JPH02220628A - Ophthalmic surface measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the unevenness degree of the surface of the eyeground with high accuracy by mounting a signal processing means detecting the phase difference of quantity-of-light distribution on the basis of the relative movement at each point on a sensor when the image of the slitlike target on a surface to be examined is relatively moved in the direction crossing the longitudinal direction of a slit to operate the unevenness degree of the surface to be examined from the detected phase difference. CONSTITUTION:The lattice part 50 of a lattice plate 5 is projected on the papilla of the eyeground Er and the peripheral part thereof. When light is detected on the pupil Ep of an eye to be examined at the detected luminous flux position 9a in the direction vertical to the stripe longitudinal direction of the lattice part 50 with respect to a projected luminous flux position 2a, the linear stripes of the lattice part 50 are curved corresponding to the unevenness of the eyeground Er. This curving is proportional to the depth of each part of the eyeground Er. The video signal at an observation point is once converted by an A/D converter to be stored in a memory and subjected to regression calculation by a signal processing part 12 to calculate depth distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus capable of measuring the degree of unevenness of the fundus of an eye to be examined, particularly the papilla.

[Prior Art] Measuring the unevenness of the fundus of an eye to be examined, particularly measuring the concave state of the papilla of the fundus, is used for diagnosing glaucoma. Conventionally, for this purpose, it has been known to project a checkered pattern onto the fundus of the subject's eye, take a photograph, measure the degree of curvature of the checkered pattern, and obtain the amount of depression.

[Problems to be Solved by the Invention] However, in the conventional example, light is scattered inside the papilla, and the contrast of the plaid stripes is significantly reduced, making it difficult to analyze the degree of curvature of the stripes using a computer. Additionally, there were blood vessels within the papilla, which confused them with the checkered pattern, making analysis even more difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ophthalmologic surface measuring device that solves the problems of the conventional method and makes it possible to measure the unevenness of the fundus surface with high accuracy.

[Means for Solving the Three Problems] In order to achieve the above object, the present invention includes a projection system that projects a slit-like index from a first region on the pupil of the subject's eye onto the subject surface; a light-receiving system that guides an image of the slit-like index reflected from the test surface to a sensor from a second region deviated from the first region in a direction intersecting the longitudinal direction of the slit; When the slit is relatively moved in a direction intersecting the longitudinal direction of the slit, a phase difference in the light amount distribution due to the relative movement at each point on the sensor is detected, and the degree of unevenness of the surface to be inspected is calculated from the detected phase difference. A signal processing means is provided.

[Embodiment] FIG. 1 shows an embodiment of the present invention, in which light from an illumination light source 1 passes through an aperture 2 that is conjugate to the pupil EP of the eye E, and then passes through a lens 3.
, the lattice stripes (a plurality of slit-like indicators) of the lattice plate 5 are projected onto the fundus Er through the lattice plate 5, the lens 6, the perforated mirror 7, and the objective lens 8, which are conjugate to the fundus Er of the eye E to be examined.

The light reflected from the fundus is reflected by the objective lens 8, and the eye to be examined is 1liEρ.
The light passes through an aperture 9 conjugate to the diaphragm 9 and a relay lens 10 (including a focusing lens and a variable magnification lens), and is received by a CCD camera II conjugate to the fundus Er of the eye E as a sensor.

The diaphragm 2 has an aperture elongated in the longitudinal direction of the checkered stripes of the lattice plate 5 outside the optical axis, while the diaphragm 9 has a circular aperture on the optical axis. The projected light beam 28 and the received light beam 9a on the pupil Ep are as shown in FIG.

Here, the grating portion 50 of the grating plate 5 shown in FIG.
It is projected onto the nipple of r and its surrounding area. And as shown in Figure 2, []! of the eye to be examined! When light is received at a receiving beam position 9a in a direction perpendicular to the longitudinal direction of the stripes of the grating section 50 with respect to the projection beam position 2a on i Ep, the linear stripes of the grating section 50 are formed as shown in FIG. 4 according to the irregularities of the fundus Er. It curves like this.

This bending is proportional to the depth of each part of the fundus Er.

Now, if we move the grid plate 5 in the direction perpendicular to the longitudinal direction of the stripes as shown by the arrow using the linear potentiometer 4 in FIG.
When the temporal change in light amount is observed at point A in FIG. 4, an output (2) as shown by curve A in FIG. 5 is obtained. If the transmittance distribution in the direction perpendicular to the stripe longitudinal direction of the grating plate 5 is sinusoidal, the curve A will also be sinusoidal.

Similarly, the output from observation point B becomes curve B.

The reason why the output I of curve B is higher than that of curve A is due to the fact that the inside of the nipple has a higher reflectance than the outside.

The inside of the nipple is depressed, and the phase difference between curves A and B is the difference in depth between point B and point A. Determining this phase difference at each point in the test area determines the depth distribution. Specifically, as an example, the DC components of sine wave curves A and B are removed to create two sine waves whose amplitudes are standardized with a common value, and the phase difference is detected from the positional relationship of the points where these intersect with the zero level. .

If a CCD image sensor is used as a sensor, information on each point can only be obtained at TV rate. That A2 A3,
A value such as BI 82 B3 is obtained. By regressing these values to a sine wave, sine wave curves A and B are obtained.

The video signal at the observation point is first-generation A/D converted, stored in a memory, and subjected to regression calculation in the signal processing section 12 to calculate the depth and depth distribution. If a photodiode array is used instead of the CCD1g1 image element as a photoelectric sensor, the signals from each element, that is, the observation point, can be obtained simultaneously, so high speed can be achieved, and eye movements will not be a problem.

By the way, in the embodiment shown in FIG. 1, a grating and a plate are used to move the stripes, but the interval between the projected and received light beams can be adjusted. In this case, the grating plate is fixed. However, when it is desired to measure the entire fundus illuminated visual field, a grid is provided on the entire surface.This grid plate may be inserted into and removed from the optical path so that it can be used in common with the fundus camera.

By the way, the number of slit-shaped indicators in the grid 50 is not limited to a plurality of indicators, but may be one. In this case, one peak or one valley will be formed in FIG. 5. This peak or valley may be returned to an appropriate sine wave to obtain the phase difference between the positions at each point.

[Effects of the Invention] As described above, according to the present invention, even if the reflectance is different at each point within the measurement site, the degree of unevenness of the test surface can be accurately detected even if the reflectance is small (contrast is low). .

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing a projected light flux and a received light flux, Fig. 3 is a diagram of a grating plate, and Fig. 4 is a diagram of a grating projected on a nipple. , Fig. 5 is a diagram showing changes in light intensity at observation points A and B. In the figure, 1 indicates the fundus illumination light source 2 is the projection aperture 10. Fig. 2 p! In FIG. 4, the potentiometer 5, the grid plate 7, the perforated mirror 11, the CCD camera 12, and the signal processing unit +3 are the nipples. 1 year old diary

Claims (1)

[Scope of Claims] 1. A projection system that projects a slit-shaped index from a first region on the pupil of the eye to be examined onto the surface to be examined; a light-receiving system that guides an image of the slit-like index reflected from the test surface from a second region located on the test surface to a sensor; for ophthalmology, characterized in that it has a signal processing means for detecting a phase difference in the light amount distribution due to the relative movement at each point on the sensor and calculating the degree of unevenness of the test surface from the detected phase difference. Surface measuring device. 2. The ophthalmological surface measuring device according to claim 1, wherein the slit-shaped index is provided to be optically substantially conjugate with the surface to be inspected and is displaceable in a plane perpendicular to the optical axis. 3. The slit-shaped index is fixed to be optically substantially conjugate to the surface to be examined, and an aperture that is in the projection system or the light receiving system and is optically substantially conjugate to the pupil of the eye to be examined is in a plane perpendicular to the optical axis. The ophthalmologic surface measuring device according to claim 1, wherein the ophthalmologic surface measuring device is movable within the ophthalmologic field.