The method comprises the steps of:a) illuminating the pupil (30) of an eye (3) of a subject (2) by means of a light source of a portable electronic device (1), said light source (12A) being formed by a lighted area displayed on a screen (11) of the portable electronic device；b) acquiring a picture of said pupil of the eye of the subject by means of an image-capture apparatus (10) of the portable electronic device, said picture comprising an image of the reflection of said light source on the retina of said eye； andc) determining a refraction feature of said eye taking into account at least a geometrical feature, a positional feature or an intensity distribution of said image of said reflection.An associated portable electronic device is also described
