frame to provide the best
possible acuity for the eyes.
In a more specific aspect of the invention,
each optical assembly comprises a first ring
secured to the frame, and a second ring rotatably
mounted on the first ring. The fixed and pivoting
optical elements are mounted on diametrically
opposed portions of the second ring.
The invention and its advantages will become
more apparent from the detailed description of the
invention presented below.
BRIEF DESCRIPTION OF THE DRAWINGS:
In the detailed description of the invention
presented below, reference is made to the
~ 30 accompanying drawings, in which:
Figure 1 is a front elevation view of a
preferred embodiment of an eye examining apparatus
of this invention with a portion thereof broken
away to show a portion of the mounting bracket;
Figure 2 is a side elevational view of the
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eye examining apparatus of Figure l;
Figure 3 is an enlarged side elevational
view, partially in section, of an optical image
- deflecting assembly mountable by a bracket to a
standard trial lens holder;
Figure 4 is a schematic view of the optical
system of the eye examining apparatus of the
invention;
Figure 5 is a schematic view of a prism for
deviating light rays, in which all of the angles
have been exaggerated for use in explaining
conversion of a wedge angle to prism diopters;
Figure 6 is a segmental front elevational
view showing one lens of prismatic eye glasses;
Figure 7 is a section view taken
substantially along line 7-7 of Figure 6;
Figure 7A is a section view of a similar
prismatic lens;
Figure 8 is a schematic view similar to
Figure 4 of an optical system for use in examining
persons having retinitis pigmentosa;
Figure 9 is a sectional schematic view, shown
exaggerated for purposes of clarity, of an eye
showing a lens prismatic element designed to
expand a normal central field of view by
refracting images from the expanded field within
and along the peripheral edge of the visually
sensitive central functional area of the retina;
Figure 10 is a front elevational view of
prismatic eye glasses made with lens elements of
the type disclosed for retinitis pigmentosa in
Figure 9;
Figure 11 is a section view of a lens element
of Figure 10 taken substantially along line A-A
with the eye glasses frame omitted;
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Figure 12 is a front elevational view of
prismatic eye glasses designed to expand a normal
field of view for a person having hemianopia;
~- Figure 13 is a reduced substantially top plan
view of the eye glasses of Figures 10 and 12
showing that the thicknesses thereof are
comparable to conventional eye glasses;
Figure 14 is a front elevational view of
prismatic clip-on eye glasses which are clipped
- 10 onto the frame of conventional prescription
corrected eye glasses;
Figure 15 is a schematic view of the optical
system of an eye examining apparatus usable in
determining the possible expanded field of view
for a person suffering from retinitis pigmentosa
and hemianopia;
Figures 16 and 17 are front elevational views
of eye charts for use with the eye examining
apparatus optical testing procedure of Figure 15;
Figure 18 is a typical top plan view of a
chart used in a conventional perimeter testing
apparatus for measuring a person's total retinal
field of view, and shows the expanded field
superimposed with a normal central field;
Figure 19 is a schematic view showing the
location of the functional visually sensitive
central areas of the eyes and the expanded
pupilary distance due to the offset between the
~~. centers of the pupil and the centers of the
visually sensitive central areas;
Figure 20 is a top plan view of a
prescription form for making prismatic field
expanding eye glasses;
Figure 21 is a front elevational view of a
test prism for use in subjectively determining
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prismatic field expanding eye glasses for a person
suffering from retinitis pigmentosa;
Figure 22 is a section view taken
- substantially along line 22-22 of the test prism
of Figure 21;
Figure 23 is a view similar to Figure 21 of
another modification of the test prism;
Figure 24 is a section view taken
substantially along line 24-24 of the test prism
of Figure 23;
- Figure 25 is a typical top plan view of a
chart from a perimeter testing apparatus showing a
person's visually sensitive, functional, central
retinal field of view;
Figure 26 is a top plan view showing the
application of computer analysis in three
dimensions for tracing a ray of light through each
prism and eyeball to find its intersection with
the retina at the ~-Y-Z axis;
Figure 27 is a graph showing the magnitude of
the shifts of a ray of light at the points (-10,0)
and (10,0) for five diopters of prism power;
Figure 28 is a graph showing the magnitude of
the shift of a ray of light at the point (0,-10)
for five diopters of prism power;
- Figure 29 is a typical plan view of a chart
used in a conventional perimeter testing apparatus
for measuring the total retinal field of view for
~ a person wearing prismatic clip-on eye glasses
- 30 which are clipped onto the frame of conventional
prescription corrected eye glasses;
Figure 30 is an enlarged side elevational
view, partially in section, of an optical
simulated prism assembly provided with a field
:- 35 stop plate having a central aperture;
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Figure 31 is a left side end view of the
-
optical simulated prism assembly of Figure 30;
Figure 32 is a perspective view of a mounting
device for supporting the eye examining apparatus
- 5 and eye test charts at pre-measured distances;
- Figure 33 is an enlarged view, partly in
section, of the support bracket assembly of the
mounting device of Figure 32 for supporting the
eye examining apparatus and eye charts; and
Figure 34 is a segmental section view taken
substantially along line 34-34 of Figure 33.
- DETAILED DESCRIPTION OF THE INVENTION:
With reference to Figures 1-3, an eye
examining apparatus 10 is disclosed comprising an
adapter bracket 12 having temple bars 14 each
hingedly connected at one of the ends thereof to
end portions of the bracket. The opposite ends of
temple bars 14 have suitable ear pieces 16 for
mounting the bracket 12 onto the head of a person
whose eyes are to be examined. The temple bars 14
may have conventional ad~justing means, not shown,
by which the length of the bars may be changed to
adjust the position of the bracket relative to the
- person's eyes. A nose piece 18 is mounted on
bracket 12 and has conventional adjusting means 20
for raising or lowering bracket 12 relative to the
person's eyes. A conventional trial lens holding
~- means 21 is affixed to bracket 12 by an L-shaped
--` retainer 17 (Fig. 3) and extends downwardly from
frame 12 for holding trial lens(es) 19. The trial
lens holding means 21 is laterally, tiltably and
rotatably adjustable by any suitable adjusting
means 23, 25, and 27 respectively.
A pair of identical optical image deflector
- 35 assemblies 22 is detachably mounted on bracket 12
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in laterally spaced relation. Each optical image
deflector assembly 22 comprises a first annular
ring 24 secured by screws 26 to slotted, spaced
`- lugs 28 extending from bracket 12, as best seen in
Figs. 1 and 3. Alternatively each optical
assembly 22 can be releasably connected to bracket
12 by any suitable quick-disconnect means, not
shown. The first ring 24 has a cylindrical inner
surface for rotatably receiving an outer
cylindrical surface of a second annular ring 30.
An "O" ring is positioned in facing grooves in the
- inner and outer surfaces for releasably securing
the first and second rings 24, 30 together for
relative rotatable movement therebetween by manual
means, or any suitable pinion and ring gear, not
shown. An annular scale member 29 is secured to
ring 24, and is provided with indicia 31 that
cooperated with an index 33 on ring 30 to indicate
the angular position of ring 30 during,rotation
thereof.
An optical element extends laterally from one
side of ring 30 and has a surface inclined 45O to
the axis of ring 30 for supporting a fixed
reflecting mirror 32 affixed thereto. An optical
element comprising a reflecting mirror 34 is
pivotally mounted on ring 30 in a position
diametrically opposed from fixed mirror 32. A
- pair of spaced, laterally extending side walls 36
have screws 38, 39 extending through openings in
the walls into threaded bores at one end of
support member 40. Pivoting mirror 34 is secured
to support member 40, and screws 38, 39 form a
pivot for the support member and mirror. Support
member 40 has an index 43 which cooperates with a
- 35 scale 42 on a wall 36 for indicating the pivotal
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position of the pivoting mirror 34 relative to a
~ zero degree position in which the pivoting mirror
is parallel to fixed mirror 32. By tightening one
or both of the screws 38, 39, the pivoting mirror
- 5 34 can be locked in any pivotally selected
position.
With reference to Figure 4, a schematic view
of an optical assembly 22 for locating the most
sensitive peripheral area of an eye 48 is
rotatable about its axis 35, which is coincident
with the optical axis O of the eye. A normal
incident light ray 44 strikes fixed reflecting
mirror 32, and is reflected onto a parallel
pivotal reflecting mirror 34, which reflects a
normal light ray 46 onto a peripheral area of eye
48. By pivoting reflecting mirror 34, the
reflected light ray scans an arcuate peripheral
area of the eye, and the total angle through which
the mirror is pivoted in scanning the sensitive
area is referred to as the wedge angle A.
To convert this wedge angle A to prism
diopters or units of refractive power needed to
laterally deviate light ray 46 from incident light
ray 44, reference is made to Figure 5. Prism
diopters is defined as a linear deviation in
centimeters which the prism produces at a distance
of one meter when a ray passes through the prism
~- at minimum deviation. For this conversion, a
prism 52 of clear plastic having an index of
refraction n of 1.5 is used as compared to an
index of refraction n for air of 1. Some
assumptions are made such as the selection of a
wedge angle A of 2, for example, and disregarding
the sines of small wedge angles when using Snell's
35~:~ law n sin ~ = n' sin ~' in which n, n'
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represent the indexes of refraction of the mediums
~ and 0, ~' the angles of incidence and
refraction, respectively. Incident and refracted
- light rays designed i, i' respectively of 1 are
- 5 used, although shown exaggerated in Figure 5 for
purposes of clarity. Accordingly, the deviation
angle D in Figure 5 is derived as follows:
D = (n' - n)A
D = (1.5 - 1)2
D = .5 x 2
D = 1
Then the linear deviation (LD) is computed as
follows: ~-
LD = (tan 1)(1 meter)
LD = .0175 x 100 centimeters (CM)
LD - 1.75 cm
Therefore, a factor for linear devision in
centimeters per degree of angle incidence is
computed as follows:
Factor = 1.75 = 1.75
Now let us assume that in the aforementioned
example illustrated with reference to Figure 4,
the wedge angle A for best peripheral vision was
determined to be 9. The incident angle which is
one-half the wedge angle is read directly from
scale 42 as 4.5. Accordingly, to convert the
wedge angle A to prism diopters, the distance the
light must be deviated or refracted from the
optical center of the eye for best peripheral
vision is equal to the incident angle of 4.5
times the factor of 1.75, or 7.87 cm. Since a
prism of one diopter bends light such that a
refracted ray deviates one cm from the projected
incident ray at a distance of one meter from the
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prism, the number of prism diopters needed is
~- 7.87 or7.87.
- In actual use, a prism 52 of eight prism
diopters would be selected.
In the operation of the eye examining
apparatus of this invention for determining a
wedge angle A and prism diopters for best
peripheral vision, the pivoting mirrors 34 and
optical assemblies 22 are initially placed in
their zero degree positions. In this position,
the mirrors 32, 34 are aligned with vertical lines
passing through the centers of the assèmblies 22.
An opaque lens 50 is placed in the lens holding
means 21 for the eye that is not being tested. No
lens of any type is placed in the trial lens
holding means 21 for the eye to be tested at this
time.
The eye examining apparatus 10 is placed on a
person whose eyes 48 are to be tested, and the
temple bars 14, nose piece 18 and lens holding
means 21 are adjusted so that the mechanical
centers of the mirror assemblies 22 are aligned
with the optical centers of the eyes.
The mirror assembly 22 for the eye being
tested is incrementally rotated through a complete
revolution, stopping, for example, at each 10
(degree) position. It may be preferable to rotate
the mirror assembly 180 in one direction, return
to the zero position, and then rotate 180 in the
opposite direction. At each position, pivoting
mirror 34 is pivoted plus or minus 15 to scan the
arcuate peripheral area of the eye. At each
position, the comments of the person being tested
with regard to visual perception of bright areas
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:. `
or objects are noted. If visual perception is
~ noted, the wedge angle that was required to
produce this perception is recorded along with the
--- incident angle read directly from scale 42. The
rotating procedure is repeated several times, each
time advancing the starting position a few degrees
until the entire annular peripheral area of the
eye is tested. The recorded peripheral area of
best vision and recorded incident and wedge angle
A for that position is determined.
A Sloan-Lighthouse eye chart is placed or
held approximately 40 cm from the person being
tested. The rotating mirror assembly Z2 for the
eye being tested is rotated to the
above-determined best angular position of
peripheral vision. The pivoting mirror 34 is set
at the center position of the determined wedge
angle A, which is the recorded incident angle at
that position. A+ 3 diopter trial lens is placed
in the trial lens holding means 21. At this
point, the determined wedge angle A can be -
converted to prism diopters as discussed earlier,
and the calculated prism 52 and trial lens 54 may
be used in the trial lens holding means 21 to
measure the vision potential of the tested eye.
Use of the mirrors 32, 34 are preferred, however,
since they have practically no distortion and will
- provide a more accurate correction for the best
-~ peripheral vision.
- 30 A standard optical procedure is applied at
this time, adding or subtracting diopters to the
trial lens 54 and/or cylinders until the eye
discerns objects at close range. If the person
being tested cannot read the letters or numbers on
the chart at the 40 cm distance, the chart is
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moved closer until the person can read a line on
~_ the chart. The resolution of the eye can be
determined by measuring the chart distance from
the eye and the size of the letters being read.
For far distance viewing, the above procedure is
repeated except that a Sloan letter low vision
- chart is used at distances of .75 meter, 1.5
meters and at 3 meters.
The aforementioned testing procedure is
repeated for the other eye. After both eyes have
- been tested, the determined wedge angle A for each
eye is converted to prism diopters by multiplying
- the recorded incident angle (one-half of wedge
angle A) times 1.75 as indicated earlier. The
optical assemblies 22 are removed from frame 12,
and the calculated prisms 52 are placed in the
lens holding means 21, and the trial lens holding
means rotated until the apex of each prism is
positioned at the angle of best peripheral vision
for each eye 48. The trial lens(es) 54 for the
best close vision of each eye is placed in the
trial lens holding means 21 between the eye 48 and
prism 52. At this time, the Sloan-Lighthouse
chart is positioned or held at a distance 40 cm
from the person being tested. The person is asked
to read the charts to determine that there is no
distortion or diplopia present, and to determine
the best resolution for the eyes. This procedure
- is also repeated for the far distance viewing
except the chart and trial lens(es) that were
determined earlier for far distance viewing will
be used.
The combination of prism 52 and trial
lens(es) 54 determined by the aforementioned
testing procedure comprises a prismatic lens 55,
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55' as seen in Figures 7, 7A respectively, and are
_ mountable in the aforementioned determined
orientation in the frame of eye glasses 56, seen
in part in Figure 6. Alternatively, the prism 52
- 5 can be mounted in a double frame, not shown, by
means, such as clips or hinges, the corrective
- lens being mounted in one set of the frames, and
the prism in the other set of frames. This type
of frame(s) or mounting provide the means to
design any combination of glasses, such as (1) a
near and far distance combination, (2) reading
glasses combined with either a near or far
distance combination, (3) ultra-violet-filter with
either a near or far distance combination, etc.
When a person first wears eye glasses 56 with
prismatic lenses 55, 55' he may see double and/or
distorted images. The double images can be
corrected by rotating the prisms 52 until the
apexes of both prisms are located precisely at the
tested angular position of best peripheral
vision. To reduce some prism distortion, a prism
52 having the next smaller prism diopter should be
used. The phenomenon of wearing prismatic glasses
for the first time is akin to a person wearing
bi-focals or tri-focals for the first time.
For a person having full vision, the optical
center of each corrective lens(es) 55, 55' is
positioned from its zero axis to approximately 3
millimeters below the eye's optical axis O,
- 30 relative to the best area of vision, so that the
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person may walk with his head in a normal attitude
_ while looking forward.
For a person having peripheral vision only, a
- re-positioning of the optical axis (O) of up to 5
- 5 millimeters towards the position of best
peripheral vision can be made, if required, to
insure that images entering the eye will be
perpendicular to the peripheral area. The new
position of the optical axis designated O' is
illustrated in exaggerated form in Figure 6
extending at 105 which, in this example, was
- selected as the position of best peripheral
vision. Also, to help eyes with peripheral vision
to focus on frontal objects, the prismatic lens 55
can be tilted up to 5 degrees towards the center
of the best peripheral vision. This is achieved
in Figures 7, 7A by grinding lens retainer rings
60, 60', 60" respectively which are offset from
the vertical by 5. Accordingly, when the
prismatic lenses 55, 55' are mounted in eye glass
frames 56, the-prismatic lenses can be tilted up
to 5 toward the center of the best peripheral
vision.
The displacement of the optical axis O and
the tilt of the prismatic lenses 55, 55' will
increase the refractive power (prism diopters) of
the prismatic lens system without increasing the
: size of the prism or corrective lens(es). This
reduces distortion, prism thickness, and the
combined weight of the eye glasses 56 to a
minimum. The increase in prism diopters depends
on prism diopter size and power of the corrective
lèns. In one example, a prismatic lens system had
a corrective lens of plus 4.5 diopters combined
with a prism of 8 prism diopters. Due to
. .
-21-
`- ` 202387~
displacement of the optical axis O and tilting of
~ the prismatic lenses 55, 55', the refractive power
-- of the system was increased approximately 3 prism
:- diopters. The prismatic lens then responds as an
11 prism diopter lens. This method can be used
when the measured prism diopters are greater than
~ 8 prism diopters. The aforementioned displacement
and tilting of the lenses will also facilitate
walking with one's head in a normal attitude-while
looking in the forward direction.
With reference to Figure 8, a modification of
this invention is illustrated for use in examining
the eye of a person having retinitis pigmentosa
(tunnel vision), or hemianopia, for example. In
this embodiment of the invention, the positions of
the fixed and pivotal mirrors 32, 34 respectively
are reversed, although this is not necessary. The
eye examining apparatus is used in the same manner
as described heretofore, except that the rotatable
- 20 ring 30 is locked on the zero or horizontal axis
of the apparatus and the pivoting mirror 3~4 is
then pivoted to determine the prism diopters
required for best lateral vision for each eye.
Each eye is scanned in the temporal and nasal
directions, and eye glasses are then designed with
determined prism diopters and corrective lens(es)
54 to provide lateral images to the visually
- sensitive central retina area of each eye to
enlarge or expand its field of vision.
Referring to Fig. 9, an eye 48 of a person
having retinitis pigmentosa ~tunnel vision) is
disclosed in exaggerated form for purposes of
clarity. The eye has a cornea 62, aqueous fluid
64, lens 66, vitreous solution 68, and a retina
-- 35 70, which for a person having retinitis pigmentosa
.: ~
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will have a central functional portion 72 that is
visually sensitive to a normal central field of
- view, and a peripheral non-functional portion 74
- that is visually insensitive. Incoming light rays
are deviated while passing through the nodal or
principle points of the eye designated Pl and
P2 to project an upright image to the retina.
Also, there are other rays of the same object or
images that pass through the prism, lens and eye
to the non-functional retina 74 which are not seen
by the person, and hence are not shown for
- purposes of clarity.
It was discovered that such a person's field
of view could be expanded by initially positioning
an eye glass or lens element 76 at the vertex
- position V-V of the eye, having a non-prism area
or portion 78 for accommodating the person's
normal functional central field of view. By
incorporating prisms 80 in the eye glass 76 with
the apexes 81 thereof accurately positioned at the
periphery of the non-prism portion 78, it was-
discovered that an expanded field of view was
refracted onto and within the peripheral edge 82
of the visually sensitive functional area 72 of
the retina 70 to expand the field of view, without
any substantial distortion or diplopia.
Positioning of the apexes 81 at the periphery of
the non-prism portion 78 is critical - if
positioned too far inwardly, diplopia will occur,
and if positioned too far outwardly, a blind spot
will result. A blind spot will also result if the
ape~ of the prism(s) is not knife edge sharp.
Although the apexes 81 appear to be parallel to
one another in Fig. 10, it should be understood
that the apexes could be tapered or non-parallel
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-` 2023875
depending upon the shape of the person's visually
sensitive functional area of the retina.
With reference to Figs. 10-12, a pair of lens
elements 76 are shown mounted in a conventional
- 5 eye glasses frame 86 to provide prismatic eye
glasses 84, for achieving adequate expanded field
of view for a person suffering from retinitis
pigmentosa.
Fig. 11 is a sectional top plan view of lens
76 shown exaggerated for clarity. It discloses
the method for manufacturing prescription
- corrected field expanding lens 76 with bifocal.
Prisms 80, non-prism area 78, bifocal 162 and the
RX base curve 161 are molded as an integral unit.
The prescription RX 160 is ground and polished as
required after a patient has been tested and their
acuity measured. (See enclosed sample lens 76.)
Fig. 12 is a top plan view 86 and 88 showing
the overall thickness of a complete prescription
corrected field expanding lenses 84 mounted into a
standard spectacle frame.
It was discovered that a pair of opposed prisms 80
of a desired power arranged or positioned
substantially symmetrical relative to a horizontal
line A-A of the lens element extending through its
optic axis O could effectively horizontally expand
the normal central field of view. Another prism
80 interposed between the opposed prisms 80 and
extending below the A-A axis substantially along a
vertical B-B axis extending through the optic axis
O of the lens element could effectively expand the
normal central field of view downwardly.
Accordingly, it was discovered that lens elements
76 having a central non-prism area 78 and only
- 35 three prisms 80 could effectively and adequately
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202387~
-~ expand a person's central visual field of view in
_ the required horizontal and vertical directions
for a person suffering from retinitis pigmentosa.
~- It was further discovered that eye glasses 88
-~ 5 having substantially half of each lens element 76
with a non-prism area 78 and the remainder of the
` lens element provided with a prism 80, as seen in
Fig. 12, could effectively expand a person's field
of view in the required horizontal and vertical
directions for a person suffering from hemianopia.
With reference to Fig. 14, field expanding
eye glasses 89 can be mounted in a frame that is
adapted to be clipped onto the person's regular
prescription glasses, by any suitable means, not
shown. The regular glasses properly focus the
person's normal central visual field of view,
whereas the clip-on eye glasses 89 shift the
expanded portion of the field within and along the
peripheral edge of the visually sensitive central
functional area of the retina. The clip-on eye
glasses 89 are preferably made by any suitable
molding process, or the like, of any suitable
filter material, such as CORNING CPF 511. The
expanded field of view obtained on a conventional
perimeter testing chart by such clip-on eye
glasses 89 for a particular person is illustrated
in Fig. 29.
The aforementioned field expanding eye
glasses for retinitis pigmentosa and hemianopia
expand a person's normal central field of vision
without eye movement, and in addition can be
prescription corrected for each person, and the
vision can be corrected to near or reading acuity
with bifocals. In the field expanding eye glasses
shown in Figs. 10-12, the prism apexes and joints
.
-25-
-- ` 2023875
are shown exaggerated for purposes of clarity.
These lenses cannot be manufactured by
conventional standard ways of producing
--- prescription lenses. Instead, these lenses must
be molded by intricately designed molds which
provide properly positioned prisms with razor or
knife sharp prism apexes. The molds also provide
the lenses with a prescription base curve and
bifocals. In the molded production lens, the apex
lines and prism joint are practically invisible in
-~ the eye glasses when worn by a person. Also, the
-~ weight of the prescription corrected field
expanding eye glasses will vary from approximately
1.5 ounces to 2.0 ounces, depending upon the
choice of eye glass frame and lens size.
Referring to Fig. 15, a preferred method for
measuring the expanded field for a patient having
retinitis pigmentosa (tunnel vision) and
hemianopia, and providing improved prismatic eye
glasses 84, 88, 89 of the type shown in Figs.
10-14, for a person will now be described.
Initially, the eye examining apparatus 10 is
mounted on a mounting device 90 of the type shown
in Figs. 32-34, to be described later, and is
laterally, tiltably and rotatably adjustable by
suitable adjusting means to position its C-C axis
(Fig. 1) on the optic axis O of the person to be
tested. One eye 48 of the person is covered, and
as indicated in a previous paragraph, the
rotatable ring 30 of the optical assembly 22 of
the eye examining apparatus 10 is rotated for the
eye being tested from its normal position shown in
Fig. 1 to a position in which index 33 is locked
on the horizontal C-C axis of the apparatus. A
specifically designed eye chart 92 for each eye,
: .
-26-
202387~
- as seen in Figs. 16 and 17, is positioned 40 cm
from the eye being tested. Assuming that the eye
being tested has a tunnel vision of approximately
10, the person being tested should then clearly
see the first circle 94 of the test chart 92,
which will be conveniently colored a specific
color, such as black, for example. Maintaining
ring 30 in its locked position, mirror 34 is
slowly pivoted, thus simulating the introduction
of a prism 80 into the system. The person looking
- into the fixed mirror 32 is requested to indicate
whether or not he notices any diplopia, blind
spots, or can see any additional colorëd circles.
Movement of the pivotal mirror 34 is
continued in the temporal direction with the
person looking straight ahead with the tested eye,
until the person can no longer see any additional
colored circles 94. The pivotal mirror 34 is then
returned to the point at which the person most
clearly sees the furthermost colored circle.
Assuming, as shown in Fig. 15, that the person is
able to clearly see the fifth circle 94 with his
tested eye, this would indicate that a properly
positioned prism 80 along the horizontal axis A-A
of a lens element would expand the person's field
of view in the temporal direction from 10 to
approximately 80. For that eye in the temporal
position, the power of the prism 80 or prism
diopters required to provide this laterally
- 30 expanded field of view is read directly from the
diopter scale on the eye examining apparatus 10.
The rotatable ring 30 is unlocked, rotated
through an angle of 180, and again locked along
the horizontal axis C-C of the examining apparatus
10 to measure the possible laterally expanded
-27-
2023~75
field in the nasal direction on the opposite side
_ of the tested eye. The same procedure is followed
utilizing the eye chart 92 of Fig. 17, having
~- similarly colored circles 94 extending in the
opposite nasal direction. Assuming again that the
person is able to see the fifth colored circle 94
on the left, the prism diopters of a prism 80
required to obtain this laterally expanded field
of view in the nasal direction would again be read
directly from the eye examining apparatus 10.
Having completed the testing for the one eye,
the same procedure is followed for the other eye
with the previously tested eye covered. The eye
is tested in the temporal and nasal directions to
obtain the prism diopters of the prisms required
to obtain the maximum expanded field of view for
the tested eye. Let us assume the person is able
to see the fifth colored circle 94 in the temporal
and nasal direction for the other tested eye.
Accordingly, to provide a total expanded field of
view of approximately 160 for a person having
tunnel vision of 10, it is necessary, as
described earlier, to provide each lens element of
the eye glasses 84, 88, 89 with a pair of opposed
prisms 80 that are substantially symmetrical with
axis A-A (Fig. 10). With the apexes 81 thereof
- positioned along the normal central field of view
of each lens, the images refracted by the prisms
80 will fall within and along the peripheral edge
of the visually sensitive central area 70 of the
retina 72 of each eye, for expanding the normal
central field of view of each eye without any
substantial distortion and diplopia. The total
expanded field of view for the person can be
tested and confirmed by a conventional perimeter
, ~
-28-
202~87~
testing apparatus to obtain the expanded field of
~ view of substantially 160 along the horizontal
axis A-A and substantially 20 above and below the
- horizontal axis along the vertical axis for the
designed eye glasses, as seen in Fig. 18. The
visually sensitive central area 70 is denoted by
endless line 96, and the total expanded field of
view is denoted by endless line 98. The expanded
field of view obtained on the chart Fig. 18 was
obtained on a conventional perimeter testing
- apparatus with the field expanding glasses
(Fig. 10) for a particular person.
Utilizing the same procedure, the rotatable
ring 30 can be unlocked, rotated 90 to position
index 33 on line D-D opposite the index position
shown in Fig. 1, locked, and the pivotal mirror 34
operated in conjunction with the vertically
arranged colored circles 94 of the test chart 92
shown in Figs. 16 and 17. This test procedure
will indicate the prism diopters of power required
to laterally expand the patient's field-of view in
a downward, vertical direction. The same
procedure could be used to expand the person's
field in a vertical plane upwardly, but since such
field expansion would be of little value to the
person, there is usually no need to do this.
Although two separate eye test charts of the
- type shown in Figs. 16 and 17 are used, it should
be understood that the two charts could be
combined in a single eye test chart in which the
7colored circles extend laterally in both
directions from the upper circle of a vertically
- downwardly oriented line of circles.
Having previously measured the expanded field
for a specific person, lens members 76 are
-29-
`. ` 202387~
designed for the specific person, each having a
~ central non-prism area or portion 78 for
accommodating the normal central visual field of
view and prescription of the person, and a prism
area, such that expanded light rays pass through
the normal central field of view of the lens
elements, and are refracted on the functional
portion or visually sensitive central area of the
retina. As indicated earlier, this central field
or tunnel of the patient is expanded by a pair of
opposed prisms 80 for each eye of the required
- prism diopters with the apex 81 of each prism
along the periphery of the non-prism portion of
the lens member, which accommodates the patient's
normal field of view. Where the functional retina
72 is slightly offset from the measured pupilary
distance for a specific person, the frame 86 of
the pair of eye glasses is designed to space the
lens members 76 so that the center of the
non-prism portions 78 of the lens members 76
substantially coincide with the centers of the
visually sensitive functional central area 72 of
the retina 70, as seen for only one eye in Fig.
19. The non-prism portions 78 of the lens
elements are prescription corrected to accommodate
the person's refracted acuity. The person's eye
are individually refracted in a conventional
manner to obtain prescription values for the best
possible acuity for the person. For near or
reading distances, normal refraction procedures
are used to determine the prescription values for
bifocals.
As indicated earlier with reference to the
"clip-on~' eye glasses of Fig. 14, the eye glasses
are non-prescription field expanders that clip
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2023875
onto a normal prescription eye glass frame. They
~ can involve either a three or four prism concept
and can be made in various filter densities to
-~- accommodate each person. The expanded field
- 5 (prisms and non-prism areas) is measured in the
same manner as discussed heretofore for field
expanding eye glasses.
After all the pertinent information and data
obtained by the eye examining apparatus has been
~- 10 tabulated, a prescription is prepared on a form of
- the type illustrated in Figure 20, to enable an
optician to manufacture the lens elements and
mount them in eye glasses.
For a patient suffering from hemianopia, in
which a semi-cylindrical portion of the retina is
functional, and the remainder non-functional, eye
glasses are designed, of the type shown in
Fig. 12. For this condition, the lateral expanded
field along the horizontal axis A-A is measured by
the same procedure used for the person having
retinitis pigmentosa. When the pivotal mirror 34
is moved to the position of best vision for the
person, the prism diopters are read directly from
the diopter scale, and such a prism 80 is
incorporated in the lens elements 76 of the eye
glasses 88. Once again, the apex 81 of the prism
80 is adjacent to the non-prism semi-circular or
half portion 78 of the eye glass 76, so that the
expanded field image is refracted along and within
- 30 the peripheral edge of the visually sensitive
functional portion 70 of the retina 72. As
indicated earlier, the location of the apex 81
relative to the non-prism portion or area 78 is
- critical, because if the non-prism area is too
narrow, diplopia will occur, whereas if the
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2023875
non-prism area 78 is too large, a blind spot will
~_ occur between the periphery of the functional
- retina 72 and the expanded field. Where
applicable, the lens elements of the eye glasses
88 may be provided with bifocals to improve the
near or reading distance viewing.
Another method of measuring the expanded
field for patients with retinitis pigmentosa or
hemianopia involves using a conventional eye
examining apparatus 10 that has been modified to
provide a central circular field stop or aperture
110. Trial prisms 102 are provided of the type
illustrated in Figs. 21-24. Each trial prism is
provided with a clear plastic or glass base
support 104 onto which are mounted three or four
prisms 80, each of the same prism diopters. Each
trial prism 102 will have prism diopters of power
ranging from 6 diopters to at least approximately
20 diopters. The trial prisms 102 will further be
provided with a varying non-prism area or portions
78 of a varying width for accommodating normal
central fields of vision varying from
approximately 5 to 50. This will require 60 or
more trial prisms 102. By subjective testing with
the trial prisms 102 in the modified test
apparatus 10, the prism diopters of power required
for optimum vision is obtained, along with the
proper non-prism area or portion 78 for minimizing
diplopia and/or blind spots. Normal refraction
procedure is used to obtain the best possible
acuity for the non-prism area.
Still another method for measuring the
expanded field for a person suffering from
retinitis pigmentosa or hemianopia involves
obtaining the normal visually sensitive central
-32-
202387~
functional portion or retina field 72 of each eye
~_ of the person on a conventional perimeter testing
apparatus. With reference to Figs. 19 and 25, the
visually sensitive retina field 72 for one eye of
a person is observed on the perimeter testing
chart to fall within a 10 field, but has a center
O' slightly offset from the center or optic axis
O. A similar determination is made for the other
eye. Accordingly, to make a pair of prismatic eye
glasses 84, 89 for such a person, a non-prism
`- portion 78 of each lens element 76 is selected of
- a width substantially equal to the width of the
normal central retina field 72 of each eye. Then,
utilizing the aforementioned Snell's Law and
derivations therefrom, and making assumptions for
the indexes of the cornea 62, aqueous 64, lens 66,
and vitreous 68, the distance between the nodal
points, etc., it is possible to mathematically
calculate the pertinent data needed, such as the
- 20 prism diopters of power for prisms 80 required to
surround the non-prism portion 78 to refract an
expanded field image along and within the
peripheral edge of the functional or central
visually sensitive retina field 72. The
calculations can be made by any suitable
calculation procedures. Knowing the sizes of the
non-prism portions 78, and the sizes in diopter of
the prisms 80 surrounding the non-prism portions,
the pupilary distance between the centers of the
visually sensitive central retina fields 72 to
place them in the non-prism areas 78 of the lens
elements 76 can be calculated. As indicated
earlier, this is necessary in those instances
where the visually sensitive retina field 72 is
offset from the normal pupilary distance between
-33-
202~7~
the eyes, as shown in Fig. 19. Having obtained
~ all of the pertinent data, a prescription of the
form shown in Fig. 20 can be prepared to enable an
optician to make the prismatic eye glasses.
With reference to Figs. 26-28, still another
method is disclosed for measuring the expanded
field of view for a person suffering from
retinitis pigmentosa or hemianopia. This method
involves the application of computer analysis in
three dimensions for tracing a ray of light
through each prism and eyeball to find its
- intersection with the retina. The points (-10,0),
(10,0) and (0,-10) were chosen because of their
near symmetry. In each case, the shift of the
image is inward in the direction of the
orientation angle of the prism. In other words, a
ray going through the upper right or left prism is
shifted inwards toward the vertical at an angle of
thirty degrees to the horizontal (Fig. 26). The
inward shift of a ray going through the lower
central prism is shifted directly upwardly~since
the orientation angle of that prism is ninety
degrees to the horizontal. The magnitude of the
shifts at the points (-10,0) and (10,0) for five
diopters of prism power is .816 mm (Fig. 27), and
at the point (0,-10) is .814 mm (Fig. 28). The
- shift in image for prisms of a different diopter
- of power can be extrapolated from the above
- findings.
When the eye examining apparatus 10 is used
for measuring the expanded field for a person
having retinitis pigmentosa or hemianopia, a field
stop plate 106 (Figs. 15, 30, 31~ of the optical
simulated prism assembly 22 is provided with a
central aperture 110 of varying diameter,
' .
-34-
- 202387~
depending upon the size in degrees of the visually
sensitive central field of vision of the person
being tested.
With reference to Figures 32-34, a redesigned
mounting device 90 is illustrated or refracting
and measuring expanded fields for persons
suffering from retinitis pigmentosa and
hemianopia. It can also be used for refracting
for persons suffering from macular degeneration.
- 10 The mounting device 90 supports the eye examining
apparatus 10, the chin of a person being tested,
- and positions the eye test charts 92 a precise
distance from the retina of an eye being tested.
The mounting device 90 comprises a conventional
base assembly having a base 118, a pair of upright
support rods 120, a C-shaped support bracket 122
mounted on the ends of support rods 120, and a
chin support member 119 slidably mounted on
support rods 120. ~ conventional adjusting
screw-type member 121 is provided on chin support
- member 119 for adjusting the position of the chin
support member for each person.
The support bracket 122 has a smooth central
cylindrical opening 124 through which an elongated
screw adapter 126 extends. The lower end portion
125 of screw adapter 126 has a non-circular
aligning recess 127 (Fig. 33) for receiving a
-- similar shaped projection 129 on the upper bracket
12 of the eye examining apparatus 10. The eye
examining apparatus 10 is secured to end portion
125 by a screw 131.
A rod-chart support bracket 128 has a smooth
cylindrical opening 130 through which screw
adapter 126 extends. Bracket 128 has a blind bore
-- 35 134 of square-shaped cross section for receiving
.
-35-
2023875
one end of an elongated rod 136 of a complementary
square-shaped cross section. The rod 136 is
secured to bracket 128 by a set screw 144. A
- scale 138 in centimeters from 10 to 50 is
inscribed on the rod 136. A test chart holder 140
--- is slidably mounted on the rod 136, and has a clip
142 for holding an eye test chart 92 of any
suitable type.
Vertical adjustment of the eye examining
apparatus 10 relative to an eye test chart 92 is
achieved by a bullet-shaped screw cap 146 which is
- threaded onto one end of the screw adapter 126,
and a locking ring 148 which is threadëd onto the
opposite end. To vertically adjust the eye
examining apparatus 10, the locking ring 148 is
loosened, and the screw cap 146 is turned to
vertically adjust screw adapter 126 and the eye
examining apparatus 10 supported thereby. When
the desired position is achieved, the locking ring
148 is tightenéd to secure the eye examining
apparatus in the desired position.
With reference to Figs. 33 and 34, to
properly align the screw adapter 126 to support
bracket 122 and to rod-chart support bracket 128,
a pair of conventional Woodruf keys 150 is
interposed between an elongated key slot 152 in
the screw adapter 126 and key recesses 154, 156 in
support bracket 122 and rod-chart support bracket
128 respectively. The keys 150 and slot 152
maintain the eye examining apparatus 10, screw
adapter 126, and rod-chart support bracket 128 in
a properly aligned position for all positions of
vertical adjustment of the eye examining apparatus.
While a preferred embodiment of the invention
has been shown and described with particularity,
-36-
202:~7~
it will be appreciated that various changes and
modifications may suggest themselves to one having
ordinary skill in the art upon being apprised of
the present invention. It is intended to
encompass all such changes and modifications as
fall within the scope and spirit of the appended
- claims.
-37-
