WO2008153235A1

WO2008153235A1 - Indirect ophthalmoscope with upright image

Info

Publication number: WO2008153235A1
Application number: PCT/KR2007/002922
Authority: WO
Inventors: Yun-Sik Yang
Original assignee: Yun-Sik Yang
Priority date: 2007-06-15
Filing date: 2007-06-15
Publication date: 2008-12-18

Abstract

The present invention provides an indirect ophthalmoscope with upright image, enabling viewing of an erect image with an existing inverted image indirect ophthalmoscope, which includes a light source directing a light beam to an eye of a subject, a condensing lens located before the eye of the subject, and a center mirror and left and right mirrors via which an image coming through the condensing lens is directed to the eyes of the inspector. The indirect ophthalmoscope with upright image further includes Schmidt prisms, a right positioned plane mirror, and a left positioned beam splitter.

Description

Description INDIRECT OPHTHALMOSCOPE WITH UPRIGHT IMAGE

Technical Field

[1] The present invention relates to an indirect ophthalmoscope with upright image through which an inspector may view not only an erect image of a subject, which is seen as the subject itself, but also an inverted image of the subject, whose left and right sides, and upper and lower sides have been reversed respectively. Background Art

[2] An ophthalmoscope for viewing inside of eyes is used to inspect an image of a retina created from the light reflected by the retina in a dark room.

[3] Currently, a fundus inspection is necessary to diagnose a retinal disease which may be considered as a main cause of blindness out of diseases related to eyes, and this may be carried out by the following three methods, each of which has its own advantages and disadvantages and is different in usage from the others:

[4] Firstly, a method using an erect image ophthalmoscope which is mainly used for screen is employed for a relatively simple fundus inspection, such as papilledema. Also, this method is used for other usual inspections in ophthalmological treatments.

[5] Secondly, a slit-lamp fundus inspection which uses a specific lens, is recently often used, and this has a merit capable of performing the fundus inspection like a general slit-lampo inspection.

[6] Finally, an inspecting method employing an inverted image indirect ophthalmoscope is slightly different from the above two methods. This method may be advantageous particularly in inspecting peripheries of retinas because of being capable of inspecting the entirety of the retinas. Also, this method may secure a wide field of view for a fundus inspection, and thus may be used for diagnosis of retinal separation, orbital tumor, etc. And, this method enables an active inspection since the eyes are inspected with sclera pressurized. Furthermore, this method enables stereovision because of allowing an inspector to perform an inspection with both eyes in contrast to erect image ophthalmoscope.

[7] Accordingly, such an inverted image indirect ophthalmoscope is an apparatus necessary in the whole ophthalmological clinics, and this is also equipped for each and every clinic in a general hospital. The indirect ophthalmoscope is necessary for a location indication of a retinal break during a retinal separation operation, and thus need to be equipped in an ophthalmological retina operation room. Disclosure of Invention Technical Problem [8] However, a current inverted image indirect ophthalmoscope provides an inverted fundus image, thus increasing needs for an indirect ophthalmoscope that may provide an erect image. Also, there is a need of an indirect ophthalmoscope with upright image that may overcome the problem, i.e. convert an inverted image into an erect image, as well as provide the whole advantages owned by the indirect ophthalmoscope. Technical Solution

[9] The present invention has been designed to solve the problems, and an object of the present invention provides an indirect ophthalmoscope with upright image that enables an inverted image from the existing inverted image indirect ophthalmoscope to be viewed as an erect image and enables an inspect to view both an erect image and an inverted image.

[10] Another object of the present invention provides an ophthalmoscope which has been designed to facilitate the operation in a vitreous cavity by the indirect ophthalmoscope with upright image.

[11] The above objects may be accomplished by an indirect ophthalmoscope with upright image including a light source directing a light beam to an eye of a subject; and a condensing lens located before the eye of the subject, wherein an image created on the condensing lens is sent through central mirrors and left and right mirrors, further including: an equilateral prism located at a lower side of the ophthalmoscope to direct an image coming from the condensing lens to a location behind the prism; a Schmidt prism receiving the image from the equilateral prism to totally reflect the received image; and a right plane mirror and a beam splitter directing the image from the Schmidt prism to eyes of an inspector.

[12] Lower ends of the right plane mirror and the beam splitter are connected to sliding bars, respectively, through a triangular body, and sides of the right plane mirror and the beam splitter are connected to handles, respectively.

[13] The Schmidt prism is configured so that a light beam directed toward a perpendicular surface or inclined surface of the prism is incident onto the other surfaces at 45 degrees and if the incident angle exceeds the critical angle of glass (about 42 degrees), the incident light beam is totally reflected.

[14] The indirect ophthalmoscope with upright image further includes: a light receiving unit of a camera, wherein an image signal is incident onto the light receiving unit through the left beam splitter, the condensing lens of the camera is maintained at a constant distance from the light receiving unit of the camera, so that the angle of view becomes equal to or less than 10 degrees to provide a monitor with a full fundus image filling up a monitor screen, and the tilt of an interim reflecting mirror is adjusted.

[15] The light source is formed of plural light emitting diodes (LEDs), each of which emits a different color of light from the others, wherein a light adjusting bar, a color selection bar, and a location adjusting bar that may select the intensity and color of the light are inserted into a protrusion of a body.

Advantageous Effects

[16] As described above, the present invention has an effect of being capable of direct image viewing and binocular inspection, which enables stereovision, by an indirect ophthalmoscope whose structure has been changed.

Brief Description of the Drawings [17] FIG. 1 is a schematic view illustrating a principle of a conventional inverted image ophthalmoscope.

[18] FIG. 2 is a perspective view illustrating a Schmidt prism used for a direct ophthalmoscope according to an exemplary embodiment of the present invention. [19] FIG. 3 is a schematic view illustrating an indirect ophthalmoscope with upright image provided with a Schmidt prism according to an exemplary embodiment of the present invention. [20] FIG. 4 is a perspective view of a portion of an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention. [21] FIG. 5 is a cross sectional view of a portion of an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention. [22] FIG. 6 is a perspective view illustrating the inside of a protrusion in an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention. [23] FIG. 7 is a view illustrating an image generated by viewing an object through an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention. [24] FIG. 8 is a cross sectional view illustrating a color selection bar formed at the inside of a protrusion in an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention. [25] FIG. 9 is a cross sectional view illustrating a light source adjustment bar formed at the inside of a protrusion in an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention.

Best Mode for Carrying Out the Invention [26] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to accompanying drawings. [27] FIG. 1 is a schematic view illustrating a principle of a conventional inverted image ophthalmoscope. [28] The conventional inverted image ophthalmoscope is configured so that a condensing lens 2 is located before an eye 1 of a subject and a light beam emitted from a light source 3 is directed to the condensing lens 2 via a lens 4.

[29] The lens 4, i.e. a convex lens, is provided to focus the light beam from the light source.

[30] And, the conventional inverted image ophthalmoscope is configured so that an image signal coming through the condensing lens 2 passes through two central mirrors 5 and 5' and then left and right mirrors 6 and 6' to eyes of an inspector.

[31] That is, an in versed image created on the subject's eye 1 is reversed by the condensing lens 2 to be an erect image, and then the left and right sides of the erect image are reversed by the central mirrors 5 and 5', and the left and right mirrors 6 and 6', so that an in versed image whose left and right sides have been reversed is created on the eyes of the inspector.

[32] The aforementioned inverted image ophthalmoscope 15 has a few advantages and disadvantages as follows:

[33] Advantages of Inversed Image Indirect Ophthalmoscope

[34] (1) the inversed image indirect ophthalmoscope may inspect the entirety of a retina;

[35] (2) the inversed image indirect ophthalmoscope has a wide field of view in funduscopy, so that it may be widely used for a diagnosis of retinal separation, orbital tumor, etc.

[36] (3) the inversed image indirect ophthalmoscope may perform an active inspection of a retina because it inspects the retina while pressurizing sclera.

[37] (4) the inversed image indirect ophthalmoscope allows for stereovision in contrast to a direct ophthalmoscope.

[38] (5) the inversed image indirect ophthalmoscope enables an inspector to carry out various operations for inside and outside of an eye with one hand, with the indirect ophthalmoscope fixed to his head and the one hand grasping the condensing lens.

[39] Disadvantages of Inversed image Indirect Ophthalmoscope

[40] (1) the left and right sides of an image created on a retinal fundus is reversed.

[41] (2) the inversed image indirect ophthalmoscope may be not properly used in performing an operation for outpatients and the inspector may have some difficulties in performing an operation while viewing the ophthalmoscope, with an apparatus inserted into a vitreous cavity.

[42] FIG. 2 is a perspective view illustrating a Schmidt prism used for a direct ophthalmoscope according to an exemplary embodiment of the present invention, which is used to change the traveling direction of a light beam.

[43] In the Schmidt prism 10, a light beam coming perpendicularly to a surface of the prism 10 or coming through an inclined surface of the prism 10 is incident onto another surface of the prism 10 at 45 degrees, and if the incident angle exceeds the critical angle of glass (about 42 degrees), the incident light beam is totally reflected so that its traveling direction changes at 180 degrees.

[44] FIG. 3 is a schematic view illustrating an indirect ophthalmoscope with upright image provided with the Schmidt prism shown in FIG. 2 according to an exemplary embodiment of the present invention.

[45] This direct ophthalmoscope is configured so that a condensing lens 2 is located before an eye of a subject and a light beam, which has passed through the condensing lens 2, goes through an equilateral prism 7 and the Schmidt prisms 10 and 10', and is reflected by a plane mirror 8 and incident onto the eye of the subject.

[46] Accordingly, an image which has been reversed by the condensing lens 2 changes its left and right sides by the equilateral prism 7 and then is reversed again by the Schmidt prisms 10 and 10' to be directed toward a left-positioned beam splitter (8-1) (not shown) and a right-positioned plane mirror 8. The resultant light beam is incident onto eyes of an inspector.

[47] That is, images coming through the condensing lens 2 are refracted on the front surface of the equilateral prism 7, entered into the equilateral prism 7, and totally internal-reflected on the equilateral surfaces of the equilateral prism 7. And, each of the images totally internal-reflected is refracted on the opposite equilateral surface of the equilateral surface on which the image is totally internal-reflected. The Schmidt prisms 10 and 10 receive the images from the equilateral surfaces of the equilateral prism 7 and totally reflect the images. One of the images totally reflected by the Schmidt prisms 10 and 10 is directed to the left eye of the inspector via the left positioned beam splitter (8-1), and the other of the images is directed to the right eye of the inspector via the right positioned plane mirror 8, so that the resultant erect image may by viewed by the eyes of the inspector.

[48] More specifically, the equilateral prism 7 enables a light beam incident onto its front surface at substantially 90 degrees to be mostly refractedly passed, the image refracted by the right surface to be mostly reflected to be internally total-reflected in the prism since it is incident onto the right surface at about 30 degrees, and the image refracted by the left surface to be total reflected by the left surface. The image total reflected by the right surface is incident onto the left surface at substantially 90 degrees, so that most of it passes through the left surface to reach the left Schmidt prism 10, and the image total reflected by the left surface is incident onto the right surface at substantially 90 degrees, so that most of it passes through the right surface to reach the right Schmidt prism 10'. As such, the two images travels out while crossing each other.

[49] FIG. 4 is a perspective view of a portion of an indirect ophthalmoscope with upright image according to an exemplary embodiment of the present invention, wherein the condensing lens 2 installed near the subject has been omitted. [50] The direct ophthalmoscope includes an equilateral prism 7 that enables an image created on an eye of a subject to be recreated at a location behind the prism 7 and crosses images from the eye of the subject, two Schmidt prisms 10 and 10' that total reflect the images coming from the equilateral prism 7, and a right positioned plane mirror 8 and a left positioned beam splitter 8-1 that direct the images coming from the Schmidt prisms 10 and 10' to eyes of an inspector.

[51] The beam splitter 8-1 reflects part of a light beam onto the eyes of the inspector so that an image may be created on the eyes of the inspector. The other of the light beam is directed to a light receiving unit 16 of a camera to be described later.

[52] In a case where the camera to be described later is not used, the beam splitter 8- 1 may be used as a left plane mirror.

[53] A condensing lens 24 is located behind the left beam splitter 8-1, and the light receiving unit 16 of the camera is mounted behind the condensing lens 24 to capture an image signal. An image signal, which has passed through the Schmidt prism 10, goes through the condensing lens 24 whose focal point may be adjusted. A reflecting mirror 12 is configured so that its tilt may be adjusted, and the light beam may be incident onto the light receiving unit 16 of the camera by the reflecting mirror 12 shown in FIG. 5.

[54] The angle of view of the camera is set to be equal to or less than 10 degrees, and the condensing lens 24 is set in refractivity to be 20 diopters and the distance between the light receiving unit 16 and the condensing lens 24 is set to be 30mm so that the light receiving unit 16 is filled with a fundus image. Also, the condensing lens 24 is positioned to adjust the focal point, and the center of the fundus image is controllably adapted to be located at the center of the light receiving unit 16.

[55] FIG. 5 is a cross sectional view of a portion of a direct-indirect ophthalmoscope according to an exemplary embodiment of the present invention.

[56] The reflecting mirror 12 is attached to a triangular fixing member, which may be tilt- controlled, so that an erect image signal may be incident onto the light receiving unit 16 of the camera.

[57] And, as described above, the equilateral prism 7 is standingly installed in a body 20, and the Schmidt prisms 10 and 10' are fixed by Schmidt prism supporting members each of which is located under each of the Schmidt prisms 10 and 10', where a fixing plate for each supporting member is installed to be adjusted and tilted upward and dow nward. The left beam splitter 8-1 and the right plane mirror 8 are attached to triangular bodies.

[58] Each triangular body is connected to each of sliding bars 21 and 21' through a connecting means. The sliding bars 21 and 21' are inserted into a long hole 22 formed in the body 20 to be slidingly moved in the long hole 22. [59] A handle 9 and 9' is connected at a side of each triangular body, and teeth formed on the handles 9 and 9' are engaged with teeth formed on the body 20 so that the sliding bars 21 and 21' may be moved, respectively.

[60] A receiving unit B for accommodating a battery is provided at the location that is behind the right plane mirror 8 and faces the light receiving unit 16. The protrusion 33 in the body 20, which is mounted with the equilibrium prism 7, has a location adjusting bar 26 formed at its lower side, and a light source adjusting bar 28 formed at its upper side.

[61] The location adjusting bar 26 is a minute adjusting bar that may change the direction of a light beam coming from a light source at 90 degrees so that the light beam may be directed to the pupil of the subject. The light adjusting bar 28 is a bar that adjusts the amount of light.

[62] This relationship will be described in more detail with reference to FIG. 6.

[63] FIG. 6 is a rear-surface perspective view illustrating the inside of a protrusion in a direct- indirect ophthalmoscope according to an exemplary embodiment of the present invention.

[64] Plural light emitting diodes (LEDs) (not shown), each of which may emit the different color of light from the others, may be mounted in the protrusion 33, and each may be fixed under an LED fixation member 32. And, the means for adjusting the amount of light (i.e. color selection bar and light adjusting bar) are embedded in the protrusion 33.

[65] Here, a focus adjusting bar 34 puts the light source in desired focus by moving the condensing lens upward and downward. The reference numeral 37 refers to a connection member for connecting the light receiving unit 16 of the camera and an image processing unit of a PC (Personal Computer).

[66] That is, in the ophthalmoscope according to the present invention, the color selection bar 27, which is shaped as a rice scoop, is formed in the protrusion 33. Plural pores are penetrated in the color selection bar 27 to select the LEDs. The color selection bar 27 is fixed by a plate spring located thereunder.

[67] FIG. 9 shows the light adjusting bar 28 formed in the protrusion 33, wherein the light adjusting bar 28 is shaped as a rice scoop and has plural pores penetrated therein, each of which is different in size from the others. The light adjusting bar 28 is fixed by a plate spring located thereunder.

[68] The light adjusting bar 28 is rotated so that a light beam may be emitted through an

LED having a desired size.

[69] That is, the light adjusting bar 28 adjusts the amount of light emitted from the light source and the color selection bar 27 selects the LED to determine the color of a light beam to be emitted. [70] A location adjusting bar 26 fixed at the lower part of the protrusion 33 adjusts the angle of the reflecting mirror 29 so that the light emitted from the light source may be directed to the retina of the subject.

[71] Upon inspection of an eye of a subject in the present invention configured as above, the amount of light emitted from the light source may be adjusted by the light adjusting bar 28 of the protrusion 33 shown in FIG. 6 and the light source emitting a desired color of light may be selected by the color adjusting bar 28 of the protrusion 33 shown in FIG. 6.

[72] Next, the location adjusting bar 26 is rotated so that the light emitted from the light source is bent to be directed to a retina of a subject.

[73] The teeth formed on the left and right handles 9 and 9' are rotatingly engaged with each other by rotating the left and right handles 9 and 9', so that the sliding bars 21 and 21' are moved in the long hole 22 to be directed to eyes of an inspector.

[74] If an inspection is carried out in a state as adjusted above, an image coming through the condensing lens is reversed as in FIG. 1, and transferred to the inspector through the left beam splitter 8-1 and the right plane mirror 8 shown in FIG. 5.

[75] And, the image coming through the condensing lens passes through the equilateral prism 7 in FIG. 5, is totally reflected by the Schmidt prisms 10 and 10', and transmitted to the inspector through the left beam splitter 8-1 and the right plane mirror 8. At this time, the principle of generating the erect image is as described above with reference to FIG. 3.

[76] In particular, in a case where a low-price personal camera module is attached to the light receiving unit 16 of the camera, it is possible to store an image displayed on a monitor. Also, the volume and weight of the ophthalmoscope may be reduced by installing only the light receiving unit 16 of the camera in the ophthalmoscope.

[77] In addition, a wireless indirect ophthalmoscope may be configured by using the battery as the power source for the LEDs. And, a micro camera module is used as the camera module, and this camera is connected to the personal computer so that the inspector may view or store the image.

Claims

[1] An indirect ophthalmoscope with upright image comprising a light source 3 directing a light beam to an eye 1 of a subject; and a condensing lens 2 located before the eye 1 of the subject, wherein an image created on the condensing lens

2 is sent through central mirrors 5 and 5' and left and right mirrors 6 and 6', further comprising: an equilateral prism 7 located at a lower side of the ophthalmoscope to direct an image coming from the condensing lens 2 to a location behind the prism 7; a Schmidt prism 10 and 10' receiving the image from the equilateral prism 7 to totally reflect the received image; and a right plane mirror 8 and a beam splitter 8-1 directing the image from the

Schmidt prism 10 and 10' to eyes of an inspector.

[2] The indirect ophthalmoscope with upright image of claim 1, wherein lower ends of the right plane mirror 8 and the beam splitter 8-1 are connected to sliding bars 21 and 21 'through a triangular body, respectively, and sides of the right plane mirror 8 and the beam splitter 8-1 are connected to handles 9 and 9', respectively.

[3] The indirect ophthalmoscope with upright image of claim 1, wherein the Schmidt prism 10 and 10' is configured so that a light beam directed toward a perpendicular surface or inclined surface of the prism 10 is incident onto the other surfaces at 45 degrees and if the incident angle exceeds the critical angle of glass (about 42 degrees), the incident light beam is totally reflected.

[4] The indirect ophthalmoscope with upright image of claim 1, further comprising: a light receiving unit 16 of a camera, wherein an image signal is incident onto the light receiving unit 16 through the left beam splitter 8-1, the condensing lens 24 of the camera is maintained at a constant distance from the light receiving unit 16 of the camera, so that the angle of view becomes equal to or less than 10 degrees to provide a monitor with a full fundus image filling up a monitor screen, and the tilt of an interim reflecting mirror 12 is adjusted.

[5] The indirect ophthalmoscope with upright image of claim 1, wherein the light source 3 is formed of plural light emitting diodes (LEDs), each of which emits a different color of light from the others, wherein a light adjusting bar 28, a color selection bar 27, and a location adjusting bar 26 that may select the intensity and color of the light are inserted into a protrusion 33 of a body 20.