US2195169A - Ophthalmoscope - Google Patents

Description

Patented Mar. 26, 1940 UNITED STATES orn'rnamoscorn Theobdd Grail, Bathenow, Germany, assign Emil Busch, Aktien-Gesellschaf or to Optimize- Industric, Bathenow, Germany Application July 21, 1 I In Germany 'lzclaims.

' 1o vantages obtained will be morefully understood by first reviewing the advantages and deficiencies characteristic of the Thorner ophthalmoscopes when compared with those of other ophthalmoscopes having self-contained illuminating means, 15 known for instance from United States Patent 2,014,888 to Forshey, and with those of the oldest and simplest type of ophthalmoscopes widely known and briefly called hereinafter the Helmhol ophthalmoscope, which has noself-congo tained illuminating means, but simply consists of a concave mirror having a central opening, and cooperating with a foreign source of light. Because of its simplicity of construction, low price, small compass and weight and the large 25 magnification of the funds obtained, which is magnified about fifteen times by the retracting cooperation of the patients pupil and which is seen in its naturalupright position, the Helm-.- holtz ophthalmoscope has been, up to the present 30 day, used by eye-specialists, more so because as a rule only eye-specialists acquire and preserve by constant practice the great manual skillrequired in successfully using the old Helmholtz ophthalmoscope. 35 As a matter of fact, known among medical practictioners, in inspecting the patients fundus with the Helmholtz ophthalmoscope great skill and dexterity is required for so manipulating and aiming the instrument, that the beam of 4 light which is to be directed into the patients eye but strongly reflected in the first instance by the convex face of the pupil-the cornea does not coincide with and does not suppress the weaker picture of the fundus composed of the 45 more diffuse light rays reflected from the latter.

A few other drawbacks inhering to ophthalmoscopes of the old Helmholtz type consist in that their fields of vision is rather small, namely restricted practically to the size of the patient's 5o pupil, that, on using the instrument indirectly, i. e. jointly with a condenser lens for enlarging the field of vision, the resultant picture is magnified only by 4 to 5 times, that the a fied fundus picture lies upsidedown instead in up- 55' right position, and-last not least-that also at 938, Serial No. 220,553

July 24, 1937 the said lens glaring lights and irritating reflexes are produced, which must beavoided by further concentration on the part of the observer in skillfully handling the instrument.

As well the use of direct method (without condenser) as the indirect method (wlth condenser) of using the ophthalmoscope was facilitated ,by the invention of the electric ophthalmoscope which diifers from the Helmholtz ophthalmoscope with respect to the self-contained illuminating means in fixed position and being known for instance from the cited United States Patent to Forshey; yet the disturbances from that. glare are unavoidable also with the use of thisophthalmoscope and they are in principal the same as with the Helmholtz ophthalmoscope.

'Ihorners and his successors improved selfilluminating ophthalmoscopes referred to above and widely used by the medical profession avoid the glaring lights reflected both-from the magni--.

fying lens used in connection with the old Helmholtz instrument and from the.patients cornea by the provision of an optical system radially different from the former, namely being enclosed in a casing or dark room and including a source 5 of light, a concave mirror directly opposed to the patients eye, another reflecting mirror, and an' eye piece co-operatively associated with a diaphragm.

Forreasons known in all details only to manu- 3 facturers of ophthalmoscopes of the Th'orner type the overall length of the latter necessary for accommodating in a' casing their complex optical system is rather large, approximating in practice about 200 millimete'rsor 8 inches; their great length causes in turn a rather long total distance of the observers eye from the patients eye, andthis what may be-called long leverage renders the handling of the instrument uncomfortable at least on examining the outer do peripheral and eccentric zones of the fundus, more so since the examination is somewhat impeded by the inverted position of the retinal image and the small rate of magnification.

In spite of these and other drawbacks including their relatively high price ophthalmoscopes of the Thorner type are widely used all over the world because of the freedom from glaring lights and delusive reflections, and have been up to the present the diagnostic instrument preferred by a great many physicians and allrouncl medical practitioners who are not eye-specialists and are not acquainted with the intricacies of ophthalmoscopes of the Helmholtz typ and who u only occasionally have to resort to diagnoses based on inspection of the patients fundus.

The principal object of the invention is to provide a structurally improved self-illuminating ophthalmoscope, wherein the various drawbacks inherent to instruments of the self and non selfilluminating types referred to above are eliminated, and which offers their advantages com bined, namely: A relatively short distance-not exceeding 100 millimeters-between the doctor's The nature and scope of the invention arebriefly outlined in the appended claims and will be more fully understood from the following specification taken together with the drawing, in which Fig. 1 is a fragmentary elevation perspectively showing by way of an example an ophthalmoscope improved according to this invention,

Fig. 2 is a section vertically taken through the instrument on its optical main axis,

Fig. 3 is a fragmentary side elevation of the upper section of the instrument with a protecting cover removed, I

Fig. 4 is a section horizontally taken through the upper section of the instrument online 4-4 in Fig. 2 and seen from below in the directio of the arrows,

Fig. 5 is a perspective view showing in a larger scale a roof shaped prism as used for the purposes of this'invention, of which the bottom and rear race through which the light rays enter and pass out respectively are the only ones which are not blackened and are marked by hatched lines.

The ophthalmoscope re-designed with the ob-' jects in view outlined above and shown by way of an example in the drawing comprises:

(1) A tubular casing 6 closed at the top and patients eye E and a rear aperture diametrically arranged to the former and facing the observer's or doctors eye E,

(2) Primary reflecting means in the form of a mirror 8 fixed within said casing at its front aperture 1 in inclined position for reflecting light rays received from below into the patients eye E and vice versa as indicated in Fig. 2 by dash lines -i and dash and dot lines i'-- (3) Secondary reflecting means comprising a roof or similar side inversing prism ll, fixed in said casing 6 at its rear aperture, in spaced relation to the mirror 8, and having blackened faces except its bottom and rear face which are marked by hatched lines in Fig. 5. and a-diaphragm ii partly covering the bottom face of the prism and leaving free only a restricted area of the latter through its rear face in the direction of the arrowr', I

(4) Illuminating means enclosed in the upper portion of the casing 6 which comprise:

An incandescent electric lamp l2 preferably presenting a rectilinear filament (not'shown),

a socket l3 wherein said lamp is fixed and through which the latter is connected with an electric circuit indicated at I4; the socket l3 wholly encloses the electric lamp l2 except at its upper right side where a condensing and reflecting element preferably in the form of a small concave mirror I6 is detachably fixed in such position opposed to the electric lamp [2 and the roof prism ID, that a beam of light indicated in Fig. 2 by its central ray i is downwardly reflected so as to closely pass by the inner end of said blackened roof prism l0,

(5) A concave mirror l8- fixed in the lower portion of casing 6 in opposed position to said illuminating and reflecting means for cooperation therewith; the distance of said lower concave mirror from said reflecting means is so chosen, that the-light rays received at and reflected from the concave mirror It enclose a relatively small angle a, substantially not exceeding 20. This is an important feature of the instrument redesigned according to this invention, inasmuch as distortions of the fundus image are avoided by virtue of the smallness of said angle'and of the strictly symmetric position of the concave .type attached to the casing 6 and comprising: A primary rotatable disc 20, wherein a primary set of lenses 2| graduated as to their retracting characteristics preferably progressing from 10 to 10 diopters is fixed, a dial 22 hearing indices which is cooperatively associated with said primary disc 20 by a toothed gearing 22', a secondary rotatable disc 24 coaxially arranged to the former which is provided with indices and wherein a secondary set of lenses 25 graduated as to their refracting characteristics, preferably 9 lenses ranging from one to nine diopters, is fixed for cooperation with the said primary set of lenses 2i, and a cover 26 having sight holes 12, n, n" and enclosing said discs 2|,v 24 and said dial 22.

The cover 28 is-so designed and proportioned that the dial 22 and the secondary disc 24 are accessible to the operator'as seen in 'Fig. 1 and can be revolved independently of each other; a selected pair of lenses 2|, 25 chosen with regard to anomalies or specific defects of vision of the patients eye can thus be quickly brought into line with the light rays issuing from the roof prism Ill at r and an amply magnified image showing the illuminated section of the fundus in natural position without lateral left to right changes will be visible to the operator.

Goods results'have been obtained with ophthalmoscopes re-designed according to this invention wherein the optical characteristics of the vital component parts described above were so chosen, that the magnification of the retinal pic-' tureranged from-15 to 20.

The absence of glare and irritating reflexes in the retinal image is due to the specific design and lightselecting arrangement of the roof prism i0 described and its cooperation with the diaphragm ii and the other optical elements of the nstrument. I

No speciei sin is required in so holding the with its reflecting means inclined toward the rear trelaflvelytothepotientseyethatthe wbeam ofiightbythe illuminatingmeansisthrownuponthefundusthrough anexcentricsectionofthepatientspupflmsay thelowerhalfofthelattenasseeninFigJfrom theinnerraysr -iindicatedbydashlinesin thiscasethereflnalimaseproducedandseenby the observer ,will be composed exclusively of light rays which are reflected from the fundus through the u sectionof the patients eye andareselected theroofprlsmllasseenfrom the light rays i'. i' indicated by dot and dash lines.

Instead of the rather costly eye piece a. the

Recoss type described chosen with the object of enabling the operator to compromise during the inspection with specific defects of vision of the patients eye,another appropriate and less e'xpensive eye piece of simpler design as known in the art maybe applied to equal advantage for the purposes of this invention.

Various other changes and modifications may be conveniently made in the structural details of ophthalmoscopes of the improved design described, without from the spirit and the salient ideas of this invention:

Forinstancethecasingioftheinstrlnnent, which because of its tubular form presents a proper handle by itself, may be provided to advantage with a separate handle 3' telacopingly and detachably fitted by means of a reduced neck 3G in the lower portion of the casing 6 for frictional engagement therewith and carrying said concave mirror I; this latter feature is advancasinghavingclosebspaced tageousbecauseonwithdrawingthehandle 36, themirrorllandtheinteriorofthecasingiare accessibleforinspection, cleaning,repairandkin- 'lhemidhandleflmaybemadehollowforthe reception of an electric dry cell and/or for accommodating aswitch for'making andbreaking theelectriccurrentsuppliedtothe electriclamp I'heuppersectionofthetubularcaslngi'carryingtheandreflectingmeans including the mirror l,.the roof prism II and the llmaybemadetoadvantageasa separateelementinthe form ofacap 4S telescom'nglyand detachablyflxcdinthecasingibyfricflonalinnomeofthe' lowercontourlinesofsaidcapliareshownat li'andlf'inlfigslandl Theopticaicharoftheeye ieceandcmcavemirror aresochosmthata u: 4 imageofthe fundusispmducemtherateofmagniflcaflon averagingflfteen.

Although a preferrcdtvof inventionhasbemanddescrimvariationswithhithetruespiritandscopeofthe samearetobebytheappended claims. whatlelaim k: b l 0 n tionanelomatcdhollowcasing m m frontandrearwalls, the closelyspaoedwallshavingoptically onein each walLa concave mirror,

mountedintheeaslngremotefromsaidend-and positionedwith'itsopticaluissuhstantlallyparallelwiththeaxisofsaidcasingand with its surface toward said end, a front mirror mounted in said casing adjacent then-ontwallapermrewithitsreflectingsurface inclinedtowardsaidfrmtwailaperturearear mirrormonmtedadiacenttherearwallapertme.

wall aperture, said front and rear wall mirrors being inclined to reflect light from the respective apertures toward the concave mirror and then from the concave mirror to the other aperture, means between the front and rear mirrors to provide a light passage to the concave mirror, and means to direct light through said passage.

.2. An ophthalmoscope comprising in combination a substantially elongated hollow casing having closely spaced front and rear walls and hav-' ing optically aligned apertures therein adjacent one end of said casing, a concave mirror mounted in said elongated casing remote from said end and positioned with its optical axis substantially parallel with the longitudinal axis of the casing, a mirror in said casing adiacent the front wall aperture having its reflecting surface inclined to- ,ward said aperture to direct images received therethrough upon said concave mirror, a refleeting prism adjacent the rear wall aperture having reflecting means inclined to said aperture to receive images from said concave mirror and direct them through the rear wall aperture, and means between the second named mirror and prism, providing a light passage to the concavemirror andparranged to direct light through said 3. An ophthalmoscope comprising in combination an elongated hollow easing, one end of the casing having closely spaced front and rear walls,

the closely spaced walls havipg optically aligned apertures, one-in each wall, a concave mirror mounted in the casing remote from said end and positioned with its reflecting surface facing toward said end, a primary reflecting means mounted in saidcasing adjacent the front wall aperture with its reflecting surface inclined toward said front wall aperture, secondary reflecting means mounted adjacent the rearwall aperture with its reflecting surface inclined toward the rear wall aperture, said reflecting means he inginclined toreflectlightfrom therespective apertures toward said concave mirror and then from the concave mirror to the other aperture,

means between the front and rear apertures to provide a. light passage to the concave mirror, and

:fllght source arra-ng ed to direct light through 4. An ophthalmoscope comprising in combination an elongated hollow casing, one end of the casing having closely spaced front and rear walls with optically aligned aperturesin said walls, a concave mirror mounted in the casing remote fromsaid end and positioned with its reflecting surface toward said end, primary reflecting means mounted in said casing adiacentrthe front wall aperture with its reflecting surface inclined toophthalmoscope' comprising in combina- Mon an elongated hollow casing having closely spacedfrontandrearwallsatoneendwithopti callyaligned apertures ineach wall, a concave e to the concave mounted hi the casing remote rromsaid ,toward said end, a primary reflecting means ,z'noufnteddn said casing adjacent the front wall aperture-with its reflecting surface inclined toward said front wall aperture, secondary reflecting means mounted adjacent the rear wall aperture with its reflecting surface inclined toward the rear wall aperture, said reflecting means being inclined to reflect light from the respective apertures toward said concave mirror and then from the concave mirror to the other aperture, means between the front and rear apertures to provide a light passage to the concave mirror, and means to direct light through said passage, said mirror and reflecting means positioned and arranged so that the angle between received and reflected light beams does not exceed in the neighborhood of about 26.

6. An ophthalmoscope comprising in combination a substantially elongated hollow casing having closely spaced front and rear walls and having optically aligned apertures therein closely adjacent one end of said casing, a concave mirror mounted in said casing remotefrom said end and positioned with its reflecting surface toward said end, a mirror in said casing adjacent the front wall aperture having its reflecting surface inclinedtoward said aperture to direct images received therethrough upon said concave mirror,

a reflecting prism adjacent the back wall aperture having reflecting means inclined to the last mentioned aperture to receive images from said concave mirror and direct them through the rear wall aperture, means between the second mirror and prisms providing a light passage to the concave mirror, a source of light in said casing, and a mirror to direct light from said source through said passage to said concave mirror.

'7. An ophthalmoscope comprising, in combination a substantially elongated hollow casing having closely spaced front and rear walls with optically aligned apertures therein closely adjacent one end of said casing, a concave mirror mounted in sail elongated casing remote from said end and positioned with its optical axis substantially parallel with the longitudinal axis of the said casing, a mirror in said casing adjacent the front wall aperture having its reflecting surfaceinclined toward said aperture to direct images received therethrough upon said concave mirror, a reflecting prism adjacent the back wall aperture having reflecting surface inclined to the last mentioned aperture to receive images from.said concave mirror and direct them through the rear wall aperture, an eye-piece optically aligned with said rear wall aperture, and means between the reflecting surface of the second mirror and prism providing a light. passage to the concave mirror and to direct light through said passage, said mirrors, eye-piece,

' and prism so arranged that the observed image is magnified in the neighborhood of about at least fifteen times.

8. An ophthalmoscope comprising in combina tion an elongated hollow casing having closely tioned with its reflecting surface toward said end, primary reflecting means mountedin said casing with its reflecting surface inclined toward said front wall aperturefisecondary reflecting means mounted in said casing with-its reflecting surface inclined toward the rear wall apertur r the concave mirror and to direct light through c 2,195,109 g ins positioned with its reflecting surface light from the respective apertures toward said first named mirror and then from the first named mirror to the other aperture, means between the front and rear apertures to provide a light passage to the concave mirror, and a light source arranged to direct light through said passage, said light source and reflecting means being so located in the casing, that the light beams directed into the observed eye and reflectedfrom the fundus thereof pass through different parts of the pupil.

9. An ophthalmoscope comprising in combination a substantially elongated hollow casing having closely spaced front and rear walls adjacent one end of said casing, and having optically aligned apertures in said walls, a concave mirror mounted in said elongated casing remote from said end and positioned with its reflecting surface facing toward said end, primary reflecting meansin said casing-adjacent the front wall aperture having its reflecting surface inclined toward said aperture to direct images received therethrough upon said concave mirror, a-secondary, reflecting means adjacent the rear wall aperture having its reflecting surface inclined to the last mentioned aperture to. receive imagesfrom said concave mirror and direct them through the rear wall aperture, means between said reflecting means, providing a light passage to the cancave mirror and todirect light through said passage, and said means allpositioned in a detachable end cap constituting a part of the aperture with its reflecting surface inclined toward the rear wall aperture, said reflecting means being inclined to reflect light from the respective apertures toward said concave mirror and then from'the concave mirror to the other aperture, means between the front and rear apertures to provide a light passage to the concave mirror and to direct light through said passage, and a detachable handgrip supporting said concave mirror and constituting an end portion for said casing.

- 11. An ophthalmoscope comprising in combination a substantially elongated hollow casing having closely spaced front and rear walls and having optically aligned apertures therein adjacent one end of said casing, a concave mirror mounted in aid casing remote from said end and positioned with its reflecting surfaces toward said end, a mirror in said casing adjacent the front wall aperture having its reflecting surface inclined toward said apertu're'to direct images received therethrough upon said concave mirror,

' a reflecting prism adjacent the rear wall aperture having a reflecting surface inclined to the said concave mirror and direct them through mirror and prism providing a light passage to said reflecting means being inclined to reflect said passage, and an apertured plate supporting 15 said prism in said casing and defining the limits of said passage. I

12.. An ophthalmoscope comprising in combination an elongated hollow casing, one end of the I casing having closely spaced front and rear walls, optically aligned apertures, one in each wall, a concave mirror mounted in the casing remote from said end and positioned with its reflecting surface toward said end, a front mirror mounted in said casing adjacent the front wall aperture with its reflecting surface inclined toward said front wall aperture, a rear mirror mountedadjacent the rear wall aperture with its reflecting means inclined toward the rear wall aperture, said front and rear wall mirrors being inclined to reflect light from the respective apertures toward the concave mirror'and then from the concave mirror to the other aperture, means between the front and rear mirrors to provide a light passage to the concave mirror and to direct light through the said passage, and a manuallyvariable eyepiece carried on said casing adjacent the rearwall aperture and arranged to vary its 10 retracting characteristics.

THEOBALD GRAFE.

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