JPS6134330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ophthalmometric apparatus, particularly an infrared ophthalmometric apparatus that performs an examination by irradiating infrared light through the pupil of an eye to be examined. Here, the term optometry is
In addition to the visual acuity test that determines the corrected refractive power by measuring the refractive power of the eye to be examined, it is used to include all diseases and other tests by observing the inside of the eyeball.The device of the present invention includes an infrared refractometer, It can be applied to infrared fundus cameras, etc.

A refractometer projects a target onto the fundus of the eye to be examined, and determines the corrective refractive power of the eye to be examined from the positional relationship between the target and the eye when the target is focused on the fundus. More specifically, the reciprocal of the distance in meters from a position 12 mm in front of the corneal surface of the eye to be examined is the corrected refractive power. In such a refractometer, if the target is projected using visible light, a self-adjustment effect may occur in the eye to be examined, which may cause errors in the measurement results. For this reason, an infrared refractometer has been developed that projects a target using infrared light and observes the fundus image using a night vision tube or TV system sensitive to near-infrared light.

When performing measurements using this type of infrared refractometer, the measurement results may be directly affected due to the difference in refractive index between infrared light and visible light and the difference in the main reflection site of infrared light and visible light in the fundus. It cannot be used as a corrective refractive power for optometry, and it is necessary to convert it to a corrective refractive power under visible light. For this reason, in conventional infrared refractometers, a certain amount of correction is applied to the measurement results using infrared light, based on the wavelength difference between the infrared light and visible light used.

In addition, in the field of fundus cameras, infrared (non-mydriatic) fundus cameras now use infrared light to observe the in-focus state and only take photos using visible light, in order to avoid the use of mydriatic drugs. being developed. In this infrared (non-mydriatic) fundus camera, in order to compensate for the difference between the imaging position of the infrared image and the imaging position of the visible light image, the optical positional relationship between the imaging plate for the infrared image and the photographic film surface is determined. are shifted by a certain amount.

However, as a result of research conducted by the present inventors, it has been found that the conventional fixed amount of correction is insufficient for the difference between the imaging positions of infrared light and visible light. More specifically, for example, the amount of correction required to obtain the corrected refractive power value under visible light from the corrected refractive power value of the eye to be examined measured using infrared light is It changes as a function. Similarly,
In the case of a fundus camera, the difference between the imaging position of the infrared image and the imaging position of the visible light image changes depending on the corrected refractive power value of the eye to be examined. The reason for this is that the difference in corrective refractive power between visible light and infrared light in corrective refractive power measurement is affected not only by the difference in the main reflection site of the light beam in the fundus, but also by the difference in the refractive index of the light beam. be understood. Here, when the value of subjective optometry is used as the visible corrected refractive power, the photoreceptor outer segment site corresponds to the main reflection site of visible light.

Furthermore, it is understood that the difference in the imaging position between the visible light image and the infrared light image in the fundus camera is affected not only by the difference in the main reflection site of the light ray in the fundus, but also by the difference in the refractive index of the light ray. be done.

The present invention aims to provide a more complete infrared ophthalmoscopy device based on the above findings. It is characterized in that it has a correction device for correction with a correction amount as a function of . When the present invention is applied to an infrared refractometer, the correction device may be constructed by correcting the corrective refractive power scale itself or by providing a suitable correction means between the target moving mechanism and the corrective refractive power scale. Bye.

Further, when the present invention is applied to an infrared fundus camera, the above-mentioned correction device may be configured by means for changing the optical positional relationship between the imaging plate of the infrared image and the photographic film according to the corrected refractive power value of the eye to be examined. good. In other words, if the eye to be examined is placed at a certain distance from the objective lens, the position of the focusing lens can be considered to be a function of the corrective refractive power of the eye to be examined, so depending on the position of the focusing lens, for example, the cam mechanism The position of the film or the infrared image forming plate may be adjusted by means of the following.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 shows an example of an infrared refractometer embodying the present invention. In the figure, the projection system includes an illumination light source 1, and the light from this light source 1 passes through an infrared transmission filter 2 and a lens 3. The light then becomes parallel light, is reflected by the prism 4, and travels along the projection optical axis 5. A target 6 is placed on the projection optical axis 5.
is located. This target 6 has a target pattern commonly used in refractometers. Further, a lens 8 and a pentaprism 9 are provided on the projection optical axis 5, and the projection light beam is reflected downward by the prism 9.

An observation optical axis 10 is located below and parallel to the projection optical axis 5, and a perforated prism 11 is arranged at a position where the observation optical axis 10 intersects the reflection optical path of the projection light beam by the prism 9. perforated prism 1
1 is a hole 11a coaxial with the observation optical axis 10 and a reflecting surface 11b that reflects the projection light beam forward along the optical axis 10.
and has. The projection light beam reflected by the reflective surface 11b of the prism 11 is projected onto the eye 13 by the projection lens 12. The projected light flux is the subject's eye 13
A target image is formed on the retina through the pupil of the eye. An image rotation element 14 is arranged between the perforated prism 11 and the projection lens 12. This image rotation element 14 is composed of an isosceles triangular prism 14a and a flat reflecting mirror 14b disposed opposite to the apex of the prism. , the projected target image is rotated.

The target image formed on the fundus of the eye is observed by an observation optical system. The observation optical system includes a lens 15 and a reflector 16 arranged on the observation optical axis 10 behind the perforated prism 11, and the fundus reflected light passes through the lens 12, the image rotation element 14, and the hole 11a of the prism 11. The light enters the photocathode of the image pickup tube 16 through the lens 15.

The illustrated refractometer has an aiming optical system for accurately setting the distance between the lens 12 and the eye 13 to be examined. This aiming optical system is arranged on an optical axis 17 directed toward the eye 13 through the objective lens 12 in a direction oblique to the optical axis 10.
a prism 20 that guides the light passing through the lenses 12 and 18 along an optical axis 19 parallel to the optical axis 10, and lenses 21, 22, arranged on the optical axis 19, 23 and 24, and the light passing through these lenses is also guided to the imaging tube by a reflecting mirror (not illuminated).

The scale projection system has an angle scale 26 that rotates in conjunction with the image rotation element 14 and a power scale 27 that moves in conjunction with the target 6. The projection light of the angle scale passes through lenses 28 and 29 and is laterally reflected by a reflecting mirror 30. The projected light of the power scale passes through the prism 31 and reaches the reflecting mirror 30, is reflected laterally, and both are guided to the image pickup tube 16.

The light projected onto the subject's eye 13 from the projection optical system is infrared light, preferably near-infrared light. Therefore, the light beams of the observation optical system and the aiming optical system are infrared light, but the light beams from the scale projection system Since the light used is visible light, the image pickup tube 36 is sensitive to at least visible light and near-infrared light.

The target image projected onto the retina by the projection optical system is correctly formed when the eye to be examined has the refractive power of emmetropia, but if the eye to be examined 13 is myopic or farsighted, the target image will be cracked. In this case, if the target 6 is moved along the projection optical axis 5 to obtain the correct imaging state, the position of the target 6 at that time will be displayed in the form of a correction power on the scale 27, and this correction The power is projected onto the image pickup tube 16 by a scale projection system. In the case of an astigmatism test, the target image is observed while rotating the image rotation element 14, and the angle of the astigmatism axis is detected.
The astigmatic axis at this time is displayed on an angular scale.

To obtain accurate measurement results, it is necessary to place the eye to be examined in a far viewing state. For this purpose, the refractometer is provided with a gaze target system. This gaze target system includes a lens 42 that guides the light from the light source 1 as a parallel light beam along an optical axis 41, a gaze target 43 provided on the optical axis 41, and a lens 44 that guides a projected light beam of this gaze target. , Pentaprism 4
5 and 46, and the light exiting the prism 46 is reflected by a reflecting mirror 47, passes through lenses 48 and 49 and the objective lens 12, and enters the eye 13 to be examined. Therefore, in the measurement, the above-described measurement may be performed while the subject is gazing at the gaze target 43.

FIG. 2 shows an example of the power scale plate 27 used in the refractometer shown in FIG. A scale 27a and a visible scale 27b converted into visible light are printed. This conversion was calculated using near-infrared light with an average wavelength of 0.912μ as the infrared light used for target projection, and assuming that the average wavelength of visible light was 0.588μ. Although FIG. 2 shows pointers 25a and 25b for reading, these do not necessarily have to be placed at positions corresponding to the scale plate 27. Further, it is not essential to attach an infrared scale 27a to the scale plate 27, and only a converted visible scale may be used. Furthermore, it is also possible to leave the scale on the scale plate 27 as conventional, and to incorporate a necessary correction device into the interlocking mechanism between the target 6 and the scale plate 27.

Figure 3 shows the relationship between the corrective refractive power obtained when using near-infrared light with an average wavelength of 0.912μ as the projection light on the vertical axis and the corrective refractive power under visible light on the horizontal axis. is shown by straight line A, and the difference between the infrared corrected refractive power and the visible corrected refractive power changes depending on the corrected refractive power of the eye to be examined, as shown by line B. Therefore,
The visible scale 27b on the scale plate 27 in FIG.
You can decide based on this chart.

4 to 6 show an example in which the present invention is applied to a fundus camera, in which an illumination system 51, an observation optical system 52, and a split projection system 53 are arranged within a housing 50. The illumination system 51 includes an illumination light source lamp 54 and a photography light source 55.
A condensing lens 56 and an infrared light transmission filter 57 are arranged between 4 and 55. The light from the light source 54 passes through the lens 56, and only the infrared light passes through the filter 57 and passes through the photography light source 55. This infrared light is further filtered through filter 5.
8. It passes through lenses 59 and 60 and is reflected by a reflecting mirror 61, and then passes through a lens 62 and is reflected by a perforated mirror 6.
3 and is projected onto the eye E through the objective lens 64.

The fundus reflected light passes through the objective lens 64 and the central hole 63a of the perforated mirror 63 to the observation optical system 52.
to go into. The observation optical system 52 includes a focusing relay lens 65 and an imaging lens 66 arranged on the optical axis of an objective lens 64, and behind the imaging lens 66 there is a lens with characteristics of infrared light reflection and visible light transmission. A reflecting mirror 67 having a diameter is provided obliquely. The infrared light reflected by the mirror 67 is reflected by the mirror 68 and forms an image on the photocathode of a night vision device, that is, an image pickup tube 69 provided at the upper part of the housing 50 .

The relay lens 65 is mounted in a guide tube 70 fixed to the housing 50 so as to be movable in the axial direction.
A pin 71 provided on the side of the lens 65 is slidably fitted into a slot 70a on the side of the guide tube 70, and is coupled to one end of an L-shaped lever 72.

The split projection system 53 includes a relay lens 74 provided above the observation optical system 52 and a sliding tube 73 that supports a split prism 75. Second
As shown in the figure, light from a split projection light source 76 passes through an infrared light transmitting filter 77, is reflected by a mirror 78, and enters a split prism 75. The infrared light that has passed through the split prism 75 and the relay lens 74 is reflected by the small mirrors 80 arranged symmetrically on both sides of the optical axis of the objective lens 64 behind the mirror 79 and the perforated mirror 63. and is projected onto the eye E to be examined.

The sliding tube 73 is supported movably in the axial direction within a guide tube 81 fixed to the housing 50, and the other end of the L-shaped lever 72 has one end connected to a pin 71 on the relay lens 65 of the observation optical system 52. combined with
It is designed to move together with the lens 65. The L-shaped lever 72 has an intermediate portion connected to the shaft 8 by a link 82.
3, and by operating knobs 85 at both ends of the shaft 83, the sliding tube 73 that supports the relay lens 74 and the split prism 75 and the relay lens 6 of the observation optical system 52 can be moved.
Focusing operation can be carried out by moving the two lenses at the same time in the same direction by the same distance. The split image formed by the split projection system facilitates determination of the in-focus state of the fundus image.

Behind the reflection mirror 67 of the observation optical system 52,
A photographic camera 86 is supported by a camera support tube 87. The camera support tube 87 is arranged so as to be slidable in the axial direction within a guide tube 88 fixed to the housing 50, and by engaging a pin 89 on the camera support tube 87 with a slot 88a in the guide tube 88. , the camera support tube 87 is structured to be prevented from rotating. The camera support tube 87 has
Cam follower rod 90 having a cam follower 90a at the end
The cam follower 90a is engaged with a cam 84a integrated with a lever 84 fixed to the shaft 83. 91 is a return spring. The axial positions of the lenses 65 and 74 in the focused state can be considered to be a function of the corrective refractive power of the eye E to be examined, and since the positions are converted into the rotation angle of the shaft 83, they are integral with the shaft 83. The rotation angle of the cam 84a that rotates is a function of the corrected refractive power of the eye E to be examined. Therefore, by appropriately determining the shape of the cam 84a, the optical positional relationship between the film 86a in the camera 86 and the imaging surface of the infrared light can be appropriately corrected according to the corrective refractive power of the eye to be examined. becomes possible. In this example, the position of the photographic film 86a is adjusted according to the corrected refractive power of the eye E to be examined.
The axial position of the image pickup tube 69 may be adjusted in conjunction with the rotation of the image pickup tube 69, or an infrared image forming plate may be provided between the mirrors 67 and 68, and the position of this image forming plate may be adjusted. .

As explained above, according to the present invention, in an optometrist that performs an examination by irradiating infrared light through the pupil of an eye to be examined, the results obtained by infrared light
Since a correction device is provided that applies correction as a function of the corrected refractive power of the eye being examined, compared to the conventional case where a fixed amount of correction is applied depending on the wavelength difference,
You can get much more accurate results. For example, if the present invention is applied to a refractometer, the measured values obtained will be very accurate.
A more appropriate corrective lens can be obtained, and when applied to a fundus camera, clearer photographs can be taken.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of the optical system of an infrared refractometer embodying the present invention, Fig. 2 is a plan view showing an example of the power scale plate, and Fig. 3 is an infrared correction refractive power and a visible correction. 4 is a vertical cross-sectional view of an infrared fundus camera embodying the present invention, FIG. 5 is a cross-sectional view taken along the line -- in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line -- in FIG. 4. It is a diagram.

Claims (1)

[Scope of Claims] 1. In an infrared ophthalmoscopy device that performs an examination by irradiating infrared light through the pupil of the eye to be examined, the test results obtained by the infrared light are corrected by a correction amount as a function of the corrected refractive power of the eye to be examined. An optometry device characterized by having a correction device for. 2 In the above item 1, the optometry device is a refractometer that determines the corrected refractive power by measuring the refractive power of the eye to be examined using infrared projection light, and the correction device measures the corrected refractive power value measured using infrared light. An optometry device comprising means for correcting. 3. The optometry apparatus according to item 2, wherein the means for correcting the measured corrected refractive power value comprises a scale that includes a correction amount as a function of the corrected refractive power. 4. The optometric apparatus according to item 2, wherein the means for correcting the measured corrective refractive power value is provided between the target moving mechanism and the corrective refractive power scale. 5 In the above item 1, the optometry device is a fundus camera that performs a focusing operation using infrared light and takes a photograph using visible light, and the correction device adjusts the position of the photographic film according to the position of the focusing pore. An optometry device characterized in that it includes means for performing. 6 In the above paragraph 1, the optometry device is a fundus camera that performs a focusing device using infrared light and takes photographs using visible light, and the correction device adjusts the position of the infrared image forming plate to the position of the focusing mechanism. An optometric device characterized in that it includes means for adjusting accordingly.