The cross-cover test, or alternating cover test is usually employed to detect<unk> . One eye is covered, and then the cover is moved immediately over to the other eye. With<unk> , when the cover is moved to the other eye, the eye that has just been uncovered can be seen to move from a deviated point. The difference between heterotropia and<unk>  can be easily understood as follows. With heterotropia, a correcting movement of the eye can be detected already by the simple cover test; with<unk> , such correcting movement only takes place in the cross-cover test. People with<unk>  are able to create and maintain binocular fusion through vergence, and the cross-cover test purposely breaks this fusion, making the latent misalignment visible. Whereas the cross-cover test allows a qualitative assessment to be done, a quantitative assessment of latent eye position disorders can be done using the Lancaster red-green test. Ernest Maddox studied different types of phoria extensively throughout his career. He developed the Maddox rod test and double Maddox rod test which are especially sensitive to deviations of the eye. The tests must be performed in low light conditions, with a dim point light source in an environment absent of specular surfaces. The test came under heavy criticism during WW1 for its lack of accuracy however it was discovered that operators had simply allowed too much light in the test room and had used a light source that was too bright. Even low levels of light stimulate fusion which is why it is imperative to perform the test with the minimum amount of light in order for the patient to observe a misalignment.
Heterophoria
Orthophoria
Esophoria
Exophoria
Polycoria
Musical anhedonia
Sexual anhedonia
Astigmatism 