JPH0394740A - Ultrasonic wave measuring instrument for ophthalmology - Google Patents

Abstract

PURPOSE:To obtain a precise measuring value by reducing an error due to irregularity on the surface of a cornea by providing a storage means to store a measuring signal obtained with a measuring means which detects length between parts in an eye-ball, and a selection means which finds the measuring value when the amount of deformation of the cornea due to the contact of an ultrasonic probe is minimized. CONSTITUTION:A transmitter/receiver 7a of the ultrasonic probe 7 emits an ultrasonic wave to the eye-ball of the eye E to be inspected, and also, receives ultrasonic reflection signals S1, S2, S3, and S4 generated due to the interface of a medium in the eye-ball, and stores them in a memory circuit part 24. At this time, since the cornea Ec becomes hollow a little, the axial length of eye i.e., a distance from S1 to S4 is reduced a little by pressing the ultrasonic probe 7. However, by depressing a push-button switch 19, the ultrasonic probe 7 is separated from the surface of the cornea Ec, and the ultrasonic reflection signal is switched to an interface signal S0 with the air. By detecting such switching, the ultrasonic reflection signals S1-S4 just before switching i.e., at a state where the minimum quantity of hollow of the cornea Ec can be obtained. Therefore, the measuring value between the parts in the eye-ball not including the error can be obtained by reading out and calculating the measuring signal at that time from the memory circuit part 24.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention emits an ultrasonic signal by bringing an ultrasound probe into contact with the cornea of the eye to be examined, and uses the reflected signal to determine the distance between the parts of the eye to be examined. This article relates to an ophthalmological ultrasonic measurement device that measures eye health. [Prior art J] For example, when measuring the axial length of an eye to be examined using an ultrasonic axial length meter, after numbing the eye to be examined with eye drops,
The tip of the ultrasound probe is pressed against the corneal surface, and in this state an ultrasound signal is emitted into the eyeball, and the axial length, which is the length from the corneal surface to the retina, is determined by detecting the ultrasound reflected signal. is being measured. In this case, in order to stably propagate the ultrasound signal into the eyeball, it is necessary to press the ultrasound probe against the corneal surface with a predetermined pressure. However, due to this pressure, the corneal surface is slightly concave, and with conventional ultrasonic axial length meters, this concavity causes errors in the measured values. [Problems to be Solved by the Invention] The amount of dent on the corneal surface caused by pressing the ultrasound probe varies depending on individual differences such as intraocular pressure even if the pressing pressure is constant. Errors in measurement values cannot be corrected simply with a fixed correction value. Furthermore, if you want to perform highly reliable axial length measurement,
There is also the problem that the examiner needs to be skilled in manual operation of the ultrasound probe. The purpose of the present invention is to improve the problems of such conventional examples,
Ultrasonic measurement for ophthalmology that reduces errors caused by corneal surface dents and makes it possible to obtain accurate measurement values by detecting ultrasound reflected signals when the cornea has almost returned to its original spherical shape. The goal is to provide equipment. [Means for Solving the Problems] In order to achieve the above object, in the ophthalmological ultrasound measuring device according to the present invention, an ultrasound probe is brought into contact with the cornea of the eye to be examined, and while being retracted, the ultrasound probe is moved inside the eyeball. a measuring means for repeatedly detecting the length between parts within the eyeball based on the ultrasound reflected signal;
a storage means for storing measurement signals obtained by the measurement means; and when the amount of corneal deformation due to contact with the ultrasound probe is minimized by selecting the longest measurement signal from the measurement signals stored in the storage means; The present invention is characterized by comprising a selection means for determining the measured value of. [Function] The ophthalmological ultrasound measuring device having the above-mentioned configuration, after bringing the ultrasound probe into contact with the cornea of the eye to be examined, continues to detect the ultrasound reflected signal waveform while viewing the ultrasound probe. Retract from the cornea in the axial direction. At this time, the measurement signals are stored sequentially, and the measurement signal when the amount of corneal deformation due to contact with the probe is the smallest is selected from among the stored measurement signals to obtain the measurement value between the parts within the eyeball. ．． [Example] The present invention will be explained in detail based on the illustrated example. FIG. 1 shows an embodiment of the ophthalmological ultrasonic measuring device according to the present invention. A movable table 2 is placed on the base 1,
The movable base 2 can be moved forward, backward, left, and right by operating the operating rod 3. An electric circuit unit, which will be described later, is housed inside the base 1, and a printer, etc. (not shown) is mounted on the front of the base 1. It is located. Furthermore, the movable table 2 is equipped with a table 5 that can be moved up and down by turning a handle 4 at the base of the operating rod 3. A holder 8 holding a child 7 is attached. As shown in FIG. 2, the holder 8 is supported by a sliding member 9 such as a stroke bearing so that it can move forward and backward with extremely small frictional force, and is pressed forward by a weak predetermined pressure by a spring 10. ．． The ultrasonic probe 7 held by such a mechanism is lightly pressed against the eye E to be examined, and when the axial length measurement signal of the eye E to be examined is not detected, the holder 8 is moved to the motor 11 and the large body connected thereto. It is designed to be retracted by a certain drive mechanism from the boom 12, small boots 13, 14, wire bell} 15, etc. Furthermore, as shown in FIG. 2, the wire belt l5 is attached to the holder 8.
Normally, the wire belt 15 does not come into contact with the holder 8 so as not to interfere with the light movement of the wire belt 15, but when the axial length measurement signal is detected and the motor 11 is driven, the wire belt 15 is caught between the electromagnetic chucks 16. holder 8 to a predetermined position at the rear.
For example, the microswitch 17 is configured to move to a detection position. In addition, 1 ± the subject's face F is placed on the base 1.
A face fixing stand l8 is provided for fixing the face, a push button switch 19 is attached to the top of the operation stick 3, and a face fixing stand l8 is provided for fixing the face.
On the front side, there is a display 20 that displays measurement signal waveforms and measured values.
is provided. FIG. 3 shows a block circuit diagram of the electric circuit section, in which an ultrasonic transmitter/receiver circuit section 21 is connected to the ultrasonic probe 7, and a measurement switch 22 and a signal processing circuit section 23 are connected to the transmitter/receiver circuit section 2l. It is connected.

The output of the signal processing circuit section 23 is connected to a memory circuit section 24 and a waveform judgment circuit section 25, and the output of the memory circuit section 24 is further connected to an arithmetic processing circuit section 26 and a display 20.
The push button switch 19 is an electromagnetic chuck ●Motor control circuit section 2
7, this electromagnetic chuck motor control circuit section 27
The outputs of are connected to the electromagnetic chuck 17 and the motor 11, respectively. To explain the operating procedure of this embodiment, as shown in FIG. By tilting 3 and rotating the handle 4, fine positioning is performed so that the tip of the ultrasound probe 7 coincides with the visual axis of the eye E to be examined. Thereafter, the operating rod 3 is tilted forward to force the tip of the ultrasound probe 7 into contact with the cornea Ec of the eye E to be examined. Then, the holder 8 of the ultrasound probe 7 is returned slightly to the rear, but since it is pressed with a predetermined pressure by the spring 10, the surface of the cornea Ec is slightly depressed, but the ultrasound probe 7 The tip of No. 7 is securely brought into contact with the surface of the cornea Ec without an intervening air layer.

In the electric circuit section, the ultrasonic transmitter/receiver circuit section 2l transmits an ultrasonic drive signal to the ultrasonic transmitter/receiver 7a in the ultrasonic probe 7 at a predetermined period based on a command from the measurement switch 22. Then, the ultrasonic transmitter/receiver 7a emits ultrasonic waves into the eyeball of the subject's eye E, and transmits an ultrasonic reflection signal St. generated by the interface of the medium inside the eyeball. Receive S2, S3, and S4. Here, the received reflected signal Sl. S2, S3
, S4 are sent to the signal processing circuit section 23 via the ultrasonic transmitting/receiving circuit section 21, and further sent to the memory circuit section 24 for storage.

At this time, the signal processing circuit section 23 also applies to the waveform judgment circuit section 25.
The output of the ultrasound probe 7 and the cornea Ec are sent to the waveform judgment circuit section 25, and the reflected signal determines whether the ultrasound probe 7 and the cornea Ec are in contact with each other or are separated from each other. The arithmetic processing circuit section 26 calculates the measured values between each site within the eyeball based on the ultrasound reflection signal read out from the memory circuit section 24. As a result, the obtained axial length measurement value and the like are displayed on the display 20 or output to a printer (not shown) as necessary. Note that the waveform information from the memory circuit unit 24 is also displayed on the display 20 so that the examiner can confirm it.

FIG. 4 shows the state in which the tip of the ultrasound probe 7 is pressed against the cornea Ec of the eye E to be examined and the ultrasound reflected signal in that case.
1 is the lens, Er is the retina, and Sl is the ultrasound probe 7.
The ultrasound reflection signal from the surface of the cornea Ec obtained by
Similarly, S2 is an ultrasound reflected signal from the front surface of the crystalline lens E1,
S3 represents an ultrasound reflection signal from the posterior surface of the crystalline lens El, and S4 represents an ultrasound reflection signal from the retina Er. While the ultrasound probe 7 is pressed against the cornea Ec, the cornea E
c is slightly concave, so the axial length of the eye, that is, the distance from Sl to 54 in Fig. 4, is slightly shorter, but after confirming on the display 20 that this measurement signal is appropriate, press the push button switch l9. Press. Then, the electromagnetic chuck 17 is energized to clamp the wire belt 15, and the motor 11 is driven to cause the ultrasound probe 7 to begin to retreat from the cornea Ec in the visual axis direction. At the same time, ultrasonic reflection signals are detected and the measured signals are sequentially stored in the memory circuit 24. Due to its inherent elastic force, the cornea Ec gradually begins to return to its original shape while in contact with the ultrasound probe 7, and eventually, as shown in FIG. 5, when the ultrasound probe 7 separates from the surface of the cornea Ec, The ultrasonic reflection signal is switched to the air interface signal SO. If such a change in the ultrasonic reflection signal waveform is detected, the ultrasonic reflection signals S1 to S4 will be detected immediately before the change, that is, just before the ultrasonic probe 7 separates from the cornea, when the amount of depression in the cornea Ec is the smallest. It becomes possible to detect. The ultrasonic reflection signals S1 to S4 at this time are ultrasonic reflection signals at a position where the cornea Ec has almost returned to its original spherical shape. It becomes possible to obtain measurement values between parts of the eyeball that do not include errors due to concavities. Therefore, in this embodiment, the measurement signal repeatedly measured when the probe 7 is retracted is temporarily stored in the memory circuit section 24, and the waveform judgment circuit section 24 detects that the signal waveform has been switched.
When the signal is detected in the memory circuit section 2, the measurement signal immediately before that
By reading out and calculating from 4, the maximum axial length with almost no dent in the cornea Ec can be obtained. In the above embodiment, after pressing the ultrasound probe 7 against the cornea Ec with a predetermined pressure, the ultrasound probe 7 is moved by the motor 1.
Although the ultrasonic probe 7 is moved backward by the drive in step 1, the present invention is not limited to this, and the ultrasonic probe 7 may be moved backward by moving the movable plate 2 by tilting the operating stick 3 toward you. Further, in the above-described embodiment, after the ultrasound probe 7 has been brought into contact with the cornea Ec, the ultrasound probe 7 is moved back in response to a command by pressing the push button switch l9. A system is introduced that can automatically detect when the probe 7 contacts the corner 1iiEc and a proper measurement signal is obtained, and when the measurement signal is detected, the motor 1l is automatically driven to move the ultrasonic probe 7. You can move it backwards. In addition, even when measuring by manually bringing the ultrasound probe 7 into contact with the cornea Ec, it is possible to manually It is also possible to perform an operation to retreat the ultrasound probe 7 from the cornea Ec along the visual axis direction. Then, the measurement signal just before the ultrasound probe 7 leaves the cornea Ec may be read out. Furthermore, instead of storing all measurement signals in the memory circuit section 24, only correct signals may be left and other signals may be deleted each time a measurement is performed. [Effects of the Invention] As explained above, the ophthalmic ultrasonic measurement device according to the present invention can be used after confirming that an appropriate ultrasonic reflection signal is detected by aligning the ultrasonic probe with the visual axis direction. , the reflected signal is detected while the ultrasound probe is retracted in the direction of the visual axis, and this measurement signal is sequentially memorized and the optimal value is selected from among them, so that it can be detected even when the cornea has returned to its original shape. Since a measurement signal is obtained, accurate measurement values can be obtained without the influence of dents caused by the contact pressure of the ultrasound probe on the cornea, and with fewer errors due to poor alignment of the measurement system.

[Brief explanation of drawings]

The drawings show an embodiment of the ophthalmological ultrasonic measuring device according to the present invention, in which Fig. 1 shows the overall configuration, Fig. 2 is a plan view of the electromagnetic chuck section, and Fig. 3 shows a block circuit of the electric circuit section. Composition diagram,
Fig. 4 is an explanatory diagram of the axial length measurement state, and Fig. 5 is an explanatory diagram of the ultrasound reflected signal when the ultrasound probe is separated from the cornea. 7 is an ultrasonic probe, 8 is a holder, 9 is a sliding member, 10 is a spring, 11 is a motor, 15 is a wire belt, 16 is an electromagnetic chuck, 17 is a micro switch, 1
9 is a push button switch, 2l is an ultrasonic transmitting/receiving circuit section, 22 is a measurement switch, 23 is a signal processing circuit section, 25 is a waveform judgment circuit section, 24 is a memory circuit section, 26 is an arithmetic processing circuit section,
27 is the electromagnetic chuck motor control circuit. Figure 1

Claims (1)

[Claims] 1. Measuring means for repeatedly detecting the length between parts within the eyeball based on ultrasound reflection signals within the eyeball while bringing an ultrasound probe into contact with the cornea of the eye to be examined and moving it back; a storage means for storing the measured measurement signals stored in the storage means; and by selecting the longest measurement signal from the measurement signals stored in the storage means, a measurement value when the amount of corneal deformation due to contact with the ultrasound probe is minimum is determined. 1. An ophthalmological ultrasonic measuring device comprising: a selection means.