In vivo thickness of the human detached retina by ultrasonic signal processing

Fourier operations on digitized radio-frequency (rf) data can provide the most sensitive measure of the thickness of thin, deterministic structures such as membranes. After deconvolution against the system transfer function, the cepstrum and the analytic signal magnitude can provide measures of membrane thickness on the order of a half-wavelength. A total of 19 patients with rhegmatogenous retinal detachments were scanned using a diagnostic ultrasound system adapted for analog to digital conversion of rf data. Data were analyzed using the signal processing techniques described above to measure retinal thickness. Recent retinal detachments tended to be significantly thicker than normal attached retinas, and thickness decreased with the age of detachment. A statistically significant correlation was found to exist between retinal thickness and the duration of detachment.