This study will be a prospective blind randomised control trial. The participants will be randomised into one study group, with participants playing a game in 3D; and a control group, with participants playing the same game in 2D. The study is blind due to the use of an independent assessor, reducing testing bias by ensuring that the tester does not know the randomisation results. The known dependant variables are the total horizontal fusional amplitudes at 1/3m and 6m and the independent variable is the use of 2D or 3D game play.