Method for determining a refraction feature of an eye of a subject using a portable electronic device (1; 1'), said portable electronic device (1; 1') including: - a screen configured to display a lighted area (12A, 12B, 12C) having a changeable size, position, and/or shape, and being adapted to illuminate a pupil of said eye of the subject; and - an image-capture apparatus adapted to acquire pictures of said pupil illuminated by said lighted area (12A, 12B, 12C), said method comprising the steps of: a) displaying the lighted area on the screen of said portable electronic device (1; 1') and illuminating said pupil of the eye of the subject by means of said lighted area (12A, 12B, 12C); b) acquiring a picture of said pupil of the eye of the subject comprising an image of the reflection of said lighted area (12A, 12B, 12C) on the retina of said eye of the subject; c) determining said refraction feature of said eye of the subject taking into account at least one of the following features of said image of the reflection of said light source: - a geometrical feature (s) of said image of the reflection of said lighted area, - a positional feature of said image of the reflection of said lighted area, - an intensity distribution within said image of the reflection of said lighted area; wherein said portable electronic device (1; 1') being held by the subject himself in front of his eyes, - in step b) said reflection of said lighted area is collected by said image-capture apparatus. - a screen configured to display a lighted area (12A, 12B, 12C) having a changeable size, position, and/or shape, and being adapted to illuminate a pupil of said eye of the subject; and - an image-capture apparatus adapted to acquire pictures of said pupil illuminated by said lighted area (12A, 12B, 12C), said method comprising the steps of: a) displaying the lighted area on the screen of said portable electronic device (1; 1') and illuminating said pupil of the eye of the subject by means of said lighted area (12A, 12B, 12C); b) acquiring a picture of said pupil of the eye of the subject comprising an image of the reflection of said lighted area (12A, 12B, 12C) on the retina of said eye of the subject; c) determining said refraction feature of said eye of the subject taking into account at least one of the following features of said image of the reflection of said light source: - a geometrical feature (s) of said image of the reflection of said lighted area, - a positional feature of said image of the reflection of said lighted area, - an intensity distribution within said image of the reflection of said lighted area; wherein said portable electronic device (1; 1') being held by the subject himself in front of his eyes, said method comprising the steps of: a) displaying the lighted area on the screen of said portable electronic device (1; 1') and illuminating said pupil of the eye of the subject by means of said lighted area (12A, 12B, 12C); b) acquiring a picture of said pupil of the eye of the subject comprising an image of the reflection of said lighted area (12A, 12B, 12C) on the retina of said eye of the subject; c) determining said refraction feature of said eye of the subject taking into account at least one of the following features of said image of the reflection of said light source: - a geometrical feature (s) of said image of the reflection of said lighted area, - a positional feature of said image of the reflection of said lighted area, - an intensity distribution within said image of the reflection of said lighted area; a) displaying the lighted area on the screen of said portable electronic device (1; 1') and illuminating said pupil of the eye of the subject by means of said lighted area (12A, 12B, 12C); b) acquiring a picture of said pupil of the eye of the subject comprising an image of the reflection of said lighted area (12A, 12B, 12C) on the retina of said eye of the subject; c) determining said refraction feature of said eye of the subject taking into account at least one of the following features of said image of the reflection of said light source: - a geometrical feature (s) of said image of the reflection of said lighted area, - a positional feature of said image of the reflection of said lighted area, - an intensity distribution within said image of the reflection of said lighted area; - a geometrical feature (s) of said image of the reflection of said lighted area, - a positional feature of said image of the reflection of said lighted area, - an intensity distribution within said image of the reflection of said lighted area; wherein said portable electronic device (1; 1') being held by the subject himself in front of his eyes, - in step b) said reflection of said lighted area is collected by said image-capture apparatus.