JPH0554329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an eye refractive power measuring device that can easily measure the distance refractive power and near addition power or near refractive power of an eye to be examined.

<Prior Art> Conventionally, so-called objective eye refractive power measuring devices have been used that project a measurement target image onto the fundus of the eye to be examined and measure the refractive power of the eye to be examined based on the focused state of this measurement target image. 2. Description of the Related Art A so-called subjective eye refractive power measuring device is known in which a subject is made to look at an eye chart through a corrective lens, and the refractive power of the subject's eye is measured based on the responses of the subject and the examiner. This type of eye refractive power measuring device is designed to measure the near addition power of the eye to be examined based on the refractive power of the eye to be examined in the state of far vision (hereinafter referred to as the distance refractive power).
This conventional eye refractive power measuring device has the following problems when measuring the near addition power based on the distance refractive power of the eye to be examined.

<Problems to be Solved by the Invention> In other words, in the conventional eye refractive power measurement device, when measuring the near addition of the eye to be examined, the distance refractive power of the eye to be examined is first measured, and then the distance refractive power is measured. The test subject is asked to view a visual acuity chart at a near distance (for example, 30 cm in front of the test subject's eye) through a corrective lens that corresponds to their power, and the visual acuity chart is properly confirmed based on the responses of the test subject and the examiner. The corrective lens and further corrective lenses are gradually added until the corrective lens is corrected, and the refractive power of the subject's eye is examined in the condition of distance vision to measure the near addition, and if necessary, the near addition and correction lens are added. Although the near refractive power is calculated based on the distance refractive power, it takes time to measure the near addition power and the near refractive power, and it is a heavy burden on the subject. There is a problem.

<Means for Solving the Problems> The present invention is based on the fact that although there are individual differences in the addition of near vision in the subject's eye, there is a correlation between the age of the subject and the addition of near vision. The eye refractive power measurement device according to the present invention is characterized by a near addition power storage unit that stores in advance a near addition power set in accordance with the age of the subject, and and a near addition output unit that outputs a near addition corresponding to the inputted age based on an input corresponding to the age.

<Function> According to the eye refractive power measuring device according to the present invention, when the distance refractive power is measured and the year name of the subject is input, the near vision addition power corresponding to the age is displayed. .

<Example> Hereinafter, an example in which the eye refractive power measuring device according to the present invention is applied to an automatic eye refractive power measuring device will be described based on the drawings.

1 to 7 show an embodiment of the present invention, and FIG. 1 shows an optical system of an automatic eye refractive power measuring device. In the figure, 1 is a target image projection system, and this target image projection system 1 has a function of projecting a measurement target image formed by irradiating an index plate for measurement with invisible light onto the fundus of the eye 2 to be examined. , 3 is an imaging optical system, and this imaging optical system 3 forms a reflected image of the measurement target image projected by the target image projection system 1 on the fundus of the eye 2 to be examined on the imaging surface 4a of the imaging device 4. Reference numeral 5 denotes a gaze target projection system, and this gaze target projection system 5 has a function of projecting a gaze target onto the subject's eye 2 when performing objective measurement.

The target image projection system 1 includes a light source, for example an LED.
(Light emitting diode) 6, this light source 6
emits infrared light, which is invisible light, in order to prevent miosis of the eye 2 to be examined. The infrared light from this light source 6 is irradiated onto a measurement index plate 8 through a condenser lens 7, and the measurement index plate 8 is movable in the optical axis x direction. As shown in FIG. 2, this measurement index plate 8 is in contact with a thin plate 8a having four slits (two sets of parallel upper and lower slits with the same interval l), and the light passing through the slits is in contact with the thin plate 8a. It is composed of four deflection prisms 8b to 8e that deflect the light beam in a direction perpendicular to the longitudinal direction. Two sets of parallel measurement target images made up of invisible light irradiated onto the measurement index plate 8 are formed by the reflection prisms 9 and 10, the relay lens 11, and the reflection prism 1.
2. Half-moon diaphragm 13 having two half-moon-shaped openings;
Slit prism 1 having a slit-like shape 14a
4, image rotator 15, objective lens 16,
The beam is projected by the beam splitter 17 onto the fundus of the eye 2 through the pupil. In addition, half-moon aperture 13
is arranged at a position conjugate with the pupil of the eye 2 to be examined.
The image rotator 15 is arranged rotatably with respect to the optical axis y in order to rotate the measurement target image projected onto the fundus of the eye 2 to be examined in a predetermined meridian direction of the eye to be examined, and the rotation angle θ of the image rotator 15 is /2, the measurement target image projected onto the fundus of the eye to be examined is rotated by θ degrees. The beam splitter 17 has a characteristic of transmitting infrared light and reflecting visible light.

In the imaging optical system 3, the measurement target image reflected on the fundus of the eye 2 to be examined is transmitted through the beam splitter 17, the objective lens 16, the image rotator 15, and the slit-shaped hole 1 of the slit prism 14.
4a, aperture stop 1 having a circular opening 18a
8, relay lens 19, reflective prism 20, 2
1, sunspot plate 22, moving lens 23, reflection mirror 2
4. An image is formed on the imaging surface 4a via the imaging lens 25. Note that the aperture stop 18 is arranged at a position conjugate with the pupil of the eye to be examined, and the aperture 18a allows only light that passes through the pupil of the eye to be examined to pass through. The black spot plate 22 removes light reflected by the objective lens 16 that is harmful to the measurement. The movable lens 23 is movable along the optical axis Z together with the black spot plate 22 and the measurement index plate 8. The measurement index plate 8 and the imaging surface 4a are always maintained in a conjugate positional relationship.

Since the measurement target image formed on the imaging surface 4a passes through the image rotator 15 again, it is rotated by the same angle in the opposite direction to the measurement target image projected onto the fundus of the eye 2 to be examined. Therefore, this shooting surface 4
Regardless of the rotation angle of the image rotator 15, the measurement target image formed at point a has the same orientation of the slit of the measurement target image formed by the measurement index plate 8, and is always held in a constant direction. On the other hand, the imaging device 4 outputs a video signal in accordance with the measurement target image formed on the imaging surface 4a. Based on this video signal, the display device 26 displays a slit measurement target image (an image reflected from the fundus of the eye 2 to be examined) formed on the imaging surface 4a.

In these target image projection system 1 and imaging optical system 3, when the measurement index plate 8 moves and the measurement target image is focused on the fundus of the eye 2 to be examined, the movement of the movable lens 23 brings the focused state to the imaging plane. The image is focused on 4a. Then, the imaging device 4 emits a video signal corresponding to the image formed. The display device 26 to which this video signal is input is in a state where the spacing between the upper and lower parallel slits of the measurement target image focused on the fundus of the eye 2 to be examined is equal (l ₁ = l ₂ ) Display.

Here, if the projected measurement target image is focused in front of the fundus of the eye to be examined 2, the display device 2
6 displays a state in which the distance between two sets of parallel slits, upper and lower, of the measurement target image is l ₁ <l ₂ as shown in FIG. Furthermore, when the projected slit measurement target image is focused behind the fundus of the eye 2 to be examined,
Contrary to FIG. 4, the display device 26 displays a state in which two sets of parallel slits, upper and lower, of the measurement target image have an interval l ₁ >l ₂ . Thereby, the examiner can always observe the focused state of the measurement target image projected on the fundus of the eye 2 to be examined.

In the gaze target projection system 5 , light from a light source 27 that emits visible light is irradiated onto a gaze target plate 30 through a color correction filter 28 and a condenser lens 29 . A gaze target is formed on the gaze target board 30. A gaze target image formed by the gaze target plate 30 by irradiation of light from the light source 27 is formed by a collimator lens 31, a moving lens 32, and a reflecting mirror 3.
3, 34, relay lens 35, reflective mirror 36,
The light is projected onto the fundus of the eye 2 to be examined via the objective lens 37, reflection mirror 38, and beam splitter 17.
Note that the movable lens 32 is movable along the optical axis, and in the case of objective measurement, is set at a position that causes the subject to see a cloudy vision according to the refractive power of the subject's eye, and adjusts the accommodative power of the subject's eye. removal and enable accurate objective measurements.

FIG. 5 is a control block diagram of the automatic refractive power measuring device for the eye to be examined. Components in the figure that are the same as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted. In the figure, the imaging device 4 is connected to a display device 26 and a signal detection section 40. Based on the video signal output from the imaging device 4, the display device 26 displays an image reflected by the fundus of the eye to be examined, and the signal detection unit 40 displays position information of the image focused on the fundus of the eye to be examined, etc. as a digital signal. Convert to Note that the signal detection section 40 includes an index image signal detection section 40a and a delay circuit 4.
0b, a reference signal forming section 40c, a timing signal forming section 40d, an index image position detecting section 40e, etc. This signal detection unit 40 is connected to a CPU 41 that inputs information such as the positional interval of the image edges of the measurement target image, calculates the refractive power of the eye to be examined based on this information, and displays it on a display device. These signal detection section 40 and CPU 41 constitute a control calculation means.

The CSU 41 also includes a measurement mode switch 43 for executing measurements, a printer 44 for printing out measurement results, and a near addition storage unit 45 for storing average near addition according to age. , an age setting switch 46 for inputting and setting the age of the subject, and a drive control section 47 are connected. The drive control section 47 includes a first control section 47a for moving the measurement target plate 8 and the objective lens 23 along the optical axes x and z, and a first control section 47a for controlling the rotation of the image rotator 15 around the optical axis y. 2
It is composed of a control section 47b and a third control section 47c for moving the objective lens 32 along the optical axis.

The near addition storage unit 45 stores, for example, the average addition corresponding to the age when the near distance is 30 cm, as shown in the table below.

(Age) (Addition power) (Age) (Addition power) 40 years old 1.0 60 years old 2.5 45 years old 1.5 65 years old 2.5 50 years old 2.0 70 years old 2.75 55 years old 2.25 75 years old 3.0 Next, this automatic eye refractive power measuring device The operation will be explained based on the flowchart shown in FIG.

First, the CPU 41 executes initialization (step 100). In this initial setting, the measurement target image is set at the zero diopter position in the target image projection system 1, the image rotator 15 is set at a position such that the longitudinal direction of the slit of the measurement target image is perpendicular, and the gazing target image is set at the position of the zero diopter in the target image projection system 5. The target image is the zero day opter position. Next, the measurement mode is determined by turning on and off the measurement mode switch 43 (step 100). When the measurement mode switch 43 is on, the addition setting mode is selected, and an age table and a cursor 48 as a selection mark as shown in FIG. 7 are displayed on the display device 26 (step 102). The examiner moves this cursor using the age setting switch 45 to set the age of the examinee (step 10).
3).

FIG. 7 shows a state in which the cursor 48 is positioned at ages 45-49. When this age selection is completed, the near addition power corresponding to the age of the subject is read from the near addition power storage unit 45 into the CPU 41 (step 104), and the CPU 41 The corresponding average near addition is temporarily stored and held (step 105). CPU41
Next, checks whether the print switch is on (step 106). If the print switch is off, a measurement mode check (step 101) is performed to perform objective measurement.

When the CPU 41 enters the objective measurement mode, first, the imaging device 4 detects the imaging state of the measurement target image projected onto the fundus of the subject's eye in the imaging optical system 3, and the image is displayed on the display device 26. At the same time, the slit spacing of the image (upper slit spacing
l ₁ and the lower slit interval l ₂ ) are calculated (step 107). The measurement index plate 8 is moved until this slit interval difference |l ₁ -l ₂ | becomes smaller than a predetermined value ε (step 108). Along with this movement, the drive circuit 47 is activated to move the movable lens 23 and the target plate 30 along the optical axis (steps 109 and 110). By moving the gaze target plate 30 in accordance with the amount of movement of the measurement index plate 8, the fog state is maintained for the eye 2 to be examined. At this time, the display device 26 displays changes in the slit intervals l ₁ and l ₂ of the measurement target image. That is, the examiner observes the measurement target image while the refractive power of the eye to be examined is automatically measured. Next, the difference in slit spacing is |l ₁ −l ₂
When |<ε (step 109), the position of the slit measurement target image is read (step 11).
1). This is done, for example, for 15 meridians (steps 111→112→113→114). That is,
Every time the slit measurement target image is rotated by 30 degrees (the image rotator is rotated by 15 degrees), the value of (l ₁ −l ₂ ) is read and the refractive power in each meridian is calculated.

For example, if the eye to be examined has astigmatism, the image rotator 15 is rotated via the drive circuit 42, and the slit measurement target image is detected shifted in the longitudinal direction of the slit. When the rotation angle of the image rotator 15 is set to θ/2, the rotation angle of the image rotator 15 corresponds to the lens amount of the slit, and the refractive power D〓 in the meridian direction of θ is obtained by equation (1).

D==A+Bcos2(θ−α) (1) Note that A, B, and α are the spherical power, astigmatic power, and astigmatic axis of the eye to be examined, respectively. This obtained refractive power
D=A by least squares method based on D= ₁ to D= ₁₅
A, B, and α of +Bcos2 (θ−α) are calculated (step 115). Sumari, S, C, necessary for optometry
A is required.

Note that S (abbreviation for spherical power) is the spherical power,
C (abbreviation for cylinder power) is the astigmatic power, A (axis
) is the astigmatic axis, and these are the distance refractive power.

Next, check whether the print switch is on or not.
The CPU 41 makes a determination (step 106). If the print switch is on, the CPU 41 prints out the distance refractive power and the near addition power (step 107).

Thereby, the examiner can know in advance the distance refractive power of the eye to be examined and the near addition power as a guide close to the accurate near addition power of the eye of the examinee. Therefore, by continuing to measure the near addition power based on this average near addition power as a reference, it is possible to quickly and accurately measure the near refractive power.

<Effects of the Invention> As explained above, the present invention is configured to output and display the near addition power as a guide in accordance with the age of the examinee. It is now possible to measure the near refractive power of the subject's eye based on the accurate near add power or the near add power close to the near refractive power, and the effect is that the measurement can be performed more quickly than before. play.

[Brief explanation of the drawing]

FIG. 1 is an optical system diagram showing an embodiment of the eye refractive power measuring device according to the present invention, FIG. 2 is a perspective view showing an enlarged configuration of the indicator plate shown in FIG. 1, and FIG. 3 is the same as shown in FIG. 1. FIG. 4 is a diagram for explaining the in-focus state of the measurement target image projected on the fundus of the subject's eye, and FIG. 4 explains the out-of-focus state of the measurement target image projected on the fundus of the subject's eye shown in FIG. Figure 5 is the first diagram for
6 is a flowchart for explaining the measurement procedure by the eye refractive power measuring device shown in FIG. 1, and FIG. 7 is shown in FIG. 1. It is a top view of the age table displayed on the display device. 1...Target imaging system, 2...Eye to be examined, 3...
...imaging optical system, 4...imaging device, 4a...imaging tube, 5...gazing target projection system, 8...measuring index plate,
26...Display device, 41...CPU, 43...Measurement mode switch, 44...Printer, 45...
Near addition storage unit, 46...Age setting switch,
48...Cursor.

Claims (1)

[Scope of Claims] 1. An eye refractive power measurement device that measures the distance refractive power of a subject's eye, comprising: a near add power storage unit that stores in advance a near add power set in accordance with the age of the eye; An eye refractive power measurement device having: a near addition power output unit that outputs a near addition power corresponding to the inputted age based on an input corresponding to the age of the subject. 2. The scope of claims characterized in that the distance refraction power is measured by objective optometry, and the distance refraction power and the near addition power corresponding to the age of the eye to be examined are displayed simultaneously. The eye refractive power measuring device according to item 1.