Apparatus and method for determining refraction error of at least an eye of a subject

Apparatus for determining refraction error of at least an eye of a subject, the apparatus comprising:

• a corrective system comprising a variable power optical system mounted in an eyewear device adapted to be worn by the user so that the user is able to see a target scene through the variable power optical system and a device for varying the variable power of said optical system;
• a beam splitter, the variable power optical system being arranged between the eye of the subject and the beam splitter,
• a measurement system of the refraction error of said eye, the measurement system comprising a light source adapted to emit a light beam, an illumination optical system adapted to direct the light beam towards the eye of the subject so as to form a reflected light beam by reflection on the retina of the eye, and an image detection system;
• the beam splitter being adapted to direct the reflected light beam towards the image detection system, the beam splitter enabling simultaneously the user to see the target scene through the optical beam splitter and the variable power optical system;
• the image detection system being adapted to detect an image of the reflected light beam by transmission through the variable power optical system;
• a computing system comprising an image processing system adapted to process said image and deduce therefrom an estimation of the refraction error of said eye, the computing system being adapted to send a feedback signal to the device for varying the variable power of said optical system, the feedback signal depending on the estimation of the refraction error of said eye.