JPH09285445A - Instrument and method for measuring cornea form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a peripheral part in a direction exactly coincident with the main meridian direction of a central part. SOLUTION: This instrument is constituted so as to be provided with a 1st projecting means X1 for projecting an index for measurement for measuring the central part of the cornea onto the cornea, 2nd projecting means X2 for projecting an index for measurement for measuring the peripheral part of the cornea onto the cornea, detection optical system 2 for detecting the cornea reflected images of indexes for measurement projected by the 1st and 2nd projecting means X1 and X2, and arithmetic part 3 for operating the form of the cornea based on the result detected by the detection optical system 2. In this case, the difference of angles between the strong or weak main meridian direction provided by measuring the central part of the cornea and a prescribed difference direction is calculated, and a display part 6 is provided for performing prescribed display so as to let a measuring person perform suitable measurement based on this difference of angles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal shape measuring apparatus for measuring the shape of the central portion and the peripheral portion of the cornea of the eyeball and a measuring method therefor.

[0002]

2. Description of the Related Art At present, in eyeglass stores and ophthalmologists, mainly for the purpose of fitting contact lenses,
A cornea shape measuring device for measuring the shape of the cornea of the eyeball is widely used. This cornea shape measuring device is generally called a keratometer or offsalmometer, and has a radius of curvature in the strong main meridian direction (minimum curvature direction) and a weak main meridian direction (maximum curvature direction) of the cornea, and these respective directions and devices. The angle difference from the reference direction (generally, since the device is placed horizontally, the reference direction becomes the horizontal direction, and the angle difference indicates the axial direction of each meridian as it is).

As a typical example of the measuring method of this corneal shape measuring apparatus, an annular index or three or more point light sources (generally, four points on the upper, lower, left and right sides) are projected on the cornea of the eye to be inspected and the corneal reflection thereof is performed. An example is one in which an image is detected and the radius of curvature and the angle difference are calculated from the position of this reflected image. A corneal shape measuring apparatus that achieves such a method has already been presented by the present applicant and is well known (Japanese Patent Publication No. 7-157).
218).

The measurement of the radius of curvature and the angle difference performed in this manner is, of course, performed on the central portion of the cornea (generally, a portion having a diameter of about 3 mm), but in addition to that, the measurement is performed outside the central portion. It may also be performed on the periphery. In particular, it is important to detect the shape of the peripheral part of the cornea in consideration of contact fitting.

In the conventional cornea measurement, the central portion and the peripheral portion are measured by projecting an annular index or three or more point light sources on the eye to be examined. That is, when measuring the central part, the eye to be inspected is directed to the front and an annular index or three or more point light sources are projected onto the central part, while when measuring the peripheral part, the eye to be inspected is measured. Was directed in any of the directions of up, down, left and right, and an annular index or three or more point light sources were projected on the peripheral portion. Then, on the premise that the cornea is an astigmatism that shows a certain amount of deformation, the shapes of the central portion and the peripheral portion of the cornea are calculated based on the results obtained by the above measurement.

[0006]

However, in such a conventional corneal shape measuring apparatus, since the results are calculated by considering the cornea as an astigmatism showing a constant deformation, various problems occur. It was That is, since the central portion of the cornea is actually less deformed, it is possible to obtain an almost accurate measurement result even in the above-mentioned measurement, but the peripheral portion is actually greatly deformed and it is impossible to regard it as an astigmatism. Sometimes it was difficult to get accurate results.

On the other hand, in recent years, the downsizing of devices has progressed, and handheld devices have also appeared. With such a hand-held device, there is no chin rest or forehead rest on the subject, and the device itself can be rotated at any angle to perform measurements. It is easy to measure the peripheral portion at any angle including the main meridian direction. However, because you can hold the handheld device in any orientation,
On the contrary, it is difficult to grasp the proper orientation of the device itself, and in reality, it is still difficult to measure the peripheral portion at any angle including the strong main meridian direction and the weak main meridian direction.

The present invention particularly relates to such a corneal shape measuring apparatus, and a corneal shape measuring apparatus and its measuring method for accurately measuring the peripheral portion of the cornea in a direction that matches the strong main meridian direction or the weak main meridian direction. Is provided.

[0009]

In order to solve the problems in the conventional corneal shape measuring method, the present invention according to claim 1 provides a first projecting means and a second projecting means. A corneal shape measuring method for measuring a shape of a cornea using a corneal shape measuring device including a detection optical system and a calculation unit, wherein a center for measuring a central portion of the cornea by the first projection means. The index for projection on the cornea, the corneal reflection image of the index for the center is detected by the detection optical system, and the cornea shape is calculated from the detection result by the detection optical system by the calculation unit,
Center part measurement step and consecutively after the step,
The second projection means projects a peripheral index for measuring the peripheral part of the cornea onto the cornea, the detection optical system detects a corneal reflection image of the peripheral index, and the computing section performs the detection. It is characterized in that it comprises a peripheral portion measuring step of calculating a corneal shape from a detection result by the optical system, and a step of alternately and continuously performing the central portion measuring step and the peripheral portion measuring step.

According to a second aspect of the present invention, the shape of the cornea is measured by using a cornea shape measuring device equipped with a first projection means, a second projection means, a detection optical system and a calculation section. A corneal shape measuring method for measuring, wherein a central index for measuring a central part of the cornea is projected onto the cornea by the first projection means, and a corneal reflection image of the central index is detected by the detection optical system. A step of continuously performing a plurality of times of central portion measurement for detecting and calculating the corneal shape from the detection result by the detection optical system in the arithmetic part, and successively to the second projection means after the step. The peripheral index for measuring the peripheral part of the cornea is projected on the cornea, the corneal reflection image of the peripheral index is detected by the detection optical system, and the cornea is detected from the detection result by the detection optical system by the calculation unit. Steps to perform peripheral measurement to calculate the shape multiple times in succession It is configured as characterized in that it consists of a.

According to a third aspect of the present invention, there is provided a first projection means for projecting a measuring index for measuring the central part of the cornea onto the cornea, and a measuring index for measuring the peripheral part of the cornea on the cornea. Second projection means for projecting, a detection optical system for detecting a corneal reflection image of the measurement index projected by the first projection means and the second projection means, and a cornea based on a detection result by the detection optical system. In a corneal shape measuring device including a calculation unit for calculating a shape, an angle difference between a strong main meridian direction or a weak main meridian direction obtained in the corneal center measurement and a predetermined reference direction is calculated, and the angular difference is calculated. It is characterized in that a display unit for providing a predetermined display for the measurer to perform an appropriate measurement based on the above is provided.

According to a fourth aspect of the present invention, in the present invention according to the third aspect, the corneal center portion measurement is performed a plurality of times, and the angular difference calculation and predetermined display are performed for each corneal center portion measurement. It is configured to do.

The present invention according to claim 5 is characterized in that, in the present invention according to claim 3 or 4, the reference direction is determined based on the reference direction of the apparatus.

The present invention according to claim 6 is characterized in that, in the present invention according to claim 3 or 4, the reference direction is determined based on an angle obtained by an arbitrary angle sensor. Has been done.

According to a seventh aspect of the present invention, in the present invention according to the third to sixth aspects, the display unit reduces the angle difference when the angle difference is a predetermined value or more. It is characterized by displaying a direction indicating mark indicating a direction in which the device should be rotated.

According to an eighth aspect of the present invention, in the inventions according to the third to seventh aspects, the display section displays the strong main meridian direction or the weak main direction when the angular difference is equal to or less than a predetermined value. It is configured to display a match mark indicating that the meridian direction and the reference direction match.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a corneal shape measuring apparatus and a measuring method thereof according to the present invention will be described in detail below with reference to the drawings. Note that the principle of measurement of the radius of curvature of the central part of the cornea and the axial direction itself are well known, and the applicant of the present invention also has a Japanese Patent Publication No.
Since it has been presented in 157218, detailed description thereof will be omitted. The present device 1 enables the measurement of the peripheral part by the same principle as the central part measurement by adding the second projection means for measuring the peripheral part to the measuring device of the central part of the cornea. Is.

FIG. 1 is a diagram showing the configuration of the optical system of this embodiment, and FIG. 2 is a diagram showing the configuration of the optical system in the plane of the paper including the optical axis O and perpendicular to FIG. In each of these drawings, the device 1 is shown by a broken line, and a first projection means X1 for projecting a measurement index for measuring the central portion of the cornea onto the cornea.
A second projection means X2 for projecting a measurement index for measuring the corneal periphery onto the cornea, and a corneal reflection image of the measurement index projected by the first and second projection means X1, X2. A detection optical system 2 for detecting and a calculation unit 3 for calculating the corneal shape based on the detection result by the detection optical system 2 are formed.

First, each of these components will be described.
The first projection means X1 for measuring the central part has four projection optical systems a to b. Of these, two projection optical systems a and b
Is the objective lens R1 of the detection optical system 1 as shown in FIG.
Within the plane including the optical axis O (in the plane of FIG. 1) of
Are arranged symmetrically with respect to. One of the projection optical systems a is composed of an illumination light source a1, a pinhole plate a2 and a collimator lens a3, and the other projection optical system b is an illumination light source b1 and a pinhole plate b.
2 and a collimator lens b3, which form the optical axes Oa and Ob of the projection optical system. The light beams emitted from the illumination light sources a1 and b1 on the optical axes Oa and Ob pass through the pinhole plates a2 and b2, and then collimator lenses a3 whose focal planes are on the pinhole plates a2 and b2. It is made into a parallel light beam by b3 and the eye E
Is projected to. Further, as shown in FIG. 2, the remaining two projection optical systems c and d of the first projection means X1 are, with respect to the optical axis O, in the plane orthogonal to the paper surface of FIG. They are arranged at symmetrical positions forming an angle α. One of the projection optical system c is an illumination light source c1 and a pinhole plate c2.
And a collimator lens c3, and the other projection optical system d is composed of an illumination light source d1, a pinhole plate d2 and a collimator lens d3, and forms optical axes Oc and Od of the projection optical system. . And these optical axes O
The light beams emitted from the illumination light sources c1 and d1 on c and Od pass through the pinhole plates c2 and d2, and then the collimator lens c3 whose focal plane is on the pinhole plates c2 and d2.
, D3 to form a parallel light beam, which is projected onto the eye E to be inspected.

On the other hand, the second projection means X2 also has four projection optical systems e to h. These projection optical systems e to h are substantially the same as the projection optical systems a to d of the first projection means X1 except that they are arranged at an angle β with respect to the optical axis O instead of the angle α. It has a similar configuration. That is, 2
The two projection optical systems e and f have an optical axis O in the plane of FIG.
The light beams emitted from the illumination light sources e1 and f1 on the respective optical axes Oe and Of at an angle β with respect to the collimator lenses e3 and f3 after passing through the pinhole plates e2 and f2.
Is converted into a parallel light flux by and is projected onto the eye E to be inspected.

As shown in FIG. 2, the projection optical systems g and h form an angle β with respect to the optical axis O in the plane orthogonal to the paper surface of FIG. 1, and on the respective optical axes Og and Oh. The luminous flux emitted from the illumination light sources g1 and h1 is the pinhole plate g.
After passing through 2 and h2, it is collimated by collimator lenses g3 and h3, and is projected onto the eye E to be examined. FIG. 3 is a view of the projection optical systems a to d of the first projection means X1 and the projection optical systems e to h of the second projection means X2 as seen from the eye E side, with the optical axis as the center. It can be seen that there are four point light sources for each of the center measurement and the peripheral measurement, that is, a total of eight point light sources in the vertical and horizontal directions.

In this way, a total of eight systems of light projected from the projection optical systems a to d and e to h onto the eye E to be examined are reflected by the eye E to be examined and enter the common measurement optical system 2. This measuring optical system 2 includes an objective lens R1 and a beam splitter BS.
And the observation optical path W1 and the measurement optical path W2. First, the reflected image incident on the measurement optical system 2 passes through the objective lens R1 and is then observed by the beam splitter BS by the observation optical path W1.
1 and the measuring optical path W2.

In the observation optical path W1, a diaphragm S1, a reflecting mirror M1, a re-imaging lens R2 forming a telecentric system together with an objective lens R1, a focusing screen ST and an eyepiece R3.
Is provided, and the reflected image separated by the beam splitter BS is observed by the measurer through the eyepiece lens R3. On the other hand, the measurement optical path W2 is provided with a diaphragm S2, a re-imaging lens R4 which constitutes a telecentric system together with the objective lens R1, a reflection mirror M2 and a photoelectric conversion device 4, and the reflection separated by the beam splitter BS. The image enters the photoelectric conversion device 4.

The reflected image that has entered the photoelectric conversion device 4 in this way is converted into a signal corresponding to its position and input to the arithmetic unit 3. Based on the input incident position, the calculation unit 3 uses known methods to calculate the curvature of the central cornea in the strong main meridian direction, the curvature in the weak main meridian direction, and the angular difference between the strong main meridian direction and the reference direction. Is calculated. That is, according to the apparatus 1 described so far, the first projection means X1
By projecting light from the projection optical systems a to d, the curvature in the strong main meridian direction, the curvature in the weak main meridian direction, and the angular difference between the strong main meridian direction and the reference direction of the central portion of the cornea are calculated (note that The angle difference is calculated as an absolute value.) By projecting light from the projection optical systems e to h of the second projection unit X2, the curvature in the strong main meridian direction and the curvature in the weak main meridian direction of the peripheral portion of the cornea. Is calculated. Here, the reference direction is a reference direction preset in the device 1, and in the present embodiment, a direction that matches a reflection image generated when the eye E to be inspected is a spherical surface is adopted. Although not shown, this reference direction is drawn as a reference line in the finder 5 of the apparatus 1.

The angle difference between the strong main meridian direction of the central portion of the cornea and the reference direction calculated in this way is indicated by the display unit 6 in the apparatus 1.
In, a magnitude comparison is performed with a predetermined value input in advance, and a predetermined display based on the angle difference and used by the measurer to perform an appropriate measurement is displayed according to the comparison result. Here, the predetermined display means, specifically, when the angular difference is equal to or larger than a predetermined value, as shown in FIG. 5, a direction indicating a direction in which the device should be rotated in order to reduce the angular difference. When the angle difference is less than or equal to a predetermined value, the indication mark 7 is a match mark 8 indicating that the strong main meridian direction and the reference direction match, as shown in FIG. As shown in FIG. 7, the device 1 including these respective elements is configured as a handy type that can be rotatably held by one hand.

Next, the measurement sequence in this embodiment will be described with reference to FIG. First, the overall flow will be briefly described, and thereafter, the steps of the main parts will be described in detail.
First, when the measurer turns on the power (S1), the previous data is initialized (S2). Then, when a measurement switch (not shown) is pressed (S3), central part measurement is first performed (S4, central part measurement step), and the curvature of the central part of the cornea in the strong main meridian direction, the curvature in the weak main meridian direction, and the strong main meridian direction. The angle difference between the reference direction and the reference direction is calculated, and the peripheral portion is continuously measured (S5, peripheral portion measuring step). After the peripheral portion measuring step is completed, the magnitude difference between the angle difference by the display unit 6 and a predetermined value is compared,
If the angle difference is less than or equal to the predetermined value, the process proceeds to the next step. If it is not less than or equal to the predetermined value, the process returns to the central portion measuring step again (S6, determination step). That is, the central portion measuring step and the peripheral portion measuring step are alternately and continuously performed until the angle difference becomes equal to or smaller than a predetermined value (S4).
~ S6). Then, each time these measurements are repeated, the direction indicator mark 7 described later is displayed on the display unit 6 (S7, instruction display step). On the other hand, if the predetermined criteria are met, the display unit 6 displays a later-described match mark 8 (S8, match display step), and the peripheral measurement result is displayed (S9, result). Display step), and the measurement ends (S10).

Here, the determination step and the instruction display step will be specifically described. For example, when the calculated angle difference is 10 degrees and the predetermined value is 5 degrees, it is determined in the determination step that the angle difference is not less than or equal to the predetermined value, and the process proceeds to the instruction display step. In this case, since the device 1 should be rotated clockwise, a clockwise arrow is displayed as the direction indicator mark 7 on the display unit 6. On the other hand, even when the calculated angle difference is −10 degrees and the predetermined value is 5 degrees, it is determined that the angle difference is not less than the predetermined value in the determination step, and the procedure moves to the instruction display step. Since the device 1 should be rotated counterclockwise, a counterclockwise arrow is displayed as the direction indicator mark 7 as shown in FIG. Therefore, in order to match the strong meridian direction of the central part of the cornea with the reference direction, the measurer looks into the finder 5,
It is possible to know in which direction the device 1 should be rotated. FIG. 8 is an external view of the device viewed from the side of the measurer. The measurer holds the grip 9 and rotates the device 1 according to the direction indicating mark 7.

While the apparatus 1 is rotated in this manner, the central portion measuring step and the peripheral portion measuring step are alternately performed. The peripheral portion measuring step is performed in the strong main meridian direction and the reference direction. The measurement result is not displayed because the measurement is performed in a state where it is not confirmed that the angles match, and the measurement cannot be said to be in a desirable state. However, since the central part measuring step and the peripheral part measuring step are alternately performed in this way, the positional relationship between the eye E to be measured at the central part and the device 1 and the eye E to be measured at the peripheral part are The positional relationship with the device 1 does not deviate from each other.

Further, the judgment step, the match display step and the result display step will be specifically described. As the measurer rotates the device 1, the angular difference between the strong main meridian direction and the reference direction gradually decreases. Then, when it is turned up to a certain point, the angle difference becomes equal to or smaller than a predetermined value, or the angles completely match. When it is determined in the determination step that the angle difference is equal to or less than the predetermined value, in the match display step, the strong main meridian direction and the reference direction are displayed on the display unit 6 as shown in FIG. A match mark 8 indicating that and match is displayed above the eye E in the finder 5. When the match mark 8 is displayed in this way, the strong main meridian direction and the reference direction match in the peripheral portion measurement, and it can be said that the measurement is performed in the most desirable state. The measurement result 10 of the measurement is displayed in the finder 5.

Although one embodiment of the present invention has been described above, the present invention may be embodied in various different forms within the scope of the technical idea thereof. For example, in the above-described embodiment, the strong main meridian direction and the reference direction are compared, but the weak main meridian direction and the reference direction may be compared and the same display may be performed. Also, when the match mark is displayed, the measurement result of the peripheral part is displayed, but the center part and the peripheral part measurement are performed more than once, and the average value of these is calculated to match the direction. Alternatively, the measurement results may be displayed after confirming the accuracy of each measurement result. Further, the direction indicating mark and the match mark may be displayed in any shape and position other than the shape and position shown in the drawing.

Alternatively, in the above-described embodiment, the central portion measuring step and the peripheral portion measuring step are alternately and continuously performed. However, first, only the central portion measuring step is continuously performed a plurality of times, and then the central portion measuring step is performed. After displaying the result and displaying the direction indicator mark, after the measurer rotates the device, it is determined in the determination step that the angle difference is less than or equal to a predetermined value, and then the peripheral measurement step is performed. You may move. Further, the reference direction to be compared with the strong main meridian direction may be the direction determined using an arbitrary two-dimensional angle sensor instead of the reference direction of the present apparatus. In this case,
The angle sensor is built into the device. Further, in the result display step, not only the measurement result of the peripheral portion but also the measurement result of the central portion may be displayed together.

[0032]

As described above, according to the present invention as set forth in claim 1, by performing the central portion measuring step and the peripheral portion measuring step alternately and continuously, the strong main meridian direction of the central portion of the cornea, etc. It is possible to measure each value in the state that the strong meridian direction of the peripheral part of the cornea and the corneal peripheral part match each other, and the positional relationship between the eye to be inspected and this device is the same during the central part measurement and the peripheral part measurement. Therefore, more accurate measurement can be performed.

Further, according to the invention of claim 2,
By performing the peripheral part measurement a plurality of times after performing the central part measurement a plurality of times, the results of the central part measurement and the peripheral part measurement are calculated as an average value of the plurality of measured values, which is more accurate. Further, similarly to the above, each value can be measured in a state where the strong main meridian direction of the central portion of the cornea and the strong main meridian direction of the peripheral portion of the cornea match each other.

Further, according to the present invention as set forth in claim 3, an angle difference between the strong main meridian direction and the like obtained by the measurement of the central portion of the cornea and a predetermined reference direction is calculated, and based on this angle difference. However, by providing a predetermined display for the measurer to perform an appropriate measurement, the measurer can determine how to hold the device just by looking at this display and measure in the proper direction. It can be done accurately and easily. As a result, the peripheral measurement can be performed in a direction that exactly matches the main meridian direction of the central portion.

Further, according to the present invention as set forth in claim 4,
By performing the corneal center measurement multiple times and calculating the angle difference and performing a predetermined display for each corneal center measurement, the predetermined display is displayed in real time based on the angle difference at that time, so the measurement The person can grasp the direction of the apparatus while rotating the apparatus, and the angle can be corrected more easily.

Further, according to the present invention as set forth in claims 5 and 6, the strong main meridian is determined by determining the reference direction based on the reference direction of the apparatus or an angle obtained by an arbitrary angle sensor. The reference direction to be compared with, etc. can always be obtained appropriately, and accurate calculation of the angle difference is guaranteed.

Further, according to the present invention of claim 7, when the angle difference is equal to or larger than a predetermined value, the display section indicates the direction in which the device should be rotated in order to reduce the angle difference. By displaying the direction indication mark, it is possible to easily know that the strong main meridian and the like do not match the reference direction and the direction in which the device should rotate in order to match, and rotate the device in that direction. It is very easy to correct the angle.

According to the present invention of claim 8, in the display section, the strong main meridian direction or the weak main meridian direction and the reference direction coincide with each other when the angular difference is not more than a predetermined value. It is possible to easily know that the strong main meridian, etc. and the reference direction match by displaying the matching mark that indicates that the measurement can be performed properly simply by holding this device in that state. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an optical system in a plane including an optical axis O and perpendicular to FIG.

FIG. 3 is a diagram of a main part of the optical system shown in FIGS.

FIG. 4 is a flowchart showing a measurement order and the like in one embodiment of the present invention.

FIG. 5 is a diagram showing a direction indicating mark together with an eye to be examined.

FIG. 6 is a diagram showing a match mark together with an eye to be examined.

FIG. 7 is a side view of the device and a subject.

FIG. 8 is a view of the present apparatus and a subject viewed from the side of the measurer.

[Explanation of symbols]

 X1 First projection means X2 Second projection means a to h Projection optical system a1 to h1 Illumination light source a2 to h2 Pinhole plate a3 to h3 Collimator lens O, Oa to Oh Optical axis BS Beam splitter W1 Observation optical path W2 Measurement optical path S1, S2 Aperture R1 Objective lens R2, R4 Re-imaging lens R3 Eyepiece M1, M2 Reflecting mirror ST Focus plate 1 Main unit 2 Detection optical system 3 Calculation unit 4 Photoelectric conversion device 5 Finder 6 Display unit 7 Direction indicator 8 Matching Mark 9 Grip 10 Measurement result

Claims (8)

[Claims] 1. A first projecting means, a second projecting means,
A corneal shape measuring method for measuring the shape of a cornea using a corneal shape measuring device equipped with a detection optical system and a calculation section, comprising the following steps. (A) The first projection means projects a central index for measuring the central part of the cornea onto the cornea, and the detection optical system detects a corneal reflection image of the central index, and the computing section A central portion measuring step of calculating a corneal shape from the detection result of the detection optical system. (B) Continuously after the step, a peripheral index for measuring the peripheral part of the cornea is projected onto the cornea by the second projection means, and the corneal reflection image of the peripheral index is detected by the detection optical system. Is detected, and the corneal shape is calculated from the detection result by the detection optical system in the calculating section, a peripheral portion measuring step. (C) Further, a step of continuously performing the central portion measuring step and the peripheral portion measuring step alternately. 2. A first projection means, a second projection means,
A corneal shape measuring method for measuring the shape of a cornea using a corneal shape measuring device equipped with a detection optical system and a calculation section, comprising the following steps. (A) The first projection means projects a central index for measuring the central part of the cornea onto the cornea, and the detection optical system detects a corneal reflection image of the central index, and the computing section And a step of continuously performing central part measurement for calculating the cornea shape from the detection result by the detection optical system a plurality of times. (B) Continuously after the step, a peripheral index for measuring the peripheral part of the cornea is projected onto the cornea by the second projection means, and the corneal reflection image of the peripheral index is detected by the detection optical system. And a peripheral part measurement for calculating the corneal shape from the detection result by the detection optical system in the calculating part, continuously performing a plurality of times. 3. A first projection means for projecting a measurement index for measuring the central part of the cornea onto the cornea, and a second projection means for projecting a measurement index for measuring the peripheral part of the cornea onto the cornea. ,
A detection optical system that detects a corneal reflection image of the measurement index projected by the first projection unit and the second projection unit, and a calculation unit that calculates a corneal shape based on a detection result of the detection optical system. In the corneal shape measuring device provided, the angle difference between the strong main meridian direction or the weak main meridian direction and the predetermined reference direction obtained in the corneal center portion measurement is calculated, and the measurer makes an appropriate measurement based on the angle difference. A corneal shape measuring apparatus, characterized in that a display unit for performing a predetermined display for performing is provided. 4. The corneal shape measuring apparatus according to claim 3, wherein the corneal center measurement is performed a plurality of times, and the angular difference is calculated and a predetermined display is performed for each corneal center measurement. 5. The corneal shape measuring apparatus according to claim 3, wherein the reference direction is determined based on the reference direction of the apparatus. 6. The cornea shape measuring device according to claim 3, wherein the reference direction is determined based on an angle obtained by an arbitrary angle sensor. 7. The display unit displays, when the angular difference is equal to or larger than a predetermined value, a direction indicator mark indicating a direction in which the device should be rotated in order to reduce the angular difference. The cornea shape measuring device according to claim 3. 8. The display unit displays a match mark indicating that the strong main meridian direction or the weak main meridian direction matches the reference direction when the angular difference is equal to or less than a predetermined value. The cornea shape measuring device according to claim 3, which is characterized in that.