A method is provided for determining the thickness of a retina. A single beam is used to illuminate the retina of a patient. Interference between reflections off different layers within the retina cause autocorrelation in the returned signal. An FFT applied to the autocorrelation signal reveals the strongest autocorrelation, which indicates the distance between the nerve fiber layer (NFL) and the layers between the inner segment/outer segment (IS/OS) and the retinal pigment epithelium (RPE), the dominant scatterers. By analyzing autocorrelation, a single beam can be used. This avoids the problem of movement of the patient, arising in the use of a standard OCT interferometer, resulting in a simpler and less expensive technique of measuring retinal thickness.
