JPH01242029A - Positioning apparatus of ophthalmic machines - Google Patents

Abstract

PURPOSE:To perform highly reliable measurement and examination, by detecting not only the position of an eye to be examined but also the data of a glance direction to correct the glance direction. CONSTITUTION:Projection optical systems 1, 3 for projecting the light from a light source 4 or the index illuminated by said light source 4 on an eye E to be examined and an image forming optical system for forming the cornea reflected image 4' of the light source or index and the image of the anterior part of the eye E to be examined on an imaging element 2 are mounted. Two kinds of threshold values of different levels are set to detection means 10, 11 with respect to the signal from the imaging element 2 and said detection means detect the first region having intensity exceeding the higher level of the threshold value among two kinds of ones and the second region having the intensity not reaching the lower level. A detection means 12 (MPU) operates the respective centers of the first and second regions. Further, when the shift of the centers between the first and second regions is larger than a predetermined value, a correction means corrects the glance direction of an examinee. As a result, highly reliable measurement and examination become possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning device for an ophthalmological instrument that can more appropriately perform positioning with an eye to be examined.

[Conventional technology]

Conventionally, in automatic ocular refraction measuring devices and corneal shape measuring devices, an index is projected onto the cornea of the eye to be examined, and the reflected corneal image and the anterior segment of the eye to be examined are captured onto an image sensor by the anterior eye imaging optical system of the device. It is known to form an image and align the apparatus and the eye to be examined based on the position of the corneal reflection image.

[Problem to be solved by the invention] However, in the above conventional example, if the subject's eye has strabismus or the shape of the cornea is significantly deformed, the subject's gaze direction is incorrect and the automatic eye With a refractometer, the light for measuring refractive power may not enter the pupil, or the reflected light from the fundus may be kicked off by the iris, making measurement impossible. This has the disadvantage that the measuring device above may shift, making it difficult to measure accurately.

[Means for solving problems]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device that eliminates the drawbacks of the conventional example described above. The center of the area recognized by the signal below the value,
The relative deviation from the center of the area recognized by the signal equal to or higher than the higher threshold value is calculated, and if the deviation is large, the position of the fixation lamp is changed.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention.

An image of the vicinity of the cornea EC of the eye E to be examined is formed on the image sensor 2 by the objective lens 1 . Also, there is a beam splitter in the optical path.
3 is inserted, a light source 4 on the optical axis is projected onto the cornea by the objective lens 1, and the same image is formed on the image sensor 2 as a corneal reflection image 4'.

FIG. 2 is a view of the anterior segment of the subject's eye formed on the image sensor 2 on a TV monitor. The corneal reflection image 4' is decentered with respect to the pupil 5 due to strabismus of the subject's eye, etc. It shows that In this state, if the corneal reflection image 4' is simply measured by a known means by aligning it with the alignment mark (not shown) displayed on the TV monitor, for example, in the case of eye refractive power measurement, the luminous flux required for measurement will be the iris of the subject's eye. This may cause kicking, making measurement impossible, or even if measurement is possible, the accuracy will be reduced. Therefore, the examiner guides the examinee's line of sight and looks at the corneal reflection image 4 as shown in Figure 3.
′ and the pupil 5 must be approximately concentric.

A first detection example in which the deviation between the centers of the corneal reflection image 4' and the pupil 5 is automatically detected is shown in FIG. In FIG. 4, the signal output from the image sensor 2 is transferred to the D/A converter 10.
converts the light intensity signal into a digital signal according to the
Store in memory 11. Here, one scanning line 1 of the TV signal in FIG. 2 is shown in FIG. 5, and one scanning line 12 in FIG. 3 is shown in FIG. For both of them, the same lower threshold value Th12. Th22, higher identical threshold T
h1l and Th21 are set in advance, and the MPU 12 sequentially compares the digital signal of the TV image in the memory 11 with the threshold value, and determines the center position of the area below the low threshold value and the center position of the area above the high threshold value. position MPU1
Calculate using 2.

Here, the pupil area is recognized as an area below a low threshold, and its center position is determined using the scanning line where the largest area is detected as an area below the low threshold among multiple scanning lines. corresponds to the midpoint between the start and end of the region below the low threshold of . Further, the corneal reflection image of the light source 4 is recognized as a region above a high threshold, and its center position is also detected in the same way as in the case of the pupil region. Note that if the corneal reflection image of the light source 4 is small on the TV monitor, the center position of the corneal reflection image can be detected with relatively little error even if it is detected using a single scanning line instead of using multiple scanning lines. Note that these calculations are performed using MP
This can be done quickly using U12.

Then, if the center positions of the two detected areas are wider than a predetermined amount (deviation), a sound generating means (not shown) automatically makes a sound to the patient to correct the direction of the patient's line of sight. Further, the operation of the device is prohibited so that subsequent measurements and inspections are not performed.

Next, FIG. 7 shows a second embodiment in which the direction of the subject's line of sight is corrected using a fixation lamp array. In FIG. 7, the light source 104 for positioning is the relay lens 105. It is reflected by the beam splitter 103 by the objective lens 101, passes through the beam splitter 106, and is projected onto the cornea Ec of the eye E to be examined. On the other hand, the corneal reflection image 104' of the light source 104 and the anterior segment of the eye are transmitted to the beam splitter 106 by the objective lens 101.
, 103 and is imaged on the image sensor 102. Here, the fixation light array 107 has a plurality of elements 108 arranged as shown in FIG. 8 so that it can be selectively turned on. As described above, when the distance between the center of the pupil and the center of the corneal reflection image is greater than a predetermined value, the elements 108 of the fixation lamp array 107 are automatically moved in the direction in which the pupil position and the corneal reflection image position approach each other. By lighting up the elements, it is possible to correct the line of sight.

Furthermore, when the distance between the center of the pupil and the center of the corneal reflection image is greater than a predetermined value, information (for example, an arrow) indicating the line of sight direction to be corrected is displayed on the TV monitor to alert the examiner. You can also do it.

Next, a second detection example in which the deviation between the centers of the corneal reflection image 4' and the pupil 5 is automatically detected is shown in FIG. In FIG. 9, the signal from the image sensor 2 has two threshold values Thl.

Two voltage comparators 13 with Th2 as a reference. 14, and when a signal higher than the higher threshold Thl is input, the voltage comparator 13 is turned ON, and the time is measured by the timer 16a using the clock 15 as a reference, and similarly the lower threshold Thl is input. When a signal lower than the value Th2 is input, the voltage comparator 14 is turned on and the timer 16b is activated.
The time is measured by This is integrated by integrator 17a, 17b for one frame, and the center of each area is calculated by MPU.
12 can be calculated and obtained.

〔Effect of the invention〕

As described above, according to the present invention, information on not only the position of the eye to be examined but also the direction of the line of sight is detected, and the direction of the line of sight is corrected to enable more reliable measurements and examinations.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the first embodiment of the present invention, FIG.
The figure is a diagram of a TV monitor. Figure 4 is a diagram of the first detection example that automatically detects the deviation between the corneal reflection image and each center of the pupil. Figures 5 and 6 are schematic diagrams of TV scanning lines. Fig. 7 is a diagram of the second embodiment using a fixation lamp array, Fig. 8 is a diagram of a fixation lamp array, and Fig. 9 is a diagram of automatically detecting the deviation between the corneal reflection image and each center of the pupil. Diagram of the second detection example. In the figure, 1.101 is an objective lens, 2.102 is an image sensor, 3.103, 106 is a beam splitter 14, 104
is a light source, 5 is a pupil, 10 is a D/A converter, 11 is a memory, and 12 is an MPU. 107 is a fixation light array, and 108 is a fixation light element.

Claims (2)

[Claims] (1) Includes a projection optical system that projects a light source or a target illuminated by the light source onto the subject's eye, and an imaging optical system that forms an image of the corneal reflection image of the light source or target and the anterior segment of the subject's eye on an imaging device. In an ophthalmological instrument alignment device, two different levels of thresholds are set for the signal from the image sensor, and the first signal has an intensity exceeding the higher of the two thresholds. a detection means for detecting a second region having an intensity that does not reach the lower level of the region; a calculation means for calculating the respective centers of the detected first region and the second region; 1. An ophthalmological instrument positioning device characterized by having a correction means for correcting the direction of the subject's line of sight when the deviation of the center of the second region is larger than a predetermined value. (2) The ophthalmological instrument positioning apparatus according to claim 1, wherein the correction means selectively turns on one of a plurality of fixation lights provided in a plane perpendicular to the optical axis.