JPH0360489B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention detects the alignment state between the device and the subject's eye, and when the device is correctly adjusted to a measurable alignment state, [Industrial Application Field] The present invention relates to an ophthalmic device configured to obtain predetermined information.

[Prior Art] Conventionally, there are many measuring devices for eye materials that require extremely accurate alignment in relation to the eye to be examined. For example, fundus cameras and non-contact tonometers require particularly precise alignment. It is known that its tolerance is extremely narrow. Therefore, a number of proposals have been made regarding mechanisms for detecting the degree of alignment between the measurement device and the eye to be examined. In recent years, with the development of such alignment detection mechanisms, if the positional relationship is correctly adjusted using the detected alignment information, measurement and measurement can be performed automatically without any special operation by the examiner. Measuring devices that perform recording are emerging.

For example, there is a non-contact tonometer with detection and automatic measurement functions as shown in FIG. The cornea Ec of the eye E to be examined is applanated using an air pulse emitted from the provided nozzle, and the intraocular pressure value of the eye E to be examined is measured. Other members attached to calculate the intraocular pressure value are not directly related to the present invention, so their explanation will be omitted. cornea of
Must be directed to Ec.

Therefore, in this conventional example, the alignment light beam emitted from the LED 5 is reflected by the mirror 6 and the half mirror 7, focused by the objective lens 4 onto the cornea Ec of the eye E, and reflected on the cornea Ec. The resulting light beam passes through the objective lens 4 again, and is further transmitted through a mirror 7 and an imaging lens 8, and then reflected by a mirror 9, and an alignment detection mechanism is provided in which the light is imaged and received on a photodetector 10. This detection mechanism is configured so that the amount of light received by the photodetector 10 is maximized when the cornea Ec is correctly aligned with the device.
The photoelectrically converted light reception signal is input to the comparator 11, where it is compared with the setting value from the setting device 12, and a trigger is generated when the deviation value is less than a certain value with respect to the amount of light reception signal when alignment is correctly performed. Vessel 1
3 activation signals are issued. The activation signal emitted from the trigger generator 13 is input to the AND circuit 14, and the other terminal of the AND circuit 14 has a
A circuit switch 15 for supplying power to the solenoid 3 is connected.

The automatic measurement system configured in this manner is capable of measuring the eye to be examined while the circuit switch 15 is turned on.
and the device is aligned within certain tolerances, the solenoid 3 is automatically energized and operated to perform the measurement of the intraocular pressure value as described above.

FIG. 7 is a state diagram of changes in the output of the photodetector 10 when the alignment between the eye E and the device shifts from front to back and left to right, the Z axis is the output of the photodetector 10, and the X axis is the left and right direction of the device. The Y axis indicates the position of the device in the front-rear direction, and FIG. 8 is a view of FIG. 7 from above. When the eye E to be examined and the device are completely aligned, the output becomes the maximum value on the Z axis.

When the eye to be examined E and the device are perfectly aligned, the deviation value in the comparator 11 will be approximately zero, but in reality it is extremely difficult to make such an adjustment, so the intraocular pressure can be adjusted to the desired accuracy. The tolerance is set so that the value is obtained. That is, automatic measurement is performed when the deviation value from the maximum output value becomes less than a certain fixed value, and the deviation value is uniquely determined. For example, if the deviation value is set to level 2, which is the intermediate tolerance in Figure 7, in Figure 8, the tolerance range in which automatic measurement is performed is surrounded by the level 2 line surrounding the origin O. range. Under these circumstances, if the trajectory of the position of the device when the examiner adjusts the alignment between the eye E and the device is, for example, S1, the measurement will be performed at the time M1 when the device enters the level 2 range. You will be killed. In such a case,
Although the level 2 range is certainly within the tolerance range within which the desired accuracy can be measured, even if it is possible to adjust the device to a range where higher accuracy can be obtained, for example to the level 3 region, the measurement must be performed one step before that. Therefore, the disadvantage is that the full performance of the device cannot be utilized.

In addition, since the subject eye E, which is the subject of accommodation, is a living eye, it constantly moves without stopping due to small movements of fixation.If the conditions worsen, the fixation of the subject eye E becomes insufficient, and its movements become extremely large. It may happen. This constant movement of the eye E to be examined corresponds to the constant movement of the XY coordinate axes in FIG. level 2
There is also the disadvantage that automatic measurement cannot be performed because the value cannot be reached forever within the range of .

[Object of the Invention] The object of the present invention is to detect the degree of alignment between the eye to be examined and the measuring device when measuring with an ophthalmic device, and select an optimal value from a plurality of tolerance ranges according to the degree of alignment. The object of the present invention is to provide an ophthalmic device that allows the best information to be obtained.

[Summary of the invention] The gist of the present invention for achieving the above object is as follows:
alignment detection means for detecting that the alignment state of the apparatus and the eye to be examined is within predetermined allowable conditions; means for automatically obtaining predetermined information about the eye to be examined based on an output signal from the alignment detection means; The ophthalmic device is characterized by comprising means for making predetermined permissible conditions variable.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 5. Note that the same reference numerals as in FIG. 6 indicate members having the same functions.

In FIG. 1, an air pulse generator consisting of a cylinder 1, a piston 2, and a solenoid 3 applanates the cornea Ec of the eye E by means of air pulses emitted from a nozzle at the center of an objective lens 4. A non-contact tonometer for measuring the intraocular pressure value of the eye E to be examined is equipped with an alignment detection mechanism for detecting the degree of alignment between the air pulse and the eye E to be examined and an automatic measurement mechanism (not shown). It is provided. As for the alignment detection mechanism, the alignment light beam emitted from the LED 5 is reflected by the mirror 6 and the half mirror 7, and is focused by the objective lens 4 onto the cornea Ec of the eye E, as in the conventional example described above. , the light beam reflected on the cornea Ec passes through the objective lens 4 again, further passes through the half mirror 7 and the imaging lens 8, is reflected by the mirror 9, and is imaged and received on the photodetector 10. ing.

The output signal of the photodetector 10 is sent to three comparators 20
a, 20b, 20c in parallel, and a setting device 21 is input to the other end of each comparator 20a, 20b, 20c.
Setting values F1, F2, and F3 are input, taking into account different deviation amounts from a, 21b, and 21c, respectively.
Each setter 21a, 21b, 21c is a seventh
As shown in Figure 8, level 1, level 2,
A permissible error range for the alignment accuracy of the eye E to be examined and the mechanism for level 3 automatic measurement is set. Comparators 20a, 20 responsible for wider tolerance ranges
The output of b is connected to pulse counters 22a and 22b, and for example, the pulse counter 22a receives the output signal from the comparator 20a five times when the high output signal is H.
The pulse counter 22b outputs the high output signal H level when the output from the comparator 20b reaches the high output signal H level three times, and the pulse counter 22b outputs the high output signal H level when the output from the comparator 20b reaches the high output signal H level three times. In each case, a low output signal of L level is output.

Further, the output signals of the pulse counters 22a and 22b and the output signal of the comparator 20c are input to an OR circuit 23, and the OR circuit 23 is connected to a trigger generator 24.
Automatic measurement is started when the output signal of any one of a, 22b and comparator 20c reaches the H level of a high output signal. The output signal of the OR circuit 23 is also input to the reset terminals of the pulse counters 22a, 22b at the same time, so that each pulse counter 22a, 22b is reset when one measurement is completed. In addition, the output of the comparator 20b is also input to the reset terminal of the pulse counter 22a corresponding to level 1, and if there is a possibility that even better alignment adjustment will be performed, the pulse counter 22a is configured to be reset.

In the device of the embodiment configured in this way, when the examiner aligns the device,
For example, trajectories S3, S4, S5 as shown in FIG.
, the respective trajectories S3, S4,
It operates to perform automatic measurements at points M3, M4, and M5 within different tolerance ranges level 1, level 2, and level 3 for S5. In other words, if the trajectory S3 is followed immediately to the origin O, which is the best alignment completion point, when adjusting the device, the comparator 2
The output signal of a becomes H level, the pulse counter 22a counts the H level once, and then once goes out of level 1 and enters level 1 again, the pulse counter 22a counts the second level as before. Perform counting. However, once it enters the level 2 region, the output signal of the comparator 20b becomes H level, the pulse counter 22b counts one, and at the same time the pulse counter 22a is reset, allowing more accurate alignment of the device. The circuit determines that something is true. After that, when the level 3 is further entered, the output signal of the comparator 20c becomes H level, and the output signal of the OR circuit 23 becomes H level regardless of the output signals of the pulse counters 22a and 22b, and the point M5 is reached. Automatic measurement is performed. Therefore, compared to the conventional apparatus which always performs measurements around level 2, this embodiment allows for more accurate measurements.

Next, when measuring the subject's eye E with slightly poor fixation, the trajectory during alignment of the device will be, for example, the trajectory S4 shown in FIG. Although it is similar to the case of the trajectory S3 described above, the trajectory S4 does not easily enter the level 3 area because the fixation is unstable. Therefore, every time the trajectory S4 enters the level 2 area, the pulse counter 22b operates, and at the third entry, the pulse counter 22b outputs a high output signal of H level to the OR circuit 23, and the logic The sum circuit 23 receives this output signal and operates to perform automatic measurement. The measurement point at that time is point M on the trajectory S4
4, and the alignment accuracy in this case is the same as that of the conventional device.

When measuring the subject's eye E whose fixation is more unstable, the trajectory during device alignment becomes, for example, trajectory S5 shown in FIG. 2, and trajectory S5 enters the level 2 area. Never. Therefore,
The conventional device had a drawback that automatic measurement was not performed forever, but in this embodiment, the comparator 20a outputs a high output signal of H level every time the trajectory S5 enters the level 1 region, and the number of times is counted by the pulse counter 22a, and automatic measurement is performed at point M5 when the vehicle enters the vehicle for the fifth time.

As mentioned above, the output signal of the OR circuit 23 is connected to the reset terminals of the pulse counters 22a, 22b, so when the measurement is completed, the pulse counters 22a, 22b are reset, and the device returns to its initial state and restarts. Measurement becomes possible.

In addition, automatic switching of the deviation value for setting the alignment tolerance range in this example is as follows:
Using the pulse counter 22 and the OR circuit 23,
This is done based on the number of times the levels within the respective allowable error ranges are entered, but it is not necessarily necessary to adopt such a method; for example, as shown in FIG. 26
It is also possible to use the method to perform switching according to the passage of time in the alignment of the apparatus. That is, comparator 2
The output signals of 0a, 20b, 20c are input to AND circuits 25a, 25b, 25c, respectively;
The output signal from the timer 26 is input to the other terminal of the timer 26, and the output signal from the comparator 20a is input to the start terminal of the timer 26.

When the H level is input to the start terminal of the timer 26, the H level of the output signal is input to the AND circuit 2.
5c, 25b, and 25a are output in this order after an appropriate elapsed time τ ₃ and τ ₂ as shown in FIG. When the output signals of the AND circuits 25a, 25b, and 25c are input to the OR circuit 23, and the output signal of the OR circuit 23 is input to the trigger generator 24 and the reset terminal of the timer 26, similar to the above case, Automatic measurement will start.

Therefore, if the output signal of the comparator 20c becomes H level within the elapsed time τ ₃ , that is, if the device is aligned within the tolerance range level 3 in FIG. Measurements are taken, and after that the tolerance range reaches level 3 with the elapsed times τ ₃ and τ ₂
The level is expanded from level 2 to level 1, and each time it is determined whether or not to perform automatic measurement based on the combination with the output signals of the comparators 20a, 20b, and 20c. Even in an apparatus having such a switching system, the accuracy is higher than that of conventional apparatuses, and measurement can be performed in any state of the eye E to be examined.

In the above example, a case was shown in which the device itself automatically selects and switches among multiple deviation values prepared as allowable errors between the alignment state of the eye E and the device. In this case, the examiner may simply manually perform such switching while observing the fixation state of the eye E to be examined. For example, as shown in FIG. 5, set values F1, F2, and F3 from setters 21a, 21b, and 21c are connected by a switch 27 in a comparator 20 for comparison with the output signal from the photodetector 10. Therefore, the examiner can freely set the allowable error range manually by changing the set value F sent to the comparator 20 by switching the switch 27 as necessary. In the embodiment shown in FIG. 5, three set values F are prepared in stages, but there is no problem in allowing them to take continuously variable values.

In addition, in practical use, it is important for the examiner himself to know within which tolerance range the measurement was performed, and in this regard, in the embodiments shown in FIGS. It is sufficient to add means for detecting from which terminal the H level of the high output signal is input, and in the embodiment of the manual switching device shown in FIG. 5, it is sufficient to display the switching status of the switch 27.

In the above embodiment, only one type of mechanism is used to detect the degree of alignment between the device and the eye to be examined.
Further, although only a non-contact tonometer was used as the measuring mechanism, it is of course possible to easily apply the present invention to various other devices.

[Effects of the Invention] As explained above, the ophthalmic device according to the present invention has the following effects:
When performing measurements that automatically obtain predetermined information, we have prepared multiple tolerance ranges for various alignment errors between the device and the eye being examined, so we can respond to the fixation state of the eye being examined, for example, and select the most accurate one. It is possible to obtain good results, and in the past, measurements were sometimes impossible if the fixation state of the eye being examined was poor.
With this device, there is no risk that measurements etc. will become impossible.

[Brief explanation of drawings]

Drawings 1 to 5 show an embodiment of the ophthalmic device according to the present invention, in which FIG. 1 is a configuration diagram thereof, FIG. 2 is a diagram of error change states, and FIG. 3 is a partial circuit configuration diagram. ,
FIG. 4 is an explanatory diagram of the timer output, FIG. 5 is a configuration diagram of another embodiment, FIG. 6 is a configuration diagram of a conventional example, and FIG. 7 is an explanatory diagram of the output state of the photodetector. FIG. 8 is a diagram showing how the error changes. 1 is a cylinder, 2 is a piston, 3 is a solenoid, 4 is an objective lens, 5 is an LED, 7 is a half mirror, 10 is a photodetector, 20a, 20b, 20
c is a comparator, 21a, 21b, 21c are setters,
22a, 22b are pulse counters, 23 is an OR circuit, 24 is a trigger generator, 25a, 25b, 2
5c is an AND circuit, 26 is a timer, and 27 is a switch.

Claims (1)

[Scope of Claims] 1. Alignment detection means for detecting that the alignment state between the device and the eye to be examined is within predetermined allowable conditions, and automatic detection of predetermined information about the eye to be examined based on an output signal from the alignment detection means. and means for making the predetermined allowable condition variable. 2. The ophthalmic device according to claim 1, wherein a plurality of the predetermined allowable conditions are prepared. 3. The ophthalmic device according to claim 2, wherein the predetermined allowable conditions are switched and used. 4. The switching of the plurality of predetermined tolerance conditions is performed by counting which tolerance range among the plurality of tolerance ranges and how many times it has been entered using a counter, and when the number of times it has entered a certain tolerance range has reached a certain predetermined number of times. The ophthalmic device according to claim 3, wherein the ophthalmic device is determined by whether or not the device is used. 5. The ophthalmic device according to claim 3, wherein the predetermined allowable conditions are switched in accordance with the elapsed time from the start of alignment adjustment using a timer. 6. The ophthalmic device according to claim 3, wherein the predetermined allowable conditions are manually switched by the examiner himself/herself. 7. The ophthalmic device according to claim 3, further comprising a display means for informing the examiner which of the predetermined allowable conditions has been used.