Angular change in backscattering of light from the human lens with nuclear cataract

Purpose To determine how many meridians are needed to optimise detection of lens nuclear opacities in Scheimpflug photography utilising the Nidek EAS-1000 system. Methods Ten eyes with nuclear cataract from 10 patients (age 53-83 years) were selected in this study. For each eye, the lens was imaged with the Nidek EAS-1000 system at the 0 degrees 30 degrees, 60 degrees, 90 degrees, 120 degrees and 150 degrees meridians, respectively The intensity of the backscattering of light within a common lens nuclear area on the lens image was measured. In addition an aqueous suspension of polystyrene spheres was employed as a standard to evaluate the possible angular change caused by the camera system. Analysis of variance and the polynomial regression was used for data analysis. Results The intensity of the backscattered light differs significantly among meridians. The highest intensity is found at the 90 degrees meridian. The intensity decreases towards the nasal and temporal side. There is also an angular variation caused by the camera system. Conclusions There is a regular change in the backscattered light documented by the Nidek EAS-1000 system. It is sufficient to Cake one meridian to estimate the lens nuclear cataract. The variation in the backscattered light at different angles is caused partly by the variation of the camera.