IMPROVEMENTS IN INSTRUMENTS FOR ESTABLISHING THE REFRACTIVE ERRORS OF THE EYE
Year: 1885

page_text: Errors of the Eye.
We ARISTIDE MARIE ANTOINE FOURNET of 6 Poultry Ophthalmic Optician and
WILLIAM CARLTON WOOD of 31 Wilson Street Export Merchant both in the city
of London do hereby declare the nature of our invention for "IMPROVEMENTS IN
INSTRUMENTS FOR ESTABLISHING THE REFRACTIVE ERRORS OF THE EYE" to be as
follows:-
This instrument consists of two sets of circular double plates carrying any
number of standard test lenses, fitted within their diametral border. These two
plates are opposed to each other and revolve independently on a common centre or
spindle, in a vertical plane. Each plate can be used separately or jointly, either
by a vacant space in each of them, or by a decentering motion to one of them.
To
The posterior plate which stands nearer the eye under examination is covered
with a shield or black plate, having a perforation on either side of its horizontal
border; so that only one lens of each plate can be seen through at a time.
prevent the moisture of the breath settling on the glasses, the right eye looks
through the left liole and the left eye looks through the right hole of the black
plate.
The plate immediately in front of the shield is mounted with spherical lenses
and revolves on the spindle by suitable mechanism such as rack work the pinion
of which is facing the operator and a spring click stops each lens in succession in
the centre of the hole that is looked through.
The second plate which superposes the last explained, is fitted with lenses
somewhat larger, that are of cylindric curvature; the axes of all of these lenses are
precisely adjusted in the same direction to the centre of the plate; so that when
any one of them lies with its axis horizontal in front of the hole, the others will
come in succession with their axes in the same direction; and by a system of cog
wheels all the cylindric lenses are made to revolve together at the same rate, and
their exact position is recorded on a large divided are on the surface of the plate.
The degree of rotation of the lenses is engraved on the plates, and so arranged
as to be easily seen by the operator; the mode of suspension of the two sets of
plates can be adapted to suit the wants of the operator and forms no part of the
patent. One of the double sets carries concave lenses and the other set convex
lenses.

page_text: Errors of the Eye.
We ARISTIDE MARIE ANTOINE FOURNET of 6 Poultry Ophthalmic Optician and
WILLIAM CARLTON WOOD of 31 Wilson Street Export Merchant both in the City
of London, 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:-
In the accompanying drawings Figure 1 is a front view (operator's side) of one
single apparatus complete, Figure 1ª is an enlarged portion of Figure 1. Figure 2
is a back view (patient's side) of the same. Figure 3 an edge view of the same.
Figure 4 a general view of the complete double apparatus as disposed about the
patient's chair and Figure 5 a like view from behind the patient's chair.
This instrument consists of two sets of circular double plates A and B carrying
any number of standard test lenses C and C₁ respectively the series of lenses
being;-
1° Concave Spherics-For the determination of the degrees of . . . . Myopia.
2° Concave Cylindrics-For the determination of the degrees of Myopic
Series 1° & 2° combined. For the determination of the degrees of Compound
Myopic Astigmatism.
Astigmatism.
3° Convex Spherics. For the determination of the degrees of..... Hypermetropia.
4° Convex Cylindrics. For the determination of the degrees of Hypermetropic
Astigmatism.
Series 3° & 4° combined.
Series 1° and 4° combined'
or
Series 3° and 2° combined
For the determination of the degrees of compound
Hypermetropic Astigmatism.
For the determination of the degrees of mixed
Astigmatism.
The two plates of each set are placed one in front of the other and revolve
independently on a common centre or spindle D in a vertical plane-Both the
front and back plates of each sot are revolved on the spindle from the operator's
side and these two plates can be used either separately or jointly by a vacant
hole (an empty hole without a glass) in each or by a decentering motion.
•
The posterior plate B which stands nearer the eye under examination is covered
with a shield or plate E (Figure 5) having a perforation E¹ on either side of its
horizontal border so that only one lens of each plate can be seen through at a time.
To prevent the moisture of the breath settling on the glasses the right eye looks
through the left hole and the left eye looks through the right hole of the plate E.
The disc B immediately in front of the shield E is mounted with spherical
lenses C² of graduated powers and revolves on the spindle D by means of any
suitable mechanism such as that shown in the drawings and consisting (as will be
seen by reference to Figure 2) of the toothed ring B which is secured upon or
connected with the plate B. The toothed wheel B2 gears with ring B₁ and is
driven by the pinion B³ firmly connected and revolving with which is the wheel B
which in its turn is driven by B5 which is connected with the handle knob B6.

page_text: The object of all this gearing is merely to reduce the relative amount of travel
imparted to ring B' by the knob Be for the sake of steariness and more accurate
adjustment. The knob B° faces the operator so that he can revolve the disc Bas
he requires. The disc can only be revolved by turning the knob B. A spring
click stops the disc B as each lens C comes in succession opposite the centre of
the hole E that the patient looks through.
The second plate or disc A which superposes the last explained is fitted with
lenses C somewhat larger of graduated powers that are of cylindric curvature; the
axes of all these lenses are precisely adjusted in the same direction to the centre of
the disc so that when any one of them lies with its axis horizontal in front of the
hole E the others will come in succession with their axes in the same direction
and by a system of cog wheels all the cylindric lenses are made to revolve together
at the same rate and their exact position is recorded on a large divided arc on the
surface of the plate. This diso A can be revolved by hand at pleasure.
This mechanism may be arranged as follows:-Each lens C is held in a suitable
toothed framed ring which gears with the toothed ring or disc G adapted to
revolve about the general centre D. With G is connected the smaller toothed ring
or disc H which is turned by the small but long pinion I fixed upon the spindle of
the knob J. When J is turned therefore the pinion I revolves H which carries G
round with it and so revolves every one of the lenses C whose frames gear with it
the lenses C must therefore all revolve at the same rate and having been originally
properly adjusted they always retain their true relative positions.
The mechanism which indicates to the operator the axial position of each of the
lenses C (and therefore of that particular one which is opposite the hole E¹ at the
time the observation is made) consists of the fixed plate K upon a portion of whose
peripheral border is set out the segmental index scale K¹ representing the 180° or
two right angles of the circle; this scale might extend further round or entirely
round but the segment shown is sufficient. In front of this is the revolvable plate
or disc L the arrows L¹ upon which serve to indicate the exact position of the
lenses C upou either side of the scale that is the amount of deviation from the
horizontal line of the lenses C.
The disc L is carried upon a collar L which also revolves about the common
centre D and is toothed at L³ and gears with the toothed wheel M which gears
with the same pinion I which drives the disc H so that the motion communicated
to M and H is identical in all respects.
The gears M and L³ are proportioned according to the divisions of the scale Ķ¹
and the diameter of the plate L so that the arrows L' truly represent upon the
scale the axial position of the lenses C.
The inclination or direction of the refractive axis of each lens of the cylindric
series is adjusted to correspond with the degree or angle indicated on the index
scale K¹ by the indices L' on the movable plate L; the latter travelling at a slower
rate than the lenses, an extended or magnified reading is thus obtained for the
sake of legibility; the denomination or dioptric value of each lens is also figured
on each disc; the figuring on the posterior plates showing through the lenses of
the front plates. When the vacant holes of each disc are brought to the perforation
in the shields E through which the patient looks the instrument is at zero.
The mode of suspension of the two sets of plates can be adapted to suit the wants
of the operator and forms no part of the invention.
A convenient way of doing this however is shown in Figures 4 (view from the
operator's side) and 5 (view from behind the patients chair).
N is a stout wooden pillar working up and down in the tube N¹ by means of a
rack and spiral pinion operated by the crank handle N'. ○ ○ are two curved
armis projecting out from the pillar N to the extremities of which are secured two
brass tubes P. These tubes have each inside of their whole length a screw on which
works à nut-that is firmly secured to the top end of the rods or tubes Q which
carry the lens, discs & each nut being let through inside of the tubes P by a slit
which is made in the underside of each. The handle P¹ can be fitted on the end

page_text: of either screw and by turning the said handle P¹ one or other of the discs can be
made to travel to and fro right across the bars. The tube N¹ is secured to the
back of a heavy arm chair and when not in use the pillar N is raised; after the
ophthalmoscopic or optometric examination of the patient he sits in the arm chair
and the pillar N is lowered by crank N to bring the apertures E to the level of
his eye; then handle P¹ can be made to cause the set required to travel to meet the
patients eye who looks with his right eye through the left edge of the plate E and
vice versa.
One of the double sets of plates carries in its posterior or back plate (patient's
side) concave spheric lenses for the determination of the degree of myopia and
the front plate carries concave cylindric lenses arranged as previously described for
the determination of the degree of myopic astigmatism. The spheric lenses in the
posterior plate can be seen through by themselves when the vacant hole in the
front plate that carries the cylindric lenses is placed in front of the aperture E'
through which the patient looks. Similarly the cylindric lenses of the front plate
can be seen through by themselves by bringing the vacant hole in the back plate
that carries the spheric lenses in front of the aperture E¹ that is being looked
through or by a decentering motion that would leave the lenses of only one of the
plates in a position to be looked through at a time. And lastly the two plates can
be used jointly for the determination of the degree of Myopia combined with
Myopic Astigmatism.
The other set of double plates carries the convex lenses and works in exactly the
same way for the determination of the degree of hypermetropia hypermetropic
astigmatism and the combination of the two.
The front plates of both double sets carrying the cylindric lenses can be removed
and changed from their spheries for the determination of mixed astigmatism for
which purpose the plate mounted with the convex cylindric lenses will be placed
in front of the concave spherics.
The arrows serve to show the direction of the movements of the various parts
when the knob J is turned in one direction; if the movement of the knob be
reversed the other movements will be also reversed.
The instrument may also have a fifth plate exactly similar to the interchange-
able plates A Figure 1 but mounted with prismatic lenses for the determination
of the refractive displacement required to assist muscular asthenopia and
strabismus.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that
what we claim is :-
1. In an instrument for determining the degree of refractive error of the eye the
combination of two discs revolvable about a common centre each fitted with a
series of standard test lenses substantially as and for the purpose specified.
2. In an instrument for. determining the degree of refractive error of the eye the
combination of two discs revolvable about a common centre the one carrying a
series of spherical lenses fixed within its peripheral margin and the other a series
of cylindric lenses similarly located but adapted to revolve each upon its own axis
substantially as specified.
3. In an instrument for determining the degree of refractive error of the eye the
combination with a disc A adapted to be revolved upon its centre of a series of
cylindric lenses carried in toothed frames or rings the whole of which gear with a
toothed ring or plate in such manner that as the said toothed ring or plate is
revolved each of said lenses is revolved about its own axis at the same rate as all
the rest substantially in the manner and for the purpose specified.
4. In an instrument for determining the degree of refractive error of the eye the
combination with a series of cylindric lenses C each carried in a frame or ring C
of a central plate & gearing with the whole of said rings C¹ and carrying a toothed

page_text: ring or plate H adapted to be turned by a pinion I the whole constructed and
operating substantially in the manner and for the purpose specified.
5. In an instrument for determining the degree of refractive error of the eye the
combination with a series of cylindric lenses adapted to be revolved simultaneously
about their own centre of an indicating mechanism consisting of a fixed graduated
plate and a moveable index disc or plate operated by the same gearing which
revolves the lenses substantially as specified.
6. In an instrument for determining the degree of refractive error of the eye and
as a means of operating a series of cylindric lenses carried in toothed rings in a
plate or disc adapted to be revolved about its own centre the combination with
said toothed rings of a central revolvable toothed ring or disc firmly secured to the
first disc and an actuating pinion the whole constructed and operating substantially
in the manner and for the purpose specified.
7. In an instrument for determining the degree of refractive error of the eye and
as a means of simultaneously revolving a series of cylindric lenses about their own
centres and at the same time indicating the amount of such movement the com-
bination with an actuating pinion I toothed plates or rings H and G and toothed
frames C¹ which contain the lenses of a toothed wheel M gearing with pinion I a
toothed collar L L³ an index plate L secured upon said collar and moveable with
it and a fixed graduated scale plate K K¹ the whole constructed and operating
substantially as specified.