A wearable display system has a first lens sub-assembly defining a first optical path and a second lens sub-assembly defining a second optical path. The first and second lens sub-assemblies are disposed in a frame in respective first and second lens-holding sub-assemblies. The frame also has a device holder configured to maintain a display of a device in the first and second optical paths. The display can be maintained within a predetermined range of distances and angles with respect to the first and second lens sub-assemblies. This arrangement permits the display, such as, for example, a smartphone display, independently to provide a specific image to each eye of a user. For example, different images can be independently provided to each eye from different portions of a common display, thereby enabling the user to perceive a three-dimensional image.