JPH0197434A - Ophthalmic measuring apparatus - Google Patents

Abstract

PURPOSE:To perform rapid and accurate measurement of the refractive power of the intraocular lens by making a circuit obtaining cornea shape data and a circuit measuring the length signal of a predetermined region common and calculating the said refractive power value based on the radius of curvature of the cornea derived from the cornea shape data and the length signal of the predetermined region of an eye to be examined by the said common operation means. CONSTITUTION:The image signal of a two-dimensional image sensing element for measuring the shape of the cornea is compared with a predetermined reference signal through an image signal processing circuit 21 and a comparator 38 to be converted to a digital signal which is, in turn, inputted to a gate circuit 40. The coordinates in a horizontal direction of four bright points are calculated from the number of clock pulses while a horizontal synchronous signal is taken in by an internal bus 25 and the coordinates in a vertical direction are calculated. An ultrasonic echo signal is converted to a digital signal by the comparator 39 present in a common circuit 24 to be inputted to a data circuit 40 and the length of the predetermined region in an eyeball is calculated. From the cornea shape data of an eye to be examined and the measured value of the length of the predetermined region, a microprocessor unit calculates the refractive power of an intraocular lens according to the predetermined operation formula written in a read only memory.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention optically measures the corneal shape of the eye to be examined, and also measures the thickness of the lens, vitreous length, axial length, etc. of the eye by using ultrasound. The present invention relates to an ophthalmological measurement device that measures each part and calculates the ocular refractive power of an intraocular lens.

[Prior Art] Conventionally, spectacle lenses or contact lenses have been used to correct refractive power, for example after cataract surgery, but in recent years, intraocular lenses have been inserted into the position of the removed crystalline lens.

In order to select an appropriate intraocular lens for patients with aphakic eyes, it is necessary to know the corneal refractive power and the axial length, that is, the length from the cornea to the retina. Therefore, in the past, corneal refractive power was measured using a corneal shape measuring device, while axial length was measured using a separate ultrasonic measuring device, and the refractive power of the intraocular lens was calculated after each measurement was completed. There is the inconvenience of having to do this, and the measurement requires a considerable amount of effort and time.

In addition, devices that have both of these two functions are also known, but in such devices, an ultrasound probe for measuring the axial length is present in the optical path when measuring the corneal shape, so the corneal reflection image is It has drawbacks such as being eclipsed by the image of the ultrasonic probe, making it difficult to make accurate measurements.

[Object of the Invention] An object of the present invention is to provide an optical measuring means for obtaining corneal shape information of the eye to be examined, and an ultrasonic measuring means for obtaining the length of a predetermined part of the eye to be examined using an ultrasonic probe. An object of the present invention is to provide an ophthalmologic measuring device that can quickly and accurately measure the refractive power of an intraocular lens using the same calculation means based on the corneal refractive power and the length of a predetermined portion.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide an optical measuring means for obtaining corneal shape information of an eye to be examined, and an ultrasonic measuring means for obtaining a length signal of a predetermined part of the eye to be examined using an ultrasonic probe. a sound wave measuring means, a circuit for obtaining the corneal shape information and a circuit for measuring the length signal of a predetermined region are shared, and the radius of corneal curvature based on the corneal shape information and the length/signal of the predetermined region of the eye to be examined are determined. This is an ophthalmological measurement device characterized in that the refractive power value of the intraocular lens is calculated from the same calculation means.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

1 and 2 show the optical system of the ophthalmological measuring device according to the present invention, FIG. 1 shows the state when measuring the shape of the cornea, and FIG. 2 shows the state when measuring the axial length of the eye. In Figure 1, the eye to be examined E
An objective lens 1 is provided facing the cornea Ec, and a mirror 2.3, an aperture 4, a relay lens 5, and a two-dimensional imaging device 6 such as a COD are arranged behind the objective lens 1 along the optical path. Further, as shown in FIG. 3, a plurality of light sources 7a to 7d are arranged around the objective lens l. The objective lens 1, mirror 2.3, and light sources 1a to 1d are integrally constructed, and can be moved from the state shown in FIG. 1 to the state shown in FIG. 2, or vice versa, by a drive mechanism (not shown). . Furthermore, an ultrasonic probe 8 is held by a sliding guide member 10 via a probe holder 9 so as to be movable back and forth along the optical axis direction of the objective lens 1 shown in FIG.

In the case of the corneal shape measurement shown in FIG. An image is formed on the image sensor 6. In this case, the ultrasound probe 8 is located behind the mirror 2.

Next, in the case of axial length measurement, as shown in FIG. The eyepiece moves forward along the motion guide member 10, approaches or contacts the cornea Ec of the eye E, and measures the axial length.

FIG. 4 shows a circuit configuration for signal processing.

Here, the output of the two-dimensional image sensor 6 is output from the image signal processing circuit 2.
1, a mixer circuit 22, and a synchronous separation circuit 23, and the output of the image signal processing circuit 21 is connected to an internal bus 25 via a common circuit 24. Further, an image memory 26 is connected to the internal bus 25, and the output of this image memory 26 is connected to a television monitor 27 via a mixer circuit 22. The output of the synchronization separation circuit 23 is connected to the internal bus 25 via a recording circuit 28 and a storage circuit 29. The output of the ultrasonic probe 8 is transmitted through the ultrasonic transmitter/receiver circuit 30 and the common circuit 2.
4 to the internal bus 25. The internal bus 25 also includes a microprocessor unit (MPU) 3.
1. Read-only memory (ROM)32. A random access memory (RAM) 33 and a nonvolatile memory 34 are connected, and the output of the internal bus 25 is connected to an interface 35 and a printer 36. Furthermore, the interface 35
A measurement switch 37 and light sources 7a to 7d are connected to.

FIG. 5 is a circuit diagram of the common circuit 24, in which the outputs of the one-image value processing circuit 21 and the ultrasonic transmitting/receiving circuit 30 are connected to a gate circuit 40 via comparators 38 and 39, respectively. The gate circuit 40 includes a clock signal generation circuit 41
The output of gate circuit 40 is connected to four counting circuits 42-45, and the outputs of these counting circuits 42-45 are connected to data storage circuits 46-4, respectively.
9 to the internal bus 25.

When performing corneal shape measurement, the zero order is adjusted so that a bright spot from the four light sources 7a to 7d appears on the cornea of the eye E shown on the television monitor 27 as shown in FIG. , when the measurement switch 37 is pressed, the imaged light sources 7a~
The image signal a of the two-dimensional image sensor 6 shown in FIG.
The signal is then compared with a predetermined reference signal and converted into a digital signal as shown in FIG. 7(b). This digital signal is input to the gate circuit 40, which generates gate signals dg as shown in FIGS. 7(d) to 7(g). The output signals d-g of the gate circuit 40 are input to the counting circuits 42 to 45, respectively, and only during this period the seventh signal dg from the clock pulse generation circuit 41 is
The number of clock pulses shown in Figure 7(h) is counted, and the number of clock pulses shown in Figure 7(b) is counted.
) The number of clock pulses at the rising edge and the number of clock pulses at the falling edge of the digital signal of the reflected image shown in ) are stored in data storage circuits 46 to 49, and 4 is calculated from these clock pulse numbers.
Calculate the horizontal coordinates of the two bright spots.

The vertical coordinate is determined by separating the horizontal synchronization signal from the image signal a of the two-dimensional image sensor 6 by the synchronization separation circuit 23, and counting the horizontal synchronization signal C shown in FIG. When detected, the horizontal synchronization signal C is taken in by the internal bus 25, and the vertical coordinates are calculated. The corneal shape is then measured using these coordinates using a known method.

A predetermined calculation formula written in the read-only memory 32 calculates the maximum radius of curvature, minimum radius of curvature, average radius of curvature, degree of corneal astigmatism, and astigmatic axis angle, which are corneal shape information, and the spherical refractive power, which is eye refractive power information. - Calculate the eye refractive astigmatism degree and astigmatism axis angle, and the results are stored in the image memory 26 and mixer circuit 22
is displayed on the television monitor 27 via.

When measuring the length of a predetermined region using ultrasound, the ultrasound probe 8 is brought into contact with the cornea of the eye E to be examined. At this time, a drive pulse is applied to the ultrasound probe 8 from the ultrasound transmission/reception circuit 30, and the ultrasound pulse signal is reflected within the eyeball. The echo signal a shown in FIG. 9(a) from within the eyeball is amplified by the ultrasonic transmitting/receiving circuit 30, and then sent to the common circuit 2.
The comparator 39 in FIG. 9 converts the digital signal into a digital signal as shown in FIG. Generate c-e. The gate signal C is a gate signal indicating the anterior chamber depth in the eyeball, the gate signal d is a gate signal indicating the crystalline lens thickness, and the gate signal e is a gate signal indicating the anterior chamber depth in the eyeball.
is a gate signal indicating the vitreous thickness. These gate output signals ce are input to the counting circuits 42 to 44, respectively, and only during this time the clock pulse generator 41 outputs the signals shown in FIG.
The clock pulses shown in D are counted, the number of clock pulses is stored in the memory circuits 46 to 48, and the length of a predetermined region within the eyeball is calculated. Further, the amplified echo signal a is converted into a digital signal by an A/D converter in the common circuit 24, is written into an image memory 26 via an internal bus 25, and is displayed as an ultrasonic reflected wave signal on a television monitor 27. are displayed corresponding to each part of the eye E as shown in FIG. At this time, the eye E to be examined is guided in the visual axis direction or the angle of the ultrasound probe 8 is changed so that the echo signal a from the crystalline lens and retina becomes maximum.

If you press the measurement switch 37 here, the interface 35
An echo signal a from within the eyeball is measured by known means. Microprocessor unit 31
calculates the axial length, anterior chamber depth, crystalline lens thickness, and vitreous thickness using a predetermined calculation formula written in the read-only memory 32, and the results are sent to the television monitor 27 via the image memory 26 and mixer circuit 22. will be displayed.

Further, the microprocessor unit 31 uses the corneal shape information of the eye E to be examined obtained as described above and the measured value of the length of the predetermined region to determine the size of the intraocular lens according to a predetermined calculation formula written in the read-only memory 32. The refractive power is calculated and the result is displayed on the television monitor 27 via the image memory 26 and the mixer circuit 22.

[Effects of the Invention] As explained above, the ophthalmological measurement device according to the present invention can measure corneal shape, axial length, etc. with one device, and can quickly select an appropriate intraocular lens. , cost reduction can be achieved by sharing circuits.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmological measuring device according to the present invention, and the first embodiment
The figure is a block diagram of the state of corneal shape measurement, Figure 2 is a block diagram of the state of ultrasound measurement, Figure 3 is the arrangement of the light source, Figure 4 is the block circuit diagram, and Figure 5 is the common circuit. Configuration diagram, No. 6
The figure is a front view of the TV monitor, Figure 7 is a diagram of the output waveforms of each circuit during corneal shape measurement, Figure 8 is a front view of the monitor during ultrasound measurement, and Figure 9 is a diagram of each circuit during ultrasound measurement. It is an output waveform diagram. Reference numeral 1 is an objective lens, 6 is a two-dimensional image sensor, and 7a to 7d.
8 is a light source, 8 is an ultrasound probe, 21 is an image signal processing circuit, 22 is a mixer circuit, 23 is a synchronous separation circuit, 24 is a common circuit, 25 is an internal bus, 26 is an image memory, 27 is a television monitor, 28.42 -45 is a counting circuit, 30 is an ultrasonic transmitting/receiving port path, 31 is a microprocessor unit, 32
is a read-only memory, 33 is a random access memory, 34 is a non-volatile memory, 37 is a measurement switch, 46-
49 is a data storage circuit. Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] 1. Optical measurement means for obtaining corneal shape information of the eye to be examined; and ultrasonic measurement means for obtaining a length signal of a predetermined part of the eye to be examined using an ultrasonic probe; The refractive power value of the intraocular lens can be calculated in the same way from the corneal curvature radius based on the corneal shape information and the length signal of the predetermined part of the eye. An ophthalmological measuring device characterized by calculating by a means. 2. The ophthalmological measuring device according to claim 1, wherein the common circuit is constituted by a plurality of counting circuits and a data storage circuit.