Detachment of the retina is a condition of such seriousness, and its treatment is so unsatisfactory, that we feel justified in placing on record even a small number of cases. There are three principal theories as to the causation of retinal detachment: Von Graefe in 1854 assumed that a hemorrhage occurred behind the retina, basing his conclusion on the sudden appearance of the condition. Arlt considered that the fluid behind the retina was due to a secretion or exudation from the choroid pressing against the vitreous humor and thus bringing about its gradual absorption. The present theory, which has a large following, assumes a primary retroretinal exudation with compensatory diminution of volume in the vitreous. Leber's theory, which embodies Müller's theory of fibrinous degeneration of the vitreous, and Iwanof's theory of detachment of the vitreous and shrinking, and Arlt's theory of rupture, or tear. Leber argued that given