JPS6315938A - Corneal topography measurement device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a corneal shape measuring device that measures corneal shape such as the radius of curvature of the cornea.

(Prior Art) Conventionally, in a corneal shape measuring device, an index formed as a virtual image on the cornea is projected by a projection optical system, and the index formed as a virtual image on the cornea is transmitted to a light receiving element through a measurement optical system. Computation processing for projecting onto a light-receiving surface to form a projected pattern image containing information on the shape of the cornea on the light-receiving surface, and determining the corneal shape based on the photoelectric output based on the projected pattern image formed on the light-receiving surface. There is a known method in which corneal shape measurement results are obtained by collecting and storing data in a memory and performing arithmetic processing on the data stored in the memory.

(Problems to be Solved by the Invention) Incidentally, the examiner may have doubts about the corneal shape measurement results obtained in this manner. For example, a part of the projected pattern image used as the basis for obtaining measurement results may be missing or distorted due to eyelashes, dirt, eye oil, etc. In some cases, the projection pattern image is not formed to the extent that it is considered appropriate for the purpose of the present invention. In such a case,
Abnormal values may occur in the measurement results, but even if the examiner has doubts about the measurement results, with conventional corneal topography devices, the data collection used as the basis for obtaining the measurement results Since the configuration was such that the projected pattern image itself could not be confirmed, it was difficult to judge whether the projected pattern image at the moment of data collection was of a level that could be considered appropriate for measurement. However, conventional methods have problems in that they are insufficient in terms of reliability of measurement results and operational performance.

(Object of the Invention) Therefore, an object of the present invention is to enable confirmation of the projection pattern image used as a basis for obtaining the measurement results of the corneal shape, thereby improving the reliability of the measurement results. Another object of the present invention is to provide a corneal shape measuring device that can improve operational performance.

(Means for Solving the Problems) A feature of the corneal topography measuring device according to the present invention is that the projection pattern image used as a basis for obtaining the measurement result of the corneal topography is displayed based on the data. It has a display means to display the information.

(Function) According to the present invention, after obtaining the measurement result, the examiner can obtain the projection pattern image at the moment when the data for calculation processing used as the basis for obtaining the measurement result of the corneal shape is collected. However, you can check.

(Example) Hereinafter, an example of the corneal shape measuring device according to the present invention will be described with reference to the drawings.

In FIG. 2, 1 is the cornea of the eye to be examined, and 2 is the projection optical system. The projection optical system 2 has an index 3 for corneal shape measurement and an illumination light source 46.The index 3 is ring-shaped,
It is illuminated by an illumination light source 4 and projected onto the cornea 1 as an index light P. A virtual image i corresponding to the shape of the index 3 is formed on the cornea 1. Here, cornea 1 has
Three virtual images i are formed approximately concentrically around an optical axis a of a measuring optical system 5, which will be described later. These three virtual images i are formed by corneal surface reflection based on the projection of three ring-shaped parallel light beams onto the cornea 1. A reflecting mirror 6.7.8 is provided to convert the light beam emitted from the cornea 3 into a parallel light beam within a cross section including the optical axis a and guide it to the cornea 1. This reflecting mirror 6.7.8 is a part of a parabola in the cross section including the optical axis Q,
It is formed of a reflective surface that is rotationally symmetrical around the optical axis 0,
The position of the index 3 is located approximately at the focal point of this parabola.

Note that the reference numeral 8' is a plane cross section that includes the optical axis a, and the optical axis is ℃
It is a reflecting surface that is rotationally symmetrical around the periphery, and is used to guide a light beam that is reflected by the first reflecting mirror 8 and becomes a parallel light beam to the cornea 1.

The measurement optical system 5 has an objective lens 9, and the index 3 formed as a virtual image i on the cornea 1 is projected onto the light receiving element 10 via the measurement optical system 5. Here, the measurement optical system 5 includes a low magnification optical system 11 and a high magnification optical system 1.
2. The low-magnification optical system 11 is roughly composed of a telecentric diaphragm 13, a low-magnification lens 14, and a shutter 15, and the high-magnification optical system 12 includes a half mirror 16, a total reflection mirror 17, a telecentric diaphragm 18, a high-magnification lens 19, and a shutter 20-. Total reflection mirror 21. half mirror
It is roughly composed of 22.

Shutter 15.20 is low magnification optical system 11 and high magnification optical system 12
When the corneal shape measuring index 3 formed as a virtual image i on the cornea 1 is projected through the low-magnification optical system 11, a projected pattern image j having a shape as shown in FIG. It is formed on the light receiving surface 10a of the light receiving element 10, and when projected through the high magnification optical system 12, a projected pattern image j having a shape as shown in FIG. 4 is formed on the light receiving surface 10a of the light receiving element 10. Here, the high-magnification optical system 12 magnifies the projection pattern image j projected onto the light-receiving surface 10a of the light-receiving element 10,
This is to enable highly accurate measurement of even the innermost projection pattern image j.

Note that this projected pattern image j is
Before projecting and forming an image on 0a, the measurement optical system 5 is aligned.
As shown in FIG. 5, an aiming scale 25 and an aiming spot 26 are projected onto the anterior segment 24 of the eye 23 to be examined, and an optical system &1 (not shown) is used.

Since a virtual image j is formed on the cornea 1 in accordance with the shape of the cornea, the projected pattern image j projected onto the light receiving surface 10a of the light receiving element 10 includes information based on the shape of the cornea. It is something that For example, if the cornea 1 has astigmatism, the virtual image i formed on the cornea 1 will have an elliptical shape that is distorted from a ring shape due to the astigmatism. In the light receiving element 10.

Here, an area sensor is used. As shown in FIG. 1, the photoelectric output of the light-receiving element 10 is digitized by an A/D converter 27, collected as data to be used in arithmetic processing by a switch operation described later, and sent to a frame via an arithmetic control circuit 28. It is stored and held in the memory 29. The arithmetic control circuit 28 has the function of performing arithmetic processing to obtain a measured value of the corneal shape based on the data stored and held in the frame memory 29 according to the program memory 30, and also has the function of outputting the measurement result to the printer 31. In addition, it has a function of displaying measurement results on a display 32 serving as a display means, and a function of storing and holding data as measurement results in an arithmetic processing result storage memory 33.

Here, by operating a switch, the display 32 displays a projection pattern image j based on the data when the data was collected. The projection pattern image j can be checked in an analog manner when data is collected to obtain measurement results according to the measurement result. First, an embodiment of the corneal shape measuring device according to the present invention is shown in FIG. The explanation will be based on the flowchart shown below. First, when the power switch is turned on (step SX), initial setting is performed (step SZ). Next, frame memory 29. The contents of the arithmetic processing result storage memory 33 are cleared (step S3),
Next, when the measurement switch is turned on (step S4), the arithmetic processing circuit 28 executes the measurement step S according to the program in the program memory 30.

Then, a determination is made as to whether or not the measurement is completed (step S6). When the measurement is finished, the process moves to step S1°, the power switch is turned off, and the measurement is finished (step S1□). If the measurement has not been completed, the process moves to a switch selection standby mode in step S7. This switch selection standby mode has three modes: measurement repeat mode, print mode, and display mode. When the measurement repeat mode switch is selected, the process moves to step S, and the measurement is repeated. When the print mode switch is selected, the measurement results are printed out by the printer 31 (step SS). When the display mode switch is selected, the measurement result K is displayed on the display 32 as shown in FIG. 7, and the projected pattern image j is displayed on the display 32.
2 (step S,), and after the display, step S8
to move to.

Note that the calculation formula for calculating the corneal shape using data based on the projection pattern image j and the calculation formula for calculating the refractive power are well known, and therefore their explanation will be omitted.

(Effects of the Invention) As explained above, the corneal topography measurement device according to the present invention displays a projection pattern image based on the data used as a basis for obtaining the measurement result of the corneal topography. Since the actor has a display means for measuring the corneal shape, the actor can confirm the projected pattern image used as the basis for obtaining the measurement result of the corneal shape, thereby increasing the reliability of the measurement result. This has the effect of improving performance and operational performance.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing the main part configuration of the corneal shape measuring device according to the present invention, FIG. 2 is a diagram showing the configuration of the optical system of the corneal shape measuring device according to the present invention, FIGS. 3 and 4 5 is a diagram showing a projected pattern image projected on the light-receiving surface of the light-receiving element according to the present invention, FIG. 5 is an explanatory diagram for explaining alignment adjustment, and FIG. 6 is a flowchart of the corneal-shaped cave device according to the present invention. , FIG. 7 is a diagram showing the display state of the projection pattern image at the moment when data used as a basis for obtaining measurement results is collected. DESCRIPTION OF SYMBOLS 1... Cornea of the eye to be examined, 3... Index 5... Measurement optical system, 10... Light receiving element 28...
Arithmetic processing circuit, 29... Frame memory 32... Display device, i... Virtual image j... Projection pattern image, K
...Measurement results Fig. 1j Fig. 5 Fig. 6 dD-5,.

Claims (1)

[Claims] (1) Projecting an index for corneal shape measurement formed as a virtual image on the cornea onto the light-receiving surface of the light-receiving element via the measurement optical system,
forming a projection pattern image containing the shape of the cornea as information on the light-receiving surface, collecting photoelectric output based on the projection pattern image formed on the light-receiving surface as data used in arithmetic processing, and storing and retaining it in a memory; The corneal shape measuring device measures the shape of the cornea by arithmetic processing of data stored in the memory, further comprising a display means for displaying a projected pattern image when the data is collected based on the data. A corneal shape measuring device featuring: