Examination of thin tissue layers in the human eye

A computer-aided interactive method based on A-scan analysis using broadband RF-signals (15 MHz centre frequency) is presented. This method is used for the characterization of tissue layers of the posterior wall of the human eye in vivo. The following topics are discussed: - Automatic signal pre-processing and formation of a patient-specific, representative echogram. - Comparative studies using various methods from the time and frequency domain for the determination of layer thickness. - Analysis of the boundary surfaces by their spectral distribution, taking into account the roughness of the surface in relation to the ultrasonic wavelength. The characterization and differentiation of tissue layers by means of sets of features are explained with examples from intact posterior wall, detached retinas, vitreous membranes and from intraocular tumours. The differentiation of detached retina and other membranes by comparison with adjacent layers is discussed.