Ophthalmic measurement optical system

Abstract

The application discloses an ophthalmic measurement optical system for measuring the corneal vertex curvature of a human eye, comprising an objective lens, an imaging lens, a camera device and a light source assembly, wherein the light source assembly, the imaging lens and the camera device are sequentially arranged on the side of the objective lens away from the human eye, the light source assembly comprises a plurality of light sources, the light emitted by the light sources is transmitted through the objective lens, is incident on the human eye, is reflected by the cornea of the human eye, is transmitted through the objective lens again, and is received by the camera device. The ophthalmic measurement optical system improves the measurement accuracy of the corneal curvature.

Description

Technical Field

[0001] This invention relates to ophthalmic optical testing equipment, and more particularly to an ophthalmic measurement optical system. Background Technology

[0002] Corneal vertex curvature is an important optical parameter of the human eye. Measuring corneal vertex curvature is of significant reference value for keratoconus surgery, LASIK (laser-assisted in cataract surgery), and myopia control in adolescents. Existing products and instruments also incorporate corneal vertex curvature measurement technology, such as corneal topographers, corneal topographers, and ophthalmic optical biometers. However, the principles used by different instruments are not entirely the same. For example, corneal topographers utilize the principle of Placido's disk to measure the curvature distribution over a large area of ​​the cornea. Ophthalmic optical biometers, on the other hand, provide corneal vertex curvature (see Chinese patent documents CN101596096A and CN111557637A); they emit light from multiple light sources distributed around the periphery of the eyepiece, which is reflected by the cornea and received by the camera optical path. By measuring the change in the relative positions of the images of multiple light sources as the corneal curvature of the eye being measured changes, the corneal vertex curvature is derived. This corneal vertex curvature measurement technology, compared to the corneal curvature topography measurement technology based on Placido's disk principle, has advantages such as fewer measurement data points, higher speed, and simpler structure.

[0003] Existing methods for measuring corneal vertex curvature involve distributing multiple light sources around the periphery of an eyepiece and acquiring corneal reflections of these light sources to obtain the central corneal curvature. This technique often requires that the distance between the reflection point of the light source and the corneal vertex be small, typically less than or equal to 3mm, 2mm, or even 1mm. However, for eyepieces with large numerical apertures, the large diameter results in a short working distance. If the multiple light sources are distributed around the periphery of the eyepiece, the light beam reflected by the cornea is difficult to receive by the imaging system behind the eyepiece (the side of the eyepiece relative to the eye being tested, referred to as "behind"). Alternatively, the light beam reflected by the cornea can be received by the imaging system behind the eyepiece, but the reflection point on the cornea is often far from the corneal vertex, exceeding 1mm, or even 2mm or 3mm. Even if the camera system obtains images of multiple light sources reflected from the cornea, the data on the corneal vertex curvature it calculates is often unreliable because the reflection point of the light beam on the cornea is far from the corneal vertex.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an ophthalmic measurement optical system that improves the measurement accuracy of corneal curvature.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention discloses an ophthalmic measurement optical system for measuring the corneal vertex curvature of a subject's eye. The system includes an eyepiece objective, an imaging lens, a camera device, and a light-emitting light source assembly. The light-emitting light source assembly, the imaging lens, and the camera device are sequentially disposed on the side of the eyepiece objective away from the subject's eye. The light-emitting light source assembly includes multiple light sources. Light emitted from these multiple light sources passes through the eyepiece objective and enters the subject's eye. After being reflected by the cornea of ​​the subject's eye, the light passes through the eyepiece objective again, is transmitted through the imaging lens, and is received by the camera device.

[0008] Preferably, the light source assembly further includes a plurality of condensing lenses, each of which corresponds to a plurality of light sources, so that the light emitted by each light source is focused by the corresponding condensing lens before being transmitted through the eyepiece objective lens.

[0009] Preferably, the ophthalmic measurement optical system further includes an aperture stop located between the eyepiece objective and the imaging lens. Light emitted from the plurality of light-emitting sources passes through the eyepiece objective and enters the subject's eye. After being reflected by the cornea of ​​the subject's eye, the light passes through the eyepiece objective again, passes through the aperture stop, and then passes through the imaging lens.

[0010] Preferably, the plurality of light-emitting sources and corresponding condenser lenses are arranged along the circumferential direction of the aperture. This effectively avoids the imaging optical path.

[0011] Preferably, the aperture is located at the image-side focal plane of the eyepiece objective. Employing the telecentric optical path principle, where the iris of the eye under test is located at the object-side focal plane of the eyepiece objective, if the eye deviates from the desired working position along the optical axis, the position of the image from multiple light sources remains unchanged. This simplifies calculations and improves measurement accuracy.

[0012] Preferably, the aperture is located at the object-side focal plane of the imaging mirror, and the imaging device is located at the image-side focal plane of the imaging mirror. In the scheme that simultaneously employs the object-side telecentric optical path principle and the image-side telecentric optical path principle, slight deviations of the tested human eye and the imaging device from their set working positions will not affect the measurement of the positions of the images of multiple light-emitting sources, further improving measurement accuracy.

[0013] Preferably, the number of the plurality of light-emitting sources is greater than or equal to 3.

[0014] Preferably, the plurality of light-emitting light sources and corresponding condenser lenses are arranged at equal intervals along the circumferential direction of the aperture.

[0015] Compared with existing technologies, the advantages of this invention are as follows: The ophthalmic measurement optical system proposed in this invention can very easily measure the corneal vertex curvature of the human eye, especially for ophthalmic measurement devices with short working distances but large eyepiece apertures. In this invention, multiple light sources are located behind the eyepiece. The light emitted from these light sources is reflected by the cornea, and the distance between the light beam reflection point on the cornea and the corneal vertex is not affected by the increase in the numerical aperture of the eyepiece. This makes it easy to achieve a distance of less than or equal to 3mm, 2mm, or even less than or equal to 1mm between the light beam reflection point on the cornea and the corneal vertex. Therefore, even if the numerical aperture of the eyepiece in the ophthalmic measurement device is large, such as in a color fundus camera system, this solution can still solve the problem that ophthalmic measurement optical systems with large numerical aperture eyepieces cannot measure the corneal vertex curvature of the human eye. Attached Figure Description

[0016] Figure 1 This is an optical path diagram of an ophthalmic measurement optical system according to a preferred embodiment of the present invention;

[0017] Figure 2 It is a schematic diagram of the arrangement of multiple light sources and apertures;

[0018] Figure 3 This is an optical path diagram of an existing ophthalmic measurement optical system;

[0019] Figure 4 This is a schematic diagram of the arrangement of multiple light sources and eyepieces in existing technology;

[0020] Figure 5 yes Figure 3 A schematic diagram of the principle of an ophthalmic measurement optical system. Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0022] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0023] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0025] like Figure 1 As shown, a preferred embodiment of the present invention discloses an ophthalmic measurement optical system for measuring the corneal vertex curvature of a subject. The system includes an eyepiece objective 101, an aperture 102, an imaging lens 103, a camera device 104, multiple light sources, and multiple condenser lenses. The aperture 102 and the multiple condenser lenses are respectively disposed between the eyepiece objective 101 and the multiple light sources. The imaging lens 103 and the camera device 104 are sequentially disposed behind the multiple light sources (in this invention, the direction away from the eye to be measured is referred to as "behind").

[0026] Among them, the light emitted from multiple light sources (including light sources 2011 to 2016) distributed behind the eyepiece objective lens 101 passes through the condenser lens (including condenser lenses 2021 to 2026), is transmitted through the eyepiece objective lens 101, and enters the subject's eye E. After being reflected by the subject's cornea Ec, the reflected light returns, passes through the eyepiece objective lens 101, passes through the aperture stop 102, is transmitted through the imaging lens 103, and is received by the camera device 104.

[0027] In a preferred embodiment, the telecentric optical path principle is employed, ensuring that the iris Ei of the eye under test is positioned at the object-side focal plane of the eyepiece objective 101, while the aperture stop 102 is positioned at the image-side focal plane of the eyepiece objective 101. In this configuration, if the tested eye E deviates from the desired working position along the optical axis L1, the position of the image relative to multiple light sources remains unchanged. This further simplifies calculations and improves measurement accuracy.

[0028] In some embodiments, if the object-side telecentric optical path principle is not employed, the positions of the images of multiple light sources will change as the eye E under test moves back and forth along the optical axis L1. The system needs to accurately obtain the corneal position of the eye under test before it can correct for these changes in the image positions and subsequently calculate the corneal vertex curvature. Therefore, compared to the object-side telecentric scheme, the scheme without the object-side telecentric optical path principle is not only more complex (requiring corneal vertex ranging) but also more computationally complex, prone to introducing errors, and reduces the accuracy of corneal vertex curvature measurement.

[0029] In a further preferred embodiment, the imaging optical path also adopts the telecentric optical path principle, that is, the double telecentric imaging optical path principle; at this time, the iris Ei of the eye under test is located at the object-side focal plane of the eyepiece objective 101, while the aperture 102 is located at the image-side focal plane of the eyepiece objective 101; and the aperture 102 is located at the object-side focal plane of the imaging mirror 103, while the imaging device 104 is located at the image-side focal plane of the imaging mirror 103. In this embodiment, slight deviations of the tested eye E and the imaging device 104 from their set working positions will not affect the measurement of the positions of the images of the multiple light sources.

[0030] In this invention, multiple light sources (including light sources 2011 to 2016) are located behind the eyepiece objective lens 101. The light emitted from the light sources (including light sources 2011 to 2016) is reflected by the cornea. The distance h between the light beam reflection point F2011 on the cornea and the corneal vertex Ec0 is not affected by the increase in the numerical aperture of the eyepiece objective lens 101. At this time, it is easy to achieve a distance h between the light beam reflection point F2011 on the cornea and the corneal vertex that is less than or equal to 3mm or 2mm, or even less than or equal to 1mm.

[0031] like Figure 2 The diagram shows the relative positions of multiple light-emitting sources (including light-emitting sources 2011-2016) and the aperture stop 102. The multiple light-emitting sources (including light-emitting sources 2011-2016) are arranged behind the eyepiece objective lens 101. Furthermore, to effectively avoid the imaging optical path, the multiple light-emitting sources (including light-emitting sources 2011-2016) are more preferably distributed around the outer periphery of the aperture stop 102. In a further embodiment, the number of multiple light-emitting sources is ≥3; in this embodiment, 6 light-emitting sources 2011-2016 are shown. The lenses in the optical path are only illustrative; for example, the eyepiece objective lens 101 and the imaging lens 103 can be single-lens lenses or combinations of lenses.

[0032] like Figure 3 and Figure 4The diagram shows the structure of a prior art ophthalmic measurement optical system. The system includes the eye under test (E), the iris (Ei), the cornea (Ec), the corneal vertex (Ec0), the eyepiece objective (Y101), the imaging system (Y10), the principal optical axis (YL1), multiple light sources (Y2011-Y2016), a beam reflection point on the cornea (YF2011), and the distance h between the beam reflection point YF2011 and the corneal vertex. Multiple light sources (Y2011-Y2016) are distributed around the outer periphery of the eyepiece objective (Y101). The light emitted by these sources is reflected by the cornea (Ec), and the reflected beams are then received by the imaging system (Y10) after passing through the eyepiece objective (Y101), thus obtaining an image of the multiple light sources (Y2011-Y2016). The distance h between the light beam reflection point YF2011 on the cornea and the corneal apex is typically required to be no larger than 3mm or 2mm, or even 1mm or less. Due to changes in corneal curvature, the relative positions of the images of multiple light sources Y2011-Y2016 also change. The corneal apex curvature can be derived from the images of these multiple light sources Y2011-Y2016.

[0033] The positions of the multiple light sources Y2011-Y2016 relative to the eyepiece objective Y101 are as follows: Figure 4 As shown, multiple light sources Y2011-Y2016 are distributed around the circumference of the eyepiece objective Y101. When the numerical aperture of the eyepiece objective Y101 increases, its relative diameter increases, and the working distance decreases. At this time, when the multiple light sources Y2011-Y2016 are reflected by the cornea Ec, if the reflected beam can pass through the eyepiece objective Y101 and be received by the camera system Y10, the distance h2 between the beam reflection point YF2011 on the cornea and the corneal apex is often large, resulting in inaccurate measurement of the corneal apex curvature. Alternatively, if the distance h between the beam reflection point YF2011 on the cornea and the corneal apex is small, the reflected beam cannot be received by the camera system Y10 behind the eyepiece objective Y101. Figure 5 As shown.

[0034] Through the above comparison, in the prior art, the measured corneal vertex curvature of a large numerical aperture eyepiece is not accurate enough, and when the distance between the light beam reflection point on the cornea and the corneal vertex is small, the reflected light beam cannot be received by the camera system behind the eyepiece. In contrast, the preferred embodiment of the present invention provides a large numerical aperture eyepiece for measuring corneal vertex curvature, and further combines it with telecentric measurement technology to improve the accuracy of corneal curvature measurement.

[0035] Furthermore, it should be noted that the ophthalmic measurement optical system proposed in the preferred embodiment of the present invention is also applicable to small numerical aperture eyepieces, and has wide applicability.

[0036] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0037] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. An ophthalmic measurement optical system for measuring the corneal vertex curvature of a subject, characterized in that, The device includes an eyepiece, an imaging lens, a camera, an aperture, and a light source assembly. The light source assembly, the imaging lens, and the camera are sequentially arranged on the side of the eyepiece away from the subject's eye. The light source assembly includes multiple light sources. The light emitted by the multiple light sources passes through the eyepiece and enters the subject's eye. After being reflected by the cornea of ​​the subject's eye, it passes through the eyepiece again, and then through the imaging lens before being received by the camera. The aperture is located between the eyepiece and the imaging lens. The light emitted by the multiple light sources passes through the eyepiece and enters the subject's eye. After being reflected by the cornea of ​​the subject's eye, it passes through the eyepiece again, passes through the aperture, and then through the imaging lens. The multiple light sources are arranged along the circumference of the aperture. Wherein, the aperture stop is located at the image-side focal plane of the eyepiece objective lens, and the aperture stop is located at the object-side focal plane of the imaging lens, and the imaging device is located at the image-side focal plane of the imaging lens.

2. The ophthalmic measurement optical system according to claim 1, characterized in that, The light source assembly also includes multiple condenser lenses, each corresponding to one of the multiple light sources, so that the light emitted by each light source is focused by the corresponding condenser lens before being transmitted through the eyepiece objective lens.

3. The ophthalmic measurement optical system according to claim 2, characterized in that, The corresponding focusing lenses of the plurality of light-emitting light sources are arranged along the circumferential direction of the aperture.

4. The ophthalmic measurement optical system according to claim 1, characterized in that, The number of light sources is greater than or equal to 3.

5. The ophthalmic measurement optical system according to claim 2, characterized in that, Multiple light sources and corresponding focusing lenses are arranged at equal intervals along the circumferential direction of the aperture.

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