Imaging of forward light-scatter by opacified posterior capsules isolated from pseudophakic donor eyes

Posterior capsule opacification (PCO) degrades visual function by reducing visual acuity, but also by increasing intraocular light-scatter. An in vitro model was used to elucidate the effect of PCO-morphology on light-scatter and its functional aspect, as can be assessed with straylight measurement.

Forward PCO-scatter by opacified capsular bags was recorded with a goniometer and camera. The camera position mimicked the anatomic position of retinal photoreceptors; the camera recorded the scattered light that the photoreceptors would sense in an in vivo situation. Scattered light was recorded at different wavelengths and scatter angles, which were divided into a near (1° < θ ≤ 7°) and far (θ > 7°) large-angle domain. Using scattered light, the camera produced grayscale PCO images. The nature of the angular dependence of PCO-scatter was compared with that of scatter in the normal eye, by rescaling PCO images relative to the normal eye's point-spread function.

The scattered light images closely followed PCO severity. The angular dependence of PCO-scatter resembled that of scatter in the normal eye, irrespective of severity and PCO type. PCO shows the type of wavelength dependence that is normal for small particles: monotonically decreasing with increasing wavelength. At the near large-angle domain, the angular dependence of PCO scatter resembled the angular dependence of scatter in the normal eye less closely.

Surprisingly, PCO scatter and scatter in the normal eye have similar underlying scattering processes. However, data obtained at the near large-angle domain demonstrates that, apart from scatter, PCO may also have a refractile component, which is most pronounced in pearl-type PCO.