 To be more specific, in the RFT, examinees are required to sit in a completely dark room without reflecting surfaces where a 3.5 foot luminous square frame with one inch wide sides contains a rod much like one of the sides.The test is properly given after brief (120-second) dark adaptation and the large glowing RFT is seven feet from the subject so it is a dramatic visual display filling much of the visual field.If the test is given with insufficient dark adaptation, many subjects will see the luminous stimulus disappear or fragment when they fixate it visually and a large proportion of them will not happen to report that.