The<unk>  (also known as the 4 PRT, or 4 Prism<unk>  Base-out<unk> , is an objective, non-dissociative<unk>  used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion. Through the use of a 4<unk>  base out prism, diplopia is induced which is the driving force for the eyes to change fixation and therefore re-gain bifoveal fixation meaning, they overcome that amount of power.
Four prism dioptre reflex test
Vernier acuity
Dix–Hallpike test
Tinetti test
String galvanometer
Prism cover test
Worth 4 dot test
Tensilon test