The Screen Test and Its Applications

Abstract

Any test used for the diagnosis of muscle imbalances must be accurate, precise, and quickly applicable in a large percentage of cases. It should make possible the measurement of phorias as well as trophias and should not be dependent on binocular vision. It should be applicable to very young children. The more objective the test can be made the better. The screen test with its modifications, screen-Maddox rod, and screen-comitance, are described in detail after the physiology and mechanics of the ocular movements have been briefly discussed, and cases are cited to emphasize the benefits of these tests. Cases of combined vertical and lateral deviations are described and the importance of measuring the combined deviations stressed. The tendency in some cases of lateral strabismus to a change from convergent to divergent squint, or vice versa when a vertical deviation is present, is discussed. Cases are cited in which this developed following operation for the lateral deviation, the vertical deviation having remained uncorrected. The same change in deviation has been observed when operation has not been resorted to. The screen test is the only test in the writer's experience that is applicable in all cases in which vision is sufficient for central fixation. Read before the Washington, D.C., Ophthalmological Society, January 6, 1936. Any test used for the diagnosis of muscle imbalances must be accurate, precise, and quickly applicable in a large percentage of cases. It should make possible the measurement of phorias as well as trophias and should not be dependent on binocular vision. It should be applicable to very young children. The more objective the test can be made the better. The screen test with its modifications, screen-Maddox rod, and screen-comitance, are described in detail after the physiology and mechanics of the ocular movements have been briefly discussed, and cases are cited to emphasize the benefits of these tests. Cases of combined vertical and lateral deviations are described and the importance of measuring the combined deviations stressed. The tendency in some cases of lateral strabismus to a change from convergent to divergent squint, or vice versa when a vertical deviation is present, is discussed. Cases are cited in which this developed following operation for the lateral deviation, the vertical deviation having remained uncorrected. The same change in deviation has been observed when operation has not been resorted to. The screen test is the only test in the writer's experience that is applicable in all cases in which vision is sufficient for central fixation. Read before the Washington, D.C., Ophthalmological Society, January 6, 1936.