Improved illumination in indirect ophthalmoscopy.

THE indirect method of ophthalmoscopy offers several advantages over the direct method; these include larger field of view, better penetration of hazy media, greater depth of focus, and closer approach to the ora serrata (Schepens and Bahn, 1950). These features are of especial importance in cases of detachment of the retina, where the necessity of studying the topography and locating all the tears was pointed out by Gonin (1934), and has since been stressed by several authors, including Weve (1934), Arruga (1946a), Schepens (1951), and McDonald (1951). Unfortunately, many ophthalmologists consider the indirect method difficult and unsatisfactory, objecting that the illumination is feeble and/or that the field is not much larger than obtained by the, direct method. The problem may be studied qualitatively by means of simple ray diagrams.