Optical system for high-speed reduction of dynamic deformation process of cornea

Abstract

The invention discloses an optical system for high-speed reduction of a dynamic deformation process of a cornea, which realizes high-precision analysis of physical characteristics of the cornea through a high-speed imaging technology, performs error compensation on the physical characteristics and realizes high-precision calculation of intraocular pressure. According to the technical scheme, the optical system comprises a slit lamp light source used for forming a cornea optical slice and ensuring the definition and the contrast ratio of a cornea slice image; the Samm lens is used for shooting a cornea optical section, inclined imaging light path design is adopted, and the depth of field meets the requirement that the cornea section keeps clear imaging in the dynamic process; and the high-speed camera is positioned behind the Chemma lens and is used for receiving the cornea optical slice image imaged by the Chemma lens so as to record the dynamic deformation process of the cornea.

Description

Technical Field

[0001] The present invention relates to the field of ophthalmic optical imaging technology, and specifically to an optical system for capturing and restoring the dynamic deformation process of the cornea in real time. High-speed imaging technology is used to achieve high-precision analysis of the physical properties of the cornea, perform error compensation, and realize high-precision calculation of intraocular pressure. Background Art

[0002] Glaucoma is one of the three leading causes of blindness worldwide. Its pathogenesis is closely related to abnormally elevated intraocular pressure (IOP). Normally, IOP remains within a relatively stable range, typically between 10 and 21 mmHg. However, intermittent or persistent elevations in IOP can cause irreversible damage to the internal structures of the eye. The optic nerve, in particular, serves as a critical pathway for transmitting visual information from the eye to the brain and is extremely sensitive to elevated IOP. Sustained elevated IOP compresses optic nerve fibers, leading to optic atrophy and, in turn, impairing visual function. Visual impairment may initially manifest as visual field loss, which gradually expands as the disease progresses. Failure to promptly and effectively treat IOP can ultimately lead to complete visual field loss, resulting in blindness. Therefore, early and accurate IOP measurement is crucial for the diagnosis and treatment of glaucoma.

[0003] Measuring intraocular pressure is an important tool for diagnosing glaucoma. Traditional methods for measuring intraocular pressure mainly include non-contact tonometers and Goldman contact tonometers. The working principle of non-contact tonometers is to project a certain amount of air along the optical axis onto the cornea of ​​the eye. As the air impacts the cornea, it deforms, gradually flattening and eventually concaving. To measure the degree of corneal deformation, the device directs a parallel beam of light obliquely onto the cornea. When the light strikes the corneal surface and reflects back, the change in the reflected light is measured. This change, combined with the air puff pressure, is then calculated using a mathematical model and formula to determine the intraocular pressure value. This non-contact measurement method has the advantages of being relatively simple to use and non-invasive to the patient, making it widely used in clinical practice. However, it also has some limitations. For example, the impact of the air may cause discomfort in the patient's eyes, and some patients may blink or involuntarily move their eyes, affecting the accuracy of the measurement results. In addition, this method mainly calculates intraocular pressure based on the macroscopic deformation of the corneal surface, and fails to fully consider the impact of the internal structure and physical properties of the cornea on the measurement results.

[0004] The Goldman contact tonometer is another commonly used IOP measurement tool. Its measurement principle is based on mechanical equilibrium. During measurement, a specific applanation head applies a mechanical force to the cornea, flattening a fixed area of ​​the corneal surface. Based on the applied force and the applanated area, the IOP value is calculated using known mechanical formulas. Compared to non-contact tonometers, the Goldman contact tonometer offers, to a certain extent, more stable and accurate measurement results. However, its operation is relatively complex, requiring specialized medical personnel. Furthermore, the measurement process exerts a certain amount of contact pressure on the cornea, which may cause discomfort to the patient and, in some cases, even minor damage. Furthermore, both non-contact and Goldman contact tonometers share a common flaw: they fail to fully consider the impact of the cornea's physical properties on the measurement results when calculating IOP. These physical properties include central corneal thickness, corneal radius of curvature, and corneal biomechanical properties. For example, the cornea of ​​some patients who have undergone laser surgery for myopia may be relatively thin. In this case, the intraocular pressure value measured by a traditional tonometer is often lower than the patient's actual intraocular pressure value, resulting in an underestimation of the intraocular pressure. For some patients with keratoconus, the radius of curvature of the cornea is steeper than that of normal people. In this case, the intraocular pressure value measured by a traditional tonometer may be higher than the patient's actual intraocular pressure value, resulting in an overestimation of the intraocular pressure. Due to the existence of these factors, the measurement accuracy of traditional tonometers is greatly limited and cannot meet the needs of early and accurate diagnosis of glaucoma.

[0005] The physical properties of the cornea, the transparent outer layer of the eye, have a crucial impact on the accuracy of intraocular pressure measurements. Central corneal thickness is a key parameter of the cornea, directly affecting its ability to conduct and distribute pressure. A thicker cornea deforms less under the same pressure, while a thinner cornea deforms more easily. The radius of corneal curvature determines the curvature of the cornea. A cornea with a smaller radius of curvature has a steeper surface, resulting in different pressure distribution and conduction patterns compared to a normal cornea. Corneal biomechanical properties involve intrinsic properties of the cornea, such as elasticity and toughness. These properties determine its ability to deform and recover under external forces. Different corneal biomechanical properties result in different deformation patterns under the same external force, thus affecting the accuracy of intraocular pressure measurements. Therefore, to improve the accuracy of intraocular pressure measurements, it is necessary to fully consider these physical properties of the cornea and accurately analyze and compensate for them.

[0006] In summary, although the traditional intraocular pressure measurement method has certain advantages in clinical applications, it fails to fully consider the impact of corneal physical properties on the calculation of intraocular pressure values, resulting in low measurement accuracy and unable to meet the needs of early and accurate diagnosis of glaucoma. Summary of the Invention

[0007] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0008] The purpose of the present invention is to solve the above problems and provide an optical system for high-speed restoration of the dynamic deformation process of the cornea. High-speed imaging technology is used to achieve high-precision analysis of the physical properties of the cornea. The high-precision analysis results can be used to compensate for errors in intraocular pressure values.

[0009] The technical solution of the present invention is as follows: The present invention discloses an optical system for high-speed restoration of the dynamic deformation process of the cornea, the optical system comprising: Slit lamp light source, used to form corneal optical sections to ensure the clarity and contrast of corneal section images; Sham lens, used for capturing corneal optical sections, features an oblique imaging optical path design, and a depth of field sufficient to maintain clear imaging of the corneal section during dynamic processes. The high-speed camera is located behind the Sham lens and is used to receive the optical section image of the cornea after imaging by the Sham lens to record the dynamic deformation process of the cornea.

[0010] According to one embodiment of the optical system for high-speed restoration of the dynamic deformation process of the cornea of ​​the present invention, the slit lamp light source includes a light source, a collecting mirror, an aperture, and a condenser, wherein the light source is located in front of the collecting mirror, and the light emitted by it is collected by the collecting mirror and focused on the aperture. The aperture is located between the collecting mirror and the condenser and is used to limit the width of the light beam. The condenser is located behind the aperture and focuses the light passing through the aperture onto the cornea to be examined to form an optical section of the cornea.

[0011] According to one embodiment of the optical system for high-speed restoration of corneal dynamic deformation process of the present invention, the light source adopts a high-brightness, narrow-band blue LED light source to provide a stable light signal for the subsequent imaging process with a wavelength of 470±10nm.

[0012] According to an embodiment of the optical system for high-speed restoration of corneal dynamic deformation process of the present invention, the frame rate of the CMOS sensor of the high-speed camera is greater than 3000 fps and the resolution is not less than 600×200 pixels.

[0013] According to one embodiment of the optical system for high-speed restoration of the dynamic deformation process of the cornea of ​​the present invention, a Sham lens is used in conjunction with a high-speed camera, and the positional relationship between the two is arranged in accordance with the conditions that comply with Sham's law: the optical axis of the corneal optical section, the main plane of the Sham lens, and the image plane of the high-speed camera intersect at the same point.

[0014] Compared with the existing technology, the present invention has the following beneficial effects: the system of the present invention is mainly composed of a slit lamp light source, a Sham lens and a high-speed camera. Compared with the traditional intraocular pressure measurement method, which is affected by the physical properties of the cornea, this system can achieve high-precision analysis of the physical properties of the cornea, including corneal thickness, corneal curvature and corneal biomechanical properties. The above high-precision analysis results can be used to compensate for errors in intraocular pressure measurement and achieve high-precision calculation of intraocular pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or characteristics may have the same or similar reference numerals.

[0016] Figure 1 An optical principle diagram of an embodiment of an optical system for high-speed restoration of corneal dynamic deformation process according to the present invention is shown.

[0017] Figure 2 Shown Figure 1 Undeformed image of a corneal slice captured by the illustrated embodiment of the optical system.

[0018] Figure 3 Shown Figure 1 Deformed image of a corneal slice captured by the illustrated embodiment of the optical system.

[0019] Reference numerals 1: Slit lamp light source 2: Light source 3: Light collecting mirror 4: Aperture hole 5: Condenser 6: Sham lens 7: High-speed camera 8: Cornea 9: Corneal optical section optical axis 10: Corneal optical sectioning 11: Principal planes of the Sham lens 12: High-speed camera image plane DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the various aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention.

[0021] Figure 1 The optical principle of an embodiment of the optical system for high-speed restoration of corneal dynamic deformation process of the present invention is shown. Figure 1 The optical system of this embodiment includes: a slit lamp light source 1, a Sham lens 6 and a high-speed camera 7.

[0022] The slit lamp light source is used to form corneal optical sections, ensuring the clarity and contrast of the corneal section image. It consists of a light source 2, a collecting lens 3, an aperture 4, and a condenser lens 5. Light source 2 is located in front of the collecting lens 3. The light it emits is collected by the collecting lens 3 and focused on the aperture 4. The aperture 4 is located between the collecting lens 3 and the condenser lens 5 and serves to limit the width of the light beam. The condenser lens 5 is located behind the aperture 4 and focuses the light passing through the aperture 4 onto the cornea being examined 8, forming a corneal optical section 10. Corneal optical section 10 is located on the cornea 8 and is the section used for imaging formed by the slit lamp light source 1.

[0023] Light source 2 typically utilizes a high-brightness, narrow-band blue LED, providing a stable optical signal with a wavelength of 470 ± 10 nm for the subsequent imaging process. Light emitted by light source 2 is collected by a light collecting lens 3 and focused onto an aperture 4. The light then passes through a condenser lens 5 and is imaged along an optical axis 9 onto the cornea 8 of the eye being examined. This optical section 10 forms a clear image of the corneal cross-section, allowing observation of physical properties such as corneal thickness and curvature.

[0024] The light collecting mirror 3 collects and focuses the light emitted by the light source 2 so that the light can be efficiently converged onto the aperture 4, thereby improving the utilization rate of light.

[0025] The aperture 4 limits the width of the light beam and controls the size of the light spot, ensuring that the formed corneal optical slice has an appropriate width. The light spot width is less than 0.4 mm, for example, 0.1 mm, to meet the requirements of high-precision imaging.

[0026] The condenser 5 further focuses the light passing through the aperture 4 so that it is imaged on the cornea 8 to be examined along the optical axis 9, forming a clear corneal optical section 10, providing high-quality optical signals for subsequent imaging.

[0027] The Sham lens 6 is used to shoot corneal optical sections 10. The tilted imaging optical path design has a depth of field that satisfies the requirement to maintain clear imaging of the corneal section during dynamic processes.

[0028] High-speed camera 7, located behind Sham lens 6, receives optical slice images of the cornea after imaging by Sham lens 6 to record the dynamic corneal deformation process and provide data support for subsequent corneal physical property analysis and intraocular pressure calculation. The CMOS sensor of high-speed camera 7 has a frame rate greater than 3000 fps, for example, 3400 fps, and a resolution of no less than 600 × 200 pixels, for example, 768 × 200 pixels, to meet the temporal and spatial resolution required to record the dynamic corneal deformation process.

[0029] To maintain clear images during dynamic imaging, the Sham lens 6 and high-speed camera 7 are used in conjunction. Their positional relationship must conform to Sham's law. Specifically, the optical axis 9 of the corneal optical section, the principal plane 11 of the Sham lens, and the image plane 12 of the high-speed camera intersect at the same point. This allows for clear capture and restoration of the corneal slice image throughout the entire deformation process. The high-speed camera's image plane 12 receives the corneal slice image after imaging by the Sham lens and serves as the final output surface of the entire optical system.

[0030] Figure 2 As shown in FIG, the undeformed image of the corneal slice captured by the optical system of this embodiment includes information on corneal thickness and corneal curvature. Figure 3 As shown, the optical system of this embodiment can capture the entire process of corneal slice deformation, which can be used for corneal biomechanics analysis.

[0031] The system uses a grayscale gradient algorithm to extract the anterior and posterior corneal contours from static corneal images captured by this optical system. The corneal radius of curvature and central corneal thickness are then used to determine intraocular pressure (IOP) error. For every 1D increase in corneal curvature, IOP is compensated by +0.3mmHg. For every 1mm increase in central corneal thickness above 520μm, IOP is compensated by -0.3mmHg.

[0032] Keyframe analysis of the corneal anterior and posterior surface deformation process recorded by a high-speed camera: initial resting point t0, first applanation point t1, maximum concavity point t2, second applanation point t3, rebound oscillation period t4-t5, can derive the following corneal biomechanical characteristic parameters: Maximum deformation: the maximum vertical displacement of the corneal vertex from the initial resting point t0 to the maximum concave point t2; Deformation speed: the average speed from the initial stationary point t0 to the maximum concave point t2; Applanation range: the width of the corneal applanation plane between the first applanation point t1 and the second applanation point t3; Recovery time: rebound oscillation period t4-t5.

[0033] The above parameter group can be used to compensate for errors in intraocular pressure measurement. For example, it can be used as the core input variable of the intraocular pressure calculation model. By establishing a multi-dimensional nonlinear compensation mechanism, the original intraocular pressure measurement value can be dynamically calibrated to optimize the impact of corneal biomechanical properties on intraocular pressure assessment and significantly improve the accuracy of intraocular pressure measurement.

[0034] Although the above methods are illustrated and described as a series of acts for simplicity of explanation, it is to be understood and appreciated that these methods are not limited by the order of the acts, as some acts may occur in a different order and / or concurrently with other acts from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art according to one or more embodiments.

[0035] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. A skilled person may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0036] The various illustrative logic blocks, modules, and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0037] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read and write information from / to the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside in a user terminal as discrete components.

[0038] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0039] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical system for high-speed restoration of corneal dynamic deformation, characterized in that: The optical system includes: Slit lamp light source, used to form corneal optical sections to ensure the clarity and contrast of corneal section images; Sham lens, used for capturing corneal optical sections, features an oblique imaging optical path design, and a depth of field sufficient to maintain clear imaging of the corneal section during dynamic processes. The high-speed camera is located behind the Sham lens and is used to receive the optical section image of the cornea after imaging by the Sham lens to record the dynamic deformation process of the cornea.

2. The optical system for high-speed restoration of corneal dynamic deformation according to claim 1, characterized in that: The slit lamp light source includes a light source, a collecting mirror, an aperture, and a condenser. The light source is located in front of the collecting mirror, and the light it emits is collected by the collecting mirror and focused on the aperture. The aperture is located between the collecting mirror and the condenser and is used to limit the width of the light beam. The condenser is located behind the aperture and focuses the light passing through the aperture onto the cornea to be examined, forming a corneal optical section.

3. The optical system for high-speed restoration of corneal dynamic deformation according to claim 2, characterized in that: The light source uses a high-brightness, narrow-band blue LED light source to provide a stable light signal for the subsequent imaging process, with a wavelength of 470±10nm.

4. The optical system for high-speed restoration of corneal dynamic deformation according to claim 1, characterized in that: The CMOS sensor of the high-speed camera has a frame rate of >3000fps and a resolution of no less than 600×200 pixels.

5. The optical system for high-speed restoration of corneal dynamic deformation according to claim 1, characterized in that: The Sham lens is used in conjunction with a high-speed camera, and the positional relationship between the two is arranged in accordance with the conditions of Sham's law: the optical axis of the corneal optical section, the principal plane of the Sham lens, and the image plane of the high-speed camera intersect at the same point.

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