Iris edge detection in optical coherence tomography

An Optical Coherence Tomography (OCT) imaging apparatus, comprising:

• a communication interface configured to obtain OCT data obtained from a scan of the eye, the OCT data comprising a plurality of A-lines, some of which pass through the iris and the lens of the eye and some of which pass through the lens but not the iris;
• and
• a processing circuit operatively coupled to the communication interface and configured to:
• detect a first interface extending across adjacent A-lines, wherein at least a portion of the detected first interface is assumed to correspond to either the anterior surface or posterior surface of the iris;
• determine, for each of the adjacent A-lines, a first metric derived from one or more A-line pixels near the detected first interface, such that the first metric reflects an OCT signal intensity associated with the first interface;
• determine, for each of the adjacent A-lines, a second metric derived from one or more A-line pixels further from the detected first interface than the one or more A-line pixels used to derive the first metric, such that the second metric reflects OCT signal attenuation at a point or points posterior to the detected first interface;
• calculate an attenuation parameter for each of the adjacent A-lines, based on the first and second metrics;
• and
• determine, for each of the adjacent A-lines, whether the A-line passes through the iris, by comparing the attenuation parameter to a threshold value.