Dysconjugate Gaze

Dysconjugate gaze results in diplopia (double vision). When the eyes are yoked appropriately, light rays from an object fall within the fovea. The fovea is the area of highest visual acuity; it has the greatest concentration of cones. Photoreceptors divide into cones, which detect color reception and provide visual resolution, and rods, which detect light-dark differentiation and detect motion. When an eye is abnormally deviated, light rays from the object deviate from their course to the fovea by the same degree as the deviation of the eye. Because the light ray falls away from the fovea and onto a less sensitive part of the retina, this abnormal eye detects a paler image than the normal eye. This paler, less distinct image is called the false image. A. Separation of images. The degree of separation of the images will increase with the degree of deviation of the eyes. Thus, the direction that produces the greatest degree of separation of the images clues you into the cause of the dysconjugate gaze. For instance, if the separation of the images is greatest with gaze to the right and the right eye detects the false image, the abnormal movement comes from the right lateral rectus muscle (the lateral rectus is responsible for right lateral gaze). The abnormality may lie within the lateral rectus muscle, itself, or the innervation to the muscle or any other factor preventing the eye from moving, but the cause of the dysconjugate gaze is failure of the right lateral rectus muscle to appropriately rotate. As a rule of diplopia, the false image projects in the opposite direction as the deviation of the eye. In our example, the right eye has not rotated to the right, so it is deviated to the left. The false image will lie to the right of the true image because the false image projects in the opposite direction of the deviation of the eye. The red image test is used to help differentiate true and false images.