Abstract: A method and system for calculating laser beam spot size, comprising: collecting a spot image of a laser beam and a corresponding background noise image along an optical axis direction; conducting pretreatment using a background subtraction method and a threshold method according to the spot image and the background noise image collected to obtain a pretreated spot image; calculating the central position of a laser spot of the pretreated spot image; and storing the pixel gray values of the spot image at the central position of the laser spot on a horizontal direction and a vertical direction, then conducting Gaussian curve fitting, calculating variances of Gaussian fitted curves on the horizontal direction and the vertical direction, and obtaining the spot radiuses of the spot image on the horizontal direction and the vertical direction according to the variances calculated.

Abstract: In exemplary implementations of this invention, a bi-ocular apparatus presents visual stimuli to one eye of a human subject in order to relax that eye, while measuring refractive aberration of the subject's other eye. Alternately, a monocular device presents stimuli to relax an eye while testing the same eye. The apparatus induces eye relaxation by displaying virtual objects at varying apparent distances from the subject. For example, the apparatus may do so by (i) changing distance between a backlit film and a lens; (ii) using extra lenses; (iii) using an adaptive lens that changes power; (v) selecting distinct positions in a progressive or multi-focal length lens; (vi) selecting distinct optical depths by fiber optical illumination; (vii) displaying a 3D virtual image at any given apparent depth; or (viii) display both a warped version of the real world and a test image at the same time.

Abstract: In a perimetry to be conducted, designating an inspection region through a region designator, stimuli are presented to regions separated in an up/down direction, an oblique direction and a right/left direction from the inspection region (“the spaced region”) in addition to the designated inspection region. At the result, examinees are not able to predict to which of both regions, the inspection region and the spaced region the stimuli are presented, thereby obtaining correct inspection results that do not receive a prediction of the examinees.

Abstract: An image processing apparatus includes a generation unit and a display control unit. The generation unit generates a subtraction image using a first region and a second region, the first region being a portion of a first fundus image acquired by performing autofluorescence imaging on a fundus of an eye to be inspected, the second region being a portion of a second fundus image acquired by performing autofluorescence imaging on the fundus of the eye to be inspected at a time different from that of the first fundus image and being at a position corresponding to the first region. The display control unit causes a display unit to display an image generated by superimposing information regarding the subtraction image at a position corresponding to the first and second regions on a fundus image acquired by performing autofluorescence imaging on the fundus.

Abstract: A method, system or apparatus for generating a wide field retinal image. System embodiments comprise a camera, which may be a smartphone camera and associated optics to capturing a digital video stream of individual retinal images and store the video stream of individual retinal images in a memory associated with the camera. The system or method then implements the steps of processing each retinal image and combining selected retinal images into a panorama in real time, during an ocular examination.

Abstract: A polarization-based colposcopy apparatus includes a polarization exchanging beam splitter pair oriented so that s- and p-polarizations are exchanged. An optical flux from a specimen is directed through the pair, and orthogonal components thereof are alternately or selectively coupled to an array detector. The detected images are processed based on image correlations to reveal specimen structures.

Abstract: An electronic SLO/OCT ophthalmoscope is equipped with a femtosecond (fs) laser for intra- or preretinal therapeutic use in the posterior segment of the eye. In one application the retina photoreceptor mosaic or Bruch's membrane is disrupted in such pattern that minimizes loss of visual functioning but reduces metabolic load of the outer retina. Using a beam splitter, one embodiment combines the SLO/OCT scanning beams with the therapeutic fs beam and an aiming beam. The therapeutic channel uses an independent x/y positioner and micro-deflector. Because the duty cycle is appropriate, a second embodiment can use the SLO/OCT scanners to also simultaneously scan a modulated therapeutic laser beam. A biometric OCT probe can be integrated in both configurations for focusing purpose. A method is disclosed to represent focus relevant tilting of the retina in the posterior pole.

Abstract: An ophthalmologic photographing apparatus includes: a photographing optical system including an optical scanner for scanning an examinee's eye with measurement light and a detector for detecting a coherent state of reflected light of the measurement light from the examinee's eye and reference light, the photographing optical system being configured to capture a tomographic image of the examinee's eye in response to an output signal from the detector; a reference data setting unit for setting a photographing condition of a previously acquired captured image as reference data for a follow-up; an image capture data setting unit for setting the reference data set by the reference data setting unit as image capture data for the follow-up; and a tomographic image acquisition controller for acquiring a tomographic image of the examinee's eye by controlling the photographing optical system based on the reference data set as the image capture data.

Abstract: An ophthalmic apparatus obtains naked-eye wavefront aberration data of an examinee's eye measured by an aberration measuring unit, and calculates first corrected wavefront aberration data intended for a prescription with a first correction power based on the naked-eye wavefront aberration data and the first correction power and generates a first evaluation index based on the first corrected wavefront aberration data. The ophthalmic apparatus further calculates second corrected wavefront aberration data intended for a prescription with a second correction power different from the first correction power in at least one of spherical power, astigmatic power, and astigmatic axis angle based on the naked-eye wavefront aberration data and the second correction power, and generates a second evaluation index based on the second corrected wavefront aberration data. The ophthalmic apparatus then displays the first and second evaluation indexes selectively or in parallel on a monitor.

Abstract: Methods for analyzing optical coherence tomography (OCT) images of the macula to reduce variance and improve disease diagnosis are presented. One embodiment of the invention is directed towards selecting analysis locations and data segmentation techniques to take advantage of structural homogeneities. Another embodiment is directed towards reducing the variance in a collection of normative data by transforming the individual members of the database to correspond to a Standard Macula. Variations in foveal size are corrected by radial transformation. Variations in layer thickness are corrected by axial shifting. Diagnosis is performed by comparing OCT images from a patient to the improved normative database.

Abstract: A non-invasive bedside tool for monitoring central nervous system effects of opioids. The tool illustratively comprises a quantitative pupillometry system for predicting a probability of at least one opioid-related central effect based on detected pupillary effects.

Abstract: An ophthalmoscope device includes a support structure, an image capture device, and a display device. The support structure is configured to be worn by a subject. The image capture device is configured to capture images of the eye fundus of the subject. The display device is configured to overlay images in the field of view of the subject. The overlaid images are used to align the pupil/fovea orientation axis with the optical axis of the image capture device.

Abstract: A method of determining a corneal thickness and an apparatus for determining the same. The method comprises the following steps of illuminating a cornea by a plurality of stimulator point light sources, capturing an image of the cornea comprising reflected images of the stimulator point light sources, obtaining a first model representing an anterior surface of the cornea, constructing a second model representing a posterior surface of the cornea from the image by ray-tracing the reflected images of the stimulator point light sources towards the first model representing the anterior surface of the cornea, and determining the corneal thickness from the first model representing the anterior surface and the second model representing the posterior surface.

Abstract: This invention teaches a binocular telescope wherein wedge prisms are positioned in the optical path of each telescope to control the amount of perceived parallax between the left and the right images. In one embodiment, a pair of thin wedge prisms are positioned in front of the objective lenses to optically manipulate the real convergence angle of an object viewed through the binocular telescope. In a second embodiment, wedge prisms are positioned after the eyepiece lenses to manipulate the apparent convergence angle of an object viewed through the binocular telescope. Depending on the position and the orientation of the wedge prisms, the invention produces benefits such as better depth perception, increased field of view, and the possibility to view close objects.

Abstract: An optical coherence tomographic imaging apparatus includes a movement amount acquisition unit configured to acquire the amount of subject's eye movement based on a plurality of images of the subject's eye acquired at different times, a determination unit configured to determine whether the amount of subject's eye movement before a scan by the scanning unit exceeds a threshold value, and a control unit configured to, in a case the amount of subject's eye movement before the scan is equal to or smaller than the threshold value, control the scanning unit to perform scanning position correction between a scan and the next scan based on the amount of movement.

Abstract: A method of determining a reference calibration setting for an adaptive optics system (1) comprising a detecting device (8) for detecting light from an object (5); and at least one controllable wavefront modifying device (9) arranged such that light from the object (5) passes via the wavefront modifying device (9) to the detecting device (8).

Abstract: A method is provided for determining the dominant eye of a person using equipment designed to acquire at least one image of the face of the person, then process the image, and finally return information enabling the person to know which eye is the dominant eye thereof. The method uses a sighting device that is identifiable and locatable in relation to the equipment, with the viewing being carried out through a window with both eyes open. The size of the window is such that it does not allow the person to see said target with both eyes at the same time. The equipment acquires at least one image for viewing the position of both eyes of the person, processing the image by performing calculations while taking into account the position of a central point located between both eyes, the position of the target and the position of the window.

Abstract: An excitation light source emits excitation light to a target sample. An image sensor includes pixels arranged one-dimensionally or two-dimensionally, and receives measurement light from the sample according to the excitation light. A polarization selector arranged between the sample and image sensor includes pixels arranged one-dimensionally or two-dimensionally. Each pixel receives a corresponding portion of the measurement light, selects light having a polarization direction that corresponds to a driving signal applied to the pixels, and supplies this light to the image sensor. A measurement control unit supplies the cyclic driving signal having a first period T1, and acquires data I1, I2, I3, and I4 from each pixel of the image sensor for each exposure time segment T2=T1/4 obtained by dividing the first period T1 by 4.

Abstract: Optical coherence tomography (OCT) scan data is used to automatically detect and characterize vitreoretinal membranes in a spatially precise manner to generate a mask image. The mask image may characterize various aspects of a vitreoretinal membrane. The mask image is then overlaid with an optical image of the retina to enable visualization of the vitreoretinal membrane.

Abstract: An ophthalmologic imaging apparatus includes: a first optical system that applies an accommodation stimulus to a subject's eye; a tomographic image forming unit that includes a second optical system that splits light from a light source into signal light and reference light, and detects interference light between the signal light having travelled via the subject's eye and the reference light, and creates a tomographic image of the subject's eye based on a detection result of the interference light; and an analyzer that compares a first tomographic image with a second tomographic image to acquire change information indicating a change in a tissue of the subject's eye due to an accommodation stimulus change. The first and second tomographic images are respectively created by the tomographic image forming unit for the subject's eye, to which first and second accommodation stimuli are respectively applied by the first and second optical systems.

Abstract: A method and system for determining a roll angle in an eye image is described. A center of an iris, an inner eye corner, and an outer eye corner in an eye image may be determined. The eye image may be normalized and transformed to a polar eye image using the center of the iris as a reference for the transformation. A shift associated with the inner eye corner and a shift associated with the outer eye corner may be determined. The shifts associated with the inner eye corner and the outer eye corner may be indicators of an orientation of the eye image or roll angle, and may be used for subsequent eye image processing and matching.

Abstract: An ophthalmologic apparatus includes a photographing optical system configured to photograph a fundus of a subject's eye via a focusing lens, a projection unit configured to project, via a mask portion including an opening, a focusing index corresponding to the opening, and a driving unit configured to drive the focusing lens along an optical path based on a position of an image corresponding to the mask portion and a position of a focusing index image corresponding to the opening in a fundus image of the subject's eye.

Abstract: In a method and apparatus for the generation of image data of a moving subject, raw data are initially acquired for a region comprising the subject at different measurement points in time in different movement phases of the subject. A reconstruction then takes place of multiple interim image data sets of the subject from the raw data that are respectively associated with different movement phases of the subject. Deviation data are then determined between the interim image data sets of the different movement phases of the subject, and the reconstruction of image data from raw data of different movement phases then takes place under consideration of the deviation data.

Abstract: In one embodiment, a wavefront sensor is combined with a slit lamp eye examination device so that real time aberration values of an eye being examined can be viewed during a slit lamp eye examination session.

Abstract: The present disclosure generally relates to a device and a method for alignment. The alignment device provides optical architecture to align the alignment device to an analyte and measure the optical properties of an analyte. The method for alignment provides steps for aligning an optical measurement device to an analyte.

Abstract: According to one embodiment, an ophthalmic examination system includes a plurality of ophthalmic examination apparatuses and a management apparatus that manages the operational status of the ophthalmic examination apparatuses. The ophthalmic examination system includes a receiver, a counting unit, a storage device, and a storage controller. The receiver receives first identification information for identifying a subject. The counting unit includes a counter provided for each apparatus group including at least one ophthalmic examination apparatus, and counts the number of times of use of the apparatus group in units of the first identification information of the subject examined with the ophthalmic examination apparatus included in the apparatus group. The storage controller acquires a counter value indicated by the counter from the counting unit, associates the counter value with second identification information for identifying the apparatus group, and stores them in the storage device.

Abstract: An excitation force (internal or external) and phase-sensitive optical coherence elastography (OCE) system, used in conjunction with a data analyzing algorithm, is capable of measuring and quantifying biomechanical parameters of tissues in situ and in vivo. The method was approbated and demonstrated on an example of the system that combines a pulsed ultrasound system capable of producing an acoustic radiation force on the crystalline lens surface and a phase-sensitive optical coherence tomography (OCT) system for measuring the lens displacement caused by the acoustic radiation force. The method allows noninvasive and nondestructive quantification of tissue mechanical properties. The noninvasive measurement method also utilizes phase-stabilized swept source optical coherence elastography (PhS-SSOCE) to distinguish between tissue stiffness, such as that attributable to disease, and effects on measured stiffness that result from external factors, such as pressure applied to the tissue.

Abstract: A method for determining reflectivity of a tear film lipid layer of a patient and recommending a course of treatment based on the same. The method includes the steps of: measuring a tear film aqueous plus lipid layer relative reflectance spectrum using a wavelength-dependent optical interferometer; converting the measured tear film aqueous plus lipid layer relative reflectance spectrum to a calculated absolute reflectance spectrum; comparing the calculated absolute reflectance spectrum to a theoretical absolute lipid reflectance spectrum to determine a tear film lipid layer thickness; and determining a reflectivity value for the tear film lipid layer thickness at a first wavelength of light corresponding to ultraviolet, violet, or blue light.

Abstract: A new device, called Afferent Pupil Tester, designed for close up and magnified examination of both pupils at the same time, superimposed, as they react to direct and consensual light, comprises of high plus lenses, measuring grid, bright LED lights controlled with momentary switches, UV lights controlled by momentary switches, batteries, built-in camera and/or external camera, detachable facemask, and a sturdy casing.

Abstract: A viewer includes a multifocal lens capable of setting one of a plurality of focal lengths. When a measuring section detects a change in gazing point distance, a selection section selects a focal length to be set among the plurality of focal lengths, and a determiner determines a time duration before a focal length of the multifocal lens is changed. A controller changes the focal length of the multifocal lens when a detector detects a blink or saccadic eye movement of the user before the determined time duration elapses.

Abstract: A medical diagnostic instrument or a plurality of disparate medical diagnostic instruments are configured with a common optical architecture that functionally creates a virtual eye to create closer proximity to a patient and therefore increase the field of view in regard to a target of interest. The optical system includes a distal optical element, at least one relay lens and an eyepiece lens in which the optical system can be integrated within at least one instrument or be provided using a releasable module. Additionally, at least one of a viewing assembly and illumination assembly of at least one medical diagnostic instrument can be assembled using a series of components that are connected by interlocking features.

Abstract: An ophthalmologic apparatus includes a refractive power application unit, a storage unit, and a control unit. The refractive power application unit is configured to be capable of changing refractive power applied to a subject's eye. The storage unit stores at least a measurement value of eye refractive power obtained by a measurement performed for the subject's eye in the past. The control unit controls the refractive power application unit to selectively apply the measurement value and one or more refractive values different from the measurement value to the subject's eye in response to the input of an instruction to change refractive power applied to the subject's eye.

Abstract: According to an illustrative embodiment, an imaging system is provided. The system includes a first imaging unit; a second imaging unit; and an objective optical system optically coupled to the first imaging unit and the second imaging unit, wherein the objective optical system has a first direction along which light is refracted and a second direction along which light is refracted differently.

Abstract: Ophthalmoscopic apparatus (10) having a frame (11) provided with references for the positioning of at least one of the user's eyes in an inspection position; a first optical unit (12) fixed to the frame (11) and faced to the inspection position references; a second optical unit (13) associated to the frame (11) and presenting an optical axis coincident with the optical axis of the first optical unit (12) and defining a main optical axis (A) incident in correspondence of the inspection position references; an image detecting device (14) fixed to the frame (11); a support (15) fixed to the frame (11) between the first optical unit (12) and the second optical unit (13), and having an operating part (B) permeable to the luminous radiation and intersected by the main optical axis (A); and a lighting means (16) associated to the support (15).

Abstract: Provided is an ophthalmologic apparatus capable of executing accurate automatic alignment even for an eye having an intraocular lens (IOL) implanted therein. The ophthalmologic apparatus includes: an optical system including a light beam projecting unit for projecting a light beam to an eye to be inspected, and a light receiving unit for receiving a reflection light beam from the eye to be inspected; a detecting unit for detecting a plurality of bright spot images from the reflection light beam received by the light receiving unit; and a calculating unit for calculating an alignment status between the eye to be inspected and the optical system based on the detected plurality of bright spot images. The ophthalmologic apparatus is further provided with a selection unit for selecting bright spot images to be used for the calculation by the calculating unit, from among the plurality of bright spot images.

Abstract: Ophthalmic lens assemblies and methods of assembly and use may include a lens assembly including a lens element and a protective cover. The lens element includes a contact lens surface and a faceted optical body including a distal portion and a faceted portion including one or more mirror facets to form a TIR activity pathway. The protective cover includes a contact aperture shaped to receive the contact lens surface, a grip portion, and a facet housing portion including an interior surface. The contact aperture of the protective cover is stretch-fit about a periphery of the contact lens surface to maintain a proximal-side fluid seal. The grip portion of the protective cover is stretch-fit about the distal portion of the lens element to maintain a distal-side fluid seal. One or more TIR-inducing air gaps are defined by the facet housing portion between the interior surface and the mirror facets.

Abstract: A system and method for generating a cancelable biometric includes providing at least one pattern and combining the at least one pattern with a biometric image by employing a transform pixel operation to generate a transformed enrollment such that information about the transform pixel operation and the at least one pattern form a security key for protecting the biometric image. The biometric image is reused to generate another security key in the event that the security key is to be canceled.

Abstract: A medical diagnostic instrument or a plurality of disparate medical diagnostic instruments are configured with a common optical architecture that functionally creates a virtual eye to create closer proximity to a patient and therefore increase the field of view in regard to a target of interest. The optical system includes a distal optical element, at least one relay lens and an eyepiece lens in which the optical system can be integrated within at least one instrument or be provided using a releasable module. Additionally, at least one of a viewing assembly and illumination assembly of at least one medical diagnostic instrument can be assembled using a series of components that are connected by interlocking features.

Abstract: An ophthalmic method for determining relationships for calculating intraocular lens (IOL) power correction values is disclosed. The method may involve obtaining estimates of the postoperative optical power of a plurality of eyes undergoing IOL implant surgery. Measurements of the postoperative optical power and of one or more characteristics (e.g., axial length) of the eyes can also be obtained. The eyes can be separated into groups based upon their axial lengths. For each of the groups, a mathematical relationship can be determined for calculating IOL power correction values based on the measured characteristics. The mathematical relationship can reduce prediction error for the respective eyes in each group when applied to the corresponding estimates of the postoperative optical power. Methods and systems are also disclosed for using the IOL power correction values.

Abstract: Imaging systems are provided allowing examination of different object regions spaced apart in a depth direction by visual microscopy and by optical coherence tomography. An axial field of view and a lateral resolution is varied depending on which object region is examined by the imaging system. The proposed imaging systems are in particular applicable for thorough examination of the human eye.

Abstract: Systems and methods for determining thickness of lipid and aqueous layers of a tear film in which a spectrum array is generated from optical coherence tomography and input into a statistical estimator, which determines the thickness of the lipid and/or aqueous layers at a nanometer resolution based on the inputted spectrum and other information, such as information about a laser intensity noise, Poisson noise, and dark noise associated with the OCT.

Abstract: An observation device includes: a holding board that holds an observation container accommodating a cornea for transplantation to be observed; a specular reflection optical system including an illumination optical system and an imaging optical system, which include a light source and an imaging unit, for observing the cornea for transplantation; and an auxiliary light source that illuminates the cornea for transplantation from the back and has an auxiliary illumination optical axis inclined with respect to an observation base axis that divides in half an intersecting angle of the illumination optical axis of the illumination optical system and an imaging optical axis of the imaging optical system, wherein the auxiliary light source is installed in a freely pivoting manner about a predetermined rotation axis so that a relative inclination angle with respect to the observation base axis of the auxiliary illumination optical axis can be continuously changed.

Abstract: A method for determining optical properties of a corneal region. The method includes the steps of obtaining a combined tear film aqueous layer plus lipid layer thickness; obtaining a tear film lipid layer thickness; subtracting the tear film lipid layer thickness from the combined tear film aqueous layer plus lipid layer thickness to obtain a tear film aqueous layer thickness; and determining a corneal layer refractive index based on the tear film lipid layer thickness and the tear film aqueous layer thickness.

Abstract: An ophthalmic apparatus includes a resting member configured to provide rest for a human patient, and an ophthalmic device configured to perform one or more procedures with respect to an eye of the patient resting on the resting member, where the one or more procedures include at least one of an eye-surgical, therapeutic and diagnostic procedure. The apparatus also includes a user interface device configured to receive log-in data from a user, and a controller configured to access stored user profile data based on the log-in data and configure one or more configurable components of the apparatus in accordance with the accessed user profile data.

Abstract: An optical measuring device is provided. An actuator of a reference mirror set drives a reference mirror to move back and forth at a scan velocity. A first light source module transmits a first light beam to an optical coupling module transmitting two parts of the first light beam respectively to an examinee object and the reference mirror set. The first light beam then is reflected by the examinee object and reference mirror set and then transmitted to the optical coupling module and the processing unit. The second light source module transmits a second light beam to the examinee object. Then the second light beam is reflected and then transmitted to the second sensing unit. The second sensing unit provides a sensing signal to the processing unit which accordingly provides a value of the relative velocity. The thickness is calculated according to the relative velocity and the scan velocity.

Abstract: An ophthalmic surgical microscope can include a first light source configured to project a first light beam at an observer's eye. The microscope can include a first wavefront sensor. The first wavefront sensor can be configured to determine aberrations in the first reflection wavefront of a reflection of the first light beam. The microscope can include adaptive optical element(s). The adaptive optical element(s) can be controlled to modify the phase of incident light. The microscope can include a computing device in communication with the first wavefront sensor and the adaptive optical element(s). The computing device can be configured to generate the control signal to compensate for the aberrations and to provide the control signal to the adaptive optical element(s). A second light source and second wavefront sensor can be provided to compensate for aberrations of a subject's eye.

Abstract: A method of operating an eye surgery system comprises operating actuators of a stand such that an apparatus for measuring the refraction of an eye is located in a measurement position relative to the eye; measuring at least one condition of the eye and determining at least one condition value representing the at least one measured condition of the eye; measuring the refraction of the eye and determining at least one refraction value presenting the measured refraction of the eye, wherein a time distance between the measuring of the condition of the eye and the measuring of the refraction of the eye is smaller than a predetermined duration; and outputting the at least one refraction value representing the measured refraction of the eye only when the condition value representing the measured condition of the eye is within a predetermined range of values.

Abstract: A spectrometer comprises a plurality of isolated optical channels comprising a plurality of isolated optical paths. The isolated optical paths decrease cross-talk among the optical paths and allow the spectrometer to have a decreased length with increased resolution. In many embodiments, the isolated optical paths comprise isolated parallel optical paths that allow the length of the device to be decreased substantially. In many embodiments, each isolated optical path extends from a filter of a filter array, through a lens of a lens array, through a channel of a support array, to a region of a sensor array. Each region of the sensor array comprises a plurality of sensor elements in which a location of the sensor element corresponds to the wavelength of light received based on an angle of light received at the location, the focal length of the lens and the central wavelength of the filter.

Abstract: An ophthalmologic apparatus includes a reflective member that reflects light from a first scanning unit that scans an object to be examined with first light and light from a second scanning unit that scans the object with second light having a wavelength different from a wavelength of the first light so as to be applied to the object. The ophthalmologic apparatus includes an optical path synthesis and separation unit that is arranged on two optical paths from the scanning units to the reflective member, and synthesizes two optical paths from the scanning units to the object and separates an optical path of return light from the object into two optical paths on which the scanning units are arranged. A reflection optical path of the optical path synthesis and separation unit is arranged opposite to the object with respect to the optical path synthesis and separation unit.

Abstract: An ophthalmologic apparatus includes a tomographic image acquisition unit configured to acquire a tomographic image of a subject's eye based on a combined beam obtained by combining a return beam from the subject's eye, which is irradiated with a measuring beam, and a reference beam corresponding to the measuring beam, an optical path length difference changing unit configured to change an optical path length difference between the measuring beam and the reference beam, and a control unit configured to, in a case where relative positions of an optical system for irradiating the subject's eye with the measuring beam and an anterior segment of the subject's eye satisfy a predetermined condition based on an image of the anterior segment, control the optical path length difference changing unit so that the optical path length difference is within a predetermined range.