JP3200236B2 - Keratometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keratometer for measuring corneal shape information of an eye to be examined and a fixation target device which can be suitably applied to the keratometer.

[0002]

2. Description of the Related Art Conventionally, a measurement index is projected on a cornea of a subject's eye,
Among keratometers that measure the radius of curvature of the cornea based on the corneal reflection image, there are keratometers that measure the radius of curvature not only of the central portion of the cornea but also of the corneal portion deviated from the center of the cornea, that is, the peripheral portion of the cornea. As a method of measuring the peripheral part of the cornea, a measurement index used for the peripheral part measurement is provided separately from the measurement index used for the central part measurement, or a fixation target for the peripheral part of the cornea is provided and provided to the eye to be examined. By causing the fixation, the cornea of the eye to be examined is displaced with respect to the measurement index,
There has been a method of performing measurement using a measurement index projected on a peripheral portion of a displaced cornea of a subject's eye.

[0003]

However, in the method of separately providing the measurement index for measuring the peripheral portion of the cornea, the measurement index for measuring the peripheral portion must be provided outside the measurement index for measuring the central portion. There was a problem that the index projection unit had to be enlarged. In addition, since the measurement index is projected on the periphery of the eye to be examined that fixes the front, the measurement index projection light for the peripheral measurement may be partially affected by the effect of the eyelids, and measurement may not be possible. There was also a problem that was large.

On the other hand, in the method of providing a fixation target for measuring the peripheral part of the cornea, the fixation target is provided separately from the measurement optical system because the fixation target is provided at a position far away from the optical axis of the apparatus. Therefore, it is desirable to provide a fixation target at a position close to the subject's eye so that the fixation target can be easily seen from the subject's eye. In this case, the fixation target is arranged to be easily fixated even from the opposite eye. When the eye on the opposite side fixes the fixation target, the subject's eye linked to the opposite eye does not fix the line of sight accurately in the fixation target direction. It may give a radius of curvature measurement.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a fixation target device for displacing the line of sight from the front direction so that the eyes on the opposite side are not affected. It is an object of the present invention to provide a keratometer capable of measuring a peripheral portion of the cornea.

[0006]

In order to achieve the above object, a keratometer according to the present invention comprises: a measuring optical system for measuring corneal shape information of an eye to be inspected; and a keratometer which is disposed closer to the eye than the measuring optical system. A light source for presenting a fixation target for corneal periphery measurement to the eye to be examined to displace the line of sight of the eye to be examined when measuring shape information of the periphery of the cornea of the eye by the measurement optical system, A component having a groove formed therein, wherein the light source is provided in the groove, and is arranged such that the light source in the groove cannot be observed from the direction of the other eye different from the eye to be examined. It is characterized by being.

[0007]

[0008]

FIG. 1 is a schematic sectional view showing the structure of an objective section according to a first embodiment of the present invention, and FIG. 2 is a front view of the objective section. In the figure, E is an eye to be examined, 1 is a constituent member constituting a projection part of a measurement index, 2 is an infrared light source for measuring corneal curvature, 3 is a light diffusing plate having a high light diffusing property for diffusing a light beam from the light source 2, Reference numeral 4 denotes a light source for observing the external eye during alignment and also serves as a fixation target for fixing the eye E to be measured at the time of measuring the peripheral part of the cornea. Reference numeral 5 denotes a printed circuit board on which the light sources 2 and 4 are mounted. Reference numeral 6 denotes a light source. Reference numeral 4 denotes an opening, reference numeral 6a denotes a groove provided on the component member 1, and reference numeral 7 denotes an opening for a measurement optical system (not shown) on the right side of the drawing. FIG. 3 is a view of the component 1 as viewed from the back side. The component 1 is formed by molding a synthetic resin or an aluminum alloy. The position where the diffusion plate 3 is attached to the component 1 and the eye E
The position of the opening 6 serving as a fixation target for fixing the image is determined in advance by this type. In addition, as shown in FIG. 1, the opening 6 is formed in a groove 6 on the component 1 so that it cannot be seen from the direction other than the direction in which the eye to be examined exists, for example, from the eye opposite to the eye to be examined.
It is provided at the bottom of a.

As shown in FIG. 2, the diffusing plate 3 is arranged in a ring shape around the optical axis O of the measuring optical system. In this embodiment, the diffusion plate 3 is fixed to the component 1 by pouring an adhesive through the bonding holes 3a provided at several places in the component 1.
The fixing of the diffusion plate 3 is not limited to this method, and may be performed, for example, by press fitting or heat.

The light source 2 is arranged in a ring shape of the diffuser plate 3,
A number of them are arranged in a circle. As the number of the light sources 2 increases, the amount of light can be increased. However, if the light sources 2 are provided too densely, the components will be separated inside and outside the ring by the light sources 2,
It is desirable to determine the number of the light sources 2 within a range where light is uniformly emitted from the diffusion plate.

As shown in FIG. 2, eight apertures 6 and light sources 4 disposed behind each aperture are arranged on the circumference. Light source 4
Is designed to emit two colors of visible light and infrared light. All eight light sources 4 emit infrared light for observation illumination so that they cannot be seen by the subject's eye when performing external eye observation at the same time during alignment and corneal center measurement. or,
In the measurement of the peripheral portion of the cornea, only the light source in the direction in which the subject's eye is desired to fixate emits visible light, and the other seven light sources emit infrared light.

The substrate 5 is fixed to the component 1 with screws,
When the light source is cut off or weakened due to aging or the like, only the substrate 5 is replaced. If the replacement of the light source is performed by another method, the light source may be bonded.

FIG. 4 is a schematic diagram of an optical system configuration of the present apparatus. In the figure, reference numeral 8 denotes an imaging lens portion of a measurement optical system, 9 denotes a movable stop, 10 denotes a two-dimensional photodetector, 11 denotes a visible light source, 12 denotes a fixation target for measuring a central portion of the cornea, 13 denotes a lens, and 14 denotes red. This is a dichroic mirror that transmits external light and reflects visible light. The operation of the present apparatus will be described with reference to FIG. Light source 2
The emitted light passes through the space of the constituent member 1 and reaches the diffusion plate 3. The inner wall of the space of the component 1 is desirably a mirror surface in order to transmit the light amount of the light source 2 without waste. The light is diffused by the diffuser plate 3 without unevenness, and is radiated to the eye E as a ring-shaped index to form an index image R 'as a corneal reflection image on the cornea EC of the eye to be inspected. The index image R ′ is formed on the two-dimensional photodetector 10 via the imaging lens unit 8 and the movable stop 9 together with the anterior eye of the subject's eye. The movable diaphragm 9 is separated from the optical axis O during alignment,
It is inserted on the optical axis O when measuring the corneal curvature. The position of the movable stop 9 on the optical axis O is such that a measurement error may occur even if the working distance between the eye E and the diffuser 3 as an index changes as disclosed in JP-A-61-249432. It is the position where it decreases. Image information detected by the detection element 10 is processed by a signal processing circuit (not shown) and displayed on a monitor.

When measuring the central part of the cornea, the light source 11 is turned on and the dichroic mirror 14 and the lens 1 are placed on the eye E to be examined.
The fixation target 12 on the optical axis is fixated through 3. In this state, the examiner aligns the main body of the apparatus relative to the eye E in the up, down, left, right, and working distance directions while looking at the monitor. FIG. 5 shows an image on the monitor 15 in a state where the alignment is completed. After alignment is completed, detection element 1
From the image signal of the index image R 'in the video signal of 0, a corneal curvature radius is measured by a well-known method by a signal processing circuit (not shown). Thereby, the corneal curvature radius at the central portion of the cornea can be measured.

Next, when measuring the peripheral portion of the cornea, the light source 11
Is turned off, the light source existing in the direction opposite to the measurement direction on the cornea in the light source 4 emits visible light, and the light emitted from the opening 6 corresponding to this light source is fixed on the eye E. In this state, the examiner looks at the monitor and places the apparatus body on the eye E to be examined.
And relative alignment. FIG. 6 shows an image on the monitor 15 in a state where the alignment is completed.
After the alignment is completed, the corneal curvature radius is measured from the image signal of the index image R ′ in the video signal of the detection element 10 by a well-known method using a signal processing circuit (not shown). As a result, the corneal curvature radius at the peripheral portion of the cornea can be measured. If the shape of the cornea at the central portion of the cornea is measured in advance, the direction of the main radius line of the corneal astigmatism can be determined. Therefore, two light sources (diagonal directions) in the direction close to the main radius line of the light sources 4 and their directions Two light sources at right angles to the
Are sequentially emitted with visible light to measure the peripheral portion of the cornea, the radius of curvature of the peripheral portion of the cornea in the direction close to the main radial direction and in the direction perpendicular thereto can be determined.

FIG. 7 is a diagram for explaining the effect of the present apparatus.
When measuring the periphery of the cornea, the eye E ′ on the opposite side of the eye E to be examined
If the fixation target can also be fixed, the fixation target may be fixed at the opposite eye E 'as described above. However, in this embodiment, since the opening 6 is provided at the bottom of the groove 6a provided in the component 1, the opening 6 cannot be fixedly viewed from the direction of the eye E '. This allows
Accurate measurement of the corneal curvature radius at the periphery of the cornea becomes possible.

Although the fixation means shown in the above embodiment is integrated with the index projection unit in the embodiment, it can be provided independently of the index projection unit. Although the number of the light sources 4 is eight in the embodiment, the number may be increased or decreased depending on the frequency of use.

FIG. 8 is a view showing a modification of the constituent members of the above-mentioned apparatus. The measurement index portion is omitted because it is the same. The constituent member 16 is different from the constituent member 1 in that the light source 1 as a fixation target does not have the opening 6 serving as a fixation target.
The head of 7 protrudes from the bottom of the groove 16 a provided in the component 16. The fixation target cannot be fixed from the eye on the opposite side of the eye to be examined due to the effect of the groove 16a, as in the above-described embodiment. If the diameter of the head of the light source 17 is large, the viewpoint of the eye to be inspected may not be determined, and it may be difficult to measure. Therefore, it is desirable that the head of the light source 12 be as small as possible.

FIG. 9 is a view showing a further modification of the constituent members. An LED 19 serving as a fixation target directed toward the eye E and a board 20 on which the LED 19 is mounted are attached to the constituent member 18. The head of the LED 14 has a spherical shape. When the radius of the spherical surface is r, the LED chip is located at a position 2 / r from the top of the head. Therefore, since parallel light is projected from the LED 14 to the eye to be inspected, the eye on the opposite side to the eye to be inspected E cannot fixate. If the substrate 20 is a flexible substrate, it can be integrated with the LED substrate at another position.

[0020]

As described above, the fixation target for one eye of the present invention is invisible to the other eye. Measurement of corneal shape has become feasible.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of an objective section according to a first embodiment of the present invention.

FIG. 2 is a front view of an objective section according to the first embodiment of the present invention.

FIG. 3 is a view of a component viewed from the back side.

FIG. 4 is a schematic diagram of an optical system configuration of the device of the first embodiment.

FIG. 5 is a diagram showing an image on a monitor.

FIG. 6 is a diagram showing an image on a monitor.

FIG. 7 is a diagram illustrating the effect of the device of the first embodiment.

FIG. 8 is a modified example of a constituent member.

FIG. 9 is a modified example of a constituent member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Constituent member 2 Light source 3 Diffusing plate 4 Light source 5 Printed circuit board 6 Opening 6a Groove 7 Opening 8 Imaging lens part 9 Moving down 10 Two-dimensional light detection element 11 Light source 12 Fixation target

Claims (3)

(57) [Claims] 1. A measuring optical system for measuring corneal shape information of an eye to be inspected, wherein the measuring optical system is disposed closer to the eye to be examined than the measuring optical system, and the measuring optical system measures shape information of a peripheral portion of the cornea of the eye to be inspected. A light source for presenting a fixation target for measuring the peripheral part of the cornea to the eye to be examined so as to displace the direction of the line of sight of the eye to be examined, and a component member having a groove formed therein. Wherein the light source in the groove cannot be observed from the direction of the other eye different from the eye to be examined. 2. An opening through which a light beam for measuring an eye to be inspected by the measuring optical system is provided in the constituent member, and a plurality of rings around the opening around the optical axis of the measuring optical system are provided around the opening. The keratometer according to claim 1, wherein the light source is provided, and an arbitrary light source can emit light when measuring the peripheral portion of the cornea. 3. The keratometer according to claim 2, wherein a light source for measuring a corneal curvature is arranged in a ring shape around the optical axis on the constituent member.