Ganglion Cell Layer Analysis by Optical Coherence Tomography (OCT)

A normal optical coherence tomography (OCT) of the macula is shown (Figure 1) and the various layers of the retina are labelled (Figure 2). The cell bodies of retinal ganglion cells (RGC) are located in the ganglion cell layer (GCL) of the retina and mostly synapse in the lateral geniculate nucleus (Figure 3). Injury to the RGC anywhere along this path may result in cell death and be seen in the retina with OCT. On the Cirrus OCT, the ganglion cell layer and inner plexiform layer are measured together and are referred to as the ganglion cell layer complex (GCC). A normal OCT of the retinal nerve fiber layer (RNFL) and GCC is shown in Figure 5 and a description of each aspect of the result printout is shown in Figure 6. A case of a 54-year-old woman with a right incongruous homonymous hemianopia due to an ischemic stroke affecting the left optic tract is shown as a case study (Figures 7 and 8). Three case examples of segmentation errors are shown in patients with central serous chorioretinopathy (Figure 9), epiretinal membrane (Figure 10), and disc edema from non-arteritic anterior ischemic optic neuropathy (NAION; Figure 11). A comparison of OCT of the RNFL and GCC is shown in a case of retrograde trans-synaptic degeneration from an occipital lobe stroke. OCT of the GCC provides valuable information when evaluating patients with optic neuropathies, chiasmal or retrochiasmal visual field defects, but must be interpreted with caution since it is prone to segmentation errors.