JP3575825B2 - Ophthalmic equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an ophthalmic apparatus for measuring an eye to be inspected, and more particularly to an ophthalmic apparatus suitable for ophthalmic measurement of a child.
[0002]
[Prior art]
2. Description of the Related Art In an ophthalmologic apparatus that measures the refractive power and the like of an eye to be inspected, it is necessary to align the eye to be inspected at an appropriate position with respect to the apparatus. 2. Description of the Related Art As a conventional alignment mechanism, there is known a method of guiding a fixation of an eye to be examined on a measurement axis of an apparatus by causing the eye to be examined to fixate a fixation target.
[0003]
When the subject is a general adult or the like, fixation of the subject's eye can be relatively easily guided on the measurement axis by using the above-described alignment mechanism when the examiner gives an instruction. However, when the subject is a child, it is often not easy to induce fixation due to fear or anxiety about the device or the examiner, and accurate measurement has been difficult.
[0004]
2. Description of the Related Art Conventionally, as a device for reducing anxiety and the like of a child, a device for measuring a distance from an eye to be examined by about 1 m has been proposed.
[0005]
[Problems to be solved by the invention]
However, if the distance between the subject's eye and the apparatus is long, the measurement error must be large, and it is better that the subject's eye and the apparatus are sufficiently close to each other for accurate measurement. Even in the above-described apparatus in which the measurement is performed at a distance of about 1 m from the eye to be examined, the measured value is of value only for extremely coarse screening.
[0006]
Further, even if a general adult can be measured with these devices, there is a drawback that the device is practically used exclusively for children due to accuracy problems.
Further, the above device has a limitation that the size of the device cannot be reduced because it is necessary to ensure a sufficient distance from the eye to be examined.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks of the conventional apparatus, and provides an ophthalmologic apparatus capable of measuring with high accuracy regardless of the age of a subject.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
[0009]
(1) In an ophthalmologic apparatus including a measurement system for measuring an eye to be examined, a fixation target that guides fixation of the eye to be examined in a predetermined direction, and an examiner with binoculars to magnify and observe the anterior segment of the eye to be examined. A convex lens that can be inserted into and removed from the optical path, and when the convex lens is removed from the optical path, an observation optical path through which a part of the examiner 's face can be viewed from the subject's eye, and a predetermined positional relationship with a predetermined portion of the anterior segment of the subject's eye. A sighting mark disposed on the observation optical path for reflecting a light beam from the sighting mark toward an examiner. And a light splitting member arranged on the optometry side.
[0010]
(2) The ophthalmologic apparatus according to (1), an index projection unit that projects an alignment index for detecting a working distance onto the cornea of the eye to be inspected, an index detection unit that detects a corneal reflection image of the index projected on the cornea, and the detection unit. Determining means for determining the alignment state based on the detection result of the above.
[0013]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view of a hand-held corneal shape measuring apparatus according to an embodiment. Reference numeral 1 denotes an apparatus main body, which houses an optical system described later and an electric system for control and arithmetic processing. Reference numeral 2 denotes a measurement window arranged on the side facing the subject's eye, and reference numeral 3 denotes an observation window. The examiner observes the subject's eye through the observation window 3 and the measurement window 2 and performs alignment. Reference numeral 4 denotes a power switch, 5 denotes a print switch for transmitting measurement data to a printer unit (not shown), and 6 and 7 denote R and L switches for specifying the left and right of the eye to be measured. Reference numeral 8 denotes a liquid crystal display for displaying measurement results and the like.
[0014]
The lower part of the apparatus main body 1 is shaped like a grip so that the examiner can hold the apparatus with one hand, and a battery 9 is removably stored below the grip.
Further, the width of the apparatus main body 1 is smaller than about twice the eye width of a child, so that even if the subject is a child, the subject can see a part of the face of the examiner forward with another eye.
[0015]
FIG. 2 is a schematic view of the arrangement of the optical system disposed in the apparatus main body 1 as viewed from the side, and FIG. 3 is a view of the observation system of the subject's eye in FIG. 2 viewed from above.
[0016]
Reference numeral 10 denotes an eye to be examined, and 11 denotes an examiner's eye. The apparatus body 1 is provided with a through-hole 12 for the examiner's eyes 11a and 11b to observe the examinee's eye 10, and an objective lens 13 and a beam splitter 14 are arranged on the observation optical axis. I have.
[0017]
If the focal length (F) of the objective lens 13 is, for example, 250 mm, the distance (A) from the objective lens 13 to the subject's eye 10 is 75 mm, and the distance (L) from the objective lens 13 to the examiner's eye 11 is 200 mm, The subject's eye can be observed at a magnification of 1.28 times. Conversely, the examiner's eye 11 appears to be blurred from the subject's eye 10. As shown in FIG. 4, the objective lens 13 is detachably held in the observation window 3 of the apparatus main body 1 by a holding member 15, and if the objective lens 13 is detached together with the holding member 15, the examinee's eye 11 can be removed from the eye 10 to be examined. Can be seen through.
[0018]
Reference numeral 16 denotes an aiming mark plate on which a mark as shown in FIG. 5, for example, is formed. The aiming mark 16a indicates an annular pattern, and 16b indicates a horizontal reference line of the apparatus. The horizontal reference line 16b indicates the 0 degree direction of the axis angle of corneal astigmatism. Reference numeral 17 denotes an aiming mark illumination light source. The light flux of the aiming mark that has passed through the aiming mark plate 16 when the light source 17 is turned on is reflected by the beam splitter 14 toward the examiner's eye 11. .
[0019]
Reference numeral 18 denotes a fixation target light source, 19 denotes a fixation target plate having a spot aperture, and 20 denotes a concave lens. Reference numeral 21 denotes a dichroic mirror for making the optical axis of a detection optical system described later and the projection optical axis of the fixation target coaxial. The fixation target plate 19 illuminated by the light source 18 is dichroic by the concave lens 20 and the imaging lens 22. The image is projected on the fundus of the eye to be examined via the mirror 21 and the beam splitter 14, so that the eye 10 to be examined can fixate on the fixation target plate 19. Reference numeral 22 denotes an imaging lens.
[0020]
Reference numeral 23 denotes an index projecting optical system, which is arranged in eight sets at 45-degree intervals on the same circumference around the observation optical axis, and the projection optical axis forms a predetermined angle with the observation optical axis. Among the eight sets of index projection optical systems, there are four sets of corneal shape measurement and working distance detection optical systems (23a to 23d) arranged at 90 degree intervals, and 23a to 23d are red light or near red light. It comprises a light source 24 such as an LED that emits light in the outer region, a spot stop 25, and a collimator lens 26 for keeping the spot stop 25 at infinity. The optotype projection optical system for detecting the working distance (23e to 23h, not shown) includes a light source 24 and a spot stop 25, and projects a finite light beam to the eye to be examined.
[0021]
Reference numeral 27 denotes a telecentric stop, which is arranged at the focal position of the imaging lens 22. Reference numeral 28 denotes a two-dimensional position detecting element, which is arranged at a position conjugate with the vicinity of the iris where a corneal reflection image is formed on the imaging lens 22. The beam splitter 14, the imaging lens 22, the telecentric stop 27, and the two-dimensional position detecting element 28 constitute a detection optical system. The two-dimensional position detecting element 28 detects the position of the corneal reflection image by the index projection optical system 23. .
[0022]
Reference numeral 29 denotes LEDs arranged at intervals of 30 degrees on the same circumference centered on the observation optical axis. The entire corneal reflection image of each LED 29 functions as a earring. The LED 29 also serves as an illumination of the anterior segment.
[0023]
FIG. 6 is an electrical block diagram of a main part of the apparatus of the embodiment.
The signal obtained by the two-dimensional position detecting element 28 is subjected to predetermined processing by a detection processing circuit 40 and is input to the microcomputer 41.
[0024]
The microcomputer 41 performs arithmetic processing based on the input position signal, and determines whether the working distance is appropriate or not and obtains a radius of curvature of the cornea described later. The measurement result obtained by the microcomputer 41 is displayed on the display 8 via the display circuit 42.
[0025]
The operation of the apparatus having the above configuration will be described.
If the subject has anxiety in a child or the like and it is difficult to induce fixation, the objective lens 13 attached to the observation window 3 of the apparatus main body 1 by the holding member 15 is removed together with the holding member 15. . When the eye is removed, the examiner's eye 11 can be seen from the eye to be inspected 10, so that the anxiety of the examinee is reduced. In addition, since the switch operation of the present apparatus is simplified and the automatic determination and automatic measurement of the aiming match are performed, even an operator who is not familiar with the apparatus can operate with a slight explanation. Therefore, when the subject is a child, a close relative such as a mother can perform the measurement. By removing the objective lens 13, the face of the mother or the like who is the measurer can be measured through the measurement window 3 from the child's eye. Is partly visible, and it is easy to guide fixation on the measurement optical axis.
[0026]
The examiner holds the apparatus main body 1 with one hand, turns on the light source by turning on the power switch 4, and presses the R switch 6 or the L switch 7 to select the left or right of the eye to be examined. After that, the measurement window 2 is brought to the selected eye to be examined, and the fixation target plate 19 is fixed to the examinee's eye, and the examiner observes the examinee's eye through the observation window 3 with both eyes.
[0027]
By observing the aiming mark 16 and the anterior segment image of the subject's eye, the device is moved so that the annular pattern 16a of the aiming mark is concentric with the iris or limbus. The observation optical axis is aligned with the visual axis of the eye to be examined.
[0028]
Next, the examiner adjusts the working distance by moving the device in the optical axis direction. Adjustment of the working distance from the eye to be inspected is performed by judging the anteroposterior relationship of the aiming mark 16 based on the position of the myering image (or the iris of the eye to be examined), and observing the aiming mark 16a at substantially the same distance. This is done by moving the device to the desired position. Adjustment of the working distance is slightly more difficult than in the case where an objective lens 13 described later is attached, but rough alignment can be sufficiently performed.
[0029]
In parallel with the adjustment of the working distance by the examiner, the apparatus detects the suitability of the working distance by the detection optical system.
[0030]
The detection of the working distance is performed by comparing the image heights of the corneal reflection images formed by the index projection optical systems 23a to 23d at infinity and the index projection optical systems 23e to 23h at finite distance (with the LEDs 24a to 24d). The LEDs 24e to 24h may be turned on alternately, or the lighting procedure is not limited. This is because when a corneal reflection image is formed by an infinite light source and a finite light source, the image height of the corneal reflection image by the infinite light source does not change even if the working distance changes, but the corneal reflection image by the finite light source Utilizes the characteristic that the image height changes. Details of this are described in Japanese Patent Application No. 4-224896 (the title of the present invention, "Alignment Detector") by the present applicant. In the comparison of the image heights of the corneal reflection images by the infinite light source and the finite light source, in the case of the light sources located at the same position, it is possible to judge whether or not the working distance is appropriate if one index image is detected. Then, an elliptical shape connecting the corneal reflection images of the infinity target projection optical systems (23a to 23d) and an ellipse shape connecting the corneal reflection images of the finite target projection optical systems (23e to 23h) by the microcomputer. Each position is obtained, the position of each ellipse in a predetermined meridian direction (a fixed angle or a method of determining astigmatic axis direction) may be extracted, and the heights thereof may be compared. When the image heights match within a predetermined allowable range, the microcomputer 41 calculates the corneal shape from the position of the index image when the image heights match. Note that, as required in the case of an eye refractometer or the like, a trigger signal may be issued and measurement can be performed when they match (the examiner may be instructed to press a measurement switch).
[0031]
For the measurement of the corneal shape, as described in Japanese Patent Application No. 59-207539 (name of the invention, "Cornea Shape Measuring Apparatus", Japanese Patent Publication No. 1-18968), if three index images are detected, the corneal shape is determined. Can be calculated. The measurement result is displayed on the display 8.
[0032]
Next, a case where the subject is an adult and the fixation target plate 19 can be fixed at an instruction of the examiner will be described. The objective lens 13 is attached to the observation window 3 of the apparatus main body 1 by the holding member 15.
[0033]
The alignment in this case is basically the same as that of a child or the like, but by attaching the objective lens 13, the alignment mark 16 is positioned before and after the aiming mark 16 based on the position of the myering image (or the iris of the eye to be inspected). The relationship can be easily determined, and the working distance can be adjusted quickly. This is for the following reason.
[0034]
When the anterior segment image of the subject's eye 10 and the aiming mark 16 are superimposed, they can be represented as shown in FIG. The distance from the examiner's eye 11 to the position of the objective lens 13 is L, the distance from the position of the objective lens 13 to the aiming mark 16 is A, and the distance difference between the aiming mark and the iris of the eye to be examined. Assuming that x is the distance between the pupils of the examiner and PD, the stereoscopic parallax of the distance difference between the aiming mark 16 and the iris of the eye to be examined when the objective lens 13 is not disposed is expressed by the following equation.
V = PD · x · K / (L + A) ²
K is a constant for converting radians into seconds.
[0035]
For example, if A is 75 mm, L is 200 mm, PD is 64 mm, x is 1 mm, and K is 206265, V is 174 ''. Generally, it is said that the minimum deep visual acuity value of the stereoscopic parallax that can identify the distance of a healthy person is about 30 ″, which means that a distance difference of about 1 mm can be sufficiently recognized.
[0036]
When the convex lens objective lens 13 having a focal length of F = 250 mm is disposed, an enlarged image of 1.28 times is obtained as described above, and the distance difference between the aiming mark 16 and the iris of the eye to be examined is obtained. Is also expanded. When the distance difference is x ′,
x ′ = F · (A + x) / (F−A−x) −FA · / (FA)
And the stereoscopic parallax V in this case is
V = PD · x ′ · K / [L + FA / (FA)] ²
It becomes. When this is calculated, 287.2 ″ of stereoscopic parallax is obtained, and by arranging the convex lens, apparent stereoscopic parallax is also enlarged.
[0037]
The embodiment of the hand-held device has been described above. However, the application of the present invention is not limited to this type, and the conventional stationary type is realized by making the measuring unit sufficiently small and facilitating operability. It can also be used for the device.
[0038]
【The invention's effect】
As described above, according to the present invention, the fixation of the eye to be examined can be achieved even if the subject is a child by arranging the convex lens in the observation / sighting optical system detachably without reducing the measurement accuracy. Guidance becomes easy, and accurate measurement can be performed.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a hand-held corneal shape measuring apparatus according to an embodiment.
FIG. 2 is an arrangement schematic diagram of an optical system arranged in the apparatus main body 1 as viewed from a side.
FIG. 3 is a diagram of the observation system of the subject's eye in FIG. 2 as viewed from above.
FIG. 4 is a diagram illustrating a holding member that holds an objective lens.
FIG. 5 is a view showing an aiming mark plate.
FIG. 6 is an electrical block diagram of a main part of the device of the embodiment.
FIG. 7 is a diagram showing a state of an optical system when an anterior eye of a subject's eye and a sighting mark are overlapped.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Apparatus main body 3 Observation window 10 Examinee's eye 11 Examiner's eye 12 Through-hole 13 Objective lens 14 Beam splitter 15 Holding member 16 Aiming mark board

Claims (2)

In an ophthalmologic apparatus equipped with a measurement system for measuring the eye to be inspected, a fixation target that guides the fixation of the eye to be examined in a predetermined direction and an examiner inserted into the optical path to magnify and observe the anterior segment of the eye with the binocular. It has a detachable convex lens, and when the convex lens is removed from the optical path, it is arranged in an observation optical path where a part of the face of the examiner can be visually recognized from the eye to be inspected, and in a predetermined positional relationship with a predetermined part of the anterior eye of the eye to be inspected. Aiming mark, and a light splitting member provided in the observation optical path to reflect the light beam from the aiming mark toward the examiner, the eye to the eye to be examined from a position where the convex lens is inserted and removed An ophthalmologic apparatus comprising: a light splitting member arranged. 2. The ophthalmologic apparatus according to claim 1, wherein the index projecting means projects an alignment index for detecting a working distance to the cornea of the subject's eye, the index detecting means detects a corneal reflection image of the index projected on the cornea, and the detection result of the detecting means. And a determination unit for determining an alignment state based on the image data.

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