Simplified Indirect Ophthalmoscope.

INDIRECT ophthalmoscopy is one of the most important methods of fundus examination, especially in cases of detachment of the retina. The advantages of this method over direct ophthalmoscopy include a larger field of view, a more brilliant image, and a greater depth of focus. It is especially valuable for the examination of the highly myopic eye. The stereoscopic view obtained with the binocular indirect ophthalmoscope separates the fundus picture into its component layers, which is very helpful in the differential diagnosis of retinal from choroidal lesions (Fison, 1959). Indirect ophthalmoscopy was introduced by Ruete (1852), who used a silvered mirror and a strong convex lens. The source of illumination was later improved (Arruga, 1946; Epstein, 1950; Anderson, 1952), and the mirror was superseded by binocular devices to provide a stereoscopic view of the fundus (Schepens, 1952; Donaldson, 1958; Fison, 1963). A further modification is here proposed, in which the condensing lens is fixed to the patient's head instead of being held in the observer's hand.