The invention relates to an eye condition determination system (1) for determining an eye condition of a person, especially of a child, during a viewing activity during which the person views an object (3). A spatial characteristics capturing unit (2) captures a spatial dimension of the object and/or a spatial position of the object relative to the person during the viewing activity, and an eye condition determination unit (4) determines an eye condition like myopia or strabismus based on the captured spatial dimension of the object and/or the captured spatial position of the object relative to the person. This allows for a determination of the eye condition during a normal viewing activity like reading a text without any assistance by, for instance, parents, especially without any user interaction.