Dynamic light scattering in the vitreous: performance of the single-mode fiber technique

We constructed an apparatus for dynamic light scattering (DLS) measurements in the posterior chamber for the eye. The setup uses single-mode technology and, with regard to future clinical use, it is combined with a commercial ophthalmologic microscope. The scattering volume is illuminated with a Gaussian beam realized by coupling a HeNe laser into a single-mode fiber. The scattered light is measured using a single-mode fiber receiver. The signal is processed with a digital autocorrelator. Our measurements on the vitreous of post mortem porcine eyes show that DLS measurements in the posterior chamber are feasible and that it is possible to keep the excitation intensity below the damage threshold of the retina. In addition, absolute measurements of light scattering in toluene confirmed the validity of DLS theory for single-mode receivers.