JPS6324383B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact type intraocular pressure measuring device having means for detecting an alignment state with respect to an eyeball during intraocular pressure measurement.

Conventional non-contact intraocular pressure measuring devices measure intraocular pressure by injecting air toward the eye being examined and measuring the time until the cornea is applanated using one projection light beam and one detector. ing. However, the alignment between the eyeball and the measurement device is achieved by projecting a single index light beam for alignment from the axial direction of the subject's eye to the center of the cornea, and measuring the intensity of the reflected light from the center of the cornea in the axial direction of the subject's eye. Since detection is performed using a photodetector, it is not possible to confirm whether or not these are accurately aligned during actual measurement, resulting in a disadvantage that the reliability of the measurement data is low.

The purpose of the present invention is to improve the drawbacks of the conventional example, to provide an intraocular pressure measuring device that can accurately detect the alignment state with respect to the eyeball even during actual measurement, and that makes it possible to measure intraocular pressure with high precision. The gist of the device is to provide a non-contact type intraocular pressure measurement device that optically detects corneal deformation by injecting fluid onto the cornea of the eye to be examined, and uses a corneal deformation member as an alignment index. The apparatus is characterized in that it includes a projection optical system for projecting images onto the target, and an alignment detection means for detecting an alignment state by receiving the reflected light of the target from the cornea.

The present invention will be explained in detail below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention,
In order to facilitate understanding, the intraocular pressure measuring optical system shown in FIG. 5 is omitted here, and the alignment inspection device is mainly shown. A piston 2 that reciprocates within a cylinder 1 is driven by a solenoid 3 to supply a fluid such as air from a small cylinder 4 to the cornea of the eye E to be examined.
It is designed to be ejected towards Ec. As will be described later, the intraocular pressure is measured by measuring the time taken until the cornea Ec is applanated to a predetermined area by this air injection using an intraocular pressure measuring optical system. In addition to this intraocular pressure measurement optical system, there is also a projection optical system that includes a light source 5, a projection lens 6, and a mask 7 that project an index for alignment with the eyeball onto the part of the deformable member on the cornea Ec, and a projection optical system that projects an index for alignment with the eyeball onto the part of the deformable member on the cornea Ec. An alignment detecting means is provided, which includes a detection optical system that images the aligned index using an objective lens 8 onto an array sensor 9 made of photoelectric elements to detect whether or not the alignment is accurate. . Note that 10 represents a window provided on the outside of the cylinder 1, and 11 represents an aperture stop.

Since the embodiment shows a case where alignment is detected using three light beams, three sets of projection optical systems and detection optical systems are arranged in front of the eye E to be examined divided into 120 degrees. That is, the projection optical system includes three light sources 5a to 5c and a projection lens 6, as shown in FIG.
a to 6c and masks 7a to 7c, and three array sensors 9a, 9b, and 9c are arranged as shown in FIG. Therefore, the light sources 5a to 5
The light beams emitted from c pass through masks 7a to 7a, respectively.
~7c, the cornea Ec via the projection lenses 6a~6c
The light is projected onto a portion outside the upper deformed portion, is reflected there, and enters the array sensors 9a to 9c via the objective lens 8, window 10, and aperture diaphragm 11, respectively.

During actual intraocular pressure measurement, if alignment to the eyeball becomes inappropriate due to, for example, movement of the line of sight, the position signals from the three sets of array sensors 9a to 9c do not match. Outputs S1, S2, and S3 shown in FIGS. 4a, b, and c represent position signals from the array sensors 9a to 9c, respectively. If the position information of these output signals exists in the range a to b, and the relative intensity ratio of the output voltages E1 to E3 is within a predetermined range, it can be determined that the alignment is correct. At this time, for example, a lamp may be turned on to indicate that the alignment has been performed correctly, that is, to indicate the reliability. Further, if the position signals from the sensors 9a to 9c do not match, it is also possible to restrict the injection of air and temporarily interrupt the intraocular pressure measurement.

Note that a position detection sensor such as a position detector may be used as the array sensor 9. For this reason, it is better to use a quick-response device to avoid corneal damage during measurement.
Since the state of Ec can be detected moment by moment, accurate measurements can be obtained.

Now, as shown in FIG. 5, the above-mentioned intraocular pressure measurement optical system directs light from the projecting light source 12 onto the cornea of the eye E to be examined.
The reflected light is reflected by the condensing lens 13,
A detector 15 consisting of a light receiving element is inserted through a mask 14.
It is designed to receive light.

FIG. 5a shows a state in which the cornea Ec is not applanated. In this state, the light from the light source 12 is reflected in each direction according to the radius of curvature on the surface of the cornea Ec, and the light is reflected by the detector 15. The light intensity is weak and the output is minimal. On the other hand, when the cornea Ec is applanated by the air injection, the luminous flux incident on the detector 15 increases and reaches the maximum output, as shown in FIG. 4b. To measure intraocular pressure, the time from the start of air injection from the small tube 4 until the cornea Ec is applanated to a predetermined area is measured, and this time is converted to intraocular pressure.
Expressed in mmHg.

Although one embodiment of the present invention has been described above, it is also possible to guide the index projected onto the cornea Ec to the intraocular pressure measuring optical system by a light splitting member placed in front of the sensor 9. be.

As described above, the intraocular pressure measuring device according to the present invention includes:
Since the alignment index is configured to be projected onto the deformed part of the cornea outside the applanation area, it is detected that the projected light beam deviates from the photodetector when measuring intraocular pressure, that is, when the cornea is deformed. Since it is possible to easily and reliably detect whether or not the alignment between the eyeball and the measuring device is accurate during actual measurement, highly accurate measured values can be obtained when measuring intraocular pressure.

[Brief explanation of drawings]

The drawings show an embodiment of the intraocular pressure measuring device according to the present invention, and FIG. 1 is an overall configuration diagram, and FIG.
The figure is a layout diagram of the alignment detection means, Figure 3 is a layout diagram of the alignment inspection device, Figure 4 is a waveform diagram of the output signal of the alignment detection means, and Figures 5a and b.
is an explanatory diagram of the principle of intraocular pressure measurement. 1 is a cylinder, 2 is a piston, 3 is a solenoid, 4 is a small cylinder, 5 is a light source, 6 is a light projection lens, 7
8 is a mask, 8 is an objective lens, 9 is an array sensor, 10 is a window, and 11 is an aperture stop.

Claims (1)

[Scope of Claims] 1. A non-contact type intraocular pressure measurement device that optically detects corneal deformation by injecting fluid onto the cornea of the eye to be examined, in which an alignment index is projected outside the deformed part of the cornea. An intraocular pressure measuring device comprising: a projection optical system for detecting an alignment state; and an alignment detecting means for detecting an alignment state by receiving reflected light of the index from the cornea. 2. The intraocular pressure measuring device according to claim 1, wherein three sets of the projection optical system and alignment detection means are provided and are arranged in 120 degree divisions in front of the eye to be examined. 3. The intraocular pressure measuring device according to claim 1, further comprising display means for indicating the reliability of the measured value based on the alignment data from the alignment detection means.