JPH0634779B2 - Eye measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an eye measuring device which is used in an ophthalmological clinic or the like to measure a cornea diameter and the like.

[Prior Art] For example, in the prescription of contact lenses, it is necessary to measure the radius of curvature of the cornea using a keratometer and measure the cornea diameter by another method. What can be measured with one device is now available. Not known until now. In addition to the radius of curvature of the cornea, information on the corneal diameter is necessary for determining the base curve and selecting the type of the contact lens, and by using both of these values, a contact lens with a good wearing feeling can be prescribed. Further, there is no known device that appropriately measures the corneal diameter.

[Object of the Invention] An object of the present invention is to provide an eye measuring device that measures the corneal diameter using the output of an observation television.

Another object of the present invention is to measure the corneal diameter using an observation television simultaneously or sequentially with the corneal curvature using one device, for example, an eye measuring device that more accurately determines the base curve of a contact lens. To provide.

[Summary of the Invention] An eye measuring device according to a first aspect of the invention for achieving the above-mentioned object includes an observation television for observing an anterior segment of an eye to be examined,
A corneal diameter measuring means for measuring the corneal diameter of the eye to be inspected based on the boundary between the sclera part and the iris part of the anterior eye part of the eye to be inspected photographed by the observation television.

Further, the eye measuring device according to the second aspect of the invention, a corneal curvature measuring means for measuring a corneal curvature of the eye to be inspected, an observation television for observing the anterior segment of the eye to be inspected, and an image taken by the observation television. A corneal diameter measuring means for measuring the corneal diameter of the eye to be inspected based on the boundary between the sclera part and the iris part of the eye to be inspected.

Embodiments of the Invention The present invention will be described in detail based on the illustrated embodiments.

FIG. 1 is an optical configuration diagram, and the optical axis is in front of the eye E to be inspected.
The objective lens 1, the light splitting member 2, the diaphragm 3, and the two-dimensional optical sensor 4 are sequentially arranged along the line 01 from the eye E side, and the ring-shaped light source 5 is arranged around the objective lens 1. . Further, on the optical axis 02 which is orthogonal to the light source 01 and passes through the light splitting member 2, the light source 6, the alignment target 7, the lens 8, the light splitting member 2, the lens 9 and the television camera 10 are sequentially arranged.
The output of the television camera 10 is connected to the television monitor 11.

A reflection image of the cornea Ec of the eye E to be inspected of the ring-shaped light source 5 is formed on the two-dimensional optical sensor 4 through the objective lens 1, the light splitting member 2 and the diaphragm 3, and its size is measured by a means described later. Then, the radius of curvature of the cornea Ec can be obtained. On the other hand, as shown in FIG. 2 (a), the image of the anterior segment of the subject's eye E is displayed on the television monitor 11 by the output of the television camera 10, and the anterior segment is an external eye illumination light source of visible light (not shown). Is illuminated by. The alignment target 7 is illuminated by the visible light source 6 and photographed by the television camera 10 via the lenses 8 and 9. An iris image Pi, an image Pr of the ring-shaped light source 5, an image Pa of the alignment target 7, a pupil image Pp, and an external eye illumination light source image Ps are displayed on the television monitor 11 in FIG. 2 (a).

The video signal of scanning line l is shown in Fig. 2 (b).
Has strong reflection, and the iris part Ei is dark and the level is low. The signal can be binarized by setting the level L in the middle, and the size of the iris image Pi can be found by finding the distance between the intersections a and b by means described later. The scanning line 1 is off the center of the eye E to avoid the light source image Ps, and can be converted into the diameter of the iris image Pi if the amount of deviation is determined in advance.

Next, FIG. 3 shows an electrical block circuit configuration diagram. First, the measurement unit of the radius of curvature of the cornea will be described. The analog signal read from the two-dimensional optical sensor 4 is the amplifier 2
The signal level is amplified by 0, the signal level is temporarily held by the sample value hold circuit 21, and the A / D converter 2 of the next stage is held.
At 2, it is converted into a digital signal. The sensor 4 is controlled by the clock signal of the driver 23. A / D
A digital signal output from the converter 22 passes through an interface 24 and a RAM (Random Access Memory) 25.
Memorized in. Reference numeral 26 is a ROM (Read Only Memory) in which a control program for operating the microprocessor 27 is written. The position of the ring image formed on the two-dimensional optical sensor 4 is obtained from the data in the RAM 25, and the radius of curvature of the cornea is obtained by fitting it to a general formula such as an ellipse. The radius of curvature of the cornea is displayed on the result display 28, if necessary. And is output to the printer 29.

Next, the corneal diameter measurement unit will be described. The video signal of the anterior segment image of the subject's eye E captured by the television camera 10 is input to the amplifier 30 and the cycle separation circuit 31 in addition to the television monitor 11. The scanning line counter 32 is operated. The output c from the scanning line counter 32 is connected to the interface 24. The video signal amplified by the amplifier 30 is input to the comparators 34 and 35 and the sample value hold circuit 36, and the output of the comparator 35 is input to the sample value hold circuit 36 via the monostable multivibrator 37. A pupil level setting signal d is connected to the other input of the comparator 35, an output e thereof drives a monostable multivibrator 37, and an output f thereof is passed through a sample value hold circuit 36 to a predetermined voltage signal g. The output signal h added by the adder 38 is connected to the input terminal of the comparator 34. The output i of the comparator 34 is connected to the gate input of the counter 39, and count control is performed by the clock output j of the oscillator 40. The count output k of the counter 39 is input to the interface 24, and the control signal m of the counter 39 is sent from the interface 24 to the counter 39.
The interface 24 has a ring-shaped light source 5 and a light source 6
Is connected and the control of turning on / off is performed.

The operation of the corneal diameter measuring unit will be described with reference to FIG. 4. Since the pupil image Pp is close to the black level and there is no individual difference, the pupil level setting signal d may be constant. If the monostable multivibrator 37 is driven by the fall of the output signal e from the comparator 35 and the video signal at the time of the fall of the signal e is held as a sample value, the level Li of the iris image Pi is determined and the individual difference Can be suppressed. By adding a predetermined level g to this level Li and comparing the level h with the output signal of the television camera 10 by the comparator 34, the iris signal i can be extracted. The signal h from the adder 38 is output for each scanning line while the pupil of the screen of the television monitor 11 is included. Based on the output c from the scanning line counter 32, when a predetermined scanning line is reached, a counter control signal m is output, the width of the iris signal i is counted by the clock output j, and the output k is read to determine the scanning line. The corneal diameter can be obtained by converting the diameter of the iris image Pi on l.

As a measurement operation procedure, while watching the TV monitor 11, first, the ring image Pr is brought into focus with the visual target image Pa, and when a measurement button (not shown) is pressed, the light sources 5 and 6 are turned off to measure the iris diameter, that is, the cornea diameter. After that, the ring-shaped light source 5 is turned on to measure the radius of curvature of the cornea, but this procedure may be reversed. In addition, it is easier to perform the signal processing when the ring-shaped light source 5 is turned off when measuring the iris diameter. Further, since the iris has a high reflectance with respect to infrared light, it is desirable to use visible light for external eye illumination. Further, if the observation optical system of the television camera 10 is a telecentric system, it is preferable that the blur does not affect the accuracy.

Further, as another measuring means, a ring-shaped corneal reflection image Pr by the light source 5 is projected on the television monitor 11, and this image Pr is generally represented by an ellipse. This ring-shaped statue Pr
The ellipse can be obtained by calculating the intersection of the rings by using at least three scanning lines according to the above, and thus the radius of curvature of the cornea in each radial direction can be calculated.

Further, the microprocessor 27 may calculate the base curve of the contact lens based on the measurement results of the radius of curvature of the cornea and the diameter of the cornea, and output the result to the result display 28 and the printer 29.

[Effects of the Invention] As described above, according to the eye measuring device according to the first invention, the corneal diameter is measured based on the image of the eye to be inspected on the television for observation, so that the measured value can be obtained easily and accurately.

Further, according to the eye measuring device according to the second aspect of the present invention, the corneal curvature radius and the corneal diameter, which are measured by separate devices, can be measured by the same device by sharing some optical systems and electric circuits. It is possible to simplify the device and the measurement procedure.

[Brief description of drawings]

The drawings show an embodiment of an eye measuring device according to the present invention,
The figure is its optical configuration, 2 (a) is the front view of the television monitor, (b) is the video signal waveform diagram of a specific scanning line, FIG. 3 is the block circuit configuration diagram, and FIG. 4 is its signal waveform diagram. Is. Reference numeral 1 is an objective lens, 2 is a light splitting member, 3 is a diaphragm, 4 is a sensor, 5 is a ring-shaped light source, 6 is a light source, 7 is an alignment target, 10 is a television camera, 11 is a television monitor, 2
1 and 36 are sample value hold circuits, 22 is A / D converter, 25 is RAM, 26 is ROM, 27 is microprocessor, 34 and 35 are comparators, 37 is monostable multivibrator, 38 is adder, 39 is counter Is.

Claims (6)

[Claims] 1. An observation television for observing the anterior ocular segment of an eye to be inspected, and an eye to be inspected based on a boundary between a sclera part and an iris part of an anterior ocular segment image of the subject's eye taken by the observation television. And a corneal diameter measuring means for measuring the corneal diameter of the eye. 2. A corneal curvature measuring means for measuring a corneal curvature of an eye to be inspected, an observation television for observing an anterior segment of the eye, and a sclera portion of the eye to be photographed by the observation television. An eye measuring device comprising: a corneal diameter measuring means for measuring a corneal diameter of an eye to be examined based on a boundary with an iris part. 3. The eye measuring device according to claim 1, wherein the corneal diameter measuring means obtains the corneal diameter by using the horizontal length of the iris part. 4. The cornea diameter measuring means determines the boundary between the sclera part and the iris part on the basis of a difference in level between the sclera part and the iris part on a specific scanning line of a video signal of the observation television, and the iris part. 7. The level of is automatically set by means for holding the scanning line level at a time point when a predetermined time has passed from the trailing edge of the light guide portion in the scanning line.
Item 2. The eye measurement device according to Item 2 or Item 2. 5. The cornea curvature measuring means according to claim 2, wherein a radius of curvature is obtained from a corneal reflection image of the light source projected on a photoelectric sensor by a light source arranged around the optical axis. Eye measuring device. 6. A base curve of a contact lens is obtained by calculating data obtained by the corneal diameter measuring means and the corneal curvature measuring means.
The eye measurement device according to the item.