Abstract: The invention relates to a novel open retinoscope comprising: a body (3) comprising a light source (31) oriented in the longitudinal direction and a first coupling means (32) for coupling to a Volk lens (51) holder in a longitudinally sliding manner; a Volk lens (51) holder (5), coupled in a longitudinally sliding manner to the body (3), where the holder (5) comprises a second longitudinal sliding coupling means (52) which is complementary to the first longitudinal sliding coupling means (32) of the body (3); and a smartphone adaptor (2) which can be connected to the body (3) in a transversely sliding manner.