Optical tomography imaging device

Abstract

To provide a technique for reducing a burden on a subject when capturing a tomographic image.SOLUTION: An optical tomographic imaging apparatus comprises: an imaging unit which captures n (n is an integer equal to or greater than 2) tomographic images from an imaging range by executing imaging processing of scanning the imaging range set to a subject eye with light; a generation unit which generates an evaluation index for evaluating the image quality of the tomographic image; and a display unit which displays the evaluation index generated by the generation unit. The generation unit generates the evaluation index for each of the n tomographic images. The display unit simultaneously displays the respective evaluation indexes of the n tomographic images on one screen.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an optical tomographic imaging apparatus. [Background technology]

[0002] Optical tomographic imaging devices have been developed to capture tomographic images of a subject's eye. The optical tomographic imaging device includes a measurement optical system that irradiates the subject's eye with light from a light source and directs the reflected light, and a reference optical system that generates reference light from the light from the light source. During measurement, a tomographic image of the subject's eye is generated from interference light obtained by combining the reflected light (measurement light) directed by the measurement optical system with the reference light generated by the reference optical system. If a tomographic image of the subject's eye is not captured properly, it may be necessary to recapture the tomographic image of the subject's eye. For this reason, such optical tomographic imaging devices may display an evaluation index on a display unit that indicates whether the tomographic image has been captured properly. For example, Patent Document 1 discloses, as an example of an evaluation index, a quality index (QI) calculated from a histogram of image brightness values. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-9798 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical tomographic imaging device of Patent Document 1 displays an evaluation index to inform the examiner whether the tomographic image has been properly captured. If the tomographic image has not been properly captured, it must be re-captured, and the examinee must be confined to the scene until the examiner confirms that the tomographic image has been properly captured. In the optical tomographic imaging device of Patent Document 1, the evaluation index is displayed for each tomographic image, so the examiner must check the evaluation index for each of the multiple tomographic images generated in one capture. This increases the time required for the examiner to check the evaluation index for all of the multiple tomographic images, and increases the time the examinee is confined to capture the images.

[0005] This specification discloses a technique for reducing the burden on a subject when capturing a tomographic image. [Means for solving the problem]

[0006] The optical tomographic imaging apparatus disclosed in this specification includes an imaging unit that captures n (n is an integer equal to or greater than 2) tomographic images from an imaging range set on an eye to be examined by performing imaging processing that scans light over the imaging range, a generation unit that generates an evaluation index for evaluating the image quality of the tomographic images, and a display unit that displays the evaluation index generated by the generation unit. The generation unit generates an evaluation index for each of the n tomographic images. The display unit simultaneously displays the evaluation indexes for the n tomographic images on one screen.

[0007] In the optical tomographic imaging device, the evaluation indices for multiple (n) tomographic images obtained by executing the imaging process are simultaneously displayed on one screen, allowing the examiner to quickly check the evaluation results for all of the multiple tomographic images captured by the imaging process. This eliminates the need to check the evaluation results for each tomographic image, and reduces the time required to check the evaluation results for all of the multiple tomographic images. [Brief explanation of the drawings]

[0008] [Figure 1]FIG. 1 is a diagram showing a schematic configuration of an optical system of an optical tomographic imaging apparatus according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a control system of the optical tomographic imaging apparatus according to the embodiment. [Figure 3] FIG. 1 is a block diagram showing the configuration of a sampling trigger / clock generator. [Figure 4] 10 is a flowchart showing an example of processing for displaying a preview screen after capturing a tomographic image of a subject's eye. [Figure 5] FIG. 1 is a diagram for explaining a formula for calculating a QI (Quality Index). [Figure 6] 10 is a flowchart showing an example of a process for calculating maximum brightness. [Figure 7] FIG. 10 is a diagram for explaining processing for thinning out A-scan information used when calculating maximum brightness. [Figure 8] 10A and 10B are diagrams for explaining the process of limiting the depth range of the A-scan information used to calculate the maximum brightness, where (a) shows the case where the subject's eye is photographed in an appropriate position, and (b) shows the case where the subject's eye is photographed in a misaligned position. [Figure 9] 10A and 10B show the results of the QI evaluation and the fixation state evaluation, where (a) shows the case where the subject's eye is in the appropriate position, (b) shows the case where the subject's eye blinks, and (c) shows the case where the subject's eye is in a misaligned position. [Figure 10] FIG. 4 is a diagram showing an example of a preview screen displayed on a monitor. [Figure 11] 10A and 10B are diagrams showing an example of a preview screen and a simple report displayed on a monitor. DETAILED DESCRIPTION OF THE INVENTION

[0009] The main features of the embodiments described below are listed below. Note that the technical elements described below are independent technical elements that exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0010] (Feature 1) In the optical tomographic imaging device disclosed in this specification, the evaluation index may include at least one of a luminance evaluation index that evaluates image quality based on the luminance of the tomographic image and a fixation evaluation index that evaluates the fixation state of the subject's eye. With this configuration, the luminance evaluation index can be used to evaluate, for example, whether alignment or focus is appropriate, or whether the subject's eye is blinking. Furthermore, the fixation evaluation index can be used to evaluate, for example, whether fixation is not appropriate due to involuntary eye movement or the like, or whether the subject's eye is blinking. Therefore, by including at least one of the luminance evaluation index and the fixation evaluation index as the evaluation index, the image quality of the tomographic image can be appropriately evaluated.

[0011] (Feature 2) In the optical tomographic imaging device disclosed in this specification, the generation unit may select m tomographic images (m is a natural number smaller than n) from the n tomographic images and further generate an inspection report indicating desired inspection results from the selected tomographic images. The display unit may further display the generated inspection report. With this configuration, by displaying the inspection report, it is possible to confirm that the imaging for the desired inspection was performed appropriately. Furthermore, when generating the inspection report, only m tomographic images selected from the n tomographic images are used, rather than all n tomographic images. Therefore, compared to generating an inspection report from n tomographic images, generating a simplified inspection report from m tomographic images takes less time. By generating the inspection report as a simplified inspection report in this manner, it is possible to confirm that the imaging was performed appropriately while shortening the time required to generate the inspection report. [Example]

[0012] The optical tomography apparatus according to this embodiment is a polarization-sensitive OCT (PS-OCT) apparatus that uses a wavelength-swept light source and is capable of capturing the polarization characteristics of a test object by wavelength-swept Fourier-domain swept-source optical coherence tomography (SS-OCT).

[0013] As shown in Figure 1, the optical tomographic imaging apparatus of this embodiment includes a light source 11, a measurement light generation unit (21-29, 31, 32) that generates measurement light from the light of the light source 11, a reference light generation unit (41-46, 51) that generates reference light from the light of the light source 11, interference light generation units 60, 70 that generate interference light by combining reflected light from the test eye 500 generated by the measurement light generation unit with reference light generated by the reference light generation unit, and interference light detection units 80, 90 that detect the interference light generated by the interference light generation units 60, 70.

[0014] (light source) The light source 11 is a wavelength sweep type light source, and the wavelength (wave number) of the emitted light changes at a predetermined cycle. Because the wavelength of the light irradiated onto the subject's eye 500 changes (sweeps), the intensity distribution of the light reflected from each part in the depth direction of the subject's eye 500 can be obtained by Fourier analysis of a signal obtained from the interference light between the reflected light from the subject's eye 500 and the reference light.

[0015] The light source 11 is connected to a polarization control device 12 and a fiber coupler 13, and the fiber coupler 13 is connected to a PMFC (polarization-maintaining fiber coupler) 14 and a sampling trigger / clock generator 100. Therefore, the light output from the light source 11 is input to the PMFC 14 and the sample trigger / clock generator 100 via the polarization control device 12 and the fiber coupler 13. The sampling trigger / clock generator 100 uses the light from the light source 11 to generate sampling triggers and sampling clocks for signal processors 83 and 93, which will be described later.

[0016] (Measurement light generation section) The measurement light generation unit (21 to 29, 31, 32) includes a PMFC 21 connected to the PMFC 14, two measurement optical paths S1 and S2 branching from the PMFC 21, a polarization beam combiner / splitter 25 connecting the two measurement optical paths S1 and S2, and a collimator lens 26, galvanometer mirrors 27 and 28, and a lens 29 connected to the polarization beam combiner / splitter 25. An optical path length difference generation unit 22 and a circulator 23 are disposed in the measurement optical path S1. Only a circulator 24 is disposed in the measurement optical path S2. Therefore, the optical path length difference ΔL between the measurement optical paths S1 and S2 is generated by the optical path length difference generation unit 22. The optical path length difference ΔL may be set longer than the measurement range in the depth direction of the eye 500 to be examined. This prevents interference light beams with different optical path length differences from overlapping. The optical path length difference generating unit 22 may be, for example, an optical fiber or an optical system such as a mirror or a prism. In this embodiment, a 1 m PM fiber is used for the optical path length difference generating unit 22. The measurement light generating unit further includes PMFCs 31 and 32. PMFC 31 is connected to circulator 23. PMFC 32 is connected to circulator 24.

[0017] One of the beams (i.e., the measurement beam) branched by the PMFC 14 is input to the measurement beam generator (21-29, 31, 32). The PMFC 21 splits the measurement beam input from the PMFC 14 into a first measurement beam and a second measurement beam. The first measurement beam split by the PMFC 21 is guided to the measurement beam path S1, and the second measurement beam is guided to the measurement beam path S2. The first measurement beam guided to the measurement beam path S1 passes through the optical path length difference generator 22 and the circulator 23 and is input to the polarization beam combiner / splitter 25. The second measurement beam guided to the measurement beam path S2 passes through the circulator 24 and is input to the polarization beam combiner / splitter 25. The PM fiber 304 is connected to the polarization beam combiner / splitter 25 rotated 90 degrees circumferentially with respect to the PM fiber 302. As a result, the second measurement light input to the polarized beam combiner / splitter 25 becomes light having a polarization component orthogonal to that of the first measurement light. Because the optical path length difference generating unit 22 is provided in the measurement light path S1, the first measurement light is delayed relative to the second measurement light by the distance of the optical path length difference generating unit 22 (i.e., an optical path length difference ΔL is generated). The polarized beam combiner / splitter 25 superimposes the input first measurement light and second measurement light. The light output from the polarized beam combiner / splitter 25 (light obtained by superimposing the first measurement light and the second measurement light) is irradiated onto the test eye 500 via a collimator lens 26, galvanometer mirrors 27 and 28, and a lens 29. The light irradiated onto the test eye 500 is scanned in the x and y directions by the galvanometer mirrors 27 and 28.

[0018] Light irradiated onto the eye 500 is reflected by the eye 500. The light reflected by the eye 500 is scattered on the surface and inside the eye 500. The reflected light from the eye 500 passes through the lens 29, galvanometer mirrors 28 and 27, and collimator lens 26 in the opposite direction to the incident path, and is then input to the polarization beam combiner / splitter 25. The polarization beam combiner / splitter 25 splits the input reflected light into two polarized components that are orthogonal to each other. For convenience, these are referred to here as horizontally polarized reflected light (horizontally polarized component) and vertically polarized reflected light (vertically polarized component). The horizontally polarized reflected light is then guided to the measurement optical path S1, and the vertically polarized reflected light is guided to the measurement optical path S2.

[0019] The optical path of the horizontally polarized reflected light is changed by the circulator 23 and input to the PMFC 31. The PMFC 31 splits the input horizontally polarized reflected light and inputs it to the PMFCs 61 and 71. Therefore, the horizontally polarized reflected light input to the PMFCs 61 and 71 contains a reflected light component due to the first measurement light and a reflected light component due to the second measurement light. The optical path of the vertically polarized reflected light is changed by the circulator 24 and input to the PMFC 32. The PMFC 32 splits the input vertically polarized reflected light and inputs it to the PMFCs 62 and 72. Therefore, the vertically polarized reflected light input to the PMFCs 62 and 72 contains a reflected light component due to the first measurement light and a reflected light component due to the second measurement light.

[0020] (Reference light generation section) The reference light generation unit (41 to 46, 51) includes a circulator 41 connected to the PMFC 14, reference delay lines (42, 43) connected to the circulator 41, a PMFC 44 connected to the circulator 41, two reference light paths R1 and R2 branching from the PMFC 44, a PMFC 46 connected to the reference light path R1, and a PMFC 51 connected to the reference light path R2. An optical path length difference generation unit 45 is disposed in the reference light path R1. No optical path length difference generation unit is provided in the reference light path R2. Therefore, the optical path length difference ΔL′ between the reference light paths R1 and R2 is generated by the optical path length difference generation unit 45. For example, an optical fiber is used for the optical path length difference generation unit 45. The optical path length ΔL′ of the optical path length difference generation unit 45 may be the same as the optical path length ΔL of the optical path length difference generation unit 22. By making the optical path length differences ΔL and ΔL′ equal, the depth positions of a plurality of interference lights, which will be described later, become the same with respect to the subject's eye 500. In other words, it is not necessary to align the positions of a plurality of tomographic images to be acquired.

[0021] The other light (i.e., reference light) branched by the PMFC 14 is input to the reference light generating unit (41 to 46, 51). The reference light input from the PMFC 14 passes through a circulator 41 and is input to a reference delay line (42, 43). The reference delay line (42, 43) is composed of a collimator lens 42 and a reference mirror 43. The reference light input to the reference delay line (42, 43) is irradiated onto the reference mirror 43 via the collimator lens 42. The reference light reflected by the reference mirror 43 is input to the circulator 41 via the collimator lens 42. Here, the reference mirror 43 is movable in a direction toward or away from the collimator lens 42. In this embodiment, before starting measurement, the position of the reference mirror 43 is adjusted so that the signal from the subject's eye 500 falls within the measurement range of the OCT in the depth direction.

[0022] The reference light reflected by reference mirror 43 has its optical path changed by circulator 41 and is input to PMFC 44. PMFC 44 splits the input reference light into a first reference light and a second reference light. The first reference light is guided to reference optical path R1, and the second reference light is guided to reference optical path R2. The first reference light passes through optical path length difference generating unit 45 and is input to PMFC 46. The reference light input to PMFC 46 is split into a first split reference light and a second split reference light. The first split reference light passes through collimator lens 47 and lens 48 and is input to PMFC 61. The second split reference light passes through collimator lens 49 and lens 50 and is input to PMFC 62. The second reference light is input to PMFC 51 and split into a third split reference light and a fourth split reference light. The third split reference light passes through collimator lens 52 and lens 53 and is input to PMFC 71. The fourth branched reference light passes through a collimator lens 54 and a lens 55 and is input to the PMFC 72 .

[0023] (Interference light generation unit) The interference light generation units 60 and 70 include a first interference light generation unit 60 and a second interference light generation unit 70. The first interference light generation unit 60 includes PMFCs 61 and 62. As described above, the PMFC 61 receives horizontally polarized reflected light from the measurement light generation unit and the first branched reference light (light having an optical path difference ΔL′) from the reference light generation unit. The horizontally polarized reflected light includes a reflected light component due to the first measurement light (light having an optical path difference ΔL) and a reflected light component due to the second measurement light (light without an optical path difference ΔL). Therefore, the PMFC 61 combines the reflected light component due to the first measurement light (light having an optical path difference ΔL) and the first branched reference light to generate the first interference light (horizontally polarized component).

[0024] Furthermore, PMFC 62 receives vertically polarized reflected light from the measurement light generator and second branched reference light (light having an optical path difference ΔL′) from the reference light generator. The vertically polarized reflected light includes a reflected light component due to the first measurement light (light having an optical path difference ΔL) and a reflected light component due to the second measurement light (light without an optical path difference ΔL). Therefore, PMFC 62 combines the reflected light component due to the first measurement light (light having an optical path difference ΔL) and the second branched reference light to generate second interference light (vertically polarized component).

[0025] The second interference light generation unit 70 has PMFCs 71 and 72. As described above, PMFC 71 receives the horizontally polarized reflected light from the measurement light generation unit and the third branched reference light (light without optical path difference ΔL′) from the reference light generation unit. Therefore, in PMFC 71, the reflected light component of the horizontally polarized reflected light due to the second measurement light (light without optical path difference ΔL) and the third branched reference light are combined to generate the third interference light (horizontally polarized component).

[0026] Furthermore, PMFC 72 receives vertically polarized reflected light from the measurement light generation unit and receives fourth branched reference light (light without optical path difference ΔL′) from the reference light generation unit. Therefore, PMFC 72 combines the reflected light component (light without optical path difference ΔL) of the vertically polarized reflected light due to the second measurement light with the fourth branched reference light to generate fourth interference light (vertically polarized component). The first interference light and second interference light correspond to the measurement light that has passed through measurement optical path S1, and the third interference light and fourth interference light correspond to the measurement light that has passed through measurement optical path S2.

[0027] (Interference light detection unit) The interference light detection units 80, 90 include a first interference light detection unit 80 that detects the interference light (first interference light and second interference light) generated by the first interference light generation unit 60, and a second interference light detection unit 90 that detects the interference light (third interference light and fourth interference light) generated by the second interference light generation unit 70.

[0028] The first interference light detection unit 80 includes balanced photodetectors 81 and 82 (hereinafter simply referred to as "detectors 81 and 82") and a signal processor 83 connected to the detectors 81 and 82. The PMFC 61 is connected to the detector 81, and the signal processor 83 is connected to the output terminal of the detector 81. The PMFC 61 splits the first interference light into two interference lights with a phase difference of 180 degrees and inputs them to the detector 81. The detector 81 performs differential amplification and noise reduction processing on the two interference lights with a phase difference of 180 degrees input from the PMFC 61, converts them into an electrical signal (first interference signal), and outputs the first interference signal to the signal processor 83. That is, the first interference signal is an interference signal HH between the horizontally polarized reflected light from the test eye 500 and the reference light due to the horizontally polarized measurement light. Similarly, the PMFC 62 is connected to the detector 82, and the signal processor 83 is connected to the output terminal of the detector 82. The PMFC 62 splits the second interference light into two interference lights with a phase difference of 180 degrees, and inputs them to the detector 82. The detector 82 performs differential amplification and noise reduction processing on the two interference lights with a phase difference of 180 degrees, converts them into an electrical signal (second interference signal), and outputs the second interference signal to the signal processor 83. That is, the second interference signal is an interference signal HV between the vertically polarized reflected light from the subject's eye 500 and the reference light due to the horizontally polarized measurement light.

[0029] The signal processor 83 includes a first signal processing unit 84 to which the first interference signal is input, and a second signal processing unit 85 to which the second interference signal is input. The first signal processing unit 84 samples the first interference signal based on a sampling trigger and a sampling clock input from a sampling trigger / clock generator 100 to the signal processor 83. The second signal processing unit 85 samples the second interference signal based on a sampling trigger and a sampling clock input from the sampling trigger / clock generator 100 to the signal processor 83. The first interference signal and the second interference signal sampled by the first signal processing unit 84 and the second signal processing unit 85 are input to a calculation unit 202, which will be described later. A known data acquisition device (so-called DAQ) can be used as the signal processor 83.

[0030] Similar to the first interference light detecting unit 80, the second interference light detecting unit 90 includes balanced photodetectors 91 and 92 (hereinafter also simply referred to as "detectors 91 and 92") and a signal processor 93 connected to the detectors 91 and 92. The PMFC 71 is connected to the detector 91, and the signal processor 93 is connected to the output terminal of the detector 91. The PMFC 71 splits the third interference light into two interference lights with a phase difference of 180 degrees and inputs them to the detector 91. The detector 91 performs differential amplification and noise reduction processing on the two interference lights with a phase difference of 180 degrees, converts them into an electrical signal (third interference signal), and outputs the third interference signal to the signal processor 93. That is, the third interference signal is an interference signal VH between the horizontally polarized reflected light from the subject's eye 500 and the reference light due to the vertically polarized measurement light. Similarly, the PMFC 72 is connected to the detector 92, and the signal processor 93 is connected to the output terminal of the detector 92. The PMFC 72 splits the fourth interference light into two interference lights with a phase difference of 180 degrees, and inputs them to the detector 92. The detector 92 performs differential amplification and noise reduction processing on the two interference lights with a phase difference of 180 degrees, converts them into an electrical signal (fourth interference signal), and outputs the fourth interference signal to the signal processor 93. That is, the fourth interference signal is an interference signal VV between the vertically polarized reflected light of the test eye 500 resulting from the vertically polarized measurement light and the reference light.

[0031] The signal processor 93 includes a third signal processing unit 94 to which the third interference signal is input and a fourth signal processing unit 95 to which the fourth interference signal is input. The third signal processing unit 94 samples the third interference signal based on a sampling trigger and a sampling clock input from a sampling trigger / clock generator 100 to the signal processor 93. The fourth signal processing unit 95 samples the fourth interference signal based on a sampling trigger and a sampling clock input from the sampling trigger / clock generator 100 to the signal processor 93. The third interference signal and the fourth interference signal sampled by the third signal processing unit 94 and the fourth signal processing unit 95 are input to a calculation unit 202 (described later). A known data acquisition device (DAQ) can also be used for the signal processor 93. This configuration allows for acquisition of interference signals representing four polarization characteristics of the subject's eye 500. Note that, although the present embodiment uses signal processors 83 and 93 each having two signal processing units, the present invention is not limited to such a configuration. For example, one signal processor having four signal processing sections may be used, or four signal processors each having one signal processing section may be used.

[0032] Next, the configuration of the control system of the optical tomographic imaging apparatus according to this embodiment will be described. As shown in FIG. 2, the optical tomographic imaging apparatus is controlled by a calculation device 200. The calculation device 200 is composed of a calculation unit 202, a first interference light detection unit 80, and a second interference light detection unit 90. The first interference light detection unit 80, the second interference light detection unit 90, and the calculation unit 202 are connected to the measurement unit 10. The calculation unit 202 outputs a control signal to the measurement unit 10 and drives the galvanometer mirrors 27 and 28 to scan the incident position of the measurement light on the subject's eye 500. The first interference light detection unit 80 acquires first sampling data based on the sampling clock 1 input from the measurement unit 10, using a sampling trigger 1 as a trigger, in response to the interference signals (interference signals HH and HV) input from the measurement unit 10, and outputs the first sampling data to the calculation unit 202. The calculation unit 202 performs calculation processing such as Fourier transform processing on the first sampling data to generate HH tomographic images and HV tomographic images. The second interference light detection unit 90 acquires second sampling data based on a sampling clock 2 input from the measurement unit 10 in response to interference signals (interference signals VH and VV) input from the measurement unit 10, using a sampling trigger 2 as a trigger, and outputs the second sampling data to the calculation unit 202. The calculation unit 202 performs calculation processing such as Fourier transform processing on the second sampling data to generate VH tomographic images and VV tomographic images. Here, the HH tomographic image, VH tomographic image, HV tomographic image, and VV tomographic image are tomographic images of the same position. Therefore, the calculation unit 202 can generate tomographic images of four polarization characteristics (HH, HV, VH, VV) that represent the Jones matrix of the subject's eye 500.

[0033] 3, the sampling trigger / clock generator 100 includes a fiber coupler 102, sampling trigger generators (140 to 152), and sampling clock generators (160 to 172). Light from a light source 11 is input to the sampling trigger generator 140 and the sampling clock generator 160 via the fiber coupler 13 and the fiber coupler 102, respectively.

[0034] (Sampling trigger generator) The sampling trigger generator 140 may generate a sampling trigger using, for example, an FBG (Fiber Bragg Grating) 144. As shown in FIG. 3 , the FBG 144 reflects only a specific wavelength of light incident from the light source 11 to generate a sampling trigger. The generated sampling trigger is input to the distributor 150. The distributor 150 distributes the sampling trigger into sampling trigger 1 and sampling trigger 2. The sampling trigger 1 is input to the calculation unit 202 via a signal delay circuit 152. The sampling trigger 2 is input directly to the calculation unit 202. The sampling trigger 1 serves as a trigger signal for the interference signals (first interference signal and second interference signal) input from the first interference light detection unit 80 to the calculation unit 202. The sampling trigger 2 serves as a trigger signal for the interference signals (third interference signal and fourth interference signal) input from the second interference light detection unit 90 to the calculation unit 202. The signal delay circuit 152 is designed so that sampling trigger 1 is delayed in time relative to sampling trigger 2 by the optical path length difference ΔL of the optical path length difference generation unit 22. This makes it possible to make the frequency at which sampling of the interference signal input from the first interference light detection unit 80 starts the same as the frequency at which sampling of the interference signal input from the second interference light detection unit 90 starts. Here, only sampling trigger 1 may be generated. Because the optical path length difference ΔL is known, when sampling the interference input from the second interference light detection unit 90, sampling can be started so as to be delayed in time by the optical path length difference ΔL from sampling trigger 1.

[0035] (Sampling clock generator) The sampling clock generator may be configured, for example, with a Mach-Zehnder interferometer. As shown in FIG. 3, the sampling clock generator generates sampling clocks of equal frequency using a Mach-Zehnder interferometer. The sampling clock generated by the Mach-Zehnder interferometer is input to a distributor 172. The distributor 172 distributes the sampling clock into sampling clock 1 and sampling clock 2. Sampling clock 1 is input to the first interference light detector 80 via a signal delay circuit 174. Sampling clock 2 is input directly to the second interference light detector 90. The signal delay circuit 174 is designed to delay the time by the optical path length difference ΔL of the optical path length difference generator 22. This allows sampling of interference light delayed by the optical path length difference generator 22 at the same timing. This prevents misalignment of multiple acquired tomographic images. In this embodiment, a Mach-Zehnder interferometer is used to generate the sampling clock. However, a Michelson interferometer or an electrical circuit may be used to generate the sampling clock, or a light source equipped with a sampling clock generator may be used to generate the sampling clock.

[0036] The optical tomographic imaging apparatus of this embodiment also includes an SLO (Scanning Laser Ophthalmoscope) optical system (not shown) that acquires a front image of the subject's eye 500. Note that the SLO optical system may be one used in known ophthalmic devices, and therefore a detailed description of its configuration will be omitted.

[0037] Next, referring to FIG. 4, a process for displaying a preview screen after capturing a tomographic image of the subject's eye 500 will be described. The preview screen is a screen used by the examiner to determine whether the image of the subject's eye 500 has been captured appropriately. In the optical tomographic imaging apparatus of this embodiment, multiple tomographic images are captured within a set range of the subject's eye 500 to obtain data related to a desired examination of the subject's eye 500 (e.g., an examination designated by a doctor). If the subject's eye 500 moves due to involuntary eye movement or blinks while capturing multiple tomographic images, all of the tomographic images may not be captured appropriately. Therefore, after capturing the subject's eye 500, an evaluation index and an image (preview screen) indicating whether each tomographic image has been captured appropriately are displayed on the monitor 120. The examiner uses the preview screen to determine whether each tomographic image has been captured appropriately and decides whether to re-capture the subject's eye 500.

[0038] As shown in FIG. 4 , first, the calculation unit 202 determines whether or not a type of examination has been selected (S12). As described above, the optical tomography apparatus of this embodiment is a polarization-sensitive optical tomography apparatus, and therefore can simultaneously acquire a tomographic image captured by irradiating the subject's eye 500 with a vertical wave and a tomographic image captured by irradiating the subject's eye 500 with a horizontal wave. By using these two types of tomographic images, the calculation unit 202 can generate not only a tomographic image showing the tissue in the subject's eye 500 by the scattering intensity (so-called normal tomographic image), but also a tomographic image showing the entropy in the subject's eye 500, a tomographic image showing the birefringence in the subject's eye 500, a tomographic image showing the running direction of fibers in the subject's eye 500, a tomographic image showing the blood flow in the subject's eye 500, and the like. The calculation unit 202 generates an examination report corresponding to the type of examination using these multiple types of tomographic images.

[0039] When starting an examination of the subject's eye 500, the examiner uses an input means (not shown) such as a mouse to select a desired examination from multiple examinations displayed on the monitor 120. Then, when the examiner has finished selecting the type of examination, the examiner instructs completion of the selection. For example, the examiner instructs completion of the selection by pressing an "OK" button displayed on the monitor 120 using the input means. The calculation unit 202 waits until the examiner instructs completion of the selection (NO in step S12).

[0040] When completion of the selection operation is instructed (YES in step S12), the calculation unit 202 acquires a front image of the subject's eye 500 (S14). Specifically, the examiner operates an operating member such as a joystick (not shown) to align the optical tomographic imaging apparatus with respect to the subject's eye 500. That is, the calculation unit 202 drives a position adjustment mechanism (not shown) in response to the examiner's operation of the operating member. This adjusts the position of the optical tomographic imaging apparatus in the x- and y-directions (vertical and horizontal directions) and the z-direction (direction of forward and backward movement) with respect to the subject's eye 500. After the optical tomographic imaging apparatus is aligned, the calculation unit 202 captures a front image of the subject's eye 500 using the SLO optical system. The captured front image is stored in a memory (not shown) of the calculation unit 202. The acquired front image is used as a reference image when evaluating the fixation state in the following process (more specifically, the process in step S22). Hereinafter, the front image acquired in step S14 will also be referred to as a "reference front image."

[0041] Next, the calculation unit 202 acquires a tomographic image of the subject's eye 500 (S16). In this embodiment, the tomographic image is acquired by irradiating the subject's eye 500 with light using a raster scan method. This acquires a tomographic image of the fundus of the subject's eye 500 in a square area centered at a set position. Note that the method for capturing the tomographic image of the fundus of the subject's eye 500 is not limited to the raster scan method. As long as the tomographic image of the fundus of the subject's eye 500 can be acquired over the entire desired area, it may be captured using, for example, a radial scan method. Furthermore, the calculation unit 202 acquires a front image of the subject's eye 500 (S18). This front image is acquired approximately simultaneously with the tomographic image acquired in step S16.

[0042] Next, the calculation unit 202 calculates a QI (Quality Index) for the tomographic image acquired in step S16 (S20). The QI is a brightness evaluation index that evaluates image quality based on the brightness of the tomographic image. For example, if the focus is not correct or the positional relationship between the subject's eye 500 and the optical tomographic imaging apparatus is not appropriate, the brightness of the tomographic image may be low, and the tomographic image may not be captured properly. Furthermore, if some of the captured tomographic images have low brightness, brightness variations may occur between the tomographic images, and the desired examination report may not be created accurately. Therefore, each tomographic image is evaluated based on its brightness. Here, an example of a method for calculating the QI will be described. The QI is calculated using the following equation (1).

[0043]

number

[0044] The function of the above formula (1) will be described with reference to FIG. 5 . “Round” indicates a function for rounding to an integer. “Max” indicates the maximum luminance 602 of the interference signal obtained from a specific position on the fundus of the subject's eye 500, and in FIG. 5 , it is, for example, approximately 65 dB. A method for calculating the maximum luminance 602 will be described in detail later. “Noise” indicates the luminance (noise floor luminance) 604 of a portion of the subject's eye 500 where no image is present (i.e., a portion where no scattered light occurs), and in FIG. 5 , it is set to, for example, approximately 40 dB or less. “Cut” indicates a luminance (cutoff luminance) 606 that does not contribute to image evaluation, and is set to, for example, a range of approximately 10 dB (approximately 40 to 50 dB in FIG. 5 ) from the noise floor luminance 604 (approximately 40 dB in FIG. 5 ). Therefore, a signal 607 indicating a luminance within the range of the cutoff luminance 606 is determined to be an unnecessary signal for calculating the QI. "Range" indicates a luminance range 608 to which 256 gradations are assigned, and is set, for example, to a range from the noise floor luminance 604 (approximately 40 dB in FIG. 5) to approximately 35 dB (approximately 40 to 75 dB in FIG. 5). Furthermore, the "10" in the above formula (1) indicates that the QI is evaluated on a 10-point scale. The QI is an index that evaluates the luminance of a range 610, which is the luminance range 608 excluding the cutoff luminance 606, on a 10-point scale.

[0045] Here, a method for calculating the maximum brightness 602 will be described. In this embodiment, in order to shorten the calculation time for the maximum brightness 602, the maximum brightness 602 is calculated by the following method. As shown in FIG. 6 , first, the calculation unit 202 selects A-scan information to be used for calculating the maximum brightness 602 from multiple A-scan information constituting a tomographic image (S32). That is, when measuring the subject's eye 500, tomographic information (so-called A-scan information) indicating the relationship between the depth position along the measurement optical axis and the signal intensity is obtained from the interference light. To obtain a tomographic image of the subject's eye 500, the measurement light is scanned to obtain multiple A-scan information, and this multiple A-scan information is used to generate the tomographic image of the subject's eye 500. In step S32, the multiple A-scan information constituting the tomographic image is thinned out to reduce the A-scan information to be used for calculating the maximum brightness 602.

[0046] A more detailed description will be given with reference to FIG. 7. FIG. 7 schematically illustrates a tomographic image, with curves indicating the retinal surface of the subject's eye 500 and arrows indicating A-scan information constituting the tomographic image. In FIG. 7, the tomographic image is assumed to be composed of 512 pieces of A-scan information. In step S32, the A-scan information is thinned out so that only one in four of the 512 pieces of A-scan information is used. That is, for consecutive A-scan information, one in four pieces of A-scan information (indicated by solid arrows in FIG. 7) is selected, and the three pieces of A-scan information in between (indicated by dashed arrows in FIG. 7) are not selected. Thus, in the example of FIG. 7, 128 pieces of A-scan information are selected from the 512 pieces of A-scan information. As a result, the amount of A-scan information used to calculate the maximum brightness 602 is reduced to one-fourth, thereby reducing the calculation cost (calculation load) to one-fourth. On the other hand, one out of every four consecutively scanned A-scan information lines is regularly selected, and the calculation accuracy of the maximum brightness 602 does not decrease significantly compared to when all of the A-scan information is used to calculate the maximum brightness 602. Therefore, by thinning out the A-scan information, the calculation cost of the maximum brightness 602 can be reduced without substantially decreasing the calculation accuracy of the maximum brightness 602.

[0047] Next, the calculation unit 202 limits the depth range of the A-scan information used to calculate the maximum brightness 602 to a preset range (S34). Specifically, as shown in FIG. 8( a), the depth range of the A-scan information used to calculate the maximum brightness 602 is limited to only a range 620 near the center of the depth range in which the subject's eye 500 is imaged when the subject's eye 500 is in an appropriate position. When a tomographic image is captured with the subject's eye 500 in an appropriate position, most of the tomographic image of the subject's eye 500 (tissues generating scattered light) is included within the range 620, while the tomographic image of the subject's eye 500 (tissues generating scattered light) is not included much in a range 622 deeper than the range 620 or a range 624 shallower than the range 620. Therefore, by limiting the depth range of the A-scan information to the range described above, the maximum brightness 602 within the depth range 620 near the center when the subject's eye 500 is in an appropriate position is calculated.

[0048] As shown in FIG. 8( b), when an image is captured of the test eye 500 that is shifted from the appropriate position, the image capture range of the test eye 500 (the portion where scattered light occurs) shifts in the depth direction (toward a range 622 deeper than the range 620 in FIG. 8( b)), and the portion captured outside the range 620 increases. If the range in the depth direction is limited to the range 620 near the center when the test eye 500 is in the appropriate position, the image capture range of the test eye 500 (the portion where scattered light occurs) is hardly included in the range 620 when the test eye 500 is captured from the appropriate position. Therefore, for a tomographic image captured when the test eye 500 is shifted from the appropriate position, the calculated maximum luminance is small, and the QI evaluation is low. Furthermore, a tomographic image captured when the test eye 500 is shifted is an inappropriate image because there is a positional shift in the depth direction compared to other tomographic images captured at appropriate positions. A low QI for such an inappropriate tomographic image does not pose a problem. Therefore, by limiting the range of the A-scan information in the depth direction, the cost (calculation load) of calculating the maximum brightness 602 can be reduced without causing problems in the evaluation by QI.

[0049] Next, the calculation unit 202 calculates an average value within the range limited in the depth direction in step S34 for each piece of A-scan information after the number of pieces of A-scan information has been thinned out in step S32 (S36). The average value calculated here is set as the brightness value of each piece of A-scan information.

[0050] Finally, the calculation unit 202 identifies the maximum brightness 602 from the brightness values ​​(average values) of the A-scan information calculated in step S36 (S38). Specifically, the calculation unit 202 identifies the maximum of the brightness values ​​(average values) of the A-scan information calculated in step S36 as the maximum brightness 602. The calculation unit 202 calculates the QI by substituting the maximum brightness 602 calculated in this way into the equation expressed by Equation 1 above. This makes it possible to calculate the QI for the acquired tomographic image.

[0051] 4, once the QI is calculated, the calculation unit 202 evaluates the fixation state (S22). The fixation state is evaluated by comparing the front image of the subject's eye 500 acquired in step S18 (i.e., the front image acquired substantially simultaneously with the tomographic image of the subject's eye 500 acquired in step S16) with the reference front image acquired in step S14.

[0052] A method for evaluating the fixation state will be described with reference to FIG. 9. FIG. 9(a) illustrates a case where the subject's eye 500 is not moving due to involuntary eye movement or the like and is in an appropriate position. When the subject's eye 500 is in an appropriate position, the front image acquired in step S18 substantially matches the reference front image. In this case, the calculation unit 202 determines that the fixation state is appropriate. As shown in FIG. 9(b), if the subject blinks, a front image is not captured in step S18. In this case, the calculation unit 202 determines that the fixation state is inappropriate for evaluation. As shown in FIG. 9(c), when the subject's eye 500 moves due to involuntary eye movement or the like, the front image acquired in step S18 does not match the reference front image. For example, in FIG. 9(c), the subject's eye 500 is photographed lower than when it is in an appropriate position (as in FIG. 9(a)), and does not match the position of the subject's eye 500 in the reference front image. In this case, the calculation unit 202 determines that the fixation state is inappropriate.

[0053] In the QI evaluation, since the depth range of the A-scan information is limited when calculating the maximum luminance 602 in step S34 as described above, if the imaging position of the subject's eye 500 is significantly displaced, the QI may be determined to be low. However, for example, if the imaging position of the subject's eye 500 is only slightly displaced, the maximum luminance 602 is calculated to be high. Furthermore, if the subject's eye 500 moves only horizontally (i.e., within a plane perpendicular to the optical axis), the maximum luminance 602 is calculated to be high. In such a case, as shown in FIG. 9(c), the QI may be determined to be high. Meanwhile, the fixation state is evaluated by comparing the front image acquired in step S18 with a reference front image. Therefore, as shown in FIG. 9(c), it is possible to accurately determine whether the subject's eye 500 has been imaged in a displaced state. In this way, by evaluating not only the QI but also the fixation state, it is possible to identify an inappropriate state that cannot be determined by QI evaluation alone (i.e., the subject's eye 500 has been imaged in a displaced state in the horizontal direction).

[0054] 4, the calculation unit 202 then determines whether or not all tomographic images have been acquired from the set imaging range (S24). If all tomographic images have not been acquired (NO in step S24), the process returns to step S16, and the processes of steps S16 to S24 are repeated.

[0055] Next, the calculation unit 202 displays a preview screen 700 including the evaluation result based on the QI and the evaluation result based on the fixation state on the monitor 120 (S26). As shown in Fig. 10, the preview screen 700 includes a front image 702 of the subject's eye 500, the evaluation result based on the QI (bar 706 in Fig. 10), the evaluation result based on the fixation state (bar 708 in Fig. 10), a tomographic image 712 of the subject's eye 500, a tomographic image 714 showing the entropy in the subject's eye 500, a save button 716, and a retake button 718. The front image 702 of the subject's eye 500 is the front image acquired in step S14 (i.e., the reference front image), and the imaging range of the tomographic image (the range surrounded by a rectangular outline) is shown within the front image 702. The tomographic image 712 is a tomographic image (a so-called normal tomographic image) that shows the tissue in the subject's eye 500 by scattering intensity, and is selected from multiple tomographic images. The tomographic image 714 that shows the entropy in the subject's eye 500 is the one at the center of the imaging range. By displaying one representative tomographic image 714 that shows the entropy in the subject's eye 500, it can be confirmed whether imaging for generating the tomographic image that shows the entropy in the subject's eye 500 was performed appropriately. The Save button 716 and the Retake button 718 are configured so that the examiner can press them using input means (not shown) such as a mouse.

[0056] The QI evaluation result is determined based on the QI calculated in step S20. For example, the calculation unit 202 classifies the QI into three categories: low QI (e.g., 1 to 4), medium QI (e.g., 5 to 7), and high QI (e.g., 8 to 10). The evaluation results of all tomographic images are simultaneously displayed on one screen so that the examiner can distinguish the evaluation results of all tomographic images at a glance. For example, in the example shown in FIG. 10 , the QI evaluation result is displayed by a bar 706 (hereinafter also referred to as the QI bar 706). The QI bar 706 indicates the three categories with different colors. For example, the QI bar 706 indicates the evaluation result in green when the QI is high, in yellow when the QI is medium, and in red when the QI is low. In this embodiment, 256 tomographic images are captured, and each tomographic image is numbered 1 to 256 along the cross section. The QI bar 706 shows the QI evaluation results of the tomographic images corresponding to each of the tomographic images No. 1 to No. 256, arranged side by side and color-coded, which allows the QI evaluation results of all the tomographic images to be confirmed at a glance.

[0057] The evaluation result based on the fixation state is displayed based on the evaluation of the fixation state in step S22. The evaluation result based on the fixation state is also displayed by a bar 708 (hereinafter also referred to as the fixation bar 708). For example, the fixation bar 708 displays the evaluation result in green when the fixation state is appropriate (i.e., when the front image acquired in step S18 approximately matches the reference front image), and displays the evaluation result in red when the fixation state is inappropriate (i.e., when the front image acquired in step S18 does not match the reference front image). Furthermore, when there is only a slight deviation between the front image acquired in step S18 and the reference front image, the evaluation result may be displayed in yellow as being moderately appropriate. The fixation bar 708 is displayed below the QI bar 706. The fixation bar 708 displays the evaluation results of the fixation state of the tomographic images corresponding to the tomographic images No. 1 to 256, arranged side by side in different colors. This allows the evaluation results of the fixation state of all tomographic images to be checked at a glance.

[0058] Above the QI bar 706 and fixation bar 708, a bar 704 indicating each tomographic image (hereinafter also referred to as the image slide bar 704) is displayed in parallel. Also, a selection button 710 for selecting each tomographic image is displayed on the monitor 120. The selection button 710 can be used to move the image slide bar 704 left and right to select a tomographic image. The selected tomographic image 712 is displayed on the monitor 120. The QI bar 706 and fixation bar 708 display the evaluation results of each tomographic image at a position corresponding to the tomographic image on the image slide bar 704. This allows the examiner to easily identify tomographic images that are deemed inappropriate by the QI bar 706 and fixation bar 708. The examiner can then display the tomographic images that are deemed inappropriate by the QI bar 706 and fixation bar 708 and individually check whether or not the tomographic images were properly captured. In this way, by using the QI bar 706 and the fixation bar 708, it is possible to easily identify tomographic images that are deemed inappropriate, thereby reducing the burden of the examiner's confirmation work.

[0059] Next, the calculation unit 202 determines whether or not the retake button 718 has been pressed (S28). The examiner can press the retake button 718 using an input means (not shown) such as a mouse. The examiner checks the preview screen 700 displayed in step S26, and presses the retake button 718 if he or she determines that the photographing of the subject's eye 500 has not been performed appropriately. If the retake button 718 has been pressed (YES in step S28), the calculation unit 202 re-photographs the subject's eye 500. That is, the process returns to step S14, and the processes of steps S14 to S28 are repeated.

[0060] On the other hand, if the Retake button 718 has not been pressed (NO in step S28), the calculation unit 202 determines whether the Save button 716 has been pressed (S30). The examiner can press the Save button 716 using an input means (not shown) such as a mouse. The examiner checks the preview screen 700 displayed in step S26, and if he or she determines that the photographing of the subject's eye 500 has been properly performed, presses the Save button 716. When the Save button 716 is pressed (YES in step S30), the calculation unit 202 stores the tomographic image of the subject's eye 500 acquired in step S16 in the memory (not shown) of the calculation unit 202 (S32). On the other hand, if the Save button 716 has not been pressed (NO in step S30), the process returns to step S28, and the processes of steps S28 to S30 are repeated until the Retake button 718 or the Save button 716 is pressed.

[0061] Once the tomographic images of the subject's eye 500 are saved, the calculation unit 202 creates a simplified report (S34). Here, the simplified report refers to an examination report corresponding to the desired examination selected in step S12, created using a portion of all tomographic images. In this embodiment, a total of 128 tomographic images of the subject's eye 500 are acquired. The calculation unit 202 selects five of the 128 tomographic images and creates a simplified examination report for the desired examination selected in step S12. Once the simplified report has been created, as shown in FIG. 11 , the calculation unit 202 displays the simplified report 720 created in step S34 on the monitor 120 together with the preview screen 700 displayed in step S26 (S36).

[0062] The simplified report reduces the time required for creation because the number of tomographic images used for analysis is limited. Even if the simplified report is insufficient as an examination report because it uses only a portion of the tomographic images for analysis, the examiner can still use the simplified report to determine whether the diseased area has been captured as intended by referring to images that cannot be displayed on the preview screen 700, such as polarization images, or to determine whether the subject's eye 500 has been properly captured by checking the comparison results with a normal eye database. An examination report created using all tomographic images (128 tomographic images in this embodiment) is automatically created after the process shown in FIG. 4 is completed and the subject's eye 500 is captured.

[0063] In this embodiment, the examiner checks the QI evaluation results, fixation state evaluation results, and simple report displayed on the monitor 120 to determine whether the imaging was performed appropriately. In this embodiment, the QI bar 706 and fixation bar 708 simultaneously display the QI evaluation results and fixation state evaluation results for all tomographic images on the same screen. This reduces the time required to determine whether the tomographic images were properly captured based on the QI and fixation state. Furthermore, the simple report allows the examiner to confirm whether the imaging was performed appropriately so that a desired examination report can be created. The simple report takes less time to create than an examination report created using all tomographic images. This reduces the time required to display the preview screen 700 and shortens the time from the start of imaging to the completion of confirmation using the preview screen 700.

[0064] Furthermore, if the examiner determines that the imaging has not been performed appropriately, the subject's eye 500 is imaged again. On the other hand, if the examiner determines that the imaging has been performed appropriately, the imaging of the subject's eye 500 is terminated. In this embodiment, the time required to determine whether the imaging has been performed appropriately can be shortened, and therefore the time required for the subject to be restrained for imaging the subject's eye 500 can be shortened.

[0065] In this embodiment, the evaluation results based on QI and the evaluation results based on the fixation state are displayed using bars, but the present invention is not limited to this configuration. It is sufficient that the evaluation results based on QI and the evaluation results based on the fixation state of all tomographic images can be displayed simultaneously on the same screen. For example, the evaluation results based on QI and the evaluation results based on the fixation state can be displayed using a graph, or can be converted into scores and displayed simultaneously on one screen.

[0066] In addition, in this embodiment, the preview screen 700 is displayed, the tomographic image of the subject's eye 500 is saved, and then the simple report 720 is created, but the present invention is not limited to this configuration. For example, the simple report 720 may be created before the tomographic image of the subject's eye 500 is saved, and the preview screen 700 and the simple report 720 may be displayed on the monitor 120. In this case, the examiner can simultaneously check the preview screen 700 and the simple report 720 to determine whether the tomographic image of the subject's eye 500 has been properly captured.

[0067] Furthermore, although a polarization-sensitive optical tomographic imaging device is used in this embodiment, the present invention is not limited to this configuration. The type of optical coherence tomography is not particularly limited, and for example, an optical tomographic imaging device that is not polarization-sensitive may also be used.

[0068] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of those objectives itself has technical utility. [Explanation of symbols]

[0069] 10: Measuring part 11:Light source 43: Reference mirror 60, 70: interference light generating unit 80, 90: Interference light detection section 81, 82, 91, 92: Balanced photodetectors 83, 93: Signal processor 84, 85, 94, 95: Signal processing section 100: Sampling trigger / clock generator 140: Sampling trigger generator 160: Sampling clock generator 200: Arithmetic device 202: Arithmetic section 500: Subject's eye 700: Preview screen 706: QI Bar 708: Fixation bar 720: Simple Report S1, S2: Measurement optical path R1, R2: Reference optical path

Claims

1. an imaging unit that performs an imaging process of scanning light over an imaging range set on the subject's eye, thereby capturing n (n is an integer of 2 or more) tomographic images from the imaging range; a generation unit that generates an evaluation index for evaluating the image quality of the tomographic image; a display unit that displays the evaluation index generated by the generation unit, the evaluation index includes a brightness evaluation index for evaluating image quality based on brightness of the tomographic image, the generating unit generates the brightness evaluation index for each of the n tomographic images; The generation unit generating the brightness evaluation index using a maximum brightness of an interference signal obtained from a specific position in the imaging range of the subject's eye; thinning out a plurality of pieces of A-scan information constituting the tomographic image and calculating the maximum brightness using A-scan information less than the plurality of pieces of A-scan information; The display unit simultaneously displays the brightness evaluation indexes for the n tomographic images on one screen.

2. The optical tomographic imaging apparatus according to claim 1 , wherein the generation unit limits a depth range of the A-scan information to a preset range, and calculates the maximum brightness using the A-scan information within the limited depth range.

3. The optical tomographic imaging apparatus according to claim 1 , wherein the evaluation index further includes a fixation evaluation index for evaluating a fixation state of the subject's eye.

4. the generation unit selects m tomographic images (m is a natural number smaller than n) from the n tomographic images, and further generates an inspection report indicating desired inspection results from the selected tomographic images; 4. The optical tomographic imaging apparatus according to claim 1, wherein the display unit further displays a generated examination report.

Images