Bilateral sixth-nerve paresis simulating divergence paralysis.

The first case of divergence paralysis was reported by Parinaud in 1883. However, the most complete description of this condi­ tion was made by Duane in 1905. There are about 60 recorded cases in the literature, but it is possible that many others are over­ looked, misdiagnosed, or pass unrecognized, because little reference to this subject is made in textbooks of ophthalmology or neu­ rology. The symptoms of divergence paralysis are: 1. Homonymous diplopia, sudden in onset, for distance, beyond 10 to 20 inches. 2. The angle of squint remains the same or decreases slightly on right or left gaze. It increases on downward gaze and decreases on upward gaze, thus the patient tends to de­ press the chin toward the chest (to minimize the diplopia). 3. Single binocular vision occurs within 10 to 20 inches from the patient (single vi­ sion by approximation), and is maintained on right and left gaze. a. Single vision maintained when prism base-in of several degrees is placed before the eyes, or b. Single vision maintained when the object is slowly carried off again some considerable distance (single vision by re­ cession). 4. Crossed diplopia, due to insufficient con­ vergence, occurs when the image is brought nearer than 10 inches. 5. Normal field of fixation (abduction). 6. Normal accommodation. 7. Normal or diminished amplitude of convergence. 8. Diminished or abolished amplitude of divergence. 9. Constant angle of squint on repeated examination. ;AL CORRECTION