We describe a simple method to assign a diagnosis of cataract to patients w
ith obscurely impaired vision as well as to those with mild lens opacities.
When the narrowest slit is used in a slitlamp examination, a small beam of
light appears on the macula. Routine fundoscopy with the 78.0 diopter lens
or a 3-mirror glass is appropriate. If a cataract is present, the beam of
light is scattered into several straight lines, distorted lines, or both. T
his has proved a useful diagnostic tool when the lens appears clear but the
patient's vision is impaired, and extensive examinations such as computer
tomography or nuclear magnetic resonance tomography for impaired vision may
be avoided. The beam-deflection method uses devices that are generally ava
ilable and can detect cataract in the early stages of development. (C) 2001
ASCRS and ESCRS.