Quantitative ophthalmic OCT image analysis provides essential thickness measurement data of the retina. In the clinical practice two thickness parameters are commonly used: total retinal thickness (TR) in macular region and retinal nerve fiber layer thickness (RNFL) in optic nerve head (ONH) region. TR is widely applied to assess various retinal pathologies involving macula (e.g., cystoid macular edema, age-related macular degeneration, macular hole, etc.). The RNFL thickness measurement is most commonly used for glaucoma assessment.

Figure III.2-1 is an example of 2D TR map computed on a 3D OCT cube data from a healthy eye. The color bar on the left provides a color-to-thickness representation to allow interpretation of the false color coded 2D thickness map in the middle. The image on the right shows one OCT frame representing a retinal cross section along the red line (across the middle of the thickness map). TR is defined as the thickness between internal limiting membrane (white line on the OCT frame on the right) and RPE/Choroid interface (blue line on the OCT frame). These two borders are automatically detected using a segmentation algorithm applied to the entire 3D volume.