CN116530926A - OCT-based human eye astigmatism measuring method - Google Patents
OCT-based human eye astigmatism measuring method Download PDFInfo
- Publication number
- CN116530926A CN116530926A CN202310704355.8A CN202310704355A CN116530926A CN 116530926 A CN116530926 A CN 116530926A CN 202310704355 A CN202310704355 A CN 202310704355A CN 116530926 A CN116530926 A CN 116530926A
- Authority
- CN
- China
- Prior art keywords
- cornea
- lens
- astigmatism
- oct
- eye
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 201000009310 astigmatism Diseases 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims description 12
- 210000004087 cornea Anatomy 0.000 claims abstract description 51
- 210000000695 crystalline len Anatomy 0.000 claims abstract description 49
- 210000001508 eye Anatomy 0.000 claims abstract description 37
- 210000001747 pupil Anatomy 0.000 claims abstract description 4
- 230000003287 optical effect Effects 0.000 claims description 7
- 210000002159 anterior chamber Anatomy 0.000 claims description 3
- 210000001742 aqueous humor Anatomy 0.000 claims description 3
- 238000000691 measurement method Methods 0.000 abstract description 6
- 238000012014 optical coherence tomography Methods 0.000 description 24
- 238000005259 measurement Methods 0.000 description 9
- 238000001514 detection method Methods 0.000 description 4
- 210000005252 bulbus oculi Anatomy 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 3
- 241000282412 Homo Species 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 201000004569 Blindness Diseases 0.000 description 1
- 206010019233 Headaches Diseases 0.000 description 1
- 208000029091 Refraction disease Diseases 0.000 description 1
- 230000004430 ametropia Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 208000003464 asthenopia Diseases 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 208000002173 dizziness Diseases 0.000 description 1
- 231100000869 headache Toxicity 0.000 description 1
- 208000014733 refractive error Diseases 0.000 description 1
- 230000004393 visual impairment Effects 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/102—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for optical coherence tomography [OCT]
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/103—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining refraction, e.g. refractometers, skiascopes
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/103—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining refraction, e.g. refractometers, skiascopes
- A61B3/1035—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining refraction, e.g. refractometers, skiascopes for measuring astigmatism
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/14—Arrangements specially adapted for eye photography
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Veterinary Medicine (AREA)
- Biophysics (AREA)
- Ophthalmology & Optometry (AREA)
- Engineering & Computer Science (AREA)
- Public Health (AREA)
- Physics & Mathematics (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Radiology & Medical Imaging (AREA)
- Eye Examination Apparatus (AREA)
Abstract
The invention provides an OCT-based human eye astigmatism measurement method, and relates to the technical field of computers. The invention uses the sweep OCT device to collect the image of the eye structure to obtain the sweep OCT image; processing the collected sweep OCT image to obtain a cornea and a reconstruction model of a crystalline lens; selecting 12 meridians centering on the pupil in the reconstruction model for cutting, obtaining the thickness of the cornea and the lens and the curvatures of the front surface and the back surface, and calculating the diopters of the eye, the cornea and the lens by using a formula: the total diopter of each of 640 points on the noon of 12 pieces of eyes is calculated through a formula, and the maximum value and the minimum value of the total diopter are found, wherein the difference value of the maximum value and the minimum value is equal to the amplitude M of astigmatism.
Description
Technical Field
The invention relates to the technical field of computers, in particular to a human eye astigmatism measurement method based on OCT.
Background
Astigmatism refers to a state of ametropia in which two focal lines and a minimum diffuse spot are formed due to the difference of refractive powers of light rays on different meridians of an eyeball, and both cornea and crystalline lens have significant influence on astigmatism. Astigmatism can cause vision loss and visual fatigue in humans, and can even cause dizziness and headache in humans. If the measurement cannot be accurately performed, the astigmatism cannot be accurately corrected and treated according to the actual situation of the patient in the astigmatism correction process.
The cornea and the lens act as the main parts of the refractive system of the eyeball, and play an important role in the refractive power of the eyeball. At present, astigmatism is mainly judged by using various parameters of the front surface of the cornea. In practical applications, the existing devices and means for measuring astigmatism do not measure cornea and lens well, mainly as follows:
1. corneal curvature gauge: keratometer is a method based on measurements of the anterior surface of the cornea. The keratometer extrapolates the refractive power of the back surface of the cornea using an empirical keratometry index, which method is biased. And its measurement range is small, it is generally unreliable in measuring astigmatism.
2. IOL-Master500: the astigmatism is measured by utilizing telecentric optics and optical reflection principles, although the measurement is relatively quick and has good repeatability, the measurement result can not reflect the whole cornea morphology, is greatly influenced by the stability of the tear film, and can not completely measure the whole surface of the cornea.
3. Pentacam: the main principle is a three-dimensional anterior ocular segment analysis and diagnosis system adopting the Scheimpflug imaging principle to perform rotary scanning, a built-in Scheimpflug camera can scan in 2s to obtain coaxial 50-amplitude crack images, and corneal curvature and refractive power are deduced from height. The measurement is affected by the transparency of the cornea and cannot be performed through a turbid cornea.
4. Optical Coherence Tomography (OCT): the resolution is higher, can shoot the image of each level of eyes, allow each structure of eyes to be visualized and measured, have higher image quality, can utilize OCT image to acquire the relevant parameter of each structure of eyes. Currently, spectrum OCT is more commonly used, and the detection range of spectrum OCT cannot meet the actual needs in application.
By contrast, swept OCT has higher accuracy and accuracy in evaluating astigmatism of the eye, and swept OCT has higher resolution and deeper detection range, and can better measure human eye structure.
If the existing instrument with higher precision can be used, a precise method for measuring astigmatism can be designed. The degree of astigmatism and the axial position of astigmatism can be accurately determined, the detection level of astigmatism of human eyes can be obviously improved, and the early correction and early treatment of astigmatism can be realized.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a human eye astigmatism measurement method based on OCT, which can accurately acquire images of human eye structures by using a sweep OCT device, and can perform related calculation on related parameters of each structure of human eyes by combining an image processing technology, and then quantitatively evaluate astigmatism by a related algorithm.
An OCT-based method for measuring astigmatism of human eye comprises the following steps:
step 1: image acquisition is carried out on the eye structure by utilizing a sweep OCT device, so as to obtain a sweep OCT image;
step 2: performing pixel and gray level correction on the collected sweep OCT image, detecting the front and rear surfaces of the cornea and the front and rear surface edges of the crystalline lens, performing enhancement treatment, extracting surface contours, and storing the surface contours in an established three-dimensional data set; fitting the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens by utilizing a three-dimensional data set, correcting the optical distortion, searching three-dimensional data of the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens by adopting sector distortion correction and optical refraction distortion correction, correcting the surface profiles of the cornea and the crystalline lens, and finally respectively carrying out three-dimensional reconstruction of the front and back surfaces of the cornea and the crystalline lens to obtain a reconstruction model of the cornea and the crystalline lens;
step 3: selecting 12 meridians centered on the pupil in a reconstruction model for cutting, wherein the meridians are uniformly distributed from 0 to 180 degrees, 640 points are taken on each meridian, the thickness of the cornea and the lens and the curvature of the front surface and the back surface are obtained, and the diopters of the eye, the cornea and the lens are calculated by utilizing a formula:
therein P, P C And P L Diopters of eye, cornea and lens, respectively, n h And n l Is the refractive index of aqueous humor and lens, R c 、R a And R is p Is the radius of curvature of the cornea, anterior lens and posterior lens, ACD is anterior chamber depth, LT is lens thickness;
step 4: the total diopter of 640 points on 12 meridians (uniformly distributed from 0 degree to 180 degrees) of human eyes is calculated by a formula, the maximum value and the minimum value of the total diopter are found, the difference value of the maximum value and the minimum value is equal to the astigmatism amplitude M, the angle of the cornea meridian corresponding to the maximum value of the total diopter is the astigmatism angle alpha, and the astigmatism axis positionPerpendicular to the angle of astigmatism, i.e. +.>
The beneficial effects of adopting above-mentioned technical scheme to produce lie in:
the invention provides an OCT-based human eye astigmatism measurement method, which has the following beneficial effects:
1. the device uses a non-contact and non-invasive measurement mode, and basically does not cause certain damage to the body of a patient.
OCT has higher resolution and deeper detection depth, and OCT is utilized to evaluate the diopter of eyes with higher precision and accuracy, so that the structure of eyes can be better measured.
3. The traditional method of measuring astigmatism is based only on the measurement of the anterior surface of the cornea, without taking into account the effect of other structures of the eye on astigmatism. We reconstruct three-dimensional reconstruction of the anterior and posterior surfaces of the cornea and of the anterior and posterior surfaces of the lens and extract the relevant parameters. This also allows the measurement method we propose to take into account the effect of the whole eye structure on astigmatism, so that the degree of astigmatism and the corresponding axis of astigmatism of the patient can be determined more accurately.
Drawings
FIG. 1 is a flowchart of an overall astigmatism measurement method in an embodiment of the present invention;
FIG. 2 is a schematic view of the OCT device according to the embodiment of the present invention;
FIG. 3 is a surface profile extraction in an embodiment of the invention;
Detailed Description
The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
An OCT-based method for measuring astigmatism of human eye, as shown in figure 1, comprises the following steps:
step 1: image acquisition is carried out on the eye structure of a patient by using the sweep OCT device shown in fig. 2, a sweep OCT image is obtained, the light source adopts 1300nm, the axial resolution of 7.5 mu m can be realized, the imaging depth can reach 10mm, and the measurement imaging can be carried out on the eyes of patients with different degrees of astigmatism;
step 2: performing pixel and gray level correction on the collected sweep OCT image, detecting the front and rear surfaces of the cornea and the front and rear surface edges of the crystalline lens, performing enhancement treatment, extracting surface contours, and storing the surface contours in an established three-dimensional data set; fitting the front and rear surfaces of the cornea and the front and rear surfaces of the crystalline lens by utilizing a three-dimensional data set, correcting the optical distortion, searching three-dimensional data of the front and rear surfaces of the cornea and the front and rear surfaces of the crystalline lens by adopting sector distortion correction and optical refraction distortion correction, correcting the surface profiles of the cornea and the crystalline lens, and finally respectively reconstructing the front and rear surfaces of the cornea and the crystalline lens to obtain a reconstruction model of the cornea and the crystalline lens, wherein in the embodiment, commercial MATLAB (MathWorks) is used;
step 3: selecting 12 meridians centered on the pupil in a reconstruction model for cutting, wherein the meridians are uniformly distributed from 0 to 180 degrees, 640 points are taken on each meridian, the thickness of the cornea and the lens and the curvature of the front surface and the back surface are obtained, and the diopters of the eye, the cornea and the lens are calculated by utilizing a formula:
therein P, P C And P L Diopters of eye, cornea and lens, respectively, n h And n l Is the refractive index of aqueous humor and lens, R c 、R a And R is p Is the radius of curvature of the cornea, anterior lens and posterior lens, ACD is anterior chamber depth, LT is lens thickness;
step 4: the total diopter of 640 points on 12 meridians (uniformly distributed from 0 degree to 180 degrees) of human eyes is calculated by a formula, the maximum value and the minimum value of the total diopter are found, the difference value of the maximum value and the minimum value is equal to the astigmatism amplitude M, the angle of the cornea meridian corresponding to the maximum value of the total diopter is the astigmatism angle alpha, and the astigmatism axis positionPerpendicular to the angle of astigmatism, i.e. +.>
Contour extraction is performed on the anterior and posterior surfaces of the cornea and the anterior and posterior surfaces of the lens as shown in fig. 3. In this embodiment, the original image of the patient's eye obtained by swept OCT is subjected to pixel and gray scale correction, and then contour extraction is performed on the anterior and posterior surfaces of the cornea and the anterior and posterior surfaces of the lens. And then stored into the established three-dimensional dataset.
The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by those skilled in the art that the scope of the invention in the embodiments of the present disclosure is not limited to the specific combination of the above technical features, but encompasses other technical features formed by any combination of the above technical features or their equivalents without departing from the spirit of the invention. Such as the above-described features, are mutually substituted with (but not limited to) the features having similar functions disclosed in the embodiments of the present disclosure.
Claims (3)
1. An OCT-based method for measuring astigmatism of a human eye, comprising the steps of:
step 1: image acquisition is carried out on the eye structure by utilizing a sweep OCT device, so as to obtain a sweep OCT image;
step 2: performing pixel and gray level correction on the collected sweep OCT image, detecting the front and rear surfaces of the cornea and the front and rear surface edges of the crystalline lens, performing enhancement treatment, extracting surface contours, and storing the surface contours in an established three-dimensional data set; fitting the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens by utilizing a three-dimensional data set, correcting the optical distortion, searching three-dimensional data of the front and back surfaces of the cornea and the front and back surfaces of the crystalline lens by adopting sector distortion correction and optical refraction distortion correction, correcting the surface profiles of the cornea and the crystalline lens, and finally respectively carrying out three-dimensional reconstruction of the front and back surfaces of the cornea and the crystalline lens to obtain a reconstruction model of the cornea and the crystalline lens;
step 3: selecting 12 meridians with pupils as centers in a reconstruction model for cutting, taking 640 points on each meridian, obtaining the thickness of cornea and lens and the curvature of front and back surfaces, and calculating diopters of eyes, cornea and lens by using a formula;
step 4: the total diopter of 640 points on the meridian is calculated by a formula, the maximum value and the minimum value of the total diopter are calculated, the difference value of the maximum value and the minimum value is equal to the amplitude M of astigmatism, and the angle of the cornea meridian corresponding to the maximum value of the total diopter is the astigmatism angle alpha and the astigmatism axis positionPerpendicular to the angle of astigmatism, i.e. +.>
2. The OCT-based method of claim 1, wherein the meridians are uniformly distributed from 0 ° to 180 °.
3. The OCT-based method of claim 1, wherein the refractive power of the eye, cornea, and lens in step 3:
therein P, P C And P L Diopters of eye, cornea and lens, respectively, n h And n l Is the refractive index of aqueous humor and lens, R c 、R a And R is p Is the radius of curvature of the cornea, anterior lens and posterior lens, ACD is anterior chamber depth, LT is the thickness of the lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310704355.8A CN116530926A (en) | 2023-06-14 | 2023-06-14 | OCT-based human eye astigmatism measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310704355.8A CN116530926A (en) | 2023-06-14 | 2023-06-14 | OCT-based human eye astigmatism measuring method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116530926A true CN116530926A (en) | 2023-08-04 |
Family
ID=87447330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310704355.8A Pending CN116530926A (en) | 2023-06-14 | 2023-06-14 | OCT-based human eye astigmatism measuring method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116530926A (en) |
-
2023
- 2023-06-14 CN CN202310704355.8A patent/CN116530926A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Dubbelman et al. | The shape of the aging human lens: curvature, equivalent refractive index and the lens paradox | |
| McAlinden et al. | A comprehensive evaluation of the precision (repeatability and reproducibility) of the Oculus Pentacam HR | |
| AU2016248638B2 (en) | An apparatus for modelling ocular structures | |
| Patel et al. | Shape and radius of posterior corneal surface | |
| Rosales et al. | Pentacam Scheimpflug quantitative imaging of the crystalline lens and intraocular lens | |
| Cho et al. | Comparison of ocular biometry using new swept-source optical coherence tomography-based optical biometer with other devices | |
| Shi et al. | Comparison of IOL-Master 700 and IOL-Master 500 biometers in ocular biological parameters of adolescents | |
| Ramasubramanian et al. | Objective measurement of accommodative biometric changes using ultrasound biomicroscopy | |
| Yuan et al. | Repeated measurements of the anterior segment during accommodation using long scan depth optical coherence tomography | |
| US9271647B2 (en) | Methods for objectively determining the visual axis of the eye and measuring its refraction | |
| CN103142210B (en) | Peripheral refraction measuring method based on OCT technology | |
| Read et al. | Influence of accommodation on the anterior and posterior cornea | |
| Mallen et al. | Measurement of retinal contour and supine axial length using the Zeiss IOLMaster | |
| Yeter et al. | Comparison of central corneal thickness measurements by Galilei Dual-Scheimpflug analyzer® and ultrasound pachymeter in myopic eyes | |
| Leng et al. | Biometry of anterior segment of human eye on both horizontal and vertical meridians during accommodation imaged with extended scan depth optical coherence tomography | |
| CN210408379U (en) | Anterior segment OCT imaging device | |
| Zhong et al. | Axial biometry of the entire eye using ultra-long scan depth optical coherence tomography | |
| Ramamurthy et al. | Topography and tomography in the diagnosis of corneal ectasia | |
| CN115336967B (en) | Retina morphology obtaining method | |
| CN116530926A (en) | OCT-based human eye astigmatism measuring method | |
| Wang et al. | Simultaneously measuring ocular aberration and anterior segment biometry during accommodation | |
| Zhang et al. | Comparison of corneal curvature parameters obtained from two different instruments—Pentacam and VX120 | |
| CN114159020A (en) | Refractometer, ophthalmological biological multi-parameter measuring instrument and measuring method | |
| Tañá-Rivero et al. | Agreement between angle-to-angle distance and aqueous depth obtained with two different optical coherence tomographers and a Scheimpflug camera | |
| US9622659B2 (en) | Method for determining the total refractive power of the cornea of an eye |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |