Method and a device for automatically measuring at least one refractive characteristic of both eyes of an individual

A method of automatically measuring at least one refractive characteristic of both eyes (OD, OG) of an individual under predefined vision conditions, the method comprising the following steps:

• a) adjusting at least one posture of the individual's head in accordance with the wishes of said individual, in a frame of reference (O, X, Y, Z) associated with an image capture device (10) adapted to convert each captured image into a signal that is representative thereof;
• b) illuminating both eyes (OD, OG) by means of at least one light source (20) of known position in said frame of reference (O, X, Y, Z) associated with the image capture device (10);
• c) measuring at least one gaze direction parameter (H) associated with the gaze direction of the individual in a frame of reference associated with the individual's head;
• i) comparing the gaze direction parameter measured in step c) with a range of values corresponding to the predefined vision conditions and, if the value of said gaze direction parameter (H) as measured in step c) is situated in said range corresponding to said predefined vision conditions, triggering the capture by said image capture device (10) of at least one image (IROD1, IROG1, IROD2, IROG2) of the retinal reflection of said light source (20) on the retinas of both eyes (OD, OG) of the individual, the image being captured in an image capture plane (PCI);
• and
• j) determining from said at least one captured image, said refractive characteristic (D) of each of the eyes (OD, OG) of the individual in said predefined vision conditions;
• wherein, in step c), at least one of the following posture parameters (DD, DG, H, AHD, AHG, AVD, AVG) of the head are measured:
• a vertical distance (H) between a pupil of the image capture device (10) and an anatomical plane (PFI) of the individual that is inclined when the individual is in a natural posture and is looking towards the image capture device, said plane corresponding to a horizon anatomical plane (PFH) that is substantially horizontal when the individual is in a natural posture and looking at the horizon;
• a distance between a pupil of the image capture device (10) and the horizon anatomical plane (PFH) that is substantially horizontal when the individual is in a natural posture and looking at the horizon;
• a first angle of inclination (AVD, AVG) of the image capture plane (PCI) relative to a first reference plane (PREFD1, PREFG1) perpendicular to the line connecting one of the individual's eyes (OD, OG) with the pupil of the image capture device (10) in a plane perpendicular to a horizontal axis (X′) of said first reference plane, which angle corresponds to the angle that exists between a line defined by the intersection between the image capture plane (PCI) and said plane perpendicular to the horizontal axis (X′), and a line defined by the intersection between the reference plane (PREFD1, PREFG1) and said plane perpendicular to the horizontal axis (X′);
• and
• a second angle of inclination (AHD, AHG) of the image capture plane (PCI) relative to said first reference plane (PREFD1, PREFG1) in a plane perpendicular to an axis (Y) of said first reference plane (PREFD1, PREFG1) perpendicular to said horizontal axis (X′), which corresponds to the angle that exists in said plane perpendicular to said axis (Y) between a line defined by the intersection between the image capture plane (PCI) and said plane perpendicular to the axis (Y), and a line defined by the intersection between the reference plane (PREFD1, PREFG1) and said plane perpendicular to the axis (Y).

A device for automatically measuring at least one refractive characteristic of both eyes (OD, OG) of an individual, the device comprising:

• a support (30);
• at least one light source (20) mounted on the support (30) in such a manner as to illuminate at least one of the individual's eyes (OD, OG);
• at least one image capture device (10) mounted on said support (30), adapted to capture at least one image (IROD1, IROG1, IROD2, IROG2) of the retinal reflection of said light source (20) on the retina of each eye of the individual and to convert each captured image into a signal that is representative thereof, said light source (20) being of known position in a frame of reference (O, X, Y, Z) associated with said image capture device (10);
• means for measuring at least one gaze direction parameter (H) associated with the individual's gaze direction in a frame of reference associated with the individual's head, the parameter being selected from the following parameters:
• a vertical distance (H) between a pupil of the image capture device (10) and an anatomical plane (PFI) of the individual that is inclined when the individual is in a natural posture and is looking towards the image capture device, said plane corresponding to a horizon anatomical plane (PFH) that is substantially horizontal when the individual is in a natural posture and looking at the horizon;
• a distance between a pupil of the image capture device (10) and the horizon anatomical plane (PFH) that is substantially horizontal when the individual is in a natural posture and looking at the horizon;
• a first angle of inclination (AVD, AVG) of the image capture plane (PCI) relative to a first reference plane (PREFD1, PREFG1) perpendicular to the line connecting one of the individual's eyes (OD, OG) with the pupil of the image capture device (10) in a plane perpendicular to a horizontal axis (X′) of said first reference plane, which angle corresponds to the angle that exists between a line defined by the intersection between the image capture plane (PCI) and said plane perpendicular to the horizontal axis (X′), and a line defined by the intersection between the reference plane (PREFD1, PREFG1) and said plane perpendicular to the horizontal axis (X′);
• and
• a second angle of inclination (AHD, AHG) of the image capture plane (PCI) relative to said first reference plane (PREFD1, PREFG1) in a plane perpendicular to an axis (Y) of said first reference plane (PREFD1, PREFG1) perpendicular to said horizontal axis (X′), which corresponds to the angle that exists in said plane perpendicular to said axis (Y) between a line defined by the intersection between the image capture plane (PCI) and said plane perpendicular to the axis (Y), and a line defined by the intersection between the reference plane (PREFD1, PREFG1) and said plane perpendicular to the axis (Y);
• and
• a computer adapted to respond to the signal representative of said at least one captured image to determine said refractive characteristic (D) of the individual's eyes (OD, OG) and to store in memory said at least one gaze direction parameter (H) associated with the gaze direction of the individual in association with the determined refractive characteristic.