ANTERIOR-CHAMBER ANGLE BIOMETRY - A COMPARISON OF SCHEIMPFLUG PHOTOGRAPHY AND ULTRASOUND BIOMICROSCOPY

Scheimpflug photography and ultrasound biomicroscopy allow measurement of anterior chamber angle width. To analyze the value of both diagnos tic tools, measurements of the same subjects were correlated. Anterior chamber angle width in both eyes of 20 volunteers without any ophthal mological case history was measured in eight meridians. Scheimpflug ph otographs were recorded on Kodak T-max 400 black-and-white film using a Topcon SL-45 camera, Measurement of chamber angle was done with the aid of a self-programmed PC software, Ultrasound biomicroscopic measur ements were obtained using a Humphrey UBM 840 system with a 50-MHz tra nsducer The chamber angle was measured as described by Pavlin et al, T he data of both methods were correlated and analysed for statistically significant differences using a paired t test (level of significance p less than or equal to 0.05). Both methods showed similar changes in chamber angle width and were able to document a variation in angle wid th with regard to location, The correlation averaged at 0.64. In 4 mer idians significant differences were found between the two methods, Sch eimpflug photography, however, is unable to visualize directly the ang le itself. Both methods are limited by the fact that the angle is defi ned by curvilinear structures, i.e. posterior corneal surface and ante rior iris surface. Scheimpflug photography is able to document changes in angle configuration, Ultrasound biomicroscopy, however, is a more precise method, because it allows direct documentation of all structur es involved in chamber angle configuration.