Hi to everybody and welcome to OptoTubeChannel, the first Italian YouTubeChannel dedicated to Optometry Today let’s talk about Brock String test, extremely enviromental test to evaluate phoria qualitatively and not quantitative. This method uses physiological diplopia to evaluate phoria, breaking binocular vision Target during the test is the brock string, a very long white rope which passes through some colored balls usually they are five or seven. One end of the rope is taken by the patient under the nouse and the other end is taken by the practicioner. Balls are displaced at the distance which is evaluated phoria. If we would evaluate near phoria at habitual reading distance and this distance is about 0.38 meters I will place one ball at 0.38 meters and two flanker balls, so one more distant and the other less distant. First step to evaluate phoria is to ask to the patient to fixate the central ball and say what he/she is seeing For physiological diplopia effect, he/she should have a double perception of the ball and the rope except of the central ball because it is in the Panum area and isn’t seen double. So these two perception will be cossed formed an ” X ” . Second step is to get informations about what kind of perception the patient has, if this ” X ” won’t appear; there would be a ” Y ” for example and it means a suppression presence and this suppression could be from near or from far compared to the fixation point, and could be of the right or left eye dependently from the rope segment which disappears. Third step is to know where is the ropes crossing. It could be exactly on the fixated ball and in that case we have an orto-phoria could be closer and in that case there is an eso-phoria, or it could be farther and it will be an exo-phoria Usually brock string test ends here but we could get more informations enlarging this test for example asking if rope components are the same or some is dissolving cause visual supension, or if they appear at the same height from the flor and in this case we’ll have informations about spatial projection So brock string test could be performed at any distance, both from near and from far, and this last aspect often happends in sport vision, during athletes preparation from a vision point of view in the sport vision which is part of vision therapy. This test can be performed in any direction, not only in main fixation direction, but also in oblique direction, for example toward down, in convergence and other… in many way, this test is very flexible as test and gives many information only from a qualitative point of view, not quantitative. So this is all for brock string test, if you liked subscribe channel and leave a like! Let’s see on the next opto-video! OPTO-VIDEO!!!