using a first camera to take a first image of a scene through a first optical lens, the first optical lens having optical characteristics according to a first ophthalmic lens design, the first camera being provided with optics arranged to simulate the optical characteristics of a human eye and displaying the first image on a display device for viewing by the potential wearer enabling the potential wearer to visualise the optical effects of the first optical lens on his viewing ability. The position of the first camera, the first optical lens and the display device are fixed with respect to a referential frame defined by the head of the potential wearer, the head of the potential wearer being movable with respect to the scene. [Fig 1]
