Imaging of the spatial density distribution on the capsule of the lens with Scheimpflug photography

The density characteristics of the anterior and posterior surfaces of the lens, although of primary importance for its optical quality, are difficult to determine. Scheimpflug photography, however, allows distinct density measurements from the optical axis towards the periphery with the only limitation of a sufficient mydriasis, so that a 3-dimensional scatter profile of both capsular surfaces can be calculated via multilinear densitometric evaluation of a sufficient number of meridians. On this methodical basis, we analysed Scheimpflug images recorded with the Topcon SL-45 on Kodak T-Max 400 film from 25 patients in an age range between 19 and 63 years. Images from the 0 degrees + 45 degrees meridians were scanned with multilinear microdensitometry and the data computed to get a density profile. In general, most scattering profiles show a marked interindividual variability. Nevertheless, a general trend can be established between the periphery and the center of the anterior and posterior capsules: (a) the anterior capsule generally has a higher density than the posterior; (b) in most cases, the center of the posterior capsule has a higher density than the periphery; (c) the anterior capsule has a more uniform spatial density distribution in all cases. From the cases evaluated, it can be concluded that the density of the peripheral posterior capsule is more importantly influenced by shading effects of the iris, so that geometrical correction is needed.