JPS6216086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to methods and apparatus for examining the eye, and more particularly to automatic perimetry systems for use in visual field testing.

BACKGROUND OF THE INVENTION Testing of a patient's visual field is a vital diagnostic tool used to identify and analyze diseases and defects of the retina and optic tract, such as glaucoma, optic nerve disease, double sclerosis, and optic nerve compression. It is. Traditionally, such tests have been performed using a manual visual field testing instrument known as a perimeter. Manual perimetry requires the labor of a physician or skilled technician. In the most widely used system (Goldmann system), the patient must be seated with his or her head clamped in place to eliminate additional head movement uncertainty. It won't happen. Currently widely used procedures unduly fatigue patients and clinicians, and due to fatigue and heavy reliance on subjective human factors, test results are inconsistent and/or irreproducible. It is becoming.

Furthermore, automatic perimeter meters have recently become commercially available and in use. However, even these essentially use the Goldman method and incorporate microprocessor control.

The Goldman method requires the patient to sit facing a hemispherical screen with his or her head strapped to a headrest. In this way, the patient must maintain a constant sitting position throughout the examination. The patient constantly fixes his eyes to a "fixation point" in the center of the screen. The test can last some time between 20 minutes and 1 hour. Small dots of light of varying intensity, size and color form the screen.
is projected onto and its position can be changed by the operator. As the light is moved radially between the circumference and center of the patient's field of vision, the limits of the field of view are determined based on the patient's indication of when the point of light enters or exits the field of view. Ru. The patient's eyes
The examiner must constantly keep an eye on the patient to ensure that the screen remains centered. If the patient's vision wanders and is not fixed on a fixed point, the examination is worthless. Thus, testing the range of visual field using the commonly available Goldmann method is essentially subjective. It depends to a large extent on the skill of the examiner, the patient's fatigue level, and the examiner's effectiveness in communicating with the patient.

It is an object of the present invention to provide a new and improved perimeter system in which the aforementioned disadvantages are substantially reduced or overcome.

SUMMARY OF THE INVENTION In accordance with the present invention, a perimetry method for automatically testing a patient's visual field is provided. The method consists of the following: a screen means positioned in front of the patient's eyes; an examination point projection means for projecting a spot of light onto the screen to be seen by the patient; and on the center of the screen. A means for monitoring eye position to ensure fixation of the patient's eyes during the test, a scanning means for scanning points on the screen, and a means for monitoring the patient's head movement during the test. a helmet that fits over the patient's head for supporting the screen means, the test point projection means, the eye position monitoring means and the scanning means so as not to interfere with the patient's head;

Further features of the invention include a microprocessor for automatically controlling the scanning means and resolving data from the eye position monitoring means during the examination. Still other features of the invention provide means for using the modality for further examination of the eye in addition to visual field testing.

GENERAL DESCRIPTION In FIG.
1 is shown. Helmet 12 is shown as being a hemispherical structure and covering the patient's face. The illustration of the helmet 12 in FIG. 1 is a partial cross-section to show the inside of the helmet. Inside the helmet is a hemispherical screen indicated by line 16. The inner surface of the helmet can serve as a screen. There is an electromechanical system 17, shown attached to the helmet, which moves a mirror scanner 18 according to a program designed to move the light spot to various positions on the screen. Includes means for moving. A spot is also generated by a spot generating optical device 19 attached to the helmet.

Means are provided for determining that the patient's eye is centered on the screen. More particularly, electro-optical eye position monitoring or detection means are generally indicated by a box 21 mounted on the outer periphery of the helmet device. Cable 22 acts as an umbilical cord connecting the helmet to the console device shown, generally at 23.

Console apparatus 23 includes means for generating the light used by the optical system to the helmet. The light source arrangement is shown generally as block 24. It should be noted that the cables that direct light from block 24 to the helmet and its equipment include a fiber optic cable system 25. The console also includes a microprocessor and interfacial circuitry in block 26 and a CRT screen with a suitable console, shown generally as block 27. Shown connected to block 27 is a keyboard arrangement 28 for entering information into the system. The hard copy output, block 29 shown to indicate a hard copy output device, provides the physician with a permanent record of the examination. With the use of a helmet, the test can be performed while the patient is seated, standing or lying down. Also, due to the use of a helmet rather than clamping the head, the test is performed much faster because any movement of the head also moves the spot and therefore does not disrupt the test.

In FIG. 2, details of the unique eye position detector 21 are shown. It works by detecting and determining the position of light reflected from the patient's eye. The detector is shown as consisting of a box 31. The box has a vertical side 32 and a horizontal side 33. Means for detecting infrared images of the eye are mounted from the vertical and horizontal sides. More specifically, photodiode arrays 34 and 36 are shown. These arrays are commercially available, such as self-scanning photodiode array No. RL-64P manufactured by Reteicon Company of the United States. The column 64 is a column of light sensors. Each sensor is
The size is 50 x 50 microns. Window 3 to allow light to enter the light sensor and shine on it
7 and 38, respectively, columns 34 and 3
6 is shown. One column displays the horizontal position of the eye, while the other column displays the vertical position of the eye.

When exposed to infrared light, the reflected image of the eye in the pupil is bright due to reflection from the retina. The iris reflex is noticeably darker. This method is thus capable of detecting pupil size to within about 0.3 mm and eye orientation to within 1 degree in each dimension. In this way, the eye position detector can be used to provide invaluable additional information to the diagnostician.
It can also be used. Eye position detector 21 also includes a fiber optic light guide 39 brought to unit 21 as part of umbilical cord 22 . In addition, an electrical cable 41 is brought to unit 21 to provide power for the photodiode array. A fiber optic light guide 39 transmits the light reflected by the mirror 42 through the lens 43 to the patient's eye 44 . Light reflected from the eye is transmitted through an acceptance lens 46 onto a beam splitter. in a light column to determine the position of the eye with respect to the horizontal and vertical axes;
A beam splitter directs the reflected light to windows 37 and 38 to produce an image.

The column outputs are returned via cable 41 to the console where they are processed. They form the basis for the microprocessor's determination of the position of the eye. When the signal indicates that the patient is no longer fixed on center and therefore the test result is no longer valid, the device automatically stops the test and displays this to the patient. The test resumes when the patient fixes his gaze on the center. This means can equally monitor fixation on other points than the central screen. Alternatively, eye movements can be recorded. During the test, the microprocessor also determines and records the pupil size based on the column output.

Screen 16 is shown in FIG. 2 positioned relatively close to the eye. In the preferred embodiment, the distance between the screen and the eyes is 10 cm. As such, FIG. 2 is clearly not to scale.

Electromechanical unit 17 for scanning or moving the light spot and optics 1 for controlling the size and focus of the light spot.
FIG. 3 shows the details of 9. Optical device 19 includes a fiber optic light guide mounted in a special fiber optic mounting bracket 49.
(light guide) 48. Opening 50
The end 51 of the fiber optic cable is positioned so as to transmit the light coming through the point sizing means, such as , to the focusing lens 52 . Lens holder assembly 5 that allows focusing on the light spot
3, a lens 52 is attached.

Bracket 49 includes a screw arrangement for tightening end 51 of fiber optical conductor 48. to the helmet 12 by means such as mounting fasteners 57;
The installed base unit 56 is attached to the bracket 4
9 are combined. A lens holder assembly is mounted within the groove 62 in the base unit 56.

Means are provided for controlling the size of the spots. In detail, the disc unit 61
is rotatably attached to the base unit 56 with screws 58. This disc unit 61 has a circular array of apertures, such as apertures 50, therethrough. The apertures have different diameters to control the size of the light spot. In this way, the end 51 of the fiber optic light guide 48
The disc unit is rotated until an aperture is located below which gives the desired size of the light spot.

A device for alternatively sizing the light spot may be provided. For example, a fiber optic bundle could be used with the fibers at the output end arranged in concentric rings. At the input end, the fiber bundle will split into smaller bundles, and each input bundle will correspond to a particular output ring. By selectively illuminating such desired input branches, output points of variable size may be obtained. This output point of variable size will be imaged onto a screen to provide a variable inspection point size.

A disk position fixing fastener arrangement 63 is provided. Further, in detail, a clamp 64 is attached to an arc-shaped member 66 fixed to the circumference of the disk. into position on the base unit 56 by means of tightening screws such as threaded fasteners 67;
The fastener 64 is tightened. This holds the disk in the desired position with the selected point size.

To admit light, the lens holder assembly is positioned at 68 so that the light impinges on the mirror 71 in the tubular unit 69 of the cut-out system 17. screen according to a clear program,
Scanning means are provided to position the point as desired by moving the mirror 71 vertically and horizontally while the mirror is illuminated so that the reflected point of light moves. . The scanning means is light and
Being efficient, it is ideally suited for attachment to a helmet 12.

Electromechanical scanning device 17 consists of a base 72 . Using the fastener 73, attach the light spot generating unit foundation 5.
A foundation 72 is attached to 6. The fastening means 49 is shown fastened to the foundation 72 with a threaded fastener 74 .

A cylindrical tube 69 houses a mirror assembly for mirror 71. The mirror 71 rotates vertically and horizontally.
is installed. Mirror 71 is rotated about horizontal axis 76 by stepping motor 77 . A stepping motor 77 causes rotation of a shaft 78 to which a gear 79 is attached by a fastener 81 . A gear 82 is fixed to the axle 76 and causes rotation of the axle 76 and thus rotation of the mirror 71 about a horizontal axis.

Bearing means 83 and 84 support shaft 78 in its rotation. With respect to cutout 68, bearing assembly clamping member 87 assists in fixing the position of the mirror. Thus, there is a set screw passing through the clamping member 87 of the bearing assembly 83.

A stepping motor 91 rotates the mirror about an axis coaxial with axis 78. Pass the band coupler (belt coupler) 93 to the band driven wheel 92,
The shaft of the stepping motor 91 rotates. Rotation of wheel 92 rotates mirror holding unit 94. Further, in detail, the wheel 92 has a collar 96.
Fixed. This ring 96 is in turn fixed to a hollow cylindrical shaft 97. This cylindrical shaft 97
extends into the outer cylindrical tube 69 and is connected to the mirror carrier assembly by means such as a set screw 99. Thus, in order to horizontally move the point of light generated in unit 19, the full mirror carrying assembly rotates in conjunction with band driven wheels 92. The light is moved according to the operation of stepping motors 91 and 77. Each stage of motor moves a point of light on screen 16 according to a programmed position.

Bearing area 10 between shaft 78 and outer cylindrical cylinder 69
Unit 17 is also shown as comprising 1. It minimizes wobble and ensures that the points move according to a program on a fixed line with minimal wobble and vibration effects.

In FIG. 4, pertinent details of the light source and optics are shown in block 24. More specifically, light source 111 is shown as comprising, for example, a quartz halogen lamp. A quartz halogen lamp is shown as being energized across the AC conducting cable 112. A cooling fan 113 is shown immediately after the halogen lamp. Fan
113 is energized across conductor 114.

The light from the lamp is transmitted twice. One transmission occurs through the optical fiber bundle 39 to the eye position detector, through the other transmission fiber bundle 48,
Originating from the test point scanner. A third bundle (not shown) transmits light from the lamp to the screen to provide uniform background illumination.

A long pass (IR) filter 116 is shown between the light source 111 and the fiber light guide 39. After the filter there is a focusing lens 117.

A pair of focusing lenses 118 separated by a series of color and intensity filters, shown generally as 121, used to control the color and intensity of the light spot.
and 119 between the light source and the test point scanning cable 48. With commands on lead 122, the filter is removed or inserted under microprocessor control. Removal and insertion of the filter is performed in a manner known to those skilled in the art. This is made possible by automatic control of the intensity and color of the point being scanned, providing other dimensions to the inspection device.

Block 26 of FIG. 4 is shown as having a microprocessor and electronic controller. Block 26 also includes some common electrical supply, such as a transformer 126 used to power the light source. Microprocessor 127 is a common commercially available microprocessor such as an LSI-11. For example, the CRT 27, the keyboard 2
8 and a hard copy unit 29.

Means are provided for using the signal received from the eye position detector to generate a position signal that can be compared to the position of the light spot. More specifically, beyond conductors 133 and 134, each row 3
Analog to digital converters 131 and 132 are shown coupled to columns 4 and 36 and receiving signals from those columns. Analog to digital converter 13
1 and 132 are commercially available units such as those supplied by Analog Equipment of the United States under No. AD7574.

A signal processing circuit 136 is coupled to the output of the analog to digital converter. A circuit 136 provides signals indicative of eye position and pupil diameter. These signals are vector quantities that take into account both horizontal and vertical coordinates. In the microprocessor, the signal is converted into coordinates of the eye's position. Those coordinates are then compared to programmed instructions. As long as the eye is properly oriented, the microprocessor continues to perform the test and activate the scanner.

The scanner control unit 13 is connected to the microprocessor over a lead indicated generally as lead 138.
7 are connected. The stepping motor pulse generators 149 and 151 are connected to the scanning control unit 1.
Contains 37. The output of the stepper motor pulse generator goes to conductors 152 and 153 for horizontal and vertical control stepped motors 77 and 91, respectively.

The microprocessor controls the pulse generator as follows. That is, from its programming and storage, the microprocessor determines the starting and ending points and the desired speed of the scan. Therefore,
pulse generator 1 which starts their operation and scans at the desired speed until the end point is reached;
49 and 151, the signal over conductor 138,
Sent by the microprocessor. Generators 149 and 1
By counting 51 pulses, the microprocessor monitors the location of the test point. When the patient manually signals that he or she has looked at the point, an electrical signal is received over lead 154 by the microprocessor.
The microprocessor then records the location where the point was seen.

In the system thus illustrated, scanning is accomplished automatically under control of a microprocessor according to a program entered through the keyboard and carried by leads such as lead 128. It will be done.
The output of the test is also transferred through the microprocessor to a hardcopy manufacturing lead, such as lead 129.

A hard copy of the records will be given to the internist. Especially since the patient's head is immobilized and the patient is therefore much more relaxed for the examination.
The test can be performed in a shorter time than it would normally take using the standard Goldman method. Much more accurate, as the human factor is reduced to a minimum.
Inspection provides reliable and repeatable measurements.

During operation, a helmet 12 is placed over the patient's head.
is placed and the patient is told to keep the eye under examination over the center of the screen. One eye is covered and the test is performed on one eye at a time. A helmet 12 is placed over the patient's head, and a spot is projected onto a screen 16. The patient is told to display that point and the test begins.
For movement, the point is then automatically programmed and the patient indicates when the patient loses the point and/or when the point returns in the patient's peripheral vision. The device automatically determines when the patient is not immobilized. In that case, the test stops and repeats. The program changes the color and intensity of the dots. Testing with the described device is automatic and can be performed by relatively unskilled personnel rather than requiring the time of a physician or skilled technician.

Although the principles of the invention have been described above with respect to specific devices and applications, it is understood that this description is made by way of example only and not as a limitation on the scope of the invention. Should.

[Brief explanation of the drawing]

The operation and use of the invention will become more fully apparent from the description of the preferred embodiment taken in conjunction with the accompanying drawings. In the accompanying drawings, FIG. 1 is a diagram illustrating a test system including a helmet strapped to a patient's head, connected to a biasing and control device.
FIG. 2 is a block diagram of the fixing means.
FIG. 3 is a block diagram of the point projection and scanning means. FIG. 4 is a block diagram showing details of the control means originally shown in FIG. 12...Helmet, 16...Screen, 1
7... Electromechanical scanning device, 18... Mirror scanner,
19... point generating optical device, 21... eye position detector.

Claims (1)

[Claims] 1. A screen means placed in front of the patient's eyes, an examination point projection means for projecting a point of light onto the screen, and an eye position monitor for constantly checking the fixation of the patient's eyes. means, scanning means for scanning points on the screen;
and an optometry system comprising support means for supporting the screen means, the examination point projection scanning and the eye position monitoring means above the patient's head so that the patient's head remains mobile throughout the examination. 2. The system of claim 1, wherein said support means comprises a helmet means, and said screen means is integral with said helmet means. 3. The eye position monitoring means comprises means for transmitting light waves to the patient's eye and means for detecting and determining the position of the light reflected by the patient's eye. The method described. 4. A method according to claim 3, comprising means sensitive to the position of the reflected light for determining whether or not to continue the inspection. 5. The system of claim 3, wherein the means for detecting and determining the position of the reflected light comprises photodiode means. 6 said photodiode means include a first column for detecting the horizontal position of the reflected light, a second column for detecting the vertical position of the reflected light, and said reflection to said first and second columns; 6. A method according to claim 5, comprising optical means for transmitting the emitted light. 7. The method according to claim 1, wherein the inspection point projection means comprises means for selecting the size of the point. 8. The system of claim 1, wherein said scanning means includes mirror means positioned to receive said points from said projection means and reflect said inspection points onto said screen means. 9. The system of claim 1, wherein means are provided for rotating the mirror about vertical and horizontal axes to cause the point to be scanned over the screen means. 10 The mirror, according to a scheduled program,
The system according to claim 9, which is rotated. 11. The system according to claim 9, wherein the mirror can rotate vertically and horizontally simultaneously. 12. The system according to claim 1, wherein the colors of the points are automatically variable. 13. The method according to claim 1, wherein the strength of the points is automatically variable. 14. Eye position monitoring means, the eye position monitoring means comprising means for transmitting light waves to the patient's eye, and photodiode means for detecting and determining the position of light reflected by the patient's eye. a first column for detecting the horizontal position of the reflected light; a second column for detecting the vertical position of the reflected light; optical means for transmitting the reflected light to the column. An optometry method according to claim 1.